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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    Biophysical landscape interactions : Bridging disciplines and scale with connectivity
    Ploeg, Martine J. van der; Baartman, Jantiene E.M. ; Robinson, David A. - \ 2018
    Land Degradation and Development 29 (2018)4. - ISSN 1085-3278 - p. 1167 - 1175.
    biophysical landscape processes - connectivity - interdisciplinary - scale
    Landscape composition and land use impact the interactions between soil and vegetation. Differences in micro-behaviour, driven by the interplay of heterogeneous soil and vegetation dynamics, affect emergent characteristics across a landscape. Scaling approaches to understand the drivers of these emergent characteristics have been attempted, but the blueprint of interacting biophysical processes in landscapes is inherently messy and often still unknown. A complicating factor is single disciplinary focus in environmental sciences. Integrated knowledge is vital especially in view of future challenges posed by climate change, population growth, and soil threats. In this paper, we give examples of biophysical interactions that occur across various temporal and spatial scales and discuss how connectivity can be useful for bridging disciplines and scales to increase our understanding.
    Long-term impact of rainfed agricultural land abandonment on soil erosion in the Western Mediterranean basin
    Cerdà, Artemi ; Rodrigo-Comino, Jesús ; Novara, Agata ; Brevik, Eric Charles ; Vaezi, Ali Reza ; Pulido, Manuel ; Giménez-Morera, Antonio ; Keesstra, Saskia Deborah - \ 2018
    Progress in Physical Geography 42 (2018)2. - ISSN 0309-1333 - p. 202 - 219.
    Land use change - plots - rainfall - runoff - scale - sediment - Spain
    Land abandonment is widespread in the Mediterranean mountains. The impact of agricultural abandonment results in a shift in ecosystem evolution due to changes in soil erosion, but little is known about long-term soil and water losses. This paper uses 11 years of measurements in two paired plots (abandoned vs control) with four subplots to determine how soil and water losses evolved after abandonment within an agricultural parcel. For two years (2004–2005) both plots were under tillage, and after 2006 one plot was abandoned. The monitored plots measured runoff and sediment concentration after each rainfall event. The results show that during the two years after abandonment there was an increase in sediment yield followed by a decrease. Once the field was abandoned, a sudden increase in runoff (× 2.1 times) and sediment concentration (× 1.2 times) was found due to the lack of vegetation and tillage. After one year, the sediment concentration and, after two years, the runoff rates were lower in the abandoned than in the tilled plots. This short transition period ended in contrasting responses between the control and abandoned plot as the impact of abandonment resulted in 21 times less sediment yield after nine years of abandonment. This occurred despite the fact that the year after the abandonment the abandoned plot had 2.9 times more erosion due to low vegetation recovery and the development of a soil crust. Agriculture land abandonment resulted in lower erosion rates over the long term, but showed an increase in soil and water losses over the short term (two years). Therefore, in the first two years after abandonment there is a particular need to apply nature-based soil and water conservation strategies to prevent soil erosion.
    Microscopic recognition and identification of fish meal in compound feeds
    Raamsdonk, L.W.D. van; Prins, Theo ; Rhee, N. van de; Vliege, J.J.M. ; Pinckaers, V.G.Z. - \ 2017
    Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 34 (2017)8. - ISSN 1944-0049 - p. 1364 - 1376.
