Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Responsible innovation by social entrepreneurs: an exploratory study of values integration in innovations
    Lubberink, Rob ; Blok, Vincent ; Ophem, Johan van; Omta, Onno - \ 2019
    Journal of Responsible Innovation 6 (2019)2. - ISSN 2329-9460 - p. 179 - 210.
    civil society - scaling - Social entrepreneurship - social innovation - strategies - value co-creation

    The upcoming concept of responsible innovation seems to gain foothold in Europe and beyond, but it still remains unknown how it can be implemented in the business context. This article explores how social entrepreneurs integrate values into their de facto responsible innovations, and provides empirically informed strategies to develop, implement and scale these innovations. It is based on an empirical investigation of 42 case studies of best-practice social entrepreneurs. This empirical study shows that social entrepreneurs focus on creating direct socio-ethical value for their target beneficiaries. They coordinate collective stakeholder action to develop, implement and scale their systems-changing solutions. And their bottom-up innovations are evaluated and scaled for impact. Ultimately, institutional support is sought to create top-down systems change. This article suggests a synthesised model of integrated strategies for responsible innovation that also covers implementation and scaling of innovation.

    Exploiting the Spur of the Moment to Enhance Healthy Consumption: Verbal Prompting to Increase Fruit Choices in a Self-Service Restaurant
    Kleef, E. van; Broek, O. van den; Trijp, J.C.M. van - \ 2015
    Applied Psychology : Health and Well-Being 7 (2015)2. - ISSN 1758-0846 - p. 149 - 166.
    safety-belt use - field-experiment - vegetable intake - strategies - consumers - children - behavior - sales - risk
    Background: People often have good intentions to eat healthily, but these inten- tions may get overruled by temporary moments of temptation. The current study examined the effectiveness of “verbal prompting” as a nudge to increase fruit salad sales in a natural setting. Methods: A ¿eld experiment was conducted in a self- service restaurant during breakfast time. After an initial baseline period, the inter- vention involved four different prompts suggesting ordering a side dish (i.e. orange juice, fruit salad, pancakes) given by cashiers to visitors. The intervention phase lasted 13 weeks. Cash register and observational data were obtained. In addition, a sample of visitors (N = 393) responded to a survey. Results: A signi¿cant increase in sales of orange juice was observed during the orange juice verbal prompts intervention periods (35–42% of all breakfasts sold) compared to baseline (20% of all breakfasts sold). Similarly, sales of fruit salad (9%) and pancakes (3%) rose to a small but signi¿cant extent compared to baseline sales (3% and 1%, respectively). Survey results showed that customers did not feel pressurised into purchasing a side dish. Conclusion: Together, ¿ndings suggest that verbal prompts involving healthy side dishes are a potential useful nudge to implement in other food service settings. Keywords: choice architecture, fruit consumption, nudge, nudging, suggestive selling, verbal prompting
    Experimental evidence for inherent Lévy search behaviour in foraging animals
    Kölzsch, A. ; Alzate, A. ; Bartumeus, F. ; Jager, M. de; Weerman, E.J. ; Hengeveld, G.M. ; Naguib, M. ; Nolet, B.A. ; Koppel, J. van de - \ 2015
    Proceedings of the Royal Society. B: Biological Sciences 282 (2015)1807. - ISSN 0962-8452 - 9 p.
    correlated-random-walks - environmental complexity - wandering albatrosses - movement patterns - marine predator - flight - strategies - success - evolve - scale
    Recently, Lévy walks have been put forward as a new paradigm for animal search and many cases have been made for its presence in nature. However, it remains debated whether Lévy walks are an inherent behavioural strategy or emerge from the animal reacting to its habitat. Here, we demonstrate signatures of Lévy behaviour in the search movement of mud snails (Hydrobia ulvae) based on a novel, direct assessment of movement properties in an experimental set-up using different food distributions. Our experimental data uncovered clusters of small movement steps alternating with long moves independent of food encounter and landscape complexity. Moreover, size distributions of these clusters followed truncated power laws. These two findings are characteristic signatures of mechanisms underlying inherent Lévy-like movement. Thus, our study provides clear experimental evidence that such multi-scale movement is an inherent behaviour rather than resulting from the animal interacting with its environment.
    Intensive groundwater use and (in)equity: Processes and governance challenges
    Hoogesteger van Dijk, J.D. ; Wester, P. - \ 2015
    Environmental Science & Policy 51 (2015). - ISSN 1462-9011 - p. 117 - 124.
    water - policies - india - sustainability - organizations - irrigation - strategies - management - highlands - depletion
    Groundwater forms the basis for millions of rural and urban livelihoods around the world. Building on insights from the theory of access, in this article we present how groundwater development has brought much well-fare in many parts of the world; and how resulting intensive groundwater use is leading to ill-fare through aquifer overexploitation and processes of water accumulation and dispossession. We show the difficulty of state regulation and the modest achievements of other governance approaches that aim to solve existing groundwater problems. To study these processes we propose a framework of analysis that is based on the study of hydrosocial-networks, the political economy of groundwater and the domains and discourses that define groundwater access. Such analysis highlights the challenges of devising policies and modes of governance that contribute to social and environmental sustainability in intensively used aquifers. These we argue should build on an analysis of equity that scrutinizes the discourses, actors, powers and procedures that define groundwater access. By inciting debates on equity a first and fundamental step can be made toward advancing more inclusive groundwater governance that crucially engages the marginalized and addresses their groundwater problems, concerns and needs.
    Economic trade-offs of biomass use in crop-livestock systems: Exploring more sustainable options in semi-arid Zimbabwe
    Homann Kee, S. ; Valbuena Vargas, D.F. ; Masikati, P. ; Descheemaeker, K.K.E. ; Nyamangara, J. ; Claessens, L.F.G. ; Erenstein, O. ; Rooyen, A.F. van; Nkomboni, D. - \ 2015
    Agricultural Systems 134 (2015). - ISSN 0308-521X - p. 48 - 60.
    conservation agriculture - smallholder farmers - intensification - productivity - challenges - strategies - countries - benefits - tropics - africa
    In complex mixed crop-livestock systems with limited resources and biomass scarcity, crop residues play an important but increasingly contested role. This paper focuses on farming systems in the semi-arid areas of Zimbabwe, where biomass production is limited and farmers integrate crop and livestock activities. Conservation Agriculture (CA) is promoted to intensify crop production, emphasizing the retention of surface mulch with crop residues (CR). This paper quantifies the associated potential economic tradeoffs and profitability of using residues for soil amendment or as livestock feed, and explores alternative biomass production options. We draw on household surveys, stakeholder feedback, crop, livestock and economic modeling tools. We use the Trade-Off Analysis Model for Multi Dimensional Impact Assessment (TOA-MD) to compare different CR use scenarios at community level and for different farm types: particularly the current base system (cattle grazing of maize residues) and sustainable intensification alternatives based on a CA option (mulching using maize residues ± inorganic fertilizer) and a maize– mucuna (Mucuna pruriens) rotation. Our results indicate that a maize–mucuna rotation can reduce trade-offs between CR uses for feed and mulch, providing locally available organic soil enhancement, supplementary feed and a potential source of income. Conservation Agriculture without fertilizer application and at non-subsidized fertilizer prices is not financially viable; whereas with subsidized fertilizer it can benefit half the farm population. The poverty effects of all considered alternative biomass options are however limited; they do not raise income sufficiently to lift farmers out of poverty. Further research is needed to establish the competitiveness of alternative biomass enhancing technologies and the socio-economic processes that can facilitate sustainable intensification of mixed crop-livestock systems, particularly in semi-arid environments.
    Navigating the obesogenic environment: How psychological sensitivity to the food environment and self-regulatory competence are associated with adolescent unhealthy snacking
    Stok, F.M. ; Vet, E. de; Wardle, J. ; Chu, M.T. ; Wit, J.B.F. ; Ridder, D.T.D. de - \ 2015
    Eating Behaviors 17 (2015). - ISSN 1471-0153 - p. 19 - 22.
    health consequences - obesity - gratification - strategies - overweight - worldwide - autonomy - children - adults - scale
    Purpose: Living in an obesogenic environment may not affect all adolescents to the same extent, depending on their psychological sensitivity to the food environment and their self-regulatory competence. The purpose of the current study was to examine associations of these two factors with unhealthy snacking among adolescents. We also investigated whether self-regulatory competence could attenuate the negative effects of being sensitive to the food environment. Methods: A survey was completed by 11,392 European adolescents (10–17 years old). The survey measured psychological sensitivity to the food environment, self-regulatory competence and self-reported unhealthy snack intake. Results: Higher food environment sensitivity and lower self-regulatory competence were associated with more unhealthy snacking. The two factors also interacted, with self-regulatory competence attenuating the influence of high food environment sensitivity. Discussion: Adolescentswho are sensitive to the food environment reported higher unhealthy snack intake.More frequent use of self-regulation strategies on the other hand was associated with lower unhealthy snack intake. Moreover, self-regulatory competence was found to moderate the influence of psychological sensitivity to the food environment on unhealthy snacking, although the effect size was small. Fostering adolescents' self-regulatory competence can help enable them to better navigate the obesogenic environment.
    Fitness consequences of indirect plant defence in the annual weed, Sinapis arvensis
    Gols, R. ; Wagenaar, R. ; Poelman, E.H. ; Kruidhof, H.M. ; Loon, J.J.A. van; Harvey, J.A. - \ 2015
    Functional Ecology 29 (2015)8. - ISSN 0269-8463 - p. 1019 - 1025.
    pieris-brassicae - herbivory - tolerance - evolution - volatiles - insects - parasitoids - strategies - selection - ecology
    Plant traits that enhance the attraction of the natural enemies of their herbivores have been postulated to function as an 'indirect defence'. An important underlying assumption is that this enhanced attraction results in increased plant fitness due to reduced herbivory. This assumption has been rarely tested. We investigated whether there are fitness consequences for the charlock mustard Sinapis arvensis, a short-lived outcrossing annual weedy plant, when exposed to groups of large cabbage white (Pieris brassicae) caterpillars parasitized by either one of two wasp species, Hyposoter ebeninus and Cotesia glomerata, that allow the host to grow during parasitism. Hyposoter ebeninus is solitary and greatly reduces host growth compared with healthy caterpillars, whereas C. glomerata is gregarious and allows the host to grow approximately as large as unparasitized caterpillars. Both healthy and parasitized P. brassicae caterpillars initially feed on the foliage, but later stages preferentially consume the flowers. In a garden experiment, plants damaged by parasitized caterpillars produced more seeds than conspecific plants damaged by unparasitized caterpillars. Reproductive potential (germination success multiplied by total seed number) was similar for plants that were not exposed to herbivory and those that were damaged by parasitized caterpillars and lower for plants that were damaged by healthy unparasitized caterpillars. However, these quantitative seed traits negatively correlated with the qualitative seed traits, individual seed size and germination success, suggesting a trade-off between these two types of traits. We show that parasitism of insect herbivores that feed on reproductive plant tissues may have positive fitness consequences for S. arvensis. The extent to which plant fitness may benefit depends on parasitoid lifestyle (solitary or gregarious), which is correlated with the amount of damage inflicted on these tissues by the parasitized host
    Climate change impact and adaptation research requires integrated assessment and farming systems analysis: a case study in the Netherlands
    Reidsma, P. ; Wolf, J. ; Kanellopoulos, A. ; Schaap, B.F. ; Mandryk, M. ; Verhagen, J. ; Ittersum, M.K. van - \ 2015
    Environmental Research Letters 10 (2015)4. - ISSN 1748-9326
    european-union - crop yields - agriculture - responses - models - wheat - variability - improvement - strategies - scenarios
    Rather than on crop modelling only, climate change impact assessments in agriculture need to be based on integrated assessment and farming systems analysis, and account for adaptation at different levels. With a case study for Flevoland, the Netherlands, we illustrate that (1) crop models cannot account for all relevant climate change impacts and adaptation options, and (2) changes in technology, policy and prices have had and are likely to have larger impacts on farms than climate change. While crop modelling indicates positive impacts of climate change on yields of major crops in 2050, a semiquantitative and participatory method assessing impacts of extreme events shows that there are nevertheless several climate risks. A range of adaptation measures are, however, available to reduce possible negative effects at crop level. In addition, at farm level farmers can change cropping patterns, and adjust inputs and outputs. Also farm structural change will influence impacts and adaptation. While the 5th IPCC report is more negative regarding impacts of climate change on agriculture compared to the previous report, also for temperate regions, our results show that when putting climate change in context of other drivers, and when explicitly accounting for adaptation at crop and farm level, impacts may be less negative in some regions and opportunities are revealed. These results refer to a temperate region, but an integrated assessment may also change perspectives on climate change for other parts of the world.
    Does temperament affect learning in calves?
    Webb, L.E. ; Reenen, C.G. van; Jensen, M.B. ; Schmitt, O. ; Bokkers, E.A.M. - \ 2015
    Applied Animal Behaviour Science 165 (2015). - ISSN 0168-1591 - p. 33 - 39.
    individual coping characteristics - different rooting materials - double demand curves - inbred rat strains - cross-point - animal preferences - yearling horses - heifer calves - pigs - strategies
    The aim of the study was to investigate how temperament affects learning ability in calves.Nine two-month-old Holstein-Friesian bull calves were subjected to four challenge tests:novel object (NOT), novel environment (NET), social isolation (SIT), and social isolationwith a novel environmental cue (SI/E). During these tests, hypothesised temperament vari-ables were recorded. Hypothesised learning variables were recorded during training on anoperant task.Principal component analysis (PCA) was conducted on temperament variables and learn-ing variables separately. Principal components (PCs) hypothesised to reflect underlyingtemperament and learning traits were extracted from these two PCAs using the Kaiserrule. Spearman’s rank correlations were carried out to determine relationships betweentemperament and learning PC scores.Four temperament PCs were extracted from the PCA on temperament variables, andthese were proposed to reflect fearfulness, activity, exploration, and attention towards theenvironment. These hypothesised underlying temperamental traits were consistent withfindings of previous studies using larger numbers of calves. Two learning PCs were extractedfrom the PCA on learning variables, and these were proposed to reflect feed motivationand working speed. A single correlation was found between temperament and learning PCscores: high activity was associated with low feed motivation. This preliminary exploratorystudy suggests that temperament, as assessed during challenge tests, may affect learningan operant conditioning task in calves. Understanding how temperament affects learningin calves can help with the training of calves on novel automated feeding apparatuses oron novel feed components, and can thus help improve calf health and welfare.
    Organizing Products with Complements versus Substitutes: Effects on Store Preferences as a Function of Effort and Assortment Perceptions
    Diehl, K. ; Herpen, E. van; Lamberton, C. - \ 2015
    Journal of Retailing 91 (2015)1. - ISSN 0022-4359 - p. 1 - 18.
    consumer choice - price sensitivity - purchase - variety - behavior - too - organization - recognition - elasticity - strategies
    Retailers often organize at least part of their assortment by displaying complementary products from different product categories together (e.g., a pair of pants with a shirt) rather than grouping items by product type (e.g., a pair of pants with other pants). However, little is known about how retailers should choose between complement-based and substitute-based organizations. The present paper shows that consumers’ preferences for such store organizations are a function of the effort and assortment perceptions cued by these organizational formats. Holding the underlying assortment constant, complement-based organizations are always more effortful than substitute-based organizations. This difference in effort can create downward pressure on complement-based store choice. Moreover, the effects of organization format on assortment perception depend on whether consumers hold a hedonic or utilitarian focus. When consumers have a highly hedonic focus, complement-based based stores create more positive assortment perceptions than substitute-based stores. Such positive assortment perceptions can, in turn, raise complement-based store choice. However, as consumers’ utilitarian focus increases, substitute-based assortments are seen as both easier and more attractive, leading to a strong advantage in store choice. Our findings provide actionable guidance for retailers considering various store organizations and suggest opportunities for future research.
    Evolutionary engineering to enhance starter culture performance in food fermentations
    Bachmann, H. ; Pronk, J.T. ; Kleerebezem, M. ; Teusink, B. - \ 2015
    Current Opinion in Biotechnology 32 (2015). - ISSN 0958-1669 - p. 1 - 7.
    yeast saccharomyces-cerevisiae - adaptive evolution - lactococcus-lactis - hyperosmotic conditions - selection - growth - population - strategies - phenotypes - stability
    Microbial starter cultures are essential for consistent product quality and functional properties such as flavor, texture, pH or the alcohol content of various fermented foods. Strain improvement programs to achieve desired properties in starter cultures are diverse, but developments in next-generation sequencing lead to an increased interest in evolutionary engineering of desired phenotypes. We here discuss recent developments of strain selection protocols and how computational approaches can assist such experimental design. Furthermore the analysis of evolved phenotypes and possibilities with complex consortia are highlighted. Studies carried out with mainly yeast and lactic acid bacteria demonstrate the power of evolutionary engineering to deliver strains with novel phenotypes as well as insight into underlying mechanisms.
    Dark green electricity comes from the sea: Capitalizing on ecological merits of offshore wind power?
    Toonen, H.M. ; Lindeboom, H.J. - \ 2015
    Renewable and Sustainable Energy Reviews 42 (2015). - ISSN 1364-0321 - p. 1023 - 1033.
    sustainable fisheries - energy - policy - farms - governance - management - strategies - responses - impacts - germany
    European consumers are willing to pay more for “green” electricity, as they highly value renewable energy sources for the contribution to combating climate change. There is a push for getting higher levels of sustainability, leading to a differentiation of Europe‘s electricity market. In this differentiation, the large potential of wind energy is recognized. More specifically, North Sea countries prefer to plan wind arrays (far) out at sea. This article offers a review of the main arguments for offshore wind energy, described in comparison with its onshore counterpart. It is stated that offshore wind farms (OWFs) generate “dark green” electricity as they mitigate greenhouse gas emissions and contribute to the protection of (some) marine life. Applying an informational governance framework, this article further assesses whether this dark green message has been exploited through further differentiation of the electricity market, and provides an analysis of why this is not (yet) the case. It is concluded that the dominant discourse in onshore wind power development hinders a favorable ecological differentiation toward offshore wind power.
    The impact of domestic energy efficiency retrofit schemes on householder attitudes and behaviours
    Long, T.B. ; Young, W. ; Webber, P. ; Gouldson, A. ; Harwatt, H. - \ 2015
    Journal of Environmental Planning and Management 58 (2015)10. - ISSN 0964-0568 - p. 1853 - 1876.
    sustainable consumption - uk households - cold homes - conservation - policy - strategies - spillover - barriers - savings - agenda
    Retrofitting existing housing stock to improve energy efficiency is often required to meet climate mitigation, public health and fuel poverty targets. Increasing uptake and effectiveness of retrofit schemes requires understanding of their impacts on householder attitudes and behaviours. This paper reports results of a survey of 500 Kirklees householders in the UK, where the Kirklees Warm Zone scheme took place. This was a local government led city scale domestic retrofit programme that installed energy efficiency measures at no charge in over 50,000 houses. The results highlight key design features of the scheme, socio-economic and attitudinal factors that affected take-up of energy efficiency measures and impacts on behaviour and energy use after adoption. The results emphasise the role that positive feedback plays in reinforcing pro-environmental attitudes and behaviours of participants and in addressing concerns of non-participants. Our findings have implications for the design and operation of future domestic energy efficiency retrofit schemes.
