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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    Explaining biomass growth of tropical canopy trees: the importance of sapwood
    Sande, M.T. van der; Zuidema, P.A. ; Sterck, F.J. - \ 2015
    Oecologia 177 (2015)4. - ISSN 0029-8549 - p. 1145 - 1155.
    woody-tissue respiration - lowland rain-forest - stem water storage - functional traits - leaf traits - good predictors - light gradient - trade-off - ecology - area
    Tropical forests are important in worldwide carbon (C) storage and sequestration. C sequestration of these forests may especially be determined by the growth of canopy trees. However, the factors driving variation in growth among such large individuals remain largely unclear. We evaluate how crown traits [total leaf area, specific leaf area and leaf nitrogen (N) concentration] and stem traits [sapwood area (SA) and sapwood N concentration] measured for individual trees affect absolute biomass growth for 43 tropical canopy trees belonging to four species, in a moist forest in Bolivia. Biomass growth varied strongly among trees, between 17.3 and 367.3 kg year-1, with an average of 105.4 kg year-1. We found that variation in biomass growth was chiefly explained by a positive effect of SA, and not by tree size or other traits examined. SA itself was positively associated with sapwood growth, sapwood lifespan and basal area. We speculate that SA positively affects the growth of individual trees mainly by increasing water storage, thus securing water supply to the crown. These positive roles of sapwood on growth apparently offset the increased respiration costs incurred by more sapwood. This is one of the first individual-based studies to show that variation in sapwood traits—and not crown traits—explains variation in growth among tropical canopy trees. Accurate predictions of C dynamics in tropical forests require similar studies on biomass growth of individual trees as well as studies evaluating the dual effect of sapwood (water provision vs. respiratory costs) on tropical tree growth.
    Fairly efficient, efficiently fair: Lessons from designing and testing payment schemes for ecosystem services in Asia
    Leimona, B. ; Noordwijk, M. van; Groot, J.C.J. ; Leemans, R. - \ 2015
    Ecosystem Services 12 (2015). - ISSN 2212-0416 - p. 16 - 28.
    pacific decadal oscillation - normalized burn ratio - western united-states - climate-change - interior alaska - north-america - landsat data - new-mexico - vegetation - area
    Paymentforecosystemservices(PES)iscommonlydefined asamarket-basedenvironmentalpolicy instrument toefficiently achieveecosystemservicesprovision.However,anincreasingbodyofliterature showsthatthisprescriptiveconceptualizationofPEScannotbeeasilygeneralizedandimplementedin practice, andthatthecommodification ofecosystemservices(ES)isproblematicandmayleadtounfair situations forrelevantPESactors.ThispapersynthesizescasestudiesinIndonesia,thePhilippinesand Nepal toprovideempiricalobservationsonemergingPESmechanismsinAsia.Lessonslearnedshow that fairnessandefficiency objectivesmustbeachievedsimultaneouslyindesigningandimplementing a sustainablePESscheme,especiallyindevelopingcountrycontexts.Neitherfairnessnorefficiency isa primary aimbutanintermediate ‘fairlyefficient andefficiently fair’ PES maybridgethegapbetweenPES theory andpracticetoincreasesustainableESprovisionandimprovelivelihoods.
    An estimate of the number of tropical tree species
    Slik, J.W.F. ; Bongers, F. ; Jansen, P.A. ; Parren, M.P.E. ; Poorter, L. ; Tchouto, M.G.P. ; Venticinque, E.M. - \ 2015
    Proceedings of the National Academy of Sciences of the United States of America 112 (2015)24. - ISSN 0027-8424 - p. 7472 - 7477.
    abundance distributions - plant diversity - global patterns - rain-forests - biodiversity - richness - coverage - sample - area
    The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher’s alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ~40,000 and ~53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ~19,000–25,000 tree species. Continental Africa is relatively depauperate with a minimum of ~4,500–6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa.