    alizarin - anosteocytic bones - Determinator - expert system - feed - fish bone structure - Fish meal - gill - scale
    Fish meal is an accepted ingredient in compound feed. Unauthorised application is primarily enforced by visual inspection, i.e., microscopy. In order to document the visually available diversity, fragments of bones and scales of 17 teleost fish species belonging to seven different orders were investigated for their diversity in the presence of structural elements: lacunae and canaliculae in bone fragments and type of growth rings and teeth of scale fragments. Despite the classical division into cellular bones and acellular bones of teleost fish, i.e., whether or not possessing osteocytes, the current examinations revealed patterns of lacunae, in some types accompanied with canaliculae, in all 17 species investigated. In total seven types of bone structures were defined, and six types of scale structures. Profiles with the relative frequency of each bone type per species were established. The share of acellular bone fragments appeared to be related to the evolutionary position of the species. Results of proficiency tests for the detection of fish meal reveal that in most cases the sensitivity and specificity for the detection of fish meal ranges from sufficient to perfect. Only some specified circumstances can hamper proper recognition and identification, most notably salmon bone fragments mimicking bone fragments from terrestrial animals, and pieces of hydrolysed proteins or minerals mimicking acellular fish bone fragments. The expertise gained in this study would help to improve the distinction between fish meal and terrestrial animal material in compound feed, and it supports the application of the species-to-species ban with respect to the valorisation of by-products from fish farms in aquafeed. In a broader perspective, the current expertise might be helpful to detect fraud throughout the feed/food production chain. The matrix of characteristics versus species is implemented in a data model running in the expert system ‘Determinator’ for facilitating identification.
    Territorial pluralism: water users’ multi-scalar struggles against state ordering in Ecuador’s highlands
    Hoogesteger, Jaime ; Boelens, Rutgerd ; Baud, Michiel - \ 2016
    Water International 41 (2016)1. - ISSN 0250-8060 - p. 91 - 106.
    Ecuador - irrigation - resistance - scale - territorial pluralism - water reforms - water user organization
    Leverages for on-farm innovation from farm typologies? An illustration for family-based dairy farms in north-west Michoacán, Mexico
    Cortez Arriola, J. ; Rossing, W.A.H. ; Amendola Massiotti, R.D. ; Scholberg, J.M.S. ; Groot, J.C.J. ; Tittonell, P.A. - \ 2015
    Agricultural Systems 135 (2015). - ISSN 0308-521X - p. 66 - 76.
    impact assessment - management - diversity - systems - scale - indicators - households - migration
    Knowledge on farm diversity provides insight into differences among farms, enables scaling from individual farm to farm population level and vice versa, and has been used in the definition of recommendation domains for introduction of novel technologies. Farm diversity can be broadly described in terms of resource endowment and resource use strategy, or in other words, in terms of scale and intensity of production. Measuring intensity of production requires much greater monitoring effort than measuring scale of production, and often only proxies of production intensity are used. Using data from a regional farm survey and from intensive on-farm monitoring the question addressed in this paper is to which extent results of farm surveys that measure primarily scale of production can inform on-farm interventions aimed at improving farm performance. The survey included a random sample of 97 out of 664 smallholder dairy farmers in a community in north-west Michoacán, Mexico. Farm types were identified by a combination of Principal Component Analysis to reduce the dimensionality of the dataset, followed by Cluster Analysis. The survey was complemented with detailed analyses of costs, revenues and productivity on 6 farms over the course of one year. Survey results revealed considerable variation among the dairy farms in land area, livestock units, amount of hired labour, and infrastructure and equipment, which led to the distinction of 4 farm types. Indicators for animal health management and feeding strategies were uniform across the 4 types. The farm types matched the distinction of family-based and semi-intensive farm types used in Mexico. The detailed analyses of the individual farms belonging to the different types, however, revealed differences in resource use strategies reflected in differences in animal productivity, labour productivity and return to labour. Differences in animal productivity and labour productivity were explained by stocking rate, albeit in different ways. Return to labour was strongly related to cost of feed. Profitability was negative for all farms and was on most farms related to high external feedstuff costs, which constituted 59–89% of the feed cost of the animal ration. The results indicate that in addition to variables reflecting resource endowment or scale of production, typologies that aim to inform on-farm interventions need to consider farm characteristics that reflect intensity of production. Which variables should be selected will need to be determined in a preliminary assessment. To enhance internal resource use efficiency as was the purpose in the current study, candidate variables expressing intensity could include the share of external feed in the ration and proxies of internal resource use, e.g. reflected in crop and milk yields. Opportunities for on-farm innovation arising from the analyses are discussed from the perspective of labour flexibility, low costs and use of internal resources.
    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.