    Rescaling spatial planning: spatial planning reforms in Denmark, England, and the Netherlands
    Roodbol-Mekkes, P.H. ; Brink, A. van den - \ 2015
    Environment and Planning C. Government and Policy 33 (2015)1. - ISSN 0263-774X - p. 184 - 198.
    local-government modernization - sustainable development - english regions - governance - space - rethinking - strategies - growth - europe - scale
    Following a wave of spatial planning reforms at the beginning of the 21st century, a second wave of reforms has recently swept through several European countries. In this study we investigate the significance of these latest developments by analysing the reforms in Denmark, England, and the Netherlands from the perspective of rescaling, the process of redividing tasks, and responsibilities between the various tiers of government. We show that the reasoning behind the new planning systems and the philosophy they were based on were remarkably similar. Typical catchphrases, such as ‘closer to the citizen’ and ‘development-oriented spatial planning’, were used in each of the countries under study. Although the second wave of changes is legitimised by much of the same wording, the changes are significantly different because comprehensive visions on the integrated spatial development at the national and regional level have been almost completely abandoned. The loss of this ‘something more’ seems to impact the core of spatial planning.
    National prevalence and associated risk factors of hypertension and prehypertension among Vietnamese adults
    Ha, Do T.P. ; Geleijnse, J.M. ; Le, M.B. ; Kok, F.J. ; Feskens, E.J.M. - \ 2015
    American Journal of Hypertension 28 (2015)1. - ISSN 0895-7061 - p. 89 - 97.
    blood-pressure - double burden - population - awareness - health - prevention - nutrition - countries - consumption - strategies
    BACKGROUND Hypertension has recently been identified as the leading risk factor for global mortality. This study aims to present the national prevalence of hypertension and prehypertension and, their determinants in Vietnamese adults. METHODS Nationally representative data were obtained from the National Adult Overweight Survey 2005. This one visit survey included 17,199 subjects aged 25–64 years, with a mean body mass index (BMI) of 20.7kg/m2. RESULTS The overall census-weighted JNC7 (the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure) defined prevalence of hypertension was 20.7% (95% confidence interval (CI) = 19.4–22.1); the prevalence of prehypertension was 41.8% (95% CI = 40.4–43.1). Hypertension and prehypertension were more prevalent in men. Higher age, overweight, alcohol use (among men), and living in rural areas (among women) were independently associated with a higher prevalence of hypertension, whereas higher physical activity and education level were inversely associated. Age, BMI, and living in rural areas were independently associated with an increased prevalence of prehypertension. Among the hypertensives, 25.9% were aware of their hypertension, 12.2% were being treated, and 2.8% had their blood pressure under control; among the treated hypertensives, 32.4% had their blood pressure controlled.
    Estimating enteric methane emissions from Chilean beef fattening systems using a mechanistic model
    Arias, R.A. ; Catrileo, A. ; Larraín, R. ; Vera, R. ; Velásquez, A. ; Toneatti, M. ; France, J. ; Dijkstra, J. ; Kebreab, E. - \ 2015
    The Journal of Agricultural Science 153 (2015)1. - ISSN 0021-8596 - p. 114 - 123.
    dairy-cows - feedlot cattle - rumen - supplementation - fermentation - performance - management - monensin - strategies - prediction
    A mechanistic model (COWPOLL) was used to estimate enteric methane (CH4) emissions from beef production systems in Chile. The results expressed as a proportion of gross energy intake (GEI) were compared with enteric fermentation data reported in the last Chilean greenhouse gases inventory, which utilized an earlier the Intergovernmental Panel on Climate Change Tier 2 approach. The simulation analysis was based on information from feedstuffs, dry matter intake (DMI), body weight (BW) and average daily gain (ADG) of steers raised and finished at two research facilities located in Central and Southern Chile, as well as three simulated scenarios for grass-based finishing systems in Southern Chile. Data for feedlot production systems in the central region were assessed by considering steers fed a forage : concentrate ratio of 23 : 77 using maize silage and wheat straw as roughage sources during the stages of backgrounding and fattening. Average DMI were 7·3±0·62 and 9·2±0·55 kg/day per steer for backgrounding and fattening, respectively, whereas ADG were 1·1±0·22 and 1·3±0·37 kg/day for backgrounding and fattening. For the Southern Chilean fattening production systems, the forage : concentrate ratio was 56 : 44 with ryegrass pasture as the sole forage source. In this case, average DMI was 9·97±0·51 and ADG was 1·1±0·24 kg/day per steer. Two of the grass-based scenarios used the same initial BW information as that used for the Central and Southern Chilean systems, but feedlot diets were replaced by ryegrass pasture. The third grass-based scenario used an initial BW of 390 kg. In all the grass-based scenarios an ADG of 0·90 kg/day, with maximum DMI estimated as a proportion of BW (0·01 of NDF, kg/kg BW), was assumed. The results of the simulation analysis showed that emission factors (Ym; fraction of GEI) ranged from 0·062 to 0·079 of GEI. Smaller values were associated with finishing systems that included a lower proportion of forage in the diet due to higher propionate production, which serves as a sink for hydrogen in the rumen. Cattle finished in feedlot systems had an average of 0·062 of GEI lost as CH4, whereas grass-based cattle had losses of 0·079 of GEI. Enteric CH4 emissions for the systems using grass-based and concentrate diets were 261 and 159 g/kg weight gain, respectively. The Chilean CH4 inventory employs a fixed Ym of 0·060 to estimate enteric fermentation for all cattle. This value is lower than the average Ym obtained in the current simulation analysis (0·071 of GEI), which results in underestimation of enteric CH4 emissions from beef cattle. However, these results need to be checked against field measurements of CH4 emissions. Implementation of mechanistic models in the preparation of national greenhouse gas inventories is feasible if appropriate information is provided, allowing dietary characteristics and regional particularities to be taken into consideration.
    Spatial Sampling Design for Estimating Regional GPP With Spatial Heterogeneities
    Wang, J.H. ; Ge, Y. ; Heuvelink, G.B.M. ; Zhou, C.H. - \ 2014
    IEEE Geoscience and Remote Sensing Letters 11 (2014)2. - ISSN 1545-598X - p. 539 - 543.
    optimization - geostatistics - strategies - maize
    The estimation of regional gross primary production (GPP) is a crucial issue in carbon cycle studies. One commonly used way to estimate the characteristics of GPP is to infer the total amount of GPP by collecting field samples. In this process, the spatial sampling design will affect the error variance of GPP estimation. This letter uses geostatistical model-based sampling to optimize the sampling locations in a spatial heterogeneous area. The approach is illustrated with a real-world application of designing a sampling strategy for estimating the regional GPP in the Babao river basin, China. By considering the heterogeneities in the spatial distribution of the GPP, the sampling locations were optimized by minimizing the spatially averaged interpolation error variance. To accelerate the optimization process, a spatial simulated annealing search algorithm was employed. Compared with a sampling design without considering stratification and anisotropies, the proposed sampling method reduced the error variance of regional GPP estimation.
    Genetic and antigenetic charactersation of serotype a FMD viruses from East Africa to select new vaccine strains.
    Bari, F.D. ; Parida, S. ; Tekleghiorghis, T. ; Dekker, A. ; Sangula, A. ; Reeve, R. ; Haydon, D.T. ; Paton, D.J. - \ 2014
    Vaccine 32 (2014)44. - ISSN 0264-410X - p. 5794 - 5800.
    mouth-disease virus - middle-east - foot - sites - identification - conservation - strategies - protection - evolution - spread
    Vaccine strain selection for emerging foot-and-mouth disease virus (FMDV) outbreaks in enzootic countries can be addressed through antigenic and genetic characterisation of recently circulating viruses. A total of 56 serotype A FMDVs isolated between 1998 and 2012, from Central, East and North African countries were characterised antigenically by virus neutralisation test using antisera to three existing and four candidate vaccine strains and, genetically by characterising the full capsid sequence data. A Bayesian analysis of the capsid sequence data revealed the viruses to be of either African or Asian topotypes with subdivision of the African topotype viruses into four genotypes (Genotypes I, II, IV and VII). The existing vaccine strains were found to be least cross-reactive (good matches observed for only 5.4–46.4% of the sampled viruses). Three bovine antisera, raised against A-EA-2007, A-EA-1981 and A-EA-1984 viruses, exhibited broad cross-neutralisation, towards more than 85% of the circulating viruses. Of the three vaccines, A-EA-2007 was the best showing more than 90% in-vitro cross-protection, as well as being the most recent amongst the vaccine strains used in this study. It therefore appears antigenically suitable as a vaccine strain to be used in the region in FMD control programmes.
    Mud, muddle and models in the knowledge value-chain to action on tropical peatland conservation
    Noordwijk, M. van; Matthews, R.B. ; Agus, F. ; Farmer, J. ; Verchot, L. ; Hergoualc’h, K. ; Persch, S. ; Tata, H.L. ; Lusiana, B. ; Widayati, A. ; Dewi, S. - \ 2014
    Mitigation and Adaptation Strategies for Global Change 19 (2014)6. - ISSN 1381-2386 - p. 887 - 905.
    greenhouse-gas emissions - hydrological restoration - central kalimantan - carbon-dioxide - climate-change - decomposition - strategies - management - indonesia - soils
    Tropical peatlands are known not only for their high, area-based, carbon emissions in response to land-use change but also as hot spots of debate about associated data uncertainties. Perspectives are still evolving on factors underlying the variability and uncertainty. Debate includes the ways of reducing emissions through rewetting, reforestation and agroforestry. A knowledge value-chain that is long and complex links (a) fundamental understanding of peat and peatland processes leading to sciencebased quantification and default values, (b) willingness and (c) ability to act towards emission reduction, and ultimately (d) to local, national and global actions that effectively provide rules, incentives and motivation to conserve peat and reduce emissions. We discuss this value chain, its stakeholders and issues that still remain partially unresolved.We conclude that, to shorten the denial and conspiracy-theory stages of debate that otherwise slow down steps B and C, networks of international and national scientists have to be involved at the early stage of identifying policysensitive environmental issues. Models span part of the knowledge value-chain but transition of analysis units requires specific attention, from soil volumes through area and commodity flows to opportunities for reductions. While drainage of peatlands triggers landscape-scale increases in emissions, factors beyond drainage depth, including nutrient supply, may have a major influence on decomposition rates. Attempts to disentangle the contributions of plant and peat-based respiration in surface flux measurements involve assumptions that cannot be easily verified in comparisons between land uses. With progress on A leading to new internationally accepted defaults and with resistance on step B reduced, the reality of C and lack of working solutions for D is currently constraining further progress.
    Ecosystem Services and Opportunity Costs Shift Spatial Priorities for Conserving Forest Biodiversity
    Schroter, M. ; Rusch, G.M. ; Barton, D.N. ; Blumentrath, S. ; Nordén, B. - \ 2014
    PLoS ONE 9 (2014)11. - ISSN 1932-6203 - 12 p.
    protected areas - trade-offs - rich forests - conservation - landscapes - strategies - payments - benefits - science - norway
    Inclusion of spatially explicit information on ecosystem services in conservation planning is a fairly new practice. This study analyses how the incorporation of ecosystem services as conservation features can affect conservation of forest biodiversity and how different opportunity cost constraints can change spatial priorities for conservation. We created spatially explicit cost-effective conservation scenarios for 59 forest biodiversity features and five ecosystem services in the county of Telemark (Norway) with the help of the heuristic optimisation planning software, Marxan with Zones. We combined a mix of conservation instruments where forestry is either completely (non-use zone) or partially restricted (partial use zone). Opportunity costs were measured in terms of foregone timber harvest, an important provisioning service in Telemark. Including a number of ecosystem services shifted priority conservation sites compared to a case where only biodiversity was considered, and increased the area of both the partial (+36.2%) and the non-use zone (+3.2%). Furthermore, opportunity costs increased (+6.6%), which suggests that ecosystem services may not be a side-benefit of biodiversity conservation in this area. Opportunity cost levels were systematically changed to analyse their effect on spatial conservation priorities. Conservation of biodiversity and ecosystem services trades off against timber harvest. Currently designated nature reserves and landscape protection areas achieve a very low proportion (9.1%) of the conservation targets we set in our scenario, which illustrates the high importance given to timber production at present. A trade-off curve indicated that large marginal increases in conservation target achievement are possible when the budget for conservation is increased. Forty percent of the maximum hypothetical opportunity costs would yield an average conservation target achievement of 79%.
    Perceptions on healthy eating, physical activity and lifestyle advice: opportunities for adapting lifestyle interventions to individuals with low socioeconomic status
    Bukman, A.J. ; Teuscher, D. ; Feskens, E.J.M. ; Baak, M.A. van; Meershoek, A. ; Renes, R.J. - \ 2014
    BMC Public Health 14 (2014). - ISSN 1471-2458 - 22 p.
    deprived neighborhoods - diabetes prevention - european countries - leisure-time - women - inequalities - food - strategies - behaviors - weight
    Background Individuals with low socioeconomic status (SES) are generally less well reached through lifestyle interventions than individuals with higher SES. The aim of this study was to identify opportunities for adapting lifestyle interventions in such a way that they are more appealing for individuals with low SES. To this end, the study provides insight into perspectives of groups with different socioeconomic positions regarding their current eating and physical activity behaviour; triggers for lifestyle change; and ways to support lifestyle change. Methods Data were gathered in semi-structured focus group interviews among low SES (four groups) and high SES (five groups) adults. The group size varied between four and nine participants. The main themes discussed were perceptions and experiences of healthy eating, physical activity and lifestyle advice. Interviews were transcribed verbatim and a thematic approach was used to analyse the data. Results In general, three key topics were identified, namely: current lifestyle is logical for participants given their personal situation; lifestyle change is prompted by feedback from their body; and support for lifestyle change should include individually tailored advice and could profit from involving others. The perceptions of the low SES participants were generally comparable to the perceptions shared by the high SES participants. Some perceptions were, however, especially shared in the low SES groups. Low SES participants indicated that their current eating behaviour was sometimes affected by cost concerns. They seemed to be especially motivated to change their lifestyle when they experienced health complaints, but were rather hesitant to change their lifestyle for preventive purposes. Regarding support for lifestyle change, low SES participants preferred to receive advice in a group rather than on their own. For physical activities, groups should preferably consist of persons of the same age, gender or physical condition. Conclusions To motivate individuals with low SES to change their lifestyle, it may be useful to (visually) raise their awareness of their current weight or health status. Lifestyle interventions targeting individuals with low SES should take possible cost concerns into account and should harness the supportive effect of (peer) groups.
    Relative growth rate variation of evergreen and deciduous savanna tree species is driven by different traits
    Tomlinson, K.W. ; Poorter, L. ; Bongers, F. ; Borghetti, F. ; Jacobs, L. ; Langevelde, F. van - \ 2014
    Annals of Botany 114 (2014)2. - ISSN 0305-7364 - p. 315 - 324.
    phylogenetically independent contrasts - adaptive significance - carbohydrate storage - shade tolerance - seedling shade - woody-plants - allocation - biomass - forest - strategies
    Background and Aims Plant relative growth rate (RGR) depends on biomass allocation to leaves (leaf mass fraction, LMF), efficient construction of leaf surface area (specific leaf area, SLA) and biomass growth per unit leaf area (net assimilation rate, NAR). Functional groups of species may differ in any of these traits, potentially resulting in (1) differences in mean RGR of groups, and (2) differences in the traits driving RGR variation within each group. We tested these predictions by comparing deciduous and evergreen savanna trees. Methods RGR, changes to biomass allocation and leaf morphology, and root non-structural carbohydrate reserves were evaluated for juveniles of 51 savanna species (34 deciduous, 17 evergreen) grown in a common garden experiment. It was anticipated that drivers ofRGRwould differ between leaf habit groups because deciduous species have to allocate carbohydrates to storage in roots to be able to flush leaves again, which directly compromises their LMF, whereas evergreen species are not subject to this constraint. Key Results Evergreen species had greaterLMFandRGRthan deciduous species. Amongdeciduous speciesLMF explained 27% of RGR variation (SLA 34% and NAR 29 %), whereas among evergreen species LMF explained between 2 and 17% of RGR variation (SLA 32–35% and NAR 38–62 %). RGR and LMF were (negatively) related to carbohydrate storage only among deciduous species. Conclusions Trade-offs between investment in carbohydrate reserves and growth occurred only among deciduous species, leading to differences in relative contribution made by the underlying components of RGR between the leaf habit groups. The results suggest that differences in drivers ofRGRoccur among savanna species because these have different selected strategies for coping with fire disturbance in savannas. It is expected that variation in the drivers of RGR will be found in other functional types that respond differently to particular disturbances.
    A push-pull system to reduce house entry of malaria mosquitoes
    Menger, D.J. ; Otieno, B. ; Rijk, M. de; Mukabana, W.R. ; Loon, J.J.A. van; Takken, W. - \ 2014
    Malaria Journal 13 (2014). - ISSN 1475-2875 - 8 p.
    vector anopheles-gambiae - host-seeking behavior - mm-x traps - spatial repellency - field-evaluation - western kenya - lactic-acid - culicidae - diptera - strategies
    Background. Mosquitoes are the dominant vectors of pathogens that cause infectious diseases such as malaria, dengue, yellow fever and filariasis. Current vector control strategies often rely on the use of pyrethroids against which mosquitoes are increasingly developing resistance. Here, a push-pull system is presented, that operates by the simultaneous use of repellent and attractive volatile odorants. Method/Results. Experiments were carried out in a semi-field set-up: a traditional house which was constructed inside a screenhouse. The release of different repellent compounds, para-menthane-3,8-diol (PMD), catnip oil e.o. and delta-undecalactone, from the four corners of the house resulted in significant reductions of 45% to 81.5% in house entry of host-seeking malaria mosquitoes. The highest reductions in house entry (up to 95.5%), were achieved by simultaneously repelling mosquitoes from the house (push) and removing them from the experimental set-up using attractant-baited traps (pull). Conclusions. The outcome of this study suggests that a push-pull system based on attractive and repellent volatiles may successfully be employed to target mosquito vectors of human disease. Reductions in house entry of malaria vectors, of the magnitude that was achieved in these experiments, would likely affect malaria transmission. The repellents used are non-toxic and can be used safely in a human environment. Delta-undecalactone is a novel repellent that showed higher effectiveness than the established repellent PMD. These results encourage further development of the system for practical implementation in the field.
    Do males evaluate female age for precopulatory mate guarding in the two-spotted spider mite?
    Oku, K. ; Saito, Y. - \ 2014
    Journal of Ethology 32 (2014)1. - ISSN 0289-0771 - p. 1 - 6.
    linyphia-litigiosa linyphiidae - urticae koch acari - tetranychus-urticae - sex-pheromone - mating success - behavior - fertilization - strategies - ratio - time
    In the two-spotted spider mite Tetranychus urticae (Acari: Tetranychidae), because only the first mating results in fertilisation, adult males guard quiescent deutonymph females, the stage immediately before adult emergence. Previous studies showed that T. urticae males prefer to guard older rather than younger females. However, as previous experimental designs have included uncertain factors, findings have not always been sufficiently rigorous. Therefore, we reexamined whether T. urticae males discriminate between the females closest to becoming receptive and younger females. One male was introduced onto leaf squares with two differently aged quiescent deutonymph females, with time lags between the females of 3, 6, 12 or 23 h, and whether the older or younger female was guarded was recorded. When the time lags between the females were 3, 6 or 12 h, males showed no preferences. Males preferred older females over younger ones only when the time lag was 23 h. Under non-choice conditions, fewer males guarded the 23-h younger females than other older females, suggesting that the attractiveness of the younger females is weaker than older females. Our results are not fully consistent with previous studies; T. urticae males do not obviously discriminate between females closest to becoming receptive and younger females.
    A Unimodal Species Response Model Relating Traits to Environment with Application to Phytoplankton Communities.