    The potential of old maps and encyclopaedias for reconstructing historic continental land cover/use change
    Fuchs, R. ; Verburg, P.H. ; Clevers, J.G.P.W. ; Herold, M. - \ 2015
    Applied Geography 59 (2015). - ISSN 0143-6228 - p. 43 - 55.
    spatially explicit - secondary lands - use transitions - wood-harvest - 3 centuries - hyde 3.1 - conservation - resolution - forests - area
    Continental to global reconstructions of historic land cover/use are important inputs for many environmental, ecological and biogeochemical studies. While local to regional reconstructions frequently make use of old topographic maps and land use statistics, continental to global reconstructions are mostly model-based reconstructions. As a result they are subject to large uncertainties. A wealth of historic land cover/use maps and statistics have been produced and these are now more accessible due to the ending of copyrights and secrecy statuses, enthusiastic hobby communities and national cartographic institutes or cadastres that have a strategy towards data sharing with society. In this paper we made use of historic statistics and old topographic maps to demonstrate the added value for model-based reconstructions of historic land cover/use for Central Europe back to 1900. We harmonized these diverse data types and different types of historic land data were incorporated into the land use reconstructions. The added value of using these data was evaluated using historical maps by performing a reconstruction with and without the historic information. The accuracy of the land allocation in the historic reconstruction was improved by 16.5% using historic maps. Additionally, historic maps improved the representation of the spatial structure of landscapes. The historic land cover/use statistics used showed a strong agreement with independent estimates, like historic maps.
    Assessing global land cover reference datasets for different user communities
    Tsendbazar, N.E. ; Bruin, S. de; Herold, M. - \ 2015
    ISPRS Journal of Photogrammetry and Remote Sensing 103 (2015). - ISSN 0924-2716 - p. 93 - 114.
    classification accuracy assessment - thematic map accuracy - validation data set - igbp discover - design - products - modis - challenges - imagery - area
    Global land cover (GLC) maps and assessments of their accuracy provide important information for different user communities. To date, there are several GLC reference datasets which are used for assessing the accuracy of specific maps. Despite significant efforts put into generating them, their availability and role in applications outside their intended use have been very limited. This study analyses metadata information from 12 existing and forthcoming GLC reference datasets and assesses their characteristics and potential uses in the context of 4 GLC user groups, i.e., climate modellers requiring data on Essential Climate Variables (ECV), global forest change analysts, the GEO Community of Practice for Global Agricultural Monitoring and GLC map producers. We assessed user requirements with respect to the sampling scheme, thematic coverage, spatial and temporal detail and quality control of the GLC reference datasets. Suitability of the datasets is highly dependent upon specific applications by the user communities considered. The LC-CCI, GOFC-GOLD, FAO-FRA and Geo-Wiki datasets had the broadest applicability for multiple uses. The re-usability of the GLC reference datasets would be greatly enhanced by making them publicly available in an expert framework that guides users on how to use them for specific applications.
    Rapid assessment of historic, current and future habitat quality for biodiversity around UK Natura 2000 sites
    Vogiatzakis, I.N. ; Stirpe, M.T. ; Rickebusch, S. ; Metzger, M.J. ; Xu, G. ; Rounsevell, M.D.A. ; Bommarco, R. ; Potts, S.G. - \ 2015
    Environmental Conservation 42 (2015)1. - ISSN 0376-8929 - p. 31 - 40.
    use change scenarios - land-use - aerial-photography - conservation - fragmentation - landscapes - dynamics - cover - area - grasslands
    Changes in landscape composition and structure may impact the conservation and management of protected areas. Species that depend on specific habitats are at risk of extinction when these habitats are degraded or lost. Designing robust methods to evaluate landscape composition will assist decision- and policy-making in emerging landscapes. This paper describes a rapid assessment methodology aimed at evaluating land-cover quality for birds, plants, butterflies and bees around seven UK Natura 2000 sites. An expert panel assigned quality values to standard Coordination of Information on the Environment (CORINE) land-cover classes for each taxonomic group. Quality was assessed based on historical (1950, 1990), current (2000) and future (2030) land-cover data, the last projected using three alternative scenarios: a growth-applied strategy (GRAS), a business-as-might-be-usual (BAMBU) scenario, and sustainable European development goal (SEDG) scenario. A quantitative quality index weighted the area of each land-cover parcel with a taxa-specific quality measure. Land parcels with high quality for all taxonomic groups were evaluated for temporal changes in area, size and adjacency. For all sites and taxonomic groups, the rate of deterioration of land-cover quality was greater between 1950 and 1990 than current rates or as modelled using the alternative future scenarios (2000–2030). Model predictions indicated land-cover quality stabilized over time under the GRAS scenario, and was close to stable for the BAMBU scenario. The SEDG scenario suggested an ongoing loss of quality, though this was lower than the historical rate of c. 1% loss per decade. None of the future scenarios showed accelerated fragmentation, but rather increases in the area, adjacency and diversity of high quality land parcels in the landscape.