    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.
    From field to atlas: Upscaling of location-specific yield gap estimates
    Bussel, L.G.J. van; Grassini, P. ; Wart, J. van; Wolf, J. ; Claessens, L. ; Yang, H. ; Boogaard, H.L. ; Groot, H.L.E. de; Saito, K. ; Cassman, K.G. ; Ittersum, M.K. van - \ 2015
    Field Crops Research 177 (2015). - ISSN 0378-4290 - p. 98 - 108.
    climate-change - weather data - crop yields - input data - resolution - model - scale - impact - maize - systems
    Accurate estimation of yield gaps is only possible for locations where high quality local data are available,which are, however, lacking in many regions of the world. The challenge is how yield gap estimates basedon location-specific input data can be used to obtain yield gap estimates for larger spatial areas. Hence,insight about the minimum number of locations required to achieve robust estimates of yield gaps atlarger spatial scales is essential because data collection at a large number of locations is expensive andtime consuming. In this paper we describe an approach that consists of a climate zonation scheme supple-mented by agronomical and locally relevant weather, soil and cropping system data. Two elements of thismethodology are evaluated here: the effects on simulated national crop yield potentials attributable tomissing and/or poor quality data and the error that might be introduced in scaled up yield gap estimatesdue to the selected climate zonation scheme. Variation in simulated yield potentials among weatherstations located within the same climate zone, represented by the coefficient of variation, served as ameasure of the performance of the climate zonation scheme for upscaling of yield potentials.We found that our approach was most appropriate for countries with homogeneous topography andlarge climate zones, and that local up-to-date knowledge of crop area distribution is required for selectingrelevant locations for data collection. Estimated national water-limited yield potentials were found to berobust if data could be collected that are representative for approximately 50% of the national harvestedarea of a crop. In a sensitivity analysis for rainfed maize in four countries, assuming only 25% coverageof the national harvested crop area (to represent countries with poor data availability), national water-limited yield potentials were found to be over- or underestimated by 3 to 27% compared to estimateswith the recommended crop area coverage of =50%. It was shown that the variation of simulated yieldpotentials within the same climate zone is small. Water-limited potentials in semi-arid areas are anexception, because the climate zones in these semi-arid areas represent aridity limits of crop productionfor the studied crops. We conclude that the developed approach is robust for scaling up yield gap estimatesfrom field, i.e. weather station data supplemented by local soil and cropping system data, to regional andnational levels. Possible errors occur in semi-arid areas with large variability in rainfall and in countrieswith more heterogeneous topography and climatic conditions in which data availability hindered full application of the approach.
    "Logistic analysis of algae cultivation"
    Slegers, P.M. ; Leduc, S. ; Wijffels, R.H. ; Straten, G. van; Boxtel, A.J.B. van - \ 2015
    Bioresource Technology 179 (2015). - ISSN 0960-8524 - p. 314 - 322.
    biofuel production - co2 capture - waste-water - microalgae - scale - availability - economics - biomass - biogas
    Energy requirements for resource transport of algae cultivation are unknown. This work describes the quantitative analysis of energy requirements for water and CO2 transport. Algae cultivation models were combined with the quantitative logistic decision model ‘BeWhere’ for the regions Benelux (Northwest Europe), southern France and Sahara. For photobioreactors, the energy consumed for transport of water and CO2 turns out to be a small percentage of the energy contained in the algae biomass (0.1–3.6%). For raceway ponds the share for transport is higher (0.7–38.5%). The energy consumption for transport is the lowest in the Benelux due to good availability of both water and CO2. Analysing transport logistics is still important, despite the low energy consumption for transport. The results demonstrate that resource requirements, resource distribution and availability and transport networks have a profound effect on the location choices for algae cultivation.