    Jamil, T. ; Kruk, C. ; Braak, C.J.F. ter - \ 2014
    PLoS ONE 9 (2014)5. - ISSN 1932-6203 - 14 p.
    bayesian variable selection - climate-change - ecology - lake - variability - strategies - diversity - habitat - classification - regression
    In this paper we attempt to explain observed niche differences among species (i.e. differences in their distribution along environmental gradients) by differences in trait values (e.g. volume) in phytoplankton communities. For this, we propose the trait-modulated Gaussian logistic model in which the niche parameters (optimum, tolerance and maximum) are made linearly dependent on species traits. The model is fitted to data in the Bayesian framework using OpenBUGS (Bayesian inference Using Gibbs Sampling) to identify according to which environmental variables there is niche differentiation among species and traits. We illustrate the method with phytoplankton community data of 203 lakes located within four climate zones and associated measurements on 11 environmental variables and six morphological species traits of 60 species. Temperature and chlorophyll-a (with opposite signs) described well the niche structure of all species. Results showed that about 25% of the variance in the niche centres with respect to chlorophyll-a were accounted for by traits, whereas niche width and maximum could not be predicted by traits. Volume, mucilage, flagella and siliceous exoskeleton are found to be the most important traits to explain the niche centres. Species were clustered in two groups with different niches structures, group 1 high temperature-low chlorophyll-a species and group 2 low temperature-high chlorophyll-a species. Compared to group 2, species in group 1 had larger volume but lower surface area, had more often flagella but neither mucilage nor siliceous exoskeleton. These results might help in understanding the effect of environmental changes on phytoplankton community. The proposed method, therefore, can also apply to other aquatic or terrestrial communities for which individual traits and environmental conditioning factors are available.
    The Influence of Between-Farm Distance and Farm Size on the Spread of Classical Swine Fever during the 1997-1998 Epidemic in The Netherlands
    Boender, G.J. ; Hengel, R. van den; Roermund, H.J.W. van; Hagenaars, T.H.J. - \ 2014
    PLoS ONE 9 (2014)4. - ISSN 1932-6203 - 7 p.
    infectious-diseases - virus - transmission - strategies - model - risk
    As the size of livestock farms in The Netherlands is on the increase for economic reasons, an important question is how disease introduction risks and risks of onward transmission scale with farm size (i.e. with the number of animals on the farm). Here we use the epidemic data of the 1997–1998 epidemic of Classical Swine Fever (CSF) Virus in The Netherlands to address this question for CSF risks. This dataset is one of the most powerful ones statistically as in this epidemic a total of 428 pig farms where infected, with the majority of farm sizes ranging between 27 and 1750 pigs, including piglets. We have extended the earlier models for the transmission risk as a function of between-farm distance, by adding two factors. These factors describe the effect of farm size on the susceptibility of a ‘receiving’ farm and on the infectivity of a ‘sending’ farm (or ‘source’ farm), respectively. Using the best-fitting model, we show that the size of a farm has a significant influence on both farm-level susceptibility and infectivity for CSF. Although larger farms are both more susceptible to CSF and, when infected, more infectious to other farms than smaller farms, the increase is less than linear. The higher the farm size, the smaller the effect of increments of farm size on the susceptibility and infectivity of a farm. Because of changes in the Dutch pig farming characteristics, a straightforward extrapolation of the observed farm size dependencies from 1997/1998 to present times would not be justified. However, based on our results one may expect that also for the current pig farming characteristics in The Netherlands, farm susceptibility and infectivity depend non-linearly on farm size, with some saturation effect for relatively large farm sizes.
    The theoretical foundations of value-informed pricing in the service-dominant logic of marketing
    Ingenbleek, P.T.M. - \ 2014
    Management Decision 52 (2014)1. - ISSN 0025-1747 - p. 33 - 53.
    resource-advantage theory - managerial practice - decision-making - competition - perceptions - perspective - strategies - framework - companies - quality
    Purpose – In the mainstream normative pricing literature, value assessment is virtually non-existent. Although the resource-based literature recognizes that pricing is a competence, value-informed pricing practices are still weakly grounded in theory. The purpose of this paper is to strengthen the theoretical grounds of such pricing practices. Design/methodology/approach – The paper applies the emerging service-dominant logic of marketing to pricing. More specifically, it apples the ten foundational premises of service-dominant logic to pricing and it places pricing in the frameworks of one of the major building blocks of service-dominant logic, namely the resource-advantage theory of competition. Findings – From a service-dominant perspective, price is the reward for the application of specialized knowledge and skills. Pricing is an operant resource, or competence, that assesses customer value, applies it in multi-dimensional price propositions, and implements it in processes of co-creating prices with customers. Value-informed pricing is the central pricing practice within such competences. Practical implications – Prices vary among others between “good” and “bad”, firms generate competitive advantage not only through value creation, but also through pricing. Learning is key to develop pricing competences. Originality/value – This paper is the first to ground value-informed pricing at high levels of abstraction in general marketing theory.
    Forest Management Approaches for Coping with the Uncertainty of Climate Change: Trade-Offs in Service Provisioning and Adaptability.
    Wagner, S. ; Nocentini, S. ; Huth, F. ; Hoogstra, M.A. - \ 2014
    Ecology and Society 19 (2014)1. - ISSN 1708-3087
    fagus-sylvatica l. - ecosystem management - summer drought - central-europe - change impacts - strategies - future - sustainability - conservation - biodiversity
    The issue of rapid change in environmental conditions under which ecosystem processes and human interventions will take place in the future is relatively new to forestry, whereas the provision of ecosystem services, e.g., timber or fresh water, is at the very heart of the original concept of forest management. Forest managers have developed ambitious deterministic approaches to provide the services demanded, and thus the use of deterministic approaches for adapting to climate change seem to be a logical continuation. However, as uncertainty about the intensity of climate change is high, forest managers need to answer this uncertainty conceptually. One may envision an indeterministic approach to cope with this uncertainty; but how the services will be provided in such a concept remains unclear. This article aims to explore the fundamental aspects of both deterministic and indeterministic approaches used in forestry to cope with climate change, and thereby point out trade-offs in service provisioning and adaptability. A forest owner needs to be able to anticipate these trade-offs in order to make decisions towards sustainable forest management under climate change.
    Costs and effectiveness of on-farm measures to reduce aquatic risks from pesticides from the Netherlands
    Eerdt, M.M. van; Spruijt-Verkerke, J. ; Wal, A.J. van der; Zeijts, H. van; Tiktak, A. - \ 2014
    Pest Management Science 70 (2014)12. - ISSN 1526-498X - p. 1840 - 1849.
    integrated pest-management - agriculture - communities - strategies - ipm
    Background The European Union requires growers to implement the principles of Integrated Pest Management (IPM) by 2014. In this paper, we provide a quantitative overview of the costs and effectiveness of voluntary IPM measures in 15 crops in the Netherlands. We will focus on aquatic risks and define effectiveness as the potential to reduce the risks posed to aquatic organisms. We further identify which of these measures have actually been adopted by growers and why certain measures have not been adopted. Results Of the 105 measures evaluated, the most effective measures with respect to risk reduction were emission reduction and substitution of high-risk pesticides (each up to 80% reduction). IPM measures directed towards lowering pesticide use generally showed a smaller risk reducing potential. However, 40% of these measures reduced the overall cost of pest management. About 60% of all 105 measures were voluntarily implemented by growers. The most commonly adopted measures were pest prevention, low-dose spraying and spray drift reduction. Cost appeared to be an important incentive for adoption; however, other factors such as risk perception, education and practicability were equally important. Conclusions Voluntary IPM measures have significantly contributed to reducing aquatic risks (15-50% risk reduction depending on crop type). Further risk reduction could be achieved when more growers adopt the most effective measures like spray drift reduction and substitution of high-risk pesticides. However, IPM hardly reduced the number of pesticide applications and therefore the dependence on chemical crop protection continued to be high.
    The impact of uncertainties on predicted GHG emissions of dairy cow production systems
    Zehetmeier, M. ; Gandorfer, M. ; Hoffmann, H. ; Muller, U.K. ; Boer, I.J.M. de - \ 2014
    Journal of Cleaner Production 73 (2014). - ISSN 0959-6526 - p. 116 - 124.
    nitrous-oxide emissions - life-cycle assessment - environmental-impact - carbon footprint - milk-production - agriculture - methane - sensitivity - strategies - germany
    Dairy farms produce significant greenhouse gas (GHG) emissions and are therefore a focal point for GHG-mitigation practices. To develop viable mitigation options, we need robust (insensitive to changes in model parameters and assumptions) predictions of GHG emissions. To this end, we developed a stochastic model to estimate the robustness of predictions based on input parameters (GHG emission factors and production traits) and their uncertainties. In our study we explored how sensitive predictions of GHG emissions are to three factors: (1) system boundaries of the emission model (2) the uncertainty of input parameters due to quality of data or methodological choices (epistemic uncertainty) and (3) inherent variability in input parameters (variability uncertainty). To assess the effect of system boundaries, we compared two different boundaries: the “dairy farm gate” boundary (all GHG emissions are allocated to milk) and “system expansion” (the model gives a GHG credit to beef derived from culled cows and bull, heifer and calf fattening of surplus dairy calves outside the farm). Results using the farm-gate boundary provide guidance to dairy farmers to reduce GHG emissions of milk production. The results using system expansion are important for defining GHG abatement policies for milk and beef production. We found that the choice of system boundary had the strongest impact on the level and variation of predicted GHG emissions. Model predictions were least robust for lower-yielding dairy cow production systems and when we used system expansion. We also explored which GHG-abatement strategies have the most leverage by assessing the influence of each input parameter on model predictions. Predicted GHG emissions were least sensitive to variability-related uncertainty in production traits (i.e. replacement rate, calving interval). Lower-yielding production systems had the highest variation, indicating the highest potential for GHG mitigation of all production systems studied. Variation in predicted GHG emissions increased substantially when both epistemic and variability uncertainty in emission factors and variability uncertainty in production traits were included in the model. If the system boundary was set at the farm gate, the emission factor of N2O from nitrogen input into the soil had the highest impact on variation in predicted GHG emissions. This variation stems from uncertainties in predicting N2O emissions (epistemic uncertainty) but also from inherent variability of N2O emissions over time and space. The uncertainty of predicted GHG emissions can be reduced by increasing the precision in predicting N2O emissions. However, this additional information does not reduce GHG emissions itself. Knowing site specific variability of N2O emissions can help reduce GHG emissions by specific management (e.g. reduce soil compaction, adopted manure management, choice of suitable crops). In case of system expansion, uncertainty in GHG emission credit for dairy beef contributed the most to increasing the variation in predicted GHG emissions. The stochastic-model approach gave important insights into the robustness of model outcomes, which is crucial in the search for cost-effective GHG-abatement options. Despite the high degree of uncertainty when using system expansion, its results help identifying global GHG mitigation options of combined milk and beef production
    Analysis of trade-offs in agricultural systems: current status and way forward
    Klapwijk, C.J. ; Wijk, M.T. van; Rosenstock, T.S. ; Asten, P.J.A. van; Thornton, P.K. ; Giller, K.E. - \ 2014
    Current Opinion in Environmental Sustainability 6 (2014)2. - ISSN 1877-3435 - p. 110 - 115.
    crop-livestock systems - land-use - conservation agriculture - management-practices - climate-change - africa - strategies - knowledge - resource - science
    Trade-off analysis has become an increasingly important approach for evaluating system level outcomes of agricultural production and for prioritizing and targeting management interventions in multifunctional agricultural landscapes. We review the state-of-the-art for trade-off analysis, assessing different techniques by exploring a concrete example of trade-offs around the use of crop residues in smallholder farming systems. The techniques for performing trade-off analyses have developed substantially in recent years aided by mathematical advancement, increased computing power, and emerging insights into systems behaviour. Combining different techniques allows the assessment of aspects of system behaviour via various perspectives, thereby generating complementary knowledge. However, this does not solve the fundamental challenge: trade-off analyses without substantial stakeholder engagement often have limited practical utility for informing practical decision-making. We suggest ways to integrate approaches and improve the potential for societal impact of future trade-off analyses.
    Gaming for smallholder participation in the design of more sustainable agricultural landscapes
    Speelman, E.N. ; García-Barrios, L.E. ; Groot, J.C.J. ; Tittonell, P.A. - \ 2014
    Agricultural Systems 126 (2014). - ISSN 0308-521X - p. 62 - 75.
    role-playing game - educational simulation tool - laboratory experiments - collective action - biosphere reserve - field experiments - decision-making - social dilemmas - lab experiments - strategies
    Smallholder farming systems often consist of a mosaic of interlinked forested and cleared-field patches that together provide a diversity of services to local and non-local stakeholders. Designing and adopting more sustainable farming systems for such mosaic landscapes involves communal decision-making and active participation of local smallholders. Currently, a wide variety of participatory approaches to involve individual farmers in such design processes is available. However, methodologies that address communal decision-making processes as seen in complex smallholder agricultural landscapes are still rare. Here, we present a gaming methodology developed to (i) actively involve farmers in the process of agroecosystem design, and (ii) to identify factors and patterns of communal decision-making through an in-depth analysis of game strategies deployed by participants. At the basis of this methodology is the RESORTES board game; a stylized yet complex land-use game rich in ecological and social outcomes. Results of four pilot sessions in a usufruct community in the buffer zone of a Man and Biosphere Reserve in Chiapas, Mexico, showed that the game sessions created an open and active discussion among participants. Discussions concerned land-use issues in the game and in real-life. It allowed participants that were new to active involvement in communal decision-making to openly discuss and share their ideas. The highly structured monitoring and analysis scheme for ex-ante/ex-post analysis was easy in use and identified communication, leadership and relatedness among participants as influential factors that smoothened the collective decision-making process. The RESORTES board game and related games can shed light on farmer’s actual views on and responses to multifunctional agricultural landscape planning and the land sharing vs. land sparing dilemmas currently in debate in academic and policy-making settings. The findings of this paper can be useful to inform strategies for community involvement in agroecosystem design in a broader set of complex socio-environmental context, using serious game to guide agricultural landscape planning processes.
    Refreshing the role of open water surfaces on mitigating the maximum urban heat island effect
    Steeneveld, G.J. ; Koopmans, S. ; Heusinkveld, B.G. ; Theeuwes, N.E. - \ 2014
    Landscape and Urban Planning 121 (2014). - ISSN 0169-2046 - p. 92 - 96.
    land-use - temperature - comfort - strategies - index - uk
    During warm summer episodes citizens in urban areas are subject to reduced human thermal comfort and negative health effects. To mitigate these adverse effects, land use planners and urban designers have used the evaporative power of water bodies as a tool to limit the urban heat island effect (UHI) and undesirable human thermal comfort. Based on weather observations by Dutch hobby meteorologists and a station network in Rotterdam (Netherlands), we show that water bodies increase rather than decrease the 95 percentile of the daily maximum UHI. The high heat capacity of water suppresses the diurnal and annual cycle over water, and water temperatures remain relatively high after evening and season transitions. This is reflected to the 2 m temperature above and in the surround of the water body, and in a relatively high UHI. Our result has consequences for the daily practice in urban design concerning microclimate effects.
    Climate-proofing spatial planning and water management projects: an analysis of 100 local and regional projects in the Netherlands
    Sedee, A.G.J. ; Swart, R.J. ; Pater, F. de; Goosen, H. ; Pijnappels, M.H.J. ; Vellinga, P. - \ 2014
    Journal of Environmental Policy and Planning 16 (2014)1. - ISSN 1523-908X - p. 55 - 74.
    klimaatverandering - regionale planning - waterbeheer - onderzoeksprojecten - inventarisaties - nederland - climatic change - regional planning - water management - research projects - inventories - netherlands - adaptation - strategies
    Since the turn of the century, an increasing number of local and regional authorities in Europe started making their city or region resilient to climate change, or ‘climate-proof’. Publications about the actual experiences with implementing these adaptation policies are as yet anecdotal, determined by the local context and the methods applied. In order to identify common processes and characteristics, moving beyond individual cases, this paper systematically assesses 100 spatial planning and water management projects in the Netherlands that included climate resilience as one of their objectives. We derive eight defining characteristics that not only increase climate resilience, but are also found to lead to a greater ‘quality’ of the project area. We structure these properties into a stylized sequence: (i) a longer timeframe, (ii) an integrative and sustainable approach, (iii) consideration of new spatial functions, (iv) a broader spatial context, (v) participation of multiple stakeholders, (vi) new opportunities for entrepreneurs, (vii) increased cost-effectiveness, and (viii) enhanced quality of the project area. The assessment also suggests four process-related conditions that contribute to the success of a project: early incorporation of adaptation; multi-actor collaboration and co-creation of knowledge; integrated, multifunctional and forward-looking solutions; and early political commitment.
    Pareto optimality and robustness in bi-blending problems
    Herrera, J.F. ; Casado, L.G. ; Hendrix, E.M.T. ; García, I. - \ 2014
    TOP 22 (2014)1. - ISSN 1134-5764 - p. 254 - 273.
    The mixture design problem for two products concerns finding simultaneously two recipes of a blending problem with linear, quadratic and semi-continuity constraints. A solution of the blending problem minimizes a linear cost objective and an integer valued objective that keeps track of the number of raw materials that are used by the two recipes, i.e. this is a bi-objective problem. Additionally, the solution must be robust. We focus on possible solution approaches that provide a guarantee to solve bi-blending problems with a certain accuracy, where two products are using (partly) the same scarce raw materials. The bi-blending problem is described, and a search strategy based on Branch-and-Bound is analysed. Specific tests are developed for the bi-blending aspect of the problem. The whole is illustrated numerically.
    The Fatter the Tail, the Fatter the Climate Agreement. Simulating the Influence of Fat Tails in Climate Change Damages on the Success of International Climate Negotiations
    Dellink, R.B. ; Dekker, T. ; Ketterer, J. - \ 2013
    Environmental and Resource Economics 56 (2013)2. - ISSN 0924-6460 - p. 277 - 305.
    international environmental agreements - stability likelihood - uncertainty - coalitions - strategies
    International climate negotiations take place in a setting where uncertainties regarding the impacts of climate change are very large. In this paper, we examine the influence of increasing the probability and impact of large climate change damages, also known as the ‘fat tail’, on the formation of an international mitigation agreement. We systematically vary the shape and location of the distribution of climate change damages using the stochastic version of the applied game-theoretical STACO model. Our aim is to identify how changes to the distributional form affect the stability of coalitions and their performance. We find that fatter upper tails increase the likelihood that more ambitious coalitions are stable as well as the performance of these stable coalitions. Fatter tails thus imply more successful, or ‘fatter’, international climate agreements
    Cold storage affects mortality, body mass, lifespan, reproduction and flight capacity of Praon volucre (Hymenoptera: Braconidae)
    Lins, J.C. ; Bueno, V.H.P. ; Sidney, L.A. ; Silva, D.B. ; Sampaio, M.V. ; Pereira, J.M. ; Nomelini, Q.S.S. ; Lenteren, J.C. van - \ 2013
    European Journal of Entomology 110 (2013)2. - ISSN 1210-5759 - p. 263 - 270.
    parasitoid species hymenoptera - aphidius-colemani hymenoptera - biological-control - low-temperatures - fat reserves - survival - quality - ervi - perspective - strategies
    The possibility of storing natural enemies at low temperatures is important for the mass production of biological control agents. We evaluated the effect of different periods of cold storage on immature mortality, mummy body mass, lifespan, reproduction and flight capacity of the parasitoid Praon volucre (Haliday). One-day-old mummies of the aphid Macrosiphum euphorbiae (Thomas) containing pre-pupae of P. volucre were stored in a climatic chamber at 5 degrees C and 70 +/- 10% RH in the dark for different periods of time (5, 10, 15 and 20 days). The control consisted of mummies kept at 22 +/- 1 degrees C, 70 +/- 10% RH and a 12 h photophase. Percentage adult emergence, mummy body mass, flight capacity and number of eggs in the ovarioles of P. volucre females decreased with increase in the period of storage, while the longevity of females was only slightly affected. Fat content of mummies, percentage of parasitized aphids and survival of progeny to emergence decreased with increase in the period of storage. Storage of P. volucre pre-pupae for up to 5 days at 5 degrees C did not affect any of the above mentioned parameters. The fact that P. volucre pre-pupae can be stored for 5 days without loss of quality and for 10 days with only a slight loss facilitates the planning of mass production and shipment.