    A cost-effective approach for improving the quality of soil sealing change detection from Landsat imagery
    Smiraglia, D. ; Rinaldo, S. ; Ceccarelli, T. ; Bajocco, S. ; Salvati, L. ; Ricotta, C. ; Perini, L. - \ 2014
    European Journal of Remote Sensing 47 (2014). - ISSN 2279-7254 - p. 805 - 819.
    urban - modis - tm - transformation - segmentation - phenology - sprawl - region - ndvi - area
    The aim of this study is to develop a cost-effective approach for soil sealing change detection integrating radiometric analysis, multi-resolution segmentation and object-based classifiers in two study areas in Italy: Campania region and Veneto region. The integrated approach uses multi-temporal satellite images and CORINE Land Cover (CLC) maps. A good overall accuracy was obtained for the soil sealing maps produced. The results show an improvement in terms of size of the minimum mapping unit and of the changed object (1,44 ha in both cases) in respect to the CLC. The approach proves to be cost-effective given the data which are provided at low or no cost and as well as the level of automation achievable.
    Prospects for Agroforestry in REDD+ landscapes in Africa
    Minang, P.A. ; Duguma, L.A. ; Bernard, F. ; Metz, O. ; Noordwijk, M. van - \ 2014
    Current Opinion in Environmental Sustainability 6 (2014). - ISSN 1877-3435 - p. 78 - 82.
    carbon sequestration - forest degradation - intensification - deforestation - conservation - challenges - systems - area
    Agroforests and agroforestry can be direct targets of Reduced Emissions from Deforestation and Forest Degradation (REDD+) programs, or indirect parts of the necessary conditions for success. Whether or not it becomes a core element of REDD+ depends on the country's forest definition. We review these dimensions of agroforestry in REDD+, with supporting examples, mostly from Africa, and highlight the implications and challenges for enhancing the contributions of agroforestry to REDD+ and corresponding sustainable benefits. Where carbon stocks in agroforestry cannot be directly targeted in REDD+, agroforestry still can be included in REDD+ strategies, as ways to (1) shift demand for land (land sparing) and (2) provide alternative sources of products otherwise derived from forest over-exploitation or conversion, thereby avoiding leakage from forest protection efforts.
    Hypothalamic vasotocin and tyrosine hydroxylase levels following maternal care and selection for low mortality in laying hens
    Hewlett, S.E. ; Zeinstra, E.C. ; Eerdenburg, Frank J.C.M. ; Rodenburg, T.B. ; Kooten, P.J.S. van; Staay, F.J. van der; Nordquist, R.E. - \ 2014
    BMC Veterinary Research 10 (2014). - ISSN 1746-6148 - 10 p.