    Site-specific dynamics in remnant populations of Northern Wheatears Oenanthe oenanthe in the Netherlands
    Oosten, H.H. van; Turnhout, C. van; Hallmann, C.A. ; Majoor, F. ; Roodbergen, M. ; Schekkerman, H. ; Versluijs, R. ; Waasdorp, S. ; Siepel, H. - \ 2015
    Ibis 157 (2015)1. - ISSN 0019-1019 - p. 91 - 102.
    spatial synchrony - environmental correlation - scale - dispersal - birds - immigration - landscape - density - impact - space
    Dynamics of populations may be synchronized at large spatial scales, indicating driving forces acting beyond local scales, but may also vary locally as a result of site-specific conditions. Conservation measures for fragmented and declining populations may need to address such local effects to avoid local extinction before measures at large spatial scales become effective. To assess differences in local population dynamics, we aimed to determine the demographic drivers controlling population trends in three remaining populations of the Northern Wheatear Oenanthe oenanthe in the Netherlands, as a basis for conservation actions. An integrated population model (IPM) was fitted to field data collected in each site in 2007–2011 to estimate fecundity, survival and immigration. Sites were 40–120 km apart, yet first-year recruits were observed to move between some of the sites, albeit rarely. All three populations were equally sensitive to changes in fecundity and first-year survival. One population was less sensitive to adult survival but more sensitive to immigration. A life table response experiment suggested that differences in immigration were important determinants of differences in population growth between sites. Given the importance of immigration for local dynamics along with high philopatry, resulting in low exchange between sites, creating a metapopulation structure by improving connectivity and the protection of local populations are important for the conservation of these populations. Site-specific conservation actions will therefore be efficient and, for the short term, we propose different site-specific conservation actions.
    Reconciling spatial and temporal soi moisture effects on aftrnoon rainfall
    Guillod, B.P. ; Orlowsky, B. ; Miralles, D.G. ; Teuling, A.J. ; Seneviratne, S.I. - \ 2015
    Nature Communications 6 (2015). - ISSN 2041-1723
    energy system ceres - stratiform precipitation - atmospheric controls - surface irradiances - land - evaporation - scale - feedback - evapotranspiration - variability
    Soil moisture impacts on precipitation have been strongly debated. Recent observational evidence of afternoon rain falling preferentially over land parcels that are drier than the surrounding areas (negative spatial effect), contrasts with previous reports of a predominant positive temporal effect. However, whether spatial effects relating to soil moisture heterogeneity translate into similar temporal effects remains unknown. Here we show that afternoon precipitation events tend to occur during wet and heterogeneous soil moisture conditions, while being located over comparatively drier patches. Using remote-sensing data and a common analysis framework, spatial and temporal correlations with opposite signs are shown to coexist within the same region and data set. Positive temporal coupling might enhance precipitation persistence, while negative spatial coupling tends to regionally homogenize land surface conditions. Although the apparent positive temporal coupling does not necessarily imply a causal relationship, these results reconcile the notions of moisture recycling with local, spatially negative feedbacks.
    Direct and indirect impacts of climate and socio-economic change in Europe: a sensitivity analysis for key land- and water-based sectors
    Kebede, A.S. ; Dunford, R. ; Mokrech, M. ; Rickebusch, S. - \ 2015
    Climatic Change 128 (2015)3-4. - ISSN 0165-0009 - p. 261 - 277.
    integrated assessment - adaptation - vulnerability - reduction - scenarios - scale - uk
    Integrated cross-sectoral impact assessments facilitate a comprehensive understanding of interdependencies and potential synergies, conflicts, and trade-offs between sectors under changing conditions. This paper presents a sensitivity analysis of a European integrated assessment model, the CLIMSAVE integrated assessment platform (IAP). The IAP incorporates important cross-sectoral linkages between six key European land- and water-based sectors: agriculture, biodiversity, flooding, forests, urban, and water. Using the IAP, we investigate the direct and indirect implications of a wide range of climatic and socioeconomic drivers to identify: (1) those sectors and regions most sensitive to future changes, (2) the mechanisms and directions of sensitivity (direct/indirect and positive/negative), (3) the form and magnitudes of sensitivity (linear/non-linear and strong/weak/insignificant), and (4) the relative importance of the key drivers across sectors and regions. The results are complex. Most sectors are either directly or indirectly sensitive to a large number of drivers (more than 18 out of 24 drivers considered). Over twelve of these drivers have indirect impacts on biodiversity, forests, land use diversity, and water, while only four drivers have indirect effects on flooding. In contrast, for the urban sector all the drivers are direct. Moreover, most of the driver–indicator relationships are non-linear, and hence there is the potential for ‘surprises’. This highlights the importance of considering cross-sectoral interactions in future impact assessments. Such systematic analysis provides improved information for decision-makers to formulate appropriate adaptation policies to maximise benefits and minimise unintended consequences.