    A bodyguard or a tastier meal? Dying caterpillar indirectly protects parasitoid cocoons by offering alternate prey to a generalist predator
    Harvey, J.A. ; Weber, D. ; Clercq, P. De; Gols, R. - \ 2013
    Entomologia Experimentalis et Applicata 149 (2013). - ISSN 0013-8703 - p. 219 - 228.
    cotesia-glomerata l. - host behavior - insect parasitoids - manipulation - wasp - hyperparasitism - populations - braconidae - strategies - usurpation
    In some parasitic Hymenoptera the dying caterpillars remain attached or close to the parasitoid cocoons. It has been suggested that the caterpillars act as ‘bodyguards’ for the vulnerable cocoons and therefore protect them against predators and/or hyperparasitoids (the ‘usurpation hypothesis’). This hypothesis has been demonstrated in associations where the caterpillars remain active and/or aggressive after parasitism. However, in other associations the caterpillars are so physiologically depleted after parasitism that they are unable to physically defend the cocoons and instead sit atop them in a moribund state. In this study a generalist predator, the spined soldier bug, Podisus maculiventris Say (Hemiptera: Pentatomidae), was provided with cocoons of the gregarious endoparasitoid Cotesia glomerata L. and the solitary endoparasitoid Microplitis mediator Haliday (both Hymenoptera: Braconidae), in turn attended by their hosts, Pieris brassicae L. (Lepidoptera: Pieridae) and Mamestra brassicae L. (Lepidoptera: Noctuidae), respectively. Cotesia glomerata produces broods of up to 40 cocoons and the dying caterpillars sit atop the cocoons where they exhibit little response to physical stimuli. Previous studies reported that dying P. brassicae caterpillars were ineffective bodyguards against two species of hyperparasitoids. In both associations, the dying host caterpillars were significantly preferred as food by P. maculiventris over the parasitoid cocoons. However, in absence of caterpillars, the bugs readily attacked the C. glomerata cocoons. Alternatively, the survival of M. mediator was very low, irrespective of whether a caterpillar was present or not. Caterpillars attacked by M. mediator are several times smaller than those attacked by C. glomerata. Consequently, the predators ran out of food much more quickly in the former and switched from one prey to the other. We show that in some host–parasitoid associations the dying caterpillars provide more visually apparent or nutritionally superior prey, rather than acting as bodyguards.
    Ecosystem-based coastal defence in the face of global change
    Temmerman, S. ; Meire, P. ; Bouma, T.J. ; Herman, P.M.J. ; Ysebaert, T. ; Vriend, H.J. de - \ 2013
    Nature 504 (2013). - ISSN 0028-0836 - p. 79 - 83.
    tidal marsh - scheldt estuary - climate-change - storm surges - sea-level - restoration - sedimentation - strategies - mangroves - carbon
    The risk of flood disasters is increasing for many coastal societies owing to global and regional changes in climate conditions, sea-level rise, land subsidence and sediment supply. At the same time, in many locations, conventional coastal engineering solutions such as sea walls are increasingly challenged by these changes and their maintenance may become unsustainable. We argue that flood protection by ecosystem creation and restoration can provide a more sustainable, cost-effective and ecologically sound alternative to conventional coastal engineering and that, in suitable locations, it should be implemented globally and on a large scale.
    Maximizing the nitrogen efficiency of a prototype mixed crop-livestock farm in The Netherlands
    Lantinga, E.A. ; Boele, E. ; Rabbinge, R. - \ 2013
    NJAS Wageningen Journal of Life Sciences 66 (2013). - ISSN 1573-5214 - p. 15 - 22.
    ammonia volatilization - slurry manure - dairy farm - management - soil - system - strategies - emissions - protein - marke
    This paper describes the year-over-year improvement of the nitrogen (N) efficiency in a prototype mixed farm system through the implementation of a coherent set of ecotechnological adjustments. This farm, the former APMinderhoudhoeve, was located on a marine clay loam soil in Oostelijk Flevoland, the Netherlands, reclaimed from the sea in the late 1950s. The designed farm structure was representative for the Dutch soil-bound agriculture in the late 1990s in terms of food crops’ choice and average level of milk production per ha of farmland. Key management strategies were the inclusion of grass-clover leys in the 7-year crop rotation, restricted grazing of the dairy herd and protein-poor and fibre-rich cattle diets including cereal straw. The farm components animal-manure-soil-crop were analysed in-depth in order to evaluate N flows and soil organic matter (SOM) dynamics at the farm system level, covering a period of six years. In its final experimental state, farm N use efficiency, expressed as the proportion of purchased crop fertilizers and cattle feed that was sold as exported products (crops, milk and cattle), was as high as 73%, Besides, total environmental losses were as low as 42 kg N ha-1 yr-1. A scenario analysis revealed that these losses could be further minimized to 30 kg N ha-1 yr-1 in the stabilization phase, of which one-third as leached nitrate and a somewhat higher fraction as volatilized ammonia. The remaining losses represented mainly denitrified harmless N2 from the stored animal slurry and farmyard manure. Soil N accumulated at an average rate of 89 kg N ha-1 yr-1, whereas SOM showed a positive trend but with fluctuations from year to year which were negatively related to the annual rainfall amount. Despite the lowered protein content in the cow diets, average annual milk production increased from 8100 tot 8700 kg cow-1. This could be mainly ascribed to a lower cow replacement rate due to less animal health problems, leading to an increased average lactation number of the dairy herd. Overall, the obtained environmental side effects on the prototype farm in its final experimental state were already below the targets set by the European Union with respect to the Nitrate Directive for the year 2020. It is concluded that when the best ecotechnological means are combined in a balanced mixed farm system a multiple win situation is attained in terms of food production capacity, cattle health and environmental quality.
    Potato Crop Response to Genotype and Environment in a Subtropical Highland Agro-ecology
    Molahlehi, L. ; Steyn, J.M. ; Haverkort, A.J. - \ 2013
    Potato Research 56 (2013)3. - ISSN 0014-3065 - p. 237 - 258.
    climate-change - planting date - yield components - harvest index - water-stress - growth - tuber - adaptation - strategies - cultivars
    Potato response to environment, planting date and genotype was studied for different agro-ecological zones in Lesotho. Field experiments were conducted at four different sites with altitudes ranging from 1,655 to 2,250 m above sea level during the 2010/2011 and 2011/2012 summer growing seasons. Treatments consisted of three cultivars that varied in maturity type, two planting dates and four sites differing in altitude and weather patterns. Various plant parts were measured periodically. To understand and quantify the influence of abiotic factors that determine and limit yields, the LINTUL crop growth model was employed which simulated potential yields for the different agro-ecological zones using weather data collected per site during the study period. Observed actual crop yields were compared with model simulations to determine the yield gap. Model simulations helped to improve our understanding of yield limitations to further expand potato production in subtropical highlands, with emphasis on increasing production through increased yields rather than increased area. Substantial variation in yield between planting date, cultivar and site were observed. Average tuber dry matter (DM) yields for the highest yielding season were above 7.5 t DM ha-1 or over 37.5 t ha-1 fresh tuber yield. The lowest yield obtained was 2.39 t DM ha-1 or 12 t ha-1 fresh tuber yield for cultivar Vanderplank in the 2011/2012 growing season at the site with the lowest altitude. Modelled potential tuber yields were 9–14 t DM ha-1 or 45–70 t ha-1 fresh yield. Drought stress frequently resulted in lower radiation use efficiencies and to a lesser degree harvest indices, which reduced tuber yield. The site with the lowest altitude and highest temperatures had the lowest yields, while the site with the highest altitude had the highest yields. Later maturing cultivars yielded more than earlier maturing ones at all sites. It is concluded that the risk of low yields in rain-fed subtropical highlands can be minimised by planting late cultivars at the highest areas possible as early as the risks of late frosts permit
    The potential of antiviral agents to control classical swine fever: A modelling study.
    Backer, J.A. ; Vrancken, R. ; Neyts, J. ; Goris, N. - \ 2013
    Antiviral Research 99 (2013)3. - ISSN 0166-3542 - p. 245 - 250.
    virus - netherlands - pigs - transmission - vaccination - strategies - epidemics - marker
    Classical swine fever (CSF) represents a continuous threat to pig populations that are free of disease without vaccination. When CSF virus is introduced, the minimal control strategy imposed by the EU is often insufficient to mitigate the epidemic. Additional measures such as preemptive culling encounter ethical objections, whereas emergency vaccination leads to prolonged export restrictions. Antiviral agents, however, provide instantaneous protection without inducing an antibody response. The use of antiviral agents to contain CSF epidemics is studied with a model describing within- and between-herd virus transmission. Epidemics are simulated in a densely populated livestock area in The Netherlands, with farms of varying sizes and pig types (finishers, piglets and sows). Our results show that vaccination and/or antiviral treatment in a 2 km radius around an infected herd is more effective than preemptive culling in a 1 km radius. However, the instantaneous but temporary protection provided by antiviral treatment is slightly less effective than the delayed but long-lasting protection offered by vaccination. Therefore, the most effective control strategy is to vaccinate animals when allowed (finishers and piglets) and to treat with antiviral agents when vaccination is prohibited (sows). As independent control measure, antiviral treatment in a 1 km radius presents an elevated risk of epidemics running out of control. A 2 km control radius largely eliminates this risk.
    Amazon poison frogs (Ranitomeya amazonica) use different phytotelm characteristics to determine their suitablility for egg and tadpole deposition
    Poelman, E.H. ; Wijngaarden, R.P.A. van; Raaijmakers, C.E. - \ 2013
    Evolutionary Ecology 27 (2013)4. - ISSN 0269-7653 - p. 661 - 674.
    dendrobates-ventrimaculatus - parental care - intraguild predation - habitat selection - oviposition-site - cannibalism - competition - strategies - anura - size
    Parents have to assess the multivariate characteristics of their reproductive sites to maximize their reproductive success through offspring performance. In addition, they may provide care to ensure optimal performance of their offspring. In poison frogs it has been identified that ecological characteristics of reproductive sites may underlie transitions in the involvement of parental sexes in care for offspring. To elucidate the ecological factors that may drive these transitions, it is important to understand which characteristics poison frogs use to assess the quality of their reproductive site. We studied the use of small water bodies in leaf axils of bromeliads, phytotelmata, for egg and tadpole deposition by Amazon poison frogs (Ranitomeya amazonica). We compared phytotelm quality characteristics for preferred egg and tadpole deposition sites and used two choice tests with plastic cups to study the causal relationship with tadpole deposition for the identified characteristics. The differences among quality characteristics of deposition sites were largest among bromeliad species, and for egg or tadpole deposition different bromeliad species were preferred. However, males were also selective in the leaf axils within a bromeliad species that they used for egg or tadpole deposition. Eggs were deposited in small, resource limited water bodies that were close to the forest floor. Tadpoles were deposited in leaf axils holding resource-rich phytotelmata with larger water volumes. Preference of detritus containing water over clear water in choice tests confirmed that Amazon poison frogs assess quality of their tadpole deposition sites on food availability. We conclude that preference for large water volume and resource rich phytotelmata plays an important role in determining male involvement in parental care and speculate that distribution of preferred resources may bring about selection on female involvement in parental care.
    Biotic plant-soil feedbacks across temporal scales
    Kardol, P. ; Deyn, G.B. de; Laliberté, E. ; Mariotte, P. ; Hawkes, C.V. - \ 2013
    Journal of Ecology 101 (2013)2. - ISSN 0022-0477 - p. 309 - 315.
    temperate tree - succession - community - responses - facilitation - strategies - grassland - diversity - pathogens - dynamics
    1. Plant effects on soil biota can result in feedbacks affecting plant performance, with consequences for plant community and ecosystem dynamics on short and long time-scales. In addition, the strength and direction of plant-soil feedbacks depend on temporal shifts in abiotic environmental conditions. 2. We synthesize current knowledge on temporal aspects of plant-soil feedbacks and present new ideas to better understand and predict the effects of plant-soil feedbacks on community and ecosystem properties across temporal scales. 3. Explaining short-term temporal feedback dynamics requires us to better understand mechanistic linkages between plants, soil organisms and locally available resources. On the other hand, we need to refine our understanding of the context-dependency of plant-soil feedbacks, as the strength and direction of feedback interactions are influenced by 'external' temporal ecosystem dynamics, such as variation in soil resource availability after disturbance or during succession. 4. Synthesis. Based on our synthesis of temporal aspects of plant-soil feedbacks, we suggest three main avenues for future research: (i) how plant-soil feedbacks changes with ontogeny, (ii) how plant and soil organism traits drive temporal variation in plant-soil feedbacks and (iii) how environmental changes across temporal scales alter the strength and direction of plant-soil feedbacks.
    Effect of frying instructions for food handlers on acrylamide concentration in French Fries: an explorative study
    Sanny, M.A.I. ; Luning, P.A. ; Jinap, S. ; Bakker, E.J. ; Boekel, T. van - \ 2013
    Journal of Food Protection 76 (2013)3. - ISSN 0362-028X - p. 462 - 472.
    quality management research - techno-managerial approach - mu-g/kg acrylamide - service establishments - reducing sugars - safety - temperature - strategies - reduction - behavior
    The objective of this study was to obtain insight into the effect of frying instructions on food handlers' control decisions in restaurants and to investigate the impact of control decisions on the variation and concentration of acrylamide in French fries. The concentrations of acrylamide and reducing sugars were analyzed, the frying temperature and time were measured, and thawing practices were observed. The results obtained before and after instructions were provided to the food handlers were compared for restaurants as a group and for each restaurant. Frying instructions supported food handlers' decisions to start frying when the oil temperature reached 175°C; all handlers started frying at the correct temperature. However, the effect of the instructions on the food handlers' decisions for frying time differed; most handlers increased the frying time beyond 240 s to achieve crispier French fries with a final color dictated by their preference. Providing instructions did not result in a significant difference in the mean concentration of acrylamide in French fries for the restaurants as a group. However, data analyzed for each restaurant revealed that when food handlers properly followed the instructions, the mean concentration of acrylamide was significantly lower (169 µg/kg) than that before instructions were provided (1,517 µg/kg). When food handlers did not complying with the frying instructions, mean acrylamide concentrations were even higher than those before instructions were provided. Two different strategies were developed to overcome the noncompliant behavior of food handlers: establishing requirements for the features of commercial fryers and strict monitoring of compliance with instructions.
    Understanding interactive knowledge development in coastal projects
    Seijger, C. ; Dewulf, G. ; Otter, H. ; Tatenhove, J. van - \ 2013
    Environmental Science & Policy 29 (2013). - ISSN 1462-9011 - p. 103 - 114.
    science-policy interface - dutch water management - river management - climate-change - search - stakeholders - information - scientists - challenges - strategies
    Various concepts have been developed that refer to interactive modes of knowledge production. Examples such as Mode 2 knowledge and post-normal science highlight the involvement of researchers, decision makers and other societal actors, in order to develop relevant knowledge for decision making. Existing research into such modes of knowledge development focuses on the interfaces between science, policy, and society. This paper introduces a conceptual framework for the connection between interactive knowledge development and a project environment. The aim of this paper is to improve the understanding of interactive knowledge development in a project environment, by presenting a case study of interactive knowledge development in a coastal project. Coastal projects intend to develop solutions in the coastal zone: a dynamic and fast changing environment. This paper adapts the policy arrangement approach to study interactive knowledge development longitudinally in the Texel dike reinforcement project. Eight mechanisms are derived that affect and explain the process of interactive knowledge development in this case. The mechanisms indicate how interactive knowledge development may result in more relevant knowledge and broadly accepted solutions.
    Challenges in the nutrition and management of herbivores in the temperate zone
    Vuuren, A.M. van; Chilibroste, P. - \ 2013
    Animal 7 (2013)s1. - ISSN 1751-7311 - p. 19 - 28.
    water-soluble carbohydrate - lolium-perenne l. - dairy-cows - milk-production - early lactation - rumen function - dry period - cattle - performance - strategies
    The expected higher global demand for animal proteins and the competition for starch and sugars between food, fuel and feed seem to favour herbivores that convert solar energy captured in fibrous plants into animal products. However, the required higher production level of herbivores questions the sustainability of this conversion. An increase in herbivore production can be achieved by increasing the number of animals associated with the increasing demand of plant biomass or by improving the efficiency with which plant biomass is converted into meat and milk. The potential to increase food production by cattle, the main food-producing herbivore in the temperate zones outside China, was considered in three production systems: grassland-based, mixed rain-fed and mixed irrigated systems. The potential to increase plant biomass production in grassland-based systems seems limited, unless fertiliser is imported in large quantities and crop production is increased, sacrificing valuable, high-quality grasslands, which often conflicts with sustainable production methods. Also, in mixed systems with high inputs of fertiliser or water, improvements in plant biomass production seem marginal and the main challenges for these systems are in breeding high-quality plant biomass at lower levels of fertiliser and the use of new co-products from food processing and bio-based economies. Consequently, the main challenge in herbivore nutrition management is to improve the efficiency of plant biomass utilisation. Stocking rate management along with seasonal variation in the grazing capacity of grasslands and moderate use of fertiliser may increase meat production in grassland-based systems by 400%. Improving plant biomass utilisation in the more industrialised mixed rain-fed systems seems possible by better feed storage technologies and for dairy cattle by improving animal health and lifetime production level. Managing the transition period seems crucial to achieve more sustainable mixed rain-fed and mixed irrigated dairy production systems. Whether sustainable production methods will be implemented also depends on macro-economic conditions and awareness of regional and global environmental concerns.
    Are lianas more drought-tolerant than trees? A test for the role of hydraulic architecture and other stem and leaf traits
    Sande, M.T. van der; Poorter, L. ; Schnitzer, S.A. ; Markesteijn, L. - \ 2013
    Oecologia 172 (2013)4. - ISSN 0029-8549 - p. 961 - 972.
    dry forest canopy - tropical forest - xylem cavitation - functional traits - lowland forest - woody-plants - trade-offs - growth - vulnerability - strategies
    Lianas are an important component of Neotropical forests, where evidence suggests that they are increasing in abundance and biomass. Lianas are especially abundant in seasonally dry tropical forests, and as such it has been hypothesized that they are better adapted to drought, or that they are at an advantage under the higher light conditions in these forests. However, the physiological and morphological characteristics that allow lianas to capitalize more on seasonal forest conditions compared to trees are poorly understood. Here, we evaluate how saplings of 21 tree and liana species from a seasonal tropical forest in Panama differ in cavitation resistance (P50) and maximum hydraulic conductivity (Kh), and how saplings of 24 tree and liana species differ in four photosynthetic leaf traits (e.g., maximum assimilation and stomatal conductance) and six morphological leaf and stem traits (e.g., wood density, maximum vessel length, and specific leaf area). At the sapling stage, lianas had a lower cavitation resistance than trees, implying lower drought tolerance, and they tended to have a higher potential hydraulic conductivity. In contrast to studies focusing on adult trees and lianas, we found no clear differences in morphological and photosynthetic traits between the life forms. Possibly, lianas and trees are functionally different at later ontogenetic stages, with lianas having deeper root systems than trees, or experience their main growth advantage during wet periods, when they are less vulnerable to cavitation and can achieve high conductivity. This study shows, however, that the hydraulic characteristics and functional traits that we examined do not explain differences in liana and tree distributions in seasonal forests
    Energy consumption practices of rural households in north China: Basic characteristics and potential for low carbon development
    Liu Wenling, Wenling ; Spaargaren, G. ; Heerink, N. ; Mol, A.P.J. ; Wang, C. - \ 2013
    Energy Policy 55 (2013). - ISSN 0301-4215 - p. 128 - 138.
    co2 emissions - cooking - province - model - electrification - alternatives - bangladesh - strategies - patterns - villages
    Reducing the climate impact of rural household energy consumption in China is complicated since it is bound up with deeply routinized daily practices and dependent from existing infrastructural systems of energy supply. To assess the potential for low carbon development we first estimate the overall CO2 emissions of rural households, followed by a more in depth description and characterization of the different energy use practices within the households. Space heating turns out to be the largest emission source among domestic energy practices in north China. We present lifestyle and context related factors that help to explain existing differences in domestic energy use practices of households. The potential for low carbon development is discussed both at the demand side and the supply side. At the demand side, the use of more efficient technologies and cleaner energy sources for space heating seems to be a high potential measure for achieving low carbon households. At the supply side the reduction of rural domestic CO2 emissions could be effectively supported by making available to householders renewable and cleaner energy sources and technologies. In order to be effective, such low carbon energy options should take into account the (income) characteristics and lifestyles of rural householders
    Representing major soil variability at regional scale by constrained Latin Hypercube Sampling of remote sensing data
    Mulder, V.L. ; Bruin, S. de; Schaepman, M.E. - \ 2013
    International Journal of applied Earth Observation and Geoinformation 21 (2013). - ISSN 0303-2434 - p. 301 - 310.
    design-based estimation - spatial prediction - classification tree - optimization - landscape - attributes - strategies - variables - desert - model
    This paper presents a sparse, remote sensing-based sampling approach making use of conditioned Latin Hypercube Sampling (cLHS) to assess variability in soil properties at regional scale. The method optimizes the sampling scheme for a defined spatial population based on selected covariates, which are assumed to represent the variability of the target variables. The optimization also accounts for specific constraints and costs expressing the field sampling effort. The approach is demonstrated using a case study in Morocco, where a small but representative sample record had to be collected over a 15,000 km2 area within 2 weeks. The covariate space of the Latin Hypercube consisted of the first three principal components of ASTER imagery as well as elevation. Comparison of soil properties taken from the topsoil with the existing soil map, a geological map and lithological data showed that the sampling approach was successful in representing major soil variability. The cLHS sample failed to express spatial correlation; constraining the LHS by a distance criterion favoured large spatial variability within a short distances resulting in an overestimation of the variograms nugget and short distance variability. However, the exhaustive covariate data appeared to be spatially correlated which supports our premise that once the relation between spatially explicit remote sensing data and soil properties has been modelled, the latter can be spatially predicted based on the densely sampled remotely sensed data. Therefore, the LHS approach is considered as time and cost efficient for regional scale surveys that rely on remote sensing-based prediction of soil properties.
    Monitoring and evaluation of spatially managed areas: A generic framework for implementation of ecoystem based marine management and its application
    Stelzenmueller, V. ; Breen, P. ; Stamford, T. ; Dankers, N.M.J.A. ; Jak, R.G. ; Hofstede, R. ter - \ 2013
    Marine Policy 37 (2013). - ISSN 0308-597X - p. 149 - 164.
    sea use management - fisheries management - methodological approach - offshore waters - indicators - conservation - uncertainty - habitats - objectives - strategies
    This study introduces a framework for the monitoring and evaluation of spatially managed areas (SMAs), which is currently being tested by nine European case studies. The framework provides guidance on the selection, mapping, and assessment of ecosystem components and human pressures, the evaluation of management effectiveness and potential adaptations to management. Moreover, it provides a structured approach with advice on spatially explicit tools for practical tasks like the assessment of cumulative impacts of human pressures or pressure-state relationships. The case studies revealed emerging challenges, such as the lack of operational objectives within SMAs, particularly for transnational cases, data access, and stakeholder involvement. Furthermore, the emerging challenges of integrating the framework assessment using scientific information with a structured governance research analysis based mainly on qualitative information are addressed. The lessons learned will provide a better insight into the full range of methods and approaches required to support the implementation of the ecosystem approach to marine spatial management in Europe and elsewhere.
    Predicted accuracy of and response to genomic selection for new traits in dairy cattle
    Calus, M.P.L. ; Haas, Y. de; Pszczola, M.J. ; Veerkamp, R.F. - \ 2013
    Animal 7 (2013)2. - ISSN 1751-7311 - p. 183 - 191.
    genetic-relationship information - breeding programs - holstein cattle - energy-balance - strategies - emissions - progress - schemes - designs - impact
    Genomic selection relaxes the requirement of traditional selection tools to have phenotypic measurements on close relatives of all selection candidates. This opens up possibilities to select for traits that are difficult or expensive to measure. The objectives of this paper were to predict accuracy of and response to genomic selection for a new trait, considering that only a cow reference population of moderate size was available for the new trait, and that selection simultaneously targeted an index and this new trait. Accuracy for and response to selection were deterministically evaluated for three different breeding goals. Single trait selection for the new trait based only on a limited cow reference population of up to 10 000 cows, showed that maximum genetic responses of 0.20 and 0.28 genetic standard deviation (s.d.) per year can be achieved for traits with a heritability of 0.05 and 0.30, respectively. Adding information from the index based on a reference population of 5000 bulls, and assuming a genetic correlation of 0.5, increased genetic response for both heritability levels by up to 0.14 genetic s.d. per year. The scenario with simultaneous selection for the new trait and the index, yielded a substantially lower response for the new trait, especially when the genetic correlation with the index was negative. Despite the lower response for the index, whenever the new trait had considerable economic value, including the cow reference population considerably improved the genetic response for the new trait. For scenarios with a zero or negative genetic correlation with the index and equal economic value for the index and the new trait, a reference population of 2000 cows increased genetic response for the new trait with at least 0.10 and 0.20 genetic s.d. per year, for heritability levels of 0.05 and 0.30, respectively. We conclude that for new traits with a very small or positive genetic correlation with the index, and a high positive economic value, considerable genetic response can already be achieved based on a cow reference population with only 2000 records, even when the reliability of individual genomic breeding values is much lower than currently accepted in dairy cattle breeding programs. New traits may generally have a negative genetic correlation with the index and a small positive economic value. For such new traits, cow reference populations of at least 10 000 cows may be required to achieve acceptable levels of genetic response for the new trait and for the whole breeding goal.
    The effect of uniform capture molecule orientation on biosensor sensitivity : dependence on analyte properties
    Trilling, A.K. ; Harmsen, M.M. ; Ruigrok, V.J. ; Zuilhof, H. ; Beekwilder, J. - \ 2013
    Biosensors and Bioelectronics 40 (2013)1. - ISSN 0956-5663 - p. 219 - 226.
    mouth-disease virus - domain antibody fragments - chain variable domain - passive-immunization - immobilization - protein - llama - immunoglobulin - biotinylation - strategies
    Uniform orientation of capture molecules on biosensors has been reported to increase sensitivity. Here it is investigated which analyte properties contribute to sensitivity by orientation. Orientation of capture molecules on biosensors was investigated using variable domains of llama heavy-chain antibodies (VHHs) as capture molecule, and a surface plasmon resonance (SPR) chip as biosensor. Two VHHs were tested in this study: one recognizing foot-and-mouth disease virus (FMDV) and another recognizing the 16 kDa heat-shock protein of Mycobacterium tuberculosis. SPR chips with randomly immobilized biotinylated VHHs were compared to streptavidin-coated SPR chips, on which similar quantities of oriented biotinylated VHHs were non-covalently immobilized. Analytes that differ in molecular weight, epitope number and epitope affinity were compared using the FMDV-recognizing VHH. When binding of intact FMDV particles (146 S; 8200 kDa) or pentameric FMDV coat protein aggregates (12 S; 282 kDa) was detected, a modest (1–
    Best Practices for New Product Pricing: Impact on Market Performance and Price Level under Different Conditions
    Ingenbleek, P.T.M. ; Frambach, R.T. ; Verhallen, Th.M.M. - \ 2013
    Journal of Product Innovation Management 30 (2013)3. - ISSN 0737-6782 - p. 560 - 573.
    organizational research - contingency approach - buyers perceptions - strategies - orientation - industrial - quality - model - perspective - advantage
    To date, research on new product pricing has predominantly been approached as a choice between market skimming and penetration pricing. Despite calls for research that addresses other complexities in new product pricing, empirical research responding to these calls remains scarce. This paper examines three managerial price-setting practices for new products, i.e., value-informed, competition-informed, and cost-informed pricing. By engaging in these practices, managers can develop and compare quantifications in order to attain an introduction price for the product. The authors draw on consumer price perception literature, Monroe's pricing discretion model, and numerical cognition literature to develop hypotheses about the impact of price-setting practices on new product market performance and price level. By studying the effects on market performance and price level, the paper provides insights that may help explain the growth of new products and address the problems of underpricing. The hypotheses are tested in a management survey of 144 production and service companies. The results indicate which pricing practices are superior for the achievement of either higher market performance or higher prices in specific product and market conditions. Whereas value-informed pricing has an unambiguous positive impact on relative price level and market performance, the results also suggest that in many cases engaging in value-informed pricing is not enough. The effects of cost-informed and competition-informed pricing may differ depending upon the objective (market performance or higher prices), product conditions (product advantage and relative product costs), and market condition (competitive intensity). Engaging in inappropriate pricing practices leads to a decline in new product performance. Moreover, bad pricing practices make the positive effect of product advantage on the outcome variables disappear. The latter finding suggests that companies can jeopardize their efforts and investments in the new product development process if they engage in the wrong price-setting practices. The findings imply that managers should consider different factors in new product pricing. First, when launching a new product, they should determine their explicit pricing objective, either stressing market performance or a higher price level. To determine the most appropriate pricing practices, however, they should next assess their situation in terms of product advantage, relative product costs, and competitive intensity. Together with the pricing objective, these conditions determine the best pricing practice. On a higher level, the findings imply that companies should invest in knowledge development in order to engage in the appropriate pricing practices for each product launch
    Foraging black-browed albatrosses target waters overlaying moraine banks-a consequence of upward benthic-pelagic coupling?
    Wakefield, E.D. ; Phillips, R.A. ; Belchier, M. ; Aarts, G. ; Mackenzie, M. ; McConnell, B.J. - \ 2012
    Antarctic Science 24 (2012)3. - ISSN 0954-1020 - p. 269 - 280.
    south-georgia - shag rocks - shelf - segregation - seabirds - ocean - diet - sea - chrysostoma - strategies
    Wide-ranging, surface-feeding pelagic seabirds are the most numerous functional group of birds in the Southern Ocean. The mesoscale habitat use of these birds is increasingly being quantified by relating their movements to remotely sensed, near surface properties of the ocean. However, prey availability at the sea surface may also be determined by habitat characteristics not measurable from space. For instance, benthic-pelagic coupling, which occurs when seabed processes affect productivity in the epipelagic zone, can link benthic habitat type to availability of surface prey. We combined acoustically derived maps of the substrate of the South Georgia shelf with GPS tracking to quantify the sub-mesoscale habitat use of breeding black-browed albatrosses. We show that albatrosses preferentially used waters overlaying glacial moraine banks near the shelf edge and that this was unrelated to the presence of trawlers targeting mackerel icefish, which are also associated with these features. Stomach temperature profiles suggest that albatrosses primarily caught krill and fish over the banks.We hypothesize that black-browed albatrosses target waters overlaying moraine banks due to upward benthic-pelagic coupling, mediated by an increase in abundance of zooplankton such as Antarctic krill. Our findings suggest that the potential effects of such processes on pelagic seabird distribution warrant wider investigation.
    Environmental flows and its evaluation of restoration effect based on LEDESS model in Yellow River Delta wetlands
    Wang, X.G. ; Lian, Y. ; Huang, C. ; Wang, X.J. ; Wang, R.L. ; Shan, K. ; Pedroli, B. ; Eupen, M. van; Elmahdi, A. ; Ali, M. - \ 2012
    Mitigation and Adaptation Strategies for Global Change 17 (2012)4. - ISSN 1381-2386 - p. 357 - 367.
    ecosystems - strategies - protection
    Due to freshwater supplement scarcity and heavy human activities, the fresh water wetland ecosystem in Yellow River Delta is facing disintegrated deterioration, and it is seriously affecting the health of the Yellow River ecosystem. This paper identifies the restoration objectives of wetland aiming to protect ecological and economic values and development as well as the water resources of the Yellow River. The hydraulic and groundwater coupling model and Landscape Ecological Decision and Evaluation Support System (LEDESS) of the Yellow River Delta were established to calculate environmental flows of degraded wetlands. LEDESS is a computer-based model developed and used to assess and evaluate the effects of land-use changes on nature. In this study, LEDESS is used to assess and evaluate the ecological effects and the restoration possibilities considering several environmental flows' supplement scenarios. This included the changes of suitable habitat conditions and its ecological carrying capacities for indicator species, e. g., Red-crowned crane (Grus japonensis), Oriental stork (Ciconia boyciana), and Saunder's gull (Larus relictus), and changing of ecological patterns. The results showed that replenishing fresh water to wetlands is one of the effective adaptive measures to mitigate wetland degradation and improve its habitat quality and carrying capacities. This study indicated that landscape ecology approach is not only considered as a good way to solve complex problems in ecosystem management but also can be used to decide on the environmental flows and assess its ecological effects in large-scale wetland rehabilitation. This integrated method could make environmental flows estimated and assessment more rational than the results of hydrologic methods. It could assist decision makers to "see" the ecological effects after water supplementing and so alleviate the contradictions between environmental flows and production water demands, and can facilitate the implementation of environmental flows in most countries with water resources shortage.
    A proposal for a new scenario framework to support research and assessment in different climate research communities
    Vuuren, D.P. van; Riahi, K. ; Moss, R. ; Edmonds, J. ; Thomson, A. ; Nakicenovic, N. ; Kram, T. ; Berkhout, F. ; Swart, R.J. ; Janetos, A. ; Rose, S.K. ; Arnell, N. - \ 2012
    Global environmental change : human and policy dimensions 22 (2012)1. - ISSN 0959-3780 - p. 21 - 35.
    expert judgments - impact assessment - vulnerability - costs - stabilization - adaptation - strategies
    In this paper, we propose a scenario framework that could provide a scenario "thread" through the different climate research communities (climate change - vulnerability, impact, and adaptation - and mitigation) in order to support assessment of mitigation and adaptation strategies and climate impacts. The scenario framework is organized around a matrix with two main axes: radiative forcing levels and socio-economic conditions. The radiative forcing levels (and the associated climate signal) are described by the new Representative Concentration Pathways. The second axis, socio-economic developments comprises elements that affect the capacity for mitigation and adaptation, as well as the exposure to climate impacts. The proposed scenarios derived from this framework are limited in number, allow for comparison across various mitigation and adaptation levels, address a range of vulnerability characteristics, provide information across climate forcing and vulnerability states and span a full century time scale. Assessments based on the proposed scenario framework would strengthen cooperation between integrated-assessment modelers, climate modelers and vulnerability, impact and adaptation researchers, and most importantly, facilitate the development of more consistent and comparable research within and across these research communities.
    A combination of functionally different plant traits provides a means to quantitatively predict a broad range of species assemblages in NW Europe
    Douma, J.C. ; Aerts, R. ; Witte, J.P.M. ; Bekker, R.M. ; Kunzmann, D. ; Metselaar, K. ; Bodegom, P.M. van - \ 2012
    Ecography 35 (2012)4. - ISSN 0906-7590 - p. 364 - 373.
    vegetatietypen - plantenecologie - vegetation types - plant ecology - relative growth-rate - community ecology - strategies - diversity - convergence - divergence - patterns - model - components - nitrogen
    Assembly theory predicts that filtering processes will select species by their attributes to build a community. Some filters increase functional similarity among species, while others lead to dissimilarity. Assuming converging processes to be dominant within habitats, we tested in this study whether species assemblages across a wide range of habitats can be distinguished quantitatively by their mean trait compositions. In addition, we investigated how many and which traits are needed to describe the differences between species assemblages best. The approach has been applied on a dataset that included 12 plant traits and 7644 vegetation releves covering a wide range of habitats in the Netherlands. We demonstrate that due to the dominant role of converging processes 1) the functional composition can explain up to 80% of the floristic differences between species assemblages using seven plant traits, showing that plant trait combinations provide a powerful tool for predicting the occurrence of species assemblages across different habitats; 2) to achieve a high performance, traits should be taken from different strategy components, i.e. traits that are functionally orthogonal, which does not necessarily coincide with low trait-trait correlations; 3) the different strategy components identified in this study correspond to the strategy components of some conventional plant ecological strategy schemes (PESS) schemes to describe the variation between individual species. However, some PESS merge traits into one strategy component that are shown to be functionally different when predicting species assemblages. If such PESS is used to predict assemblages, this leads to a loss in predictive capacity. Potentially, our new approach is globally applicable to quantify community assembly patterns. However this needs to be tested.
    Towards the implementation of an integrated ecosystem fleet-based management of European fisheries
    Gascuel, D. ; Merino, G. ; Döring, R.D. ; Druon, D.N. ; Goti, L. ; Guénette, S. ; Macher, C. ; Soma, K. ; Travers-Trolet, M. ; Mackinson, S. - \ 2012
    Marine Policy 36 (2012)5. - ISSN 0308-597X - p. 1022 - 1032.
    marine food webs - fish stocks - trophic-level - celtic sea - indicators - strategies - evaluate - policies - model
    Using the Celtic Sea and the North Sea as case studies, the fleet-based approach is shown to be the pathway to implement an effective ecosystem approach to fisheries management (EAFM) in European seas. First, a diagnostic on the health of each ecosystem is proposed based on the reconstruction of long time-series of catch, the analysis of mean indicators or stocks trajectories derived from ICES stock assessment results, and the analysis of ecosystem indicators. Then, a fleet-based synthesis is presented using indicators of both the ecological impact and the economic performances of the major fleets operating within each ecosystem. In particular, assessment diagrams show whether each fleet segment, on average, sustainably exploits the stocks. Although results are preliminary due to the poor quality of available data, the analysis shows that simple indicators can be estimated and clearly highlight contrasts between fleet segments. Such an approach contributes to the evolution from a stock-based to a fleet-based management, which reflects the ecological, economical and social pillars of the sustainable development of fisheries.
    Bioconjugation of Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicone Nitride
    Nguyen, A.T. ; Baggerman, J. ; Paulusse, J.M.J. ; Zuilhof, H. ; Rijn, C.J.M. van - \ 2012
    Langmuir 28 (2012)1. - ISSN 0743-7463 - p. 604 - 610.
    biosensor applications - poly(ethylene glycol) - antibody microarrays - surface - adsorption - well - membranes - plasma - immobilization - strategies
    A new method for attaching antibodies to protein-repellent zwitterionic polymer brushes aimed at recognizing microorganisms while preventing the nonspecific adsorption of proteins is presented. The poly(sulfobetaine methacrylate) (SBMA) brushes were grafted from a-bromo isobutyryl initiator-functionalized silicon nitride (SixN4, x = 3) surfaces via controlled atom-transfer radical polymerization (ATRP). A trifunctional tris(2-aminoethyl)amine linker was reacted with the terminal alkylbromide of polySBMA chains. N-Hydroxysuccinimide (NHS) functionalization was achieved by reacting the resultant amine-terminated polySBMA brush with bifunctional suberic acid bis(N-hydroxysuccinimide ester). Anti-Salmonella antibodies were subsequently immobilized onto polySBMA-grafted SixN4 surfaces through these NHS linkers. The protein-repellent properties of the polySBMA-grafted surface after antibody attachment were evaluated by exposing the surfaces to Alexa Fluor 488-labeled fibrinogen (FIB) solution (0.1 g·L–1) for 1 h at room temperature. Confocal laser scanning microscopy (CLSM) images revealed the minimal adsorption of FIB onto the antibody-coated polySBMA in comparison with that of antibody-coated epoxide monolayers and also bare SixN4 surfaces. Subsequently, the interaction of antibodies immobilized onto polySBMA with SYTO9-stained Salmonella solution without using blocking solution was examined by CLSM. The fluorescent images showed that antibody-coated polySBMA efficiently captured Salmonella with only low background noise as compared to antibody-coated monolayers lacking the polymer brush. Finally, the antibody-coated polySBMA surfaces were exposed to a mixture of Alexa Fluor 647-labeled FIB and Salmonella without the prior use of a blocking solution to evaluate the ability of the surfaces to capture bacteria while simultaneously repelling proteins. The fluorescent images showed the capture of Salmonella with no adsorption of FIB as compared to antibody-coated epoxide surfaces, demonstrating the potential of the zwitterionic layer in preventing the nonspecific adsorption of the proteins during the detection of bacteria in complex matrices.