    Comparison of methods to identify crop productivity constraints in developing countries. A review
    Kraaijvanger, R.G.M. ; Sonneveld, M.P.W. ; Almekinders, C.J.M. ; Veldkamp, T. - \ 2015
    Agronomy for Sustainable Development 35 (2015)2. - ISSN 1774-0746 - p. 625 - 637.
    northern ethiopian highlands - soil fertility - agricultural-research - farmers - conservation - knowledge - adoption - systems - yield - scale
    Selecting a method for identifying actual crop productivity constraints is an important step for triggering innovation processes. Applied methods can be diverse and although such methods have consequences for the design of intervention strategies, documented comparisons between various methods are scarce. Different variables can be used to characterize these methods. To typify them, we used two of these variables in a heuristic model: control over the research process and represented opinion. Here, we review 16 published papers that present outcomes of different methods to identify productivity constraints. The major findings are the following: (1) Variation in methods is wide. (2) Applying the heuristic model results in three main clusters of methods: farmer-control/farmer-opinion, scientist-control/scientist-opinion, and scientist-control/farmer-opinion. (3) These clusters are scale level dependent. As a follow up, we compared in a case study the three different methods, representative for the three main clusters of the heuristic model, in order to assess their congruency. These methods (focus group discussion, individual surveys, and contextual data collection) were applied in four localities in Tigray, Northern Ethiopia. We found that congruency between the methods, as indicated by Spearman-¿ correlations, was not significant. In addition, we found that outcomes of individual surveys and contextual data collection among the different locations were correlated (R¿>¿0.70). No such correlation was found using focus group discussion. Both findings indicate that for a specific location different methods yielded different constraints and that variability between the locations is not reflected by using individual surveys and contextual data collection. Combined the review and case study demonstrate that process control and represented opinion have a manifest impact on generated outcomes. Because outcomes of productivity constraints assessments are methodology dependent, researchers are recommended to justify a priori their choice of method using the presented heuristic model.
    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.
    Dynamic and Static Behaviour with Respect to Energy Use and Investment of Dutch Greenhouse Firms
    Verreth, D.M.I. ; Emvalomatis, G. ; Bunte, F.H.J. ; Oude Lansink, A.G.J.M. - \ 2015
    Environmental and Resource Economics 61 (2015)4. - ISSN 0924-6460 - p. 595 - 614.
    adjustment costs - agriculture - industry - scale - model
    Dutch greenhouse horticulture firms are energy-intensive and major emitters of greenhouse gases. This paper develops a theoretically consistent model that is able to describe the greenhouse firms’ behaviour regarding energy use and investments in energy technology. The behaviour of the firm is modelled using a combination of a dynamic cost function and a static profit function framework. The optimal quantity of energy is derived from the link between these two functions. The model is applied to a panel of 97 Dutch greenhouse firms over the period 2001–2008. The results show that most Dutch greenhouse firms shift from being net electricity users to net electricity producers in the long term. Investing in energy capital contributes to reducing net energy use, however it increases the quantity of carbon dioxide emissions due to an increase in electricity production. A 1 % increase of the price of gas reduces carbon dioxide emissions by 1.6 %.