    Uncertainty and climate treaties: Does ignorance pay?
    Dellink, R.B. ; Finus, M. - \ 2012
    Resource and Energy Economics 34 (2012)4. - ISSN 0928-7655 - p. 565 - 584.
    international environmental agreements - stability likelihood - irreversibility - strategies - coalitions - emissions - model
    Uncertainty and learning play an important role in the management of many environmental and resource problems and in particular in climate change. In stylized game-theoretic models of international environmental treaty formation, which capture the strategic interactions between nations, learning usually has a negative impact on the success of cooperation. We use a richer climate model that captures the large heterogeneity between different world regions and considers uncertainty about the benefits and costs from climate mitigation. By explicitly exploiting differences between regions and allowing transfers to mitigate free-rider incentives, we derive much more positive conclusions about the role of learning.
    Effect of host-cocoon mass on adult size in the secondary hyperparasitoid wasp, Pteromalus semotus (Hymenoptera: Pteromalidae)
    Harvey, J.A. ; Gumovsky, A. ; Gols, R. - \ 2012
    Insect Science 19 (2012)3. - ISSN 1672-9609 - p. 383 - 390.
    coccygomimus-turionellae - lysibia-nana - parasitoids - strategies - ichneumonidae - quality - fitness - larvae - constraints - growth
    Parasitoids have long proven to be model organisms in studying resource-related constraints on immature development. Here we examine the relationship between host cocoon (= pupal) size in the gregarious endoparasitoid wasp, Cotesia glomerata, and development time and adult size in the solitary idiobiont hyperparasitoid, Pteromalus semotus. Little is known about the biology or ecology of this ecto-hyperparasitoid species, although it is one of the major secondary hyperparasitoids of C. glomerata. The size of the adult wasp covaried with the size of the host cocoon at parasitism. Moreover, female wasps were larger than male wasps for a given cocoon size. Adult wasps have remarkably long life-spans, 3 months on average. Longevity did not significantly differ with sex. We also examined how larvae of P. semotus exclude other potential competitors. P. semotus is protandrous, with females taking significantly longer to complete their development than males. In experiments where several eggs of P. semotus were placed on individual pupae of C. glomerata, newly hatched hyperparasitoid larvae moved rapidly over the surface of the host and destroyed the eggs of any conspecifics by biting them before they would initiate feeding on host tissues. Our results are discussed in relation to those with other studies with solitary ichneumonid idiobiont hyperparasitoids of C. glomerata.
    Effect of Maruca vitrata (Lepidoptera: Crambidae) host plants on life-history parameters of the parasitoid Apanteles taragamae (Hymenoptera: Braconidae)
    Dannon, A.E. ; Tamo, M. ; Agboton, C. ; Huis, A. van; Dicke, M. - \ 2012
    Insect Science 19 (2012)4. - ISSN 1672-9609 - p. 518 - 528.
    legume pod borer - natural enemies - insect parasitoids - geyer lepidoptera - high-mortality - slow-growth - sex-ratios - pyralidae - wasp - strategies
    The effect of four host plant species of the herbivore Maruca vitrata Fabricius (Lepidoptera: Crambidae) on development time, longevity, fecundity and sex ratio of the parasitoid Apanteles taragamae Viereck (Hymenoptera: Braconidae) was investigated under laboratory conditions. The larvae were parasitized when in the second instar. Maruca vitrata larvae were fed with flowers of four legumes, that is, Vigna unguiculata (cowpea), Sesbania rostrata, Lonchocarpus sericeus and Pterocarpus santalinoides, or an artificial diet both before and after parasitization. The parasitoid did not develop in hosts feeding on L. sericeus or V. unguiculata at 25°C, or on P. santalinoides at 25°C or 29°C. Apanteles taragamae had the shortest development time on artificial diet at both 25°C and 29°C while the longest development time was recorded on L. sericeus at 29°C. Female wasps took longer to develop compared to males at the two temperatures, regardless of the feeding substrate of their host. The longevity of the wasps at 25°C varied among feeding substrates, but not at 29°C. Survival rate of parasitized larvae depends on the feeding substrate. Moreover, infection of host larvae with Maruca vitrata multi-nucleopolyhedrovirus (MaviMNPV) killed larger proportions of parasitized larvae at 25°C than at 29°C, which was likely caused by the difference in parasitoid developmental rate. The proportion of female parasitoids was lowest on L. sericeus. The daily fecundity showed a nonlinear trend regardless of the feeding substrate, indicating that A. taragamae is a pro-ovigenic species. The data support the slow growth–high mortality hypothesis.
    Lessons from Agriculture for the Sustainable Management of Malaria Vectors
    Thomas, M.B. ; Godfray, H.C.J. ; Read, A.F. ; Berg, H. van den; Tabashnik, B.E. ; Lenteren, J.C. van; Waage, J.K. ; Takken, W. - \ 2012
    PLOS Medicine 9 (2012)7. - ISSN 1549-1676
    anopheles-gambiae - pest-management - insecticide resistance - borne diseases - field trial - mosquito - strategies - impacts - africa - system
    The effectiveness of insecticide-treated bed nets and indoor insecticide sprays to control adult mosquito vectors is being threatened by the spread of insecticide resistance. We argue for expanding beyond “insecticide monotherapy” to more sustainable integrated vector management strategies that use optimal suites of control tactics. Experience in agriculture suggests that such integrated approaches can provide more effective and durable pest management. This shift will require increased investment in research and translational science. Failure to act risks a resurgence of malaria and erosion of community support and donor commitment.
    The effect of different dietary sugars and honey on longevity and fecundity in two hyperparasitoid wasps
    Harvey, J.A. ; Cloutier, J. ; Visser, B. ; Ellers, J. ; Wäckers, F.L. ; Gols, R. - \ 2012
    Journal of Insect Physiology 58 (2012)6. - ISSN 0022-1910 - p. 816 - 823.
    lifetime reproductive success - parasitoid aphytis-melinus - hymenopteran parasitoids - cotesia-glomerata - nutritional-value - mannose toxicity - aphid honeydew - floral nectar - strategies - evolution
    In nature adult insects, such as parasitic wasps or ‘parasitoids’ often depend on supplemental nutritional sources, such as sugars and other carbohydrates, to maximize their life-expectancy and reproductive potential. These food resources are commonly obtained from animal secretions or plant exudates, including honeydew, fruit juices and both floral and extra-floral nectar. In addition to exogenous sources of nutrition, adult parasitoids obtain endogenous sources from their hosts through ‘host-feeding’ behavior, whereby blood is imbibed from the host. Resources obtained from the host contain lipids, proteins and sugars that are assumed to enhance longevity and/or fecundity. Here we conducted an experiment exploring the effects of naturally occurring sugars on longevity and fecundity in the solitary hyperparasitoids, Lysibia nana and Gelis agilis. Although both species are closely related, L. nana does not host-feed whereas G. agilis does. In a separate experiment, we compared reproduction and longevity in G. agilis reared on either honey, a honey-sugar ‘mimic’, and glucose. Reproductive success and longevity in both hyperparasitoids varied significantly when fed on different sugars. However, only mannose- and water-fed wasps performed significantly more poorly than wasps fed on four other sugar types. G. agilis females fed honey produced twice as many progeny as those reared on the honey-sugar mimic or on glucose, whereas female longevity was only reduced on the mimic mixture. This result shows not only that host feeding influences reproductive success in G. agilis, but also that non-sugar constituents in honey do. The importance of non-sugar nutrients in honey on parasitoid reproduction is discussed.
    Quantifying the functional responses of vegetation to drought and oxygen stress in temperate ecosystems
    Douma, J.C. ; Bardin, V. ; Bartholomeus, R.P. ; Bodegom, P.M. van - \ 2012
    Functional Ecology 26 (2012)6. - ISSN 0269-8463 - p. 1355 - 1365.
    plant traits - soil-conditions - water-balance - strategies - patterns - aerenchyma - submergence - communities - tolerance - climate
    1. Our understanding of the generality of plant functional responses to water availability is limited; current field studies use either very rough approximations of water and oxygen availability or only focus on water-stressed ecosystems. Studies that relate species' responses to a surplus of water are limited to controlled experiments. 2. The aim of this study was to investigate how traits are selected along a gradient of soil moisture, ranging from oxygen-stressed to drought-stressed. We tested 15 traits: eight leaf traits, two root traits, two seed traits and three allometry traits and related their community means to process-based measures of drought stress and oxygen stress for 171 plots in the Netherlands. Because the trait values had been taken from a large database, an independent field survey was carried out to validate the relationships thus derived. 3. We show that root porosity and seed floating capacity are mostly strongly related, although still moderately, to oxygen and drought stress (R-2 = 27% and 42%, respectively). Leaf traits responded weakly to either of the stressors. The field survey yielded similar relationships. Trait combinations were much more closely related to oxygen or drought stress than individual traits, suggesting that there are multiple trait solutions at a given level of water and oxygen stress. 4. The relatively weak relationships found between traits and water-related stressors contrast with the strong control of other environmental drivers (disturbance, nutrients) on traits and suggest that these strong constraints imposed by other environmental drivers necessitate varied solutions to cope with water availability.
    Conservation Agriculture in mixed crop–livestock systems: Scoping crop residue trade-offs in Sub-Saharan Africa and South Asia
    Valbuena, D.F. ; Erenstein, O. ; Homann-Kee Tui, S. ; Abdoulaye, T. ; Claessens, L.F.G. ; Duncan, A.J. ; Gerard, B. ; Rufino, M. ; Teufel, N. ; Wijk, M.T. van - \ 2012
    Field Crops Research 132 (2012). - ISSN 0378-4290 - p. 175 - 184.
    smallholder farming systems - soil fertility management - pressure - food - productivity - strategies - community - dynamics - patterns - zimbabwe
    Conservation Agriculture (CA) is being advocated to enhance soil health and sustain long term crop productivity in the developing world. One of CA's key principles is the maintenance of soil cover often by retaining a proportion of crop residues on the field as mulch. Yet smallholder crop–livestock systems across Africa and Asia face trade-offs among various options for crop residue use. Knowledge of the potential trade-offs of leaving more residues as mulch is only partial and the objective of this research is to address some of these knowledge gaps by assessing the trade-offs in contrasting settings with mixed crop–livestock systems. The paper draws from village surveys in 12 sites in 9 different countries across Sub-Sahara Africa and South Asia. Sites were clustered into 3 groups along the combined population and livestock density gradients to assess current crop residue management practices and explore potential challenges to adopting mulching practices in different circumstances. Results show that although high-density sites face higher potential pressure on resources on an area basis, biomass production tends to be more substantial in these sites covering demands for livestock feed and allowing part of the residues to be used as mulch. In medium-density sites, although population and livestock densities are relatively lower, biomass is scarce and pressure on land and feed are high, increasing the pressure on crop residues and their opportunity cost as mulch. In low-density areas, population and livestock densities are relatively low and communal feed and fuel resources exist, resulting in lower potential pressure on residues on an area basis. Yet, biomass production is low and farmers largely rely on crop residues to feed livestock during the long dry season, implying substantial opportunity costs to their use as mulch. Despite its potential benefit for smallholder farmers across the density gradient, the introduction of CA-based mulching practices appears potentially easier in sites where biomass production is high enough to fulfil existing demands for feed and fuel. In sites with relatively high feed and fuel pressure, the eventual introduction of CA needs complementary research and development efforts to increase biomass production and/or develop alternative sources to alleviate the opportunity costs of leaving some crop residues as mulch.
    Value of information and mobility constraints for sampling with mobile sensors
    Ballari, D.E. ; Bruin, S. de; Bregt, A.K. - \ 2012
    Computers and Geosciences 49 (2012). - ISSN 0098-3004 - p. 102 - 111.
    networks - management - optimization - algorithms - strategies - tracking - fitness - design
    Wireless sensor networks (WSNs) play a vital role in environmental monitoring. Advances in mobile sensors offer new opportunities to improve phenomenon predictions by adapting spatial sampling to local variability. Two issues are relevant: which location should be sampled and which mobile sensor should move to do it? This paper proposes a form of adaptive sampling by mobile sensors according to the expected value of information (EVoI) and mobility constraints. EVoI allows decisions to be made about the location to observe. It minimises the expected costs of wrong predictions about a phenomenon using a spatially aggregated EVoI criterion. Mobility constraints allow decisions to be made about which sensor to move. A cost-distance criterion is used to minimise unwanted effects of sensor mobility on the WSN itself, such as energy depletion. We implemented our approach using a synthetic data set, representing a typical monitoring scenario with heterogeneous mobile sensors. To assess the method, it was compared with a random selection of sample locations. The results demonstrate that EVoI enables selecting the most informative locations, while mobility constraints provide the needed context for sensor selection. This paper therefore provides insights about how sensor mobility can be efficiently managed to improve knowledge about a monitored phenomenon.
    Is lowering reducing sugars concentration in French fries an effective measure to reduce acrylamide concentration in food service establishments?
    Sanny, M.A.I. ; Jinap, S. ; Bakker, E.J. ; Boekel, M.A.J.S. van; Luning, P.A. - \ 2012
    Food Chemistry 135 (2012)3. - ISSN 0308-8146 - p. 2012 - 2020.
    mu-g/kg acrylamide - risk-assessment - potatoes - temperature - asparagine - strategies - formation/elimination - exposure - kinetics - options
    The objective of this study was to obtain insight into the actual effectiveness of lowering reducing sugars concentration in par-fried potato strips on the concentration and variation of acrylamide in French fries prepared in real-life situations in food service establishments. Acrylamide, frying time, frying temperature, and reducing sugars were measured and characteristics of fryers were recorded. Data showed that the use of par-fried potato strips with lower concentrations of reducing sugars than the commonly used potato strips was an effective measure to reduce acrylamide concentrations in French fries prepared under standardised frying conditions. However, there was still large variation in the acrylamide concentrations in French fries, although the variation in reducing sugars concentrations in low and normal types of par-fried potato strips was very small and the frying conditions were similar. Factors that could affect the temperature–time profile of frying oil were discussed, such as setting a lower frying temperature at the end than at the start of frying, product/oil ratio and thawing practice. These need to be controlled in daily practice to reduce variation in acrylamide.
    Functional interactions between members of the REPAT family of insect pathogen-induced proteins
    Navarro-Cerrillo, G. ; Ferré, J. ; Maagd, R.A. de; Herrero, S. - \ 2012
    Insect Molecular Biology 21 (2012)3. - ISSN 0962-1075 - p. 335 - 342.
    bacillus-thuringiensis - spodoptera-exigua - molecular characterization - choristoneura-fumiferana - baculovirus infection - expression patterns - larvae - toxin - activation - strategies
    Studies on the transcriptional response to pathogens in the insect larval gut have shown the regulation of several genes after the infection. Repat (REsponse to PAThogens) genes were first identified in Spodoptera exigua midgut as being up-regulated in response to the exposure to Bacillus thuringiensis toxins and baculovirus. Recently, new members of the REPAT family showed a constitutive up-regulation in a B. thuringiensis-resistant population. Based on a yeast two-hybrid screening, we have detected the interaction of REPAT1 with other members of the REPAT family, leading to the discovery of a new member: REPAT8. The functional role of this interaction was shown by following the changes of the subcellular localization of REPAT1 in the presence of REPAT8. REPAT1 alone was localized exclusively in the cytoplasm, while the presence of REPAT8 led to the migration of REPAT1 to the nucleus. Finally, analysis of the expression pattern of eight REPAT members has shown that B. thuringiensis-related treatments (Cry1Ca toxin, Xentari™ product and an acrystalliferous strain) induced a general up-regulation of repat genes, especially of repat2. In contrast, no significant effect was detected after treatment with Escherichia coli or Enterococcus sp., or by the presence of microbiota in the midgut. The results suggest that the different repat genes play different roles in response to pathogens.
    Understanding growers' decisions to manage invasive pathogens at the farm level
    Breukers, A. ; Asseldonk, M.A.P.M. van; Bremmer, J. ; Beekman, V. - \ 2012
    Phytopathology 102 (2012)6. - ISSN 0031-949X - p. 609 - 619.
    perceived behavioral-control - planned behavior - citrus canker - risk analysis - disease - spread - pest - eradication - perceptions - strategies
    Globalization causes plant production systems to be increasingly threatened by invasive pests and pathogens. Much research is devoted to support management of these risks. Yet, the role of growers' perceptions and behavior in risk management has remained insufficiently analyzed. This article aims to fill this gap by addressing risk management of invasive pathogens from a sociopsychological perspective. An analytical framework based on the Theory of Planned Behavior was used to explain growers' decisions on voluntary risk management measures. Survey information from 303 Dutch horticultural growers was statistically analyzed, including regression and cluster analysis. It appeared that growers were generally willing to apply risk management measures, and that poor risk management was mainly due to perceived barriers, such as high costs and doubts regarding efficacy of management measures. The management measures applied varied considerably among growers, depending on production sector and farm-specific circumstances. Growers' risk perception was found to play a role in their risk management, although the causal relation remained unclear. These results underscore the need to apply a holistic perspective to farm level management of invasive pathogen risk, considering the entire package of management measures and accounting for sector- and farm-specific circumstances. Moreover, they demonstrate that invasive pathogen risk management can benefit from a multidisciplinary approach that incorporates growers' perceptions and behavior.
    The dynamics of digital dermatitis in populations of dairy cattle: Model-based estimates of transition rates and implications for control
    Dopfer, D. ; Holzhauer, M. ; Boven, M. van - \ 2012
    The Veterinary Journal 193 (2012)3. - ISSN 1090-0233 - p. 648 - 653.
    interdigital papillomatosis - foot lesions - risk-factors - herd-level - cows - strategies - copper
    Five groups of dairy cows affected by digital dermatitis were subjected to five different footbath strategies and evaluated at regular 3-weekly intervals. A standard protocol was used to record five different stages of disease from early (M1), acute ulcerative (M2), healing (M3) and chronic lesions (M4) in addition to the negative stage of disease (M0). The effect of the footbathing was evaluated using mathematical modelling for the transmission dynamics of infections and summarized using the reproduction ratio R(0). Sensitivity analysis for a range of parameters in the mathematical model showed that the speed of detecting acute lesions and the efficiency with which those lesions were treated were the key parameters which determined whether lesions became more severe or whether they healed.
    Improved functional immobilization of llama single-domain antibody fragments to polystyrene surfaces using small peptides
    Harmsen, M.M. ; Fijten, H.P.D. - \ 2012
    Journal of Immunoassay and Immunochemistry 33 (2012)3. - ISSN 1532-1819 - p. 234 - 251.
    linked-immunosorbent-assay - escherichia-coli - passive-immunization - mouth-disease - in-vitro - microarrays - strategies - bivalent - pigs - hydrophobins
    We studied the effect of different fusion domains on the functional immobilization of three llama single-domain antibody fragments (VHHs) after passive adsorption to polystyrene in enzyme-linked immunosorbent assays (ELISA). Three VHHs produced without any fusion domain were efficiently adsorbed to polystyrene, which, however, resulted in inefficient antigen binding. Functional VHH immobilization was improved by VHH fusion to a consecutive myc-His6-tag and was even more improved by fusion to the llama antibody long hinge region containing an additional His6-tag (LHc-His6). The partial dimerization of VHH-LHc-His6 fusion proteins through LHc-mediated disulfide-bond formation was not essential for their improved functional immobilization. VHH fusions to specific polystyrene binding peptides, hydrophobins, or other, unrelated VHH domains were less suitable for increasing functional VHH immobilization because of reduced microbial expression levels. Thus, VHH-LHc-His6 fusion proteins are most suited for functional passive adsorption in ELISA.
    The effect of an acidified, ionized copper sulphate solution on digital dermatitis in dairy cows
    Holzhauer, M. ; Bartels, C.J. ; Bergsten, C. ; Riet, M.M.J. van; Frankena, K. ; Lam, T.J.G.M. - \ 2012
    The Veterinary Journal 193 (2012)3. - ISSN 1090-0233 - p. 659 - 663.
    level risk-factors - herd-level - cattle - formaldehyde - strategies - footbaths - lameness - netherlands - prevalence - formalin
    Digital dermatitis (DD) is the most important infectious claw disorder in dairy cattle and herd-based foot bathing with antibacterials, such as 4% formalin, is often used to prevent it. However, there is a lack of long-term studies of the effectiveness of such regimes and in this study the preventive and curative effect of 4% formalin was compared with that of an acidified, ionized copper sulphate solution over a 4-month period on a commercial 120-cow dairy farm. The cows were walked through a split-leg footbath where left claws were treated with an acidified copper solution twice daily for 5 days/week, while right claws were treated with 4% formalin twice daily for 1 day/every second week. Hind claws were scored for the presence and severity of DD in a trimming chute at the start of the study and every 4 weeks throughout the study period. At the start of the study 21/110 cows had ulcerative DD lesions with 10 on the left hind foot, 8 on the right and 3 on both. These lesions, as well as any new lesions which arose during the study, were treatedwith chlortetracycline spray. During the study 440 observations were made and seven new DD lesionswere recorded on left feet (copper treated) and 20 on right feet (formalin treated). Based on survival analysis, the risk of developing a new ulcerative DD lesion on copper-treated (left hind) feet was almost three times less (RR = 0.37, 95% CI 0.16–0.91) than formalin-treated (right hind) feet. Cure rates of DD lesions were not different between copper and formalin.
    Vaccination against foot-and-mouth disease I: Epidemiological consequences
    Backer, J.A. ; Hagenaars, T.H.J. ; Nodelijk, G. ; Roermund, H.J.W. van - \ 2012
    Preventive Veterinary Medicine 107 (2012)1-2. - ISSN 0167-5877 - p. 27 - 40.
    great-britain - virus transmission - emergency vaccination - contact transmission - clinical variation - fmd epidemic - dairy-cows - pigs - outbreak - strategies
    An epidemic of foot-and-mouth disease (FMD) can have devastating effects on animal welfare, economic revenues, the export position and society as a whole, as occurred during the 2001 FMD epidemic in the Netherlands. Following the preemptive culling of 260,000 animals during this outbreak, the Dutch government adopted emergency vaccination as preferred control policy. However, a vaccination-to-live strategy has not been applied before, posing unprecedented challenges for effectively controlling the epidemic, regaining FMD-free status and minimizing economic losses. These three topics are covered in an interdisciplinary model analysis. In this first part we evaluate whether and how emergency vaccination can be effectively applied to control FMD epidemics in the Netherlands. For this purpose we develop a stochastic individual-based model that describes FMD virus transmission between animals and between herds, taking heterogeneity between host species (cattle, sheep and pigs) into account. Our results in a densely populated livestock area with >4 farms/km2 show that emergency ring vaccination can halt the epidemic as rapidly as preemptive ring culling, while the total number of farms to be culled is reduced by a factor of four. To achieve this reduction a larger control radius around detected farms and a corresponding adequate vaccination capacity is needed. Although sufficient for the majority of simulated epidemics with a 2 km vaccination zone, the vaccination capacity available in the Netherlands can be exhausted by pig farms that are on average ten times larger than cattle herds. Excluding pig farms from vaccination slightly increases the epidemic, but more than halves the number of animals to be vaccinated. Hobby flocks – modelled as small-sized sheep flocks – do not play a significant role in propagating the epidemic, and need not be targeted during the control phase. In a more sparsely populated livestock area in the Netherlands with about 2 farms/km2 the minimal control strategy of culling only detected farms seems sufficient to control an epidemic
    HIV and severity of seasonal household food-related coping behaviors in rural Ghana
    Akrofi, S. ; Price, L.L. ; Struik, P.C. - \ 2012
    Ecology of Food and Nutrition 51 (2012)2. - ISSN 0367-0244 - p. 148 - 175.
    sub-saharan africa - hiv/aids - security - insecurity - strategies - frequency - diversity - aids
    In-depth research was conducted to evaluate the seasonal food insecurity of HIV-positive and HIV-negative farm households in the Eastern Region, Ghana. A Coping Strategy Index (CSI) was used to assess household food-related coping behaviors. HIV-positive farm households often relied on both less severe and more severe coping behaviors, had a higher CSI, cultivated a smaller field area, harvested fewer food species from farms and gardens, and obtained income from fewer sources than HIV-negative farm households in both the post-harvest and lean seasons. We conclude that food insecurity is more severe in HIV-positive than in HIV-negative farm households in both seasons
    High-Resolution Mapping of Two Broad-Spectrum Late Blight Resistance Genes from Two Wild Species of the Solanum circaeifolium Group
    Verzaux, E.C. ; Arkel, G. van; Vleeshouwers, V.G.A.A. ; Vossen, E.A.G. van der; Niks, R.E. ; Jacobsen, E. ; Vossen, J.H. ; Visser, R.G.F. - \ 2012
    Potato Research 55 (2012)2. - ISSN 0014-3065 - p. 109 - 123.
    phytophthora-infestans resistance - potato-virus-y - disease resistance - nb-lrr - plants - cisgenesis - strategies - organisms - cloning - genome
    High levels of resistance to Phytophthora infestans in Solanum are predominantly based on the gene-for-gene interaction. Identification of hitherto unknown R genes is essential for future pyramiding approaches. This could be achieved either through classic introgression breeding or through cisgenesis and could lead to sustainable control of late blight. Here, we report on the mapping of Rpi-cap1 and Rpi-qum1, two late blight R genes identified in the wild species Solanum capsicibaccatum and Solanum circaeifolium ssp. quimense, respectively, to very similar positions on the long arm of chromosome 11. Despite the difficulties encountered for marker development, a high-resolution genetic map with cleaved amplified polymorphic sequence markers was constructed. Furthermore, an R gene cluster-directed profiling approach led to the development of markers that closely
    The composition of fish communities of nine Ethiopian lakes along a north-south gradient: threats and possible solutions
    Vijverberg, J. ; Dejen, E. ; Getahun, A. ; Nagelkerke, L.A.J. - \ 2012
    Animal Biology 62 (2012)3. - ISSN 1570-7555 - p. 315 - 335.
    rift-valley lakes - fresh-water ecosystems - species flock pisces - reproductive segregation - cyprinidae - tana - barbs - strategies - diversity - example
    Fish populations of nine Ethiopian freshwater lakes were quantitatively sampled with a standardized protocol, using multi-mesh gill nets. In total, 27 species were identified, but only 14 species were common. Based on the common species, the fish communities showed large differences in their species composition, except for Lake Abaya and Lake Chamo which were similar. Most fish species were observed in only one or two lakes. Compared with the information reported in literature the present study generally underestimated the species richness. The empirical model of Amarasinghe and Welcomme (2002) for African lakes was used to estimate fish species richness, which was compared with species presence reported in literature. Biodiversity in the two northern highland lakes is low, but not lower than the model estimate. Lake Tana has a high biodiversity which is close to what is estimated by the model, but three Rift Valley lakes have low biodiversity, lower than estimated by the model. There are also strong indications for the Rift Valley lakes that species richness was higher in the past because the species richness reported in the older literature was generally much higher than those observed by us in the present study and those reported in the more recent literature. Threats like overfishing, high sediment load and degradation of habitats were identified. It is recommended that Ethiopia should develop guidelines for fishery legislation and implement it through an enforcement agency. Moreover, catchments management should be practiced to save the water bodies and their fish communities
    Diagnosing constraints to market participation of small ruminant producers in northern Ghana: An innovation systems analysis
    Amankwah, K. ; Klerkx, L.W.A. ; Oosting, S.J. ; Sakyi-Dawson, O. ; Zijpp, A.J. van der - \ 2012
    NJAS Wageningen Journal of Life Sciences 60-63 (2012). - ISSN 1573-5214 - p. 37 - 47.
    livestock production - strategies - management - farmers - policy
    This paper assesses why participation in markets for small ruminants is relatively low in northern Ghana by analysing the technical and institutional constraints to innovation in smallholder small ruminant production and marketing in Lawra and Nadowli Districts. The results show that the limitations experienced by smallholders, i.e., water shortages during the dry season, high mortality and theft of livestock, persist because of institutional constraints. These include structural limitations related to availability of arable lands, weak support systems for animal production and health services delivery, community values that are skewed towards crop production more than animal husbandry, ineffective traditional and formal structures for justice delivery, and gaps in the interaction between communities and district and national level organizations such as the Ministry of Food and Agriculture, district assemblies, rural banks, and non-governmental organizations as well as traders and butchers. Confronted with such constraints, the strategies that most smallholders have adopted to be resilient entail diversified sources of livelihood, low input use in small ruminant production, and maintaining the herd as a capital stock and insurance. Only a few smallholders (i.e., ‘positive deviants’) engage in market or demand-driven production or exhibit successful strategies in small ruminant husbandry. It is argued in this paper that for the majority of smallholders, market production, which requires high levels of external inputs or intensification of resource use, is not a viable option. The main implications of the study are (1) that other institutional constraints than market access constraints should be addressed, (2) that commercial livestock production should not be idealized as the best or only option (as is being done in many contemporary interventions that aim at incorporating smallholders into commodity value chains), and (3) that different types of small ruminant system innovation pathways should be explored by making use of local positive deviants.
    Modeling the sensitivity of agricultural water use to price variability and climate change - An application to Swiss maize production
    Finger, R. - \ 2012
    Agricultural Water Management 109 (2012)June. - ISSN 0378-3774 - p. 135 - 143.
    simulation-model - irrigation - risk - markets - uncertainty - switzerland - strategies - experience - grassland - cropsyst
    We analyze the sensitivity of crop management under current and future climate scenarios to changes in economic boundary conditions. In particular, we focus on the effects of changing price risks. We combine a bio-economic modeling approach and a crop growth model CropSyst with an economic model that represents the decision making process of a risk-averse farmer. We apply the models to irrigated maize production in Switzerland. To analyze the sensitivity of optimal water and nitrogen use to likely future states of several economic variables, we conduct sensitivity analyses with respect to changes in price variability, the price–yield correlation, water and maize prices as well as farmers’ risk preferences. Results show that climate change leads to a strong increase in optimal water use for irrigation, with consequent increases in maize yields. However, our analysis also reveals that the consideration of economic drivers for farmers’ irrigation decisions is indispensable. Strong effects on optimal water use are found for changes in crop (positive) and water (negative) prices. We also find strong implications of risk aversion and price variability on irrigation decisions. A doubling of price variability, which would represent a shift from the current Swiss situation to price variability levels in its neighboring countries, could reduce optimal water use by up to 40%. We conclude that investigations of water demand should consider, beyond expectations on output and input price levels, also the variability of prices.
    A longitudinal study of changes in noticing and treating patients' overweight by Dutch GPs between 1997 and 2007
    Dijk, E.H. van; Kampen, J.K. ; Hiddink, G.J. ; Renes, R.J. ; Binsbergen, J.J. van; Woerkum, C.M.J. van - \ 2012
    Family Practice 29 (2012)Suppl 1. - ISSN 0263-2136 - p. i61 - i67.
    primary-care physicians - nutrition communication styles - family doctors - guidance practices - general-practice - self-efficacy - barriers - obesity - information - strategies
    Background. One of the stakeholders in tackling the rise and health consequences of overweight and obesity is the general practice physician (GP). GPs are in a good position to inform and give nutrition guidance to overweight patients. Objective. Assessment of working mechanism of determinants of the nutrition guidance practice: noticing patients’ overweight and guidance of treatment by GPs [linear analysis of structural relations (LISREL) path model] in a longitudinal study. Methods. This longitudinal study measured data in 1992, 1997 and 2007. The 1992 LISREL path model (Hiddink GJ, Hautvast J, vanWoerkum CMJ, Fieren CJ, vantHof MA. Nutrition guidance by primary-care physicians: LISREL analysis improves understanding. Prev Med 1997; 26: 29–36.) demonstrated that ‘noticing patients’ overweight and guidance of treatment’ was directly and indirectly influenced by predisposing factors, driving forces and perceived barriers. This article defines and discusses the path analysis of the 2007 data (compared with 1997). Results. This analysis shows both similarity and differences in working mechanism of determinants of noticing patients’ overweight and guidance of treatment between 1997 and 2007. The backbone of the mechanism with four predisposing factors is the similarity. The number of driving forces and of paths through intermediary factors to the dependent variable constitutes the difference. Conclusions. The backbone of the working mechanism of determinants of the nutrition guidance practice: noticing patients’ overweight and guidance of treatment by GPs was similar in 2007 and 1997. The influence of GPs task perception on noticing patients’ overweight and guidance of treatment considerably increased in 2007 compared to 1997. The longitudinal character of this article gives a strong practice-based evidence for weight management by GPs
    Smallholder Livelihood Adaptation in the Context of Neoliberal Policy Reforms: A Case of Maize Farmers in Southern Veracruz, Mexico.
    Groenewald, S.F. ; Berg, M.M. van den - \ 2012
    Journal of Development Studies 48 (2012)3. - ISSN 0022-0388 - p. 429 - 444.
    trade liberalization - rural livelihoods - expenditure data - united-states - poverty - growth - strategies - vulnerability - inequality - framework
    Governments around the world have embraced trade liberalisation as a means of enhancing efficiency to realise economic growth and alleviate poverty. Likewise, the Mexican government implemented neoliberal policy reforms, the NAFTA in particular, to stimulate sustainable development. Using the Mexican maize sector as illustration, this article describes the adaptation process of smallholders to market changes shaped by these reforms. Going beyond the aggregated level, we have investigated smallholders' livelihood strategies. Contrary to what economic models estimated, our data suggests that farmers intensified the cultivation of maize rather than switch to sectors in which Mexico has a comparative advantage.
    Rural development through the construction of new, nested, markets: comparative perspectives from China, Brazil and the European Union
    Ploeg, J.D. van der; Ye Yingzhong, ; Schneider-Rudnicki, C. - \ 2012
    The Journal of Peasant Studies 39 (2012)1. - ISSN 0306-6150 - p. 133 - 173.
    alternative food networks - strategies - multifunctionality - embeddedness - resistance - knowledge - politics - farmers - economy - divide
    This article discusses and compares the rural development processes and practices currently occurring in China, Brazil and the European Union. Although these are strongly rooted in the specificities of time and space, they also share important commonalities. We argue that rural development can be viewed as an evolving set of responses to market failures. A key element of these responses is that they are unfolding through the construction of new markets: a seemingly contradictory phenomenon that has, as yet, hardly been scrutinized or theoretically elaborated. We describe these newly emerging markets as ‘nested markets’ and support our argument with a careful reconsideration of the dynamics of long-established nested markets. We then extend this analysis, firstly, by arguing that the construction of such new markets occurs through a process of social struggle and, secondly, by exploring the strength of these newly emerging constellations in relation to the hegemony exerted by food empires. Our analysis puts common-pool resources, which underlie these new, nested markets, centre stage
    Editorial: Rumen Health: A 360° Analysis
    Vuuren, A.M. van; Calsamiglia, S. ; Udén, P. - \ 2012
    Animal Feed Science and Technology 172 (2012). - ISSN 0377-8401 - p. 1 - 3.
    strategies - milk - odd
    This preface outlines the context for initiating the special issue, comments on the review process, provides a brief summary of the papers in this issue and discusses some implications of these papers concerning rumen health.
    A framework for designing robust food supply chains
    Vlajic, J.V. ; Vorst, J.G.A.J. van der; Haijema, R. - \ 2012
    International Journal of Production Economics 137 (2012)1. - ISSN 0925-5273 - p. 176 - 189.
    disruption risks - vulnerability - optimization - methodology - model - environment - strategies - management - simulation - systems
    After years of emphasis on leanness and responsiveness businesses are now experiencing their vulnerability to supply chain disturbances. Although more literature is appearing on this subject, there is a need for an integrated framework to support the analysis and design of robust food supply chains. In this paper we present such a framework. We define the concept of robustness and classify supply chain disturbances, sources of food supply chain vulnerability, and adequate redesign principles and strategies to achieve robust supply chain performances. To test and illustrate its applicability, the research framework is applied to a meat supply chain
    Tourism and water use: Supply, demand, and security. An international review
    Gössling, S. ; Peeters, P.M. ; Hall, C.M. ; Ceron, J.P. ; Dubois, G. ; Lehmann, L.V. ; Scott, D. - \ 2012
    Tourism Management 33 (2012)1. - ISSN 0261-5177 - p. 1 - 15.
    waste-water - climate-change - management - desalination - resources - islands - consequences - communities - consumption - strategies
    This article reviews direct freshwater consumption in tourism from both quantitative and qualitative viewpoints to assess the current water demand of the tourism sector and to identify current and future management challenges. The article concludes that even though tourism increases global water consumption, direct tourism-related water use is considerably less than 1% of global consumption, and will not become significant even if the sector continues to grow at anticipated rates of around 4% per year (international tourist arrivals). The situation differs at the regional level because tourism concentrates traveller flows in time and space, and often-in dry destinations where water resources are limited. Furthermore, the understanding of tourism’s indirect water requirements, including the production of food, building materials and energy, remains inadequately understood, but is likely to be more substantial than direct water use. The article concludes that with expected changes in global precipitation patterns due to climate change, it is advisable in particular for already water scarce destinations to engage in proactive water management. Recommendations for managing tourism’s water footprint are made.
    Everyday realities of climate change adaptation in Mozambique
    Artur, L. ; Hilhorst, D.J.M. - \ 2012
    Global environmental change : human and policy dimensions 22 (2012)2. - ISSN 0959-3780 - p. 529 - 536.
    vulnerability - strategies - drought
    This paper analyzes discourses and practices of flood response and adaptation to climate change in Mozambique. It builds on recent publications on climate change adaptation that suggest that the successes and failures of adaptation highly depend on the cultural and political realms of societal perceptions and the sensitivity of institutions. To capture this, the paper adopted a multi-sited ethnographic approach. Acknowledging that there is no central locus of representation that can unveil the working of disaster response in Mozambique, the paper brings together five vignettes of research in different ‘sites’ of concern to the rise in floods in Mozambique. These are the politics of climate change adaptation at the national institutional level, societal responses to increased flooding, local people's responses to floods, the evacuation and resettlement programme following the 2007 flood. The paper finds how adaptation to climate change becomes part of everyday politics, how actors aim to incorporate responses into the continuation of their normal behavior and how elites are better positioned to take advantage of adaptation programmes than the vulnerable people that were targeted. It argues that climate change adaptation must be made consonant with historically grown and ongoing social and institutional processes. It concludes with lessons that the analysis and methodology of the research can provide for the practice of climate change adaptation.
    Risk based culling for highly infectious diseases of livestock
    Beest, E. te; Hagenaars, T.H.J. ; Stegeman, A. ; Koopmans, M.P.G. ; Boven, R.M. van - \ 2011
    Veterinary Research 42 (2011). - ISSN 0928-4249 - 9 p.
    influenza-a virus - mouth-disease - great-britain - h7n7 epidemic - foot - transmission - netherlands - impact - poultry - strategies
    The control of highly infectious diseases of livestock such as classical swine fever, foot-and-mouth disease, and avian influenza is fraught with ethical, economic, and public health dilemmas. Attempts to control outbreaks of these pathogens rely on massive culling of infected farms, and farms deemed to be at risk of infection. Conventional approaches usually involve the preventive culling of all farms within a certain radius of an infected farm. Here we propose a novel culling strategy that is based on the idea that farms that have the highest expected number of secondary infections should be culled first. We show that, in comparison with conventional approaches (ring culling), our new method of risk based culling can reduce the total number of farms that need to be culled, the number of culled infected farms (and thus the expected number of human infections in case of a zoonosis), and the duration of the epidemic. Our novel risk based culling strategy requires three pieces of information, viz. the location of all farms in the area at risk, the moments when infected farms are detected, and an estimate of the distance-dependent probability of transmission.