    The Wageningen Lowland Runoff Simulator (WALRUS): a lumped rainfall-runoff model for catchments with shallow groundwater
    Brauer, C.C. ; Teuling, A.J. ; Torfs, P.J.J.F. ; Uijlenhoet, R. - \ 2014
    Geoscientific Model Development 7 (2014)5. - ISSN 1991-959X - p. 2313 - 2332.
    flow route contributions - surface water interactions - soil-moisture - process conceptualization - hydrological models - root-growth - tile drain - scale - calibration - discharge
    We present the Wageningen Lowland Runoff Simulator (WALRUS), a novel rainfall-runoff model to fill the gap between complex, spatially distributed models which are often used in lowland catchments and simple, parametric (conceptual) models which have mostly been developed for sloping catchments. WALRUS explicitly accounts for processes that are important in lowland areas, notably (1) groundwater-unsaturated zone coupling, (2) wetness-dependent flow routes, (3) groundwater-surface water feedbacks and (4) seepage and surface water supply. WALRUS consists of a coupled groundwater-vadose zone reservoir, a quickflow reservoir and a surface water reservoir. WALRUS is suitable for operational use because it is computationally efficient and numerically stable (achieved with a flexible time step approach). In the open source model code default relations have been implemented, leaving only four parameters which require calibration. For research purposes, these defaults can easily be changed. Numerical experiments show that the implemented feedbacks have the desired effect on the system variables.
    Lumped surface and sub- surface runoff for erosion modeling within a small hilly watershed in northern Vietnam
    Bui, Y.T. ; Orange, D. ; Visser, S.M. ; Hoanh, C.T. ; Laissus, M. ; Poortinga, A. ; Tran, D.T. ; Stroosnijder, L. - \ 2014
    Hydrological Processes 28 (2014)6. - ISSN 0885-6087 - p. 2961 - 2974.
    land-use changes - soil-erosion - sediment transport - steep slopes - sensitivity-analysis - scale - infiltration - catchments - framework - thailand
    Developing models to predict on-site soil erosion and off-site sediment transport at the agricultural watershed scale represent an on-going challenge in research today. This study attempts to simulate the daily discharge and sediment loss using a distributed model that combines surface and sub-surface runoffs in a small hilly watershed (<1km(2)). The semi-quantitative model, Predict and Localize Erosion and Runoff (PLER), integrates the Manning-Strickler equation to simulate runoff and the Griffith University Erosion System Template equation to simulate soil detachment, sediment storage and soil loss based on a map resolution of 30m x 30m and over a daily time interval. By using a basic input data set and only two calibration coefficients based, respectively, on water velocity and soil detachment, the PLER model is easily applicable to different agricultural scenarios. The results indicate appropriate model performance and a high correlation between measured and predicted data with both Nash-Sutcliffe efficiency (Ef) and correlation coefficient (r(2)) having values>0.9. With the simple input data needs, PLER model is a useful tool for daily runoff and soil erosion modeling in small hilly watersheds in humid tropical areas.
    Land management implications for ecosystem services in a South African rangeland
    Petz, K. ; Glenday, J. ; Alkemade, J.R.M. - \ 2014
    Ecological Indicators 45 (2014). - ISSN 1470-160X - p. 692 - 703.
    semiarid succulent thicket - eastern cape - biodiversity loss - scale - 21st-century - conservation - metaanalysis - restoration - vegetation - resources
    In South Africa, restoration and sustainable management of historically overgrazed and degraded rangelands are promoted to increase biodiversity and ecosystem service provision. This study evaluates different land management scenarios in terms of ecosystem services in a South African rangeland, the Baviaanskloof catchment. As measured data were limited, we used simple models to quantify and map the effect of the different combination of agricultural, nature conservation and restoration practices on multiple ecosystem services. The land management scenarios were evaluated against management targets set for individual ecosystem services. Results highlight how the provision of ecosystem services is related to land management as unmanaged, pristine ecosystems provide a different mix of ecosystem services than ecosystems recently restored or managed as grazing lands. Results also indicate that historically overgrazed lands provide no forage, may retain 40% less sediment and have 38% lower biodiversity, while providing 60% more fuel wood and supplying two and half times more water (i.e. retaining less water), than pristine or restored lands. We conclude that a combination of light grazing, low input agriculture, nature conservation and restoration is the best for the sufficient provision of multiple ecosystem services. Applying such mixed management would improve biodiversity, ecotourism and maintain forage production and regulating services on farmers' land. This management option also fits into and further optimizes local decision-makers' vision regarding the future management of the area. (C) 2014 Elsevier Ltd. All rights reserved.
    The Wageningen Lowland Runoff Simulator (WALRUS): application to the Hupsel Brook catchement and Cabauw polder
    Brauer, C.C. ; Torfs, P.J.J.F. ; Teuling, A.J. ; Uijlenhoet, R. - \ 2014
    Hydrology and Earth System Sciences 18 (2014). - ISSN 1027-5606 - p. 4007 - 4028.
    surface parameterization schemes - distributed hydrological model - flow route contributions - land-surface - groundwater interactions - spatial variability - rainfall - scale - netherlands - validation
    The Wageningen Lowland Runoff Simulator (WALRUS) is a new parametric (conceptual) rainfall–runoff model which accounts explicitly for processes that are important in lowland areas, such as groundwater-unsaturated zone coupling, wetness-dependent flowroutes, groundwater–surface water feedbacks, and seepage and surface water supply (see companion paper by Brauer et al., 2014). Lowland catchments can be divided into slightly sloping, freely draining catchments and flat polders with controlled water levels. Here, we apply WALRUS to two contrasting Dutch catchments: the Hupsel Brook catchment and the Cabauw polder. In both catchments, WALRUS performs well: Nash–Sutcliffe efficiencies obtained after calibration on 1 year of discharge observations are 0.87 for the Hupsel Brook catchment and 0.83 for the Cabauw polder, with values of 0.74 and 0.76 for validation. The model also performs well during floods and droughts and can forecast the effect of control operations. Through the dynamic division between quick and slow flowroutes controlled by a wetness index, temporal and spatial variability in groundwater depths can be accounted for, which results in adequate simulation of discharge peaks as well as low flows. The performance of WALRUS is most sensitive to the parameter controlling the wetness index and the groundwater reservoir constant, and to a lesser extent to the quickflow reservoir constant. The effects of these three parameters can be identified in the discharge time series, which indicates that the model is not overparameterised (parsimonious). Forcing uncertainty was found to have a larger effect on modelled discharge than parameter uncertainty and uncertainty in initial conditions.
    Transboundary ecological networks as an adaptation strategy to climate change: The example of the Dutch - German border
    Rüter, S. ; Vos, C.C. ; Eupen, M. van; Rühmkorf, H. - \ 2014
    Basic and Applied Ecology 15 (2014)8. - ISSN 1439-1791 - p. 639 - 650.
    maculinea-teleius - conservation - range - butterflies - impacts - biodiversity - landscapes - models - scale - recommendations
    Establishing ecological networks across national boundaries is essential for species to adapt to shifts in future suitable climate zones. This paper presents a method to assess whether the existing ecological network in the Dutch – German border region is “climate proof”. Using distribution data and climate envelope models for 846 species in Europe (mammals, birds, reptiles, amphibians and butterflies) we identified 216 species with climate-induced range shifts in the border region. A range expansion is predicted for 99 species and the ranges of 117 species are predicted to contract. The spatial cohesion of the ecological network was analysed for selected species that vary in habitat requirements and colonisation ability (forest species: Brenthis daphne, Dendrocopos medius; wetland species: Maculinea teleius, Lutra lutra). The assessment shows that optimising transboundary networks and developing corridors seems a suitable adaptation strategy for the forest species and for L. lutra. For the immobile butterfly M. teleius, the present habitat network is too weak and translocation into future suitable climate space seems to be a more appropriate adaptation measure. Our results underline that due to climate change landscape planning and management should not only focus on areas where target species occur today. The presented method can identify strongholds and bottlenecks in transboundary ecological networks and incorporate demands of climate adaptation into spatial planning which forms the basis for taking measures at a more detailed level.
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