    Climate Science, Development Practice, and Policy Interactions in Dryland Agroecological Systems
    Twyman, C. ; Fraser, E.D.G. ; Stringer, L.C. ; Quinn, C. ; Dougill, A.J. ; Crane, T.A. ; Sallu, S.M. - \ 2011
    Ecology and Society 16 (2011)3. - ISSN 1708-3087 - p. 14 - 14.
    human-geography - past famines - food systems - vulnerability - livelihoods - scenarios - scale - desertification - resilience - strategies
    The literature on drought, livelihoods, and poverty suggests that dryland residents are especially vulnerable to climate change. However, assessing this vulnerability and sharing lessons between dryland communities on how to reduce vulnerability has proven difficult because of multiple definitions of vulnerability, complexities in quantification, and the temporal and spatial variability inherent in dryland agroecological systems. In this closing editorial, we review how we have addressed these challenges through a series of structured, multiscale, and interdisciplinary vulnerability assessment case studies from drylands in West Africa, southern Africa, Mediterranean Europe, Asia, and Latin America. These case studies adopt a common vulnerability framework but employ different approaches to measuring and assessing vulnerability. By comparing methods and results across these cases, we draw out the following key lessons: (1) Our studies show the utility of using consistent conceptual frameworks for vulnerability assessments even when quite different methodological approaches are taken; (2) Utilizing narratives and scenarios to capture the dynamics of dryland agroecological systems shows that vulnerability to climate change may depend more on access to financial, political, and institutional assets than to exposure to environmental change; (3) Our analysis shows that although the results of quantitative models seem authoritative, they may be treated too literally as predictions of the future by policy makers looking for evidence to support different strategies. In conclusion, we acknowledge there is a healthy tension between bottom-up/ qualitative/place-based approaches and top-down/quantitative/generalizable approaches, and we encourage researchers from different disciplines with different disciplinary languages, to talk, collaborate, and engage effectively with each other and with stakeholders at all levels.
    Bio-economic modeling of water quality improvements using a dynamic applied general equilibrium approach
    Dellink, R. ; Brouwer, R. ; Linderhof, V.G.M. ; Stone, K. - \ 2011
    Ecological Economics 71 (2011). - ISSN 0921-8009 - p. 63 - 79.
    nutrient abatement - river-basin - management - cost - netherlands - uncertainty - strategies - economy - impacts
    An integrated bio-economic model is developed to assess the impacts of pollution reduction policies on water quality and the economy. Emission levels of economic activities to water are determined based on existing environmental accounts. These emission levels are built into a dynamic economic model for the Dutch economy and subsequently coupled to a national water quality model. The modular approach has the advantage that the impacts on the economy and water quality are evaluated simultaneously, but each within their own domain based on the appropriate scale and level of detail. The dynamic nature of the economic model allows us to also evaluate a derogated water policy as foreseen in the European Water Framework Directive. The indirect costs of different water quality improvement policy scenarios are at least as high as the direct costs related to investments in pollution abatement technology. The stricter the policy scenario, the more important the role of economic adjustment and restructuring mechanisms at the macro-economic level. Significant water quality improvements can be achieved through stringent domestic emission reductions. However, reaching water quality standards is highly dependent on water quality improvement policy in surrounding river basin countries and climate change.
    Biofunctional Silicon Nanoparticles by Means of Thiol-Ene Click Chemistry
    Ruizendaal, M.H. ; Pujari, S.P. ; Gevaerts, V. ; Paulusse, J.M.J. ; Zuilhof, H. - \ 2011
    Chemistry an Asian Journal 6 (2011)10. - ISSN 1861-4728 - p. 2776 - 2786.
    semiconductor quantum dots - dna nanosensor - nanocrystals - cytotoxicity - cells - photoluminescence - strategies - emission - light - size
    The preparation and characterization of butylene-terminated silicon nanoparticles (SiNPs) and their functionalization using thiol-ene chemistry is described, as well as the coupling of DNA strands. Bromide-terminated SiNPs were prepared by means of the oxidation of magnesium silicide and functionalized with butylene chains through treatment with the corresponding Grignard reagent. The successful coupling was confirmed by NMR and FTIR spectroscopy. TEM measurements revealed a silicon-core diameter of (2.4±0.5) nm. The fluorescence emission maximum is at ¿max=525 nm when excited at ¿exc=430 nm. The conjugation of these alkene-terminated SiNPs by means of thiol-ene chemistry is described for a variety of functional thiols. Efficient coupling was evidenced by NMR and FTIR spectroscopy. Moreover, the characteristic fluorescence properties of the SiNPs remained unaltered, thus demonstrating the value of this approach towards functional oxide-free SiNPs. Activation of the attached carboxylic acid moieties allowed for conjugation of NH2-terminated oligo-ssDNA (ss=single strand) to the SiNPs. Successful coupling was confirmed by a characteristic new UV absorption band at 260 nm, and by the still-present distinctive fluorescence of the SiNPs at 525 nm. Gel electrophoresis confirmed coupling of 2 to 3 DNA strands onto the SiNPs, whereas no uncoupled DNA was observed.
    Development of Mamestra brassicae and its solitary endoparasitoid Microplitis mediator on two populations of the invasive weed Bunias orientalis
    Harvey, J.A. ; Gols, R. - \ 2011
    Population Ecology 53 (2011)4. - ISSN 1438-3896 - p. 587 - 596.
    4 trophic levels - insect herbivores - plant allelochemicals - cotesia-congregata - biological-control - bottom-up - evolution - host - strategies - chemistry
    The warty cabbage Bunias orientalis is an invasive pest in much of central Europe, including much of Germany since the 1980s, whereas in other countries, such as The Netherlands, it is a less common exotic species. Here, healthy larvae of Mamestra brassicae, which has been found feeding on B. orientalis plants in Germany, and larvae parasitized by one of its major larval endoparasitoids Microplitis mediator, were reared on both herbivoreinduced and noninduced leaves of B. orientalis originating from single large populations growing in The Netherlands and central Germany. Herbivore performance was less negatively affected than parasitoid performance by differences in plant quality. Development times in both M. brassicae and Mi. mediator were shorter on Dutch than German plants and also shorter on noninduced than induced plants. Moreover, survival and body size of the parasitoid was more strongly affected by plant population and induction than survival of healthy M. brassicae. Chemical analyses of defensive secondary metabolites [glucosinolates (GS)] revealed that concentrations of the major GS sinalbin were constitutively expressed in German plants whereas they were induced in Dutch plants. However, in separate feeding bioassays in which preference for induced and noninduced leaves was compared separately, L3 instars of M. brassicae preferred noninduced German plants over Dutch plants but induced Dutch plants over German plants, revealing that changes in primary metabolites or an unidentified non-GS compound mediates population- related differences in plant quality. The results reveal asymmetric effects of plant quality in exotic plants on organisms in the second and third trophic level.
    Greenhouse gas emission profiles of European livestock sectors
    Lesschen, J.P. ; Berg, M. van den; Westhoek, H.J. ; Witzke, H.P. ; Oenema, O. - \ 2011
    Animal Feed Science and Technology 166-167 (2011). - ISSN 0377-8401 - p. 16 - 28.
    milk-production - dairy farms - management - nitrogen - deforestation - agriculture - strategies - losses - energy - meat
    There are increasing concerns about the ecological footprint of global animal production. Expanding livestock sectors worldwide contribute to expansion of agricultural land and associated deforestation, emissions of greenhouse gases (GHG), eutrophication of surface waters and nutrient imbalances. Farm based studies indicate that there are large differences among farms in animal productivity and environmental performance. Here, we report on regional variations in dairy, beef, pork, poultry and egg production, and related GHG emissions in the 27 Member States of the European Union (EU-27), based on 2003–2005 data. Analyses were made with the MITERRA-Europe model which calculates annual nutrient flows and GHG emissions from agriculture in the EU-27. Main input data were derived from CAPRI (i.e., crop areas, livestock distribution, feed inputs), GAINS (i.e., animal numbers, excretion factors, NH3 emission factors), FAO statistics (i.e., crop yields, fertilizer consumption, animal production) and IPCC (i.e., CH4, N2O, CO2 emission factors). Sources of GHG emissions included were enteric fermentation, manure management, direct and indirect N2O soil emissions, cultivation of organic soils, liming, fossil fuel use and fertilizer production. The dairy sector had the highest GHG emission in the EU-27, with annual emission of 195 Tg CO2-eq, followed by the beef sector with 192 Tg CO2-eq. Enteric fermentation was the main source of GHG emissions in the European livestock sector (36%) followed by N2O soil emissions (28%). On a per kg product basis, beef had by far the highest GHG emission with 22.6 kg CO2-eq/kg, milk had an emission of 1.3 kg CO2-eq/kg, pork 3.5 kg CO2-eq/kg, poultry 1.6 kg CO2-eq/kg, and eggs 1.7 kg CO2-eq/kg. However large variations in GHG emissions per unit product exist among EU countries, which are due to differences in animal production systems, feed types and nutrient use efficiencies. There are, however, substantial uncertainties in the base data and applied methodology such as assumptions surrounding allocation of feeds to livestock species. Our results provide insight into differences in GHG sources and emissions among animal production sectors for the various regions of Europe.
    Rapid Establishment of a Regular Distribution of Adult Tropical Drosophila Parasitoids in a Multi-Patch Environment by Patch Defence Behaviour.
    Jong, P.W. de; Hemerik, L. ; Gort, G. ; Alphen, J.J.M. van - \ 2011
    PLoS ONE 6 (2011)7. - ISSN 1932-6203 - 7 p.
    interspecific host discrimination - asobara-tabida nees - time allocation - adaptive superparasitism - solitary parasitoids - insect parasitoids - wasps - interference - strategies - efficiency
    Females of the larval parasitoid of Drosophila, Asobara citri, from sub-Saharan Africa, defend patches with hosts by fighting and chasing conspecific females upon encounter. Females of the closely related, palearctic species Asobara tabida do not defend patches and often search simultaneously in the same patch. The effect of patch defence by A. citri females on their distribution in a multi-patch environment was investigated, and their distributions were compared with those of A. tabida. For both species 20 females were released from two release-points in replicate experiments. Females of A. citri quickly reached a regular distribution across 16 patches, with a small variance/mean ratio per patch. Conversely, A. tabida females initially showed a clumped distribution, and after gradual dispersion, a more Poisson-like distribution across patches resulted (variance/mean ratio was closer to 1 and higher than for A. citri). The dispersion of A. tabida was most probably an effect of exploitation: these parasitoids increasingly made shorter visits to already exploited patches. We briefly discuss hypotheses on the adaptive significance of patch defence behaviour or its absence in the light of differences in the natural history of both parasitoid species, notably the spatial distribution of their hosts.
    A State Space Augmentation Algorithm for the Replenishment Cycle Inventory Policy
    Rossi, R. ; Tarim, S.A. ; Hnich, B. ; Prestwich, S.D. - \ 2011
    International Journal of Production Economics 133 (2011)1. - ISSN 0925-5273 - p. 377 - 384.
    service-level constraints - shortest-path problem - lot-sizing problem - strategies
    In this work we propose an efficient dynamic programming approach for computing replenishment cycle policy parameters under non-stationary stochastic demand and service level constraints. The replenishment cycle policy is a popular inventory control policy typically employed for dampening planning instability. The approach proposed in this work achieves a significant computational efficiency and it can solve any relevant size instance in trivial time. Our method exploits the well known concept of state space relaxation. A filtering procedure and an augmenting procedure for the state space graph are proposed. Starting from a relaxed state space graph our method tries to remove provably suboptimal arcs and states (filtering) and then it tries to efficiently build up (augmenting) a reduced state space graph representing the original problem. Our experimental results show that the filtering procedure and the augmenting procedure often generate a small filtered state space graph, which can be easily processed using dynamic programming in order to produce a solution for the original problem.
    Participatory farm management adaptations to reduce environmental impact on commercial pilot dairy farms in the Netherlands
    Oenema, J. ; Keulen, H. van; Schils, R.L.M. ; Aarts, H.F.M. - \ 2011
    NJAS Wageningen Journal of Life Sciences 58 (2011)1-2. - ISSN 1573-5214 - p. 39 - 48.
    nitrogen use efficiency - nutrient management - european-community - systems - opportunities - regulations - perceptions - performance - strategies - balances
    Regulations in the Netherlands with respect to nutrient use force dairy farmers to improve nutrient management at the whole-farm level. On experimental farm ‘De Marke’, a coherent set of simple measures at farm level has been implemented, which has resulted in a drastic reduction in input of nutrients without affecting production intensity (milk production; kg milk per ha). To promote adoption of these measures in commercial dairy farming, the project ‘Cows & Opportunities’ was initiated in which 16 commercial pilot farms participated. Data were collected over a 6-year period (1998–2003). This paper describes and analyses the different farm management strategies adopted on these farms, using two classifications of the farms at the start of the project (the base situation), one based on nitrogen (N) surplus (kg ha-1), the other on production intensity. In both classifications, the farms were split in two equal groups. Changes over time in farm characteristics (farm development) were described through linear regression for each group and the variance among farms within a group was used to test for differences between groups. Under the influence of economic driving forces, the pilot farms, on average, expanded land area and increased their milk quota. However, the most intensive farms could comply with regulations only by reducing production intensity. From 1998 to 2002, average nutrient surpluses on the pilot farms decreased by 33% for N and 53% for phosphorus (P). Important measures were reducing the use of inorganic fertilizer, optimizing the use of home-produced organic manure, reducing grazing time, reducing the number of replacement stock and lowering crude protein content in the ration. Over the years, variation in N surpluses among farms (inter-farm variation) remained almost constant. Differences in farm management strategy could not unequivocally be related to farm typology (high/low N surplus; high/low production intensity). It was concluded that decisions by individual farmers on farm development are not always based on ‘rational’ arguments, but are co-determined by ‘emotional’ perceptions.
    Comments to "Is an integrated farm more resilient against climate change? A micro-econometric analysis of portfolio diversitification in African agriculture"
    Rufino, M. ; Reidsma, P. ; Nillesen, E.E.M. - \ 2011
    Food Policy 36 (2011)3. - ISSN 0306-9192 - p. 452 - 454.
    livestock systems - economic-impacts - land-use - adaptation - heterogeneity - strategies - market
    Managing soil fertility diversity to enhance resource use efficiencies in smallholder farming systems: a case from Murewa District, Zimbabwe
    Zingore, S. ; Tittonell, P.A. ; Corbeels, M. ; Wijk, M.T. van; Giller, K.E. - \ 2011
    Nutrient Cycling in Agroecosystems 90 (2011)1. - ISSN 1385-1314 - p. 87 - 103.
    nutrient use efficiencies - organic-matter - western kenya - management - scale - balances - field - variability - strategies - gradients
    Smallholder farms in sub-Saharan African exhibit substantial heterogeneity in soil fertility, and nutrient resource allocation strategies that address this variability are required to increase nutrient use efficiencies. We applied the Field-scale resource Interactions, use Efficiencies and Long-term soil fertility Development (FIELD) model to explore consequences of various manure and fertilizer application strategies on crop productivity and soil organic carbon (SOC) dynamics on farms varying in resource endowment in a case study village in Murewa District, Zimbabwe. FIELD simulated a rapid decline in SOC and maize yields when native woodlands were cleared for maize cultivation without fertilizer inputs coupled with removal of crop residues. Applications of 10 t manure ha-1 year-1 for 10 years were required to restore maize productivity to the yields attainable under native woodland. Long-term application of manure at 5 and 3 t ha-1 resulted in SOC contents comparable to zones of high and medium soil fertility observed on farms of wealthy cattle owners. Targeting manure application to restore SOC to 50–60% of contents under native woodlands was sufficient to increase productivity to 90% of attainable yields. Short-term increases in crop productivity achieved by reallocating manure to less fertile fields were short-lived on sandy soils. Preventing degradation of the soils under intensive cultivation is difficult, particularly in low input farming systems, and attention should be paid to judicious use of the limited nutrient resources to maintain a degree of soil fertility that supports good crop response to fertilizer application
    Implementation of mitigation on intensive dairy farms: farmers' preferences and variation in cost effectiveness
    Vellinga, Th.V. ; Haan, M.H.A. de; Schils, R.L.M. ; Evers, A.G. ; Pol, A. van den - \ 2011
    Livestock Science 137 (2011)1-3. - ISSN 1871-1413 - p. 185 - 195.
    greenhouse-gas emissions - ruminant livestock systems - nitrogen management - methane production - agriculture - sustainability - netherlands - performance - strategies - inputs
    The need for mitigation of greenhouse gas (GHG) emissions from dairy farms has been widely acknowledged. However, there is barely any knowledge on GHG emissions and mitigation options on commercial dairy farms. Most of the farmers are not aware of the GHG emissions on their farms and their attitude towards suggested mitigation measures is largely unknown. This study aims to provide insight in the variation of GHG emissions on commercial dairy farms and in the farmers' preferences for mitigation options and to investigate the effects of these options on GHG emissions and farm economy. The average GHG emission on the commercial farms was 1.08 kg CO2-equivalents per kg milk. The variation in emissions could be attributed to a combination of factors as soil type, fertilizer input, grazing system and feeding management. The preferred mitigation options were an increase of the milk production per cow, replacement of concentrates with single by-products, the use of more maize in animal feeding, the use of a heat pump and heat re-use from milk and reduction of the fertilizer N input. Farmers tend to choose mitigation options that are relatively simple and either cost effective or with only relatively small additional costs. The most promising mitigation options with respect to cost effectiveness are less replacement of dairy cattle and replacement of concentrates by single by-products grown in the vicinity of the farm. Other mitigation options which lead to land use change might be less effective due to possible trade offs. Overall, a total mitigation of 310 to 360 g CO2-equivalents per kg milk is achievable. This is a reduction of 25 to 30% compared to 1990. It is expected that this reduction can be achieved with relatively little costs.
    Maize silage for dairy cows: mitigation of methane emissions can be offset bij and use change
    Vellinga, Th.V. ; Hoving, I.E. - \ 2011
    Nutrient Cycling in Agroecosystems 89 (2011)3. - ISSN 1385-1314 - p. 413 - 426.
    greenhouse-gas emissions - ruminant livestock systems - carbon balance model - long-term - soil - management - strategies - tillage - impacts - fluxes
    Increasing the digestibility of cattle rations by feeding grains and whole plant silages from maize have been identified as effective options to mitigate greenhouse gas emissions. The effect of ploughing grassland for maize crops have not been taken into account yet. A intensive dairy farm is used as an example to demonstrate the trade offs by this type of land use change when more maize silage is fed to dairy cows. The model DAIRY WISE has been used to calculate the mitigation by the changed ration, the Introductory Carbon Balance Model to calculate the changes in soil organic carbon and nitrogen caused by ploughing grassland for maize crops. The losses of soil carbon and the loss of sequestration potential are much larger than the annual mitigation by feeding more maize. The ecosystem carbon payback time defines the years of mitigation that are needed before the emissions due to land use change are compensated. For ploughing grassland on sandy soils, the carbon payback time is 60 years. A higher global warming potential for methane can reduce the carbon payback time with 30%. Ploughing clay soils with a higher equilibrium level of soil organic matter increases the payback time by maximally 70%. The payback times occur only in the case of permanent maize cropping, grass maize rotations cause annual losses of nitrous oxide that are larger than the mitigation by feeding more maize.
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