    feather pecking behavior - gallus-domesticus - dopamine neurons - social-behavior - hpa axis - stress - brain - chicken - system - area
    BACKGROUND: Feather pecking and cannibalism are major concerns in poultry farming, both in terms of animal welfare and farm economics. Genetic selection and introduction of (aspects of) maternal care have been suggested as potential interventions to reduce feather pecking in laying hens. Altered brain development has been proposed to reflect welfare states in animals, and can provide more insight into the underlying processes involved in feather pecking. Both vasotocin (the avian homologue of vasopressin) and dopaminergic neural circuitry have roles in control of social behaviors as well as in the stress response, and may be linked to feather pecking. Thus, the hypothalamus of adult laying hens selected for low early mortality (LML), which show low feather pecking, was examined and compared with a control line of adult laying hens selected for production characteristics only (CL). The effect of foster hen rearing on the two genetic lines and their hypothalamic morphology was also investigated. RESULTS: We demonstrated an increase in the number of neurons positive for the rate-limiting enzyme in dopamine production, tyrosine hydroxylase, in the periventricular area of the hypothalamus in the LML hens compared to CL hens. Hen-reared chicks showed more vasotocin -positive neurons in the medial pre-optic area compared to the hens raised without a hen. No correlations were found between behavior in an open field at 5-6 weeks of age, and the histology of the same hens at adulthood. CONCLUSION: The hypothalamic dopaminergic and vasotinergic systems are altered in hens following genetic selection or maternal care, indicating a potential role for these systems in feather pecking. Keywords: Hypothalamus, Vasotocin, Vasopressin, Tyrosine hydroxylase, Dopamine, Welfare, Laying hen
    Farmers' Perceptions of Land Degradation and their Investments in Land Management: a Case Study in the Cental Rift Valley of Ethiopia
    Adimassu, Zenebe ; Kessler, A. ; Yirga, C. - \ 2013
    Environmental Management 51 (2013)5. - ISSN 0364-152X - p. 989 - 998.
    soil fertility management - conservation practices - nutrient balances - tenure security - south wello - highlands - adoption - smallholders - erosion - area
    To combat land degradation in the Central Rift Valley (CRV) of Ethiopia, farmers are of crucial importance. If farmers perceive land degradation as a problem, the chance that they invest in land management measures will be enhanced. This study presents farmers’ perceptions of land degradation and their investments in land management, and to what extent the latter are influenced by these perceptions. Water erosion and fertility depletion are taken as main indicators of land degradation, and the results show that farmers perceive an increase in both indicators over the last decade. They are aware of it and consider it as a problem. Nevertheless, farmers’ investments to control water erosion and soil fertility depletion are very limited in the CRV. Results also show that farmers’ awareness of both water erosion and soil fertility decline as a problem is not significantly associated with their investments in land management. Hence, even farmers who perceive land degradation on their fields and are concerned about its increase over the last decade do not significantly invest more in water erosion and soil fertility control measures than farmers who do not perceive these phenomena. Further research is needed to assess which other factors might influence farmers’ investments in land management, especially factors related to socioeconomic characteristics of farm households and plot characteristics which were not addressed by this study.
    Alternative treatments for indoor residual spraying for malaria control in a village with pyrethroid- and DDT-resistant vectors in The Gambia
    Tangena, J.A.A. ; Adiamoh, M. ; Alessandro, U. D'; Jarju, L. ; Jawara, M. ; Jeffries, D. ; Malik, N. ; Nwakanma, D. ; Kaur, H. ; Takken, W. ; Lindsay, S.W. ; Pinder, M. - \ 2013
    PLoS ONE 8 (2013)9. - ISSN 1932-6203
    insecticide-treated nets - anopheles-gambiae - pirimiphos-methyl - molecular-forms - area - complex - susceptibility - identification - protection - mozambique
    Background: Malaria vector control is threatened by resistance to pyrethroids, the only class of insecticides used for treating bed nets. The second major vector control method is indoor residual spraying with pyrethroids or the organochloride DDT. However, resistance to pyrethroids frequently confers resistance to DDT. Therefore, alternative insecticides are urgently needed. Methodology/Principal Findings: Insecticide resistance and the efficacy of indoor residual spraying with different insecticides was determined in a Gambian village. Resistance of local vectors to pyrethroids and DDT was high (31% and 46% mortality, respectively) while resistance to bendiocarb and pirimiphos methyl was low (88% and 100% mortality, respectively). The vectors were predominantly Anopheles gambiae s.s. with 94% of them having the putative resistant genotype kdr 1014F. Four groups of eight residential compounds were each sprayed with either (1) bendiocarb, a carbamate, (2) DDT, an organochlorine, (3) microencapsulated pirimiphos methyl, an organophosphate, or (4) left unsprayed. All insecticides tested showed high residual activity up to five months after application. Mosquito house entry, estimated by light traps, was similar in all houses with metal roofs, but was significantly less in IRS houses with thatched roofs (p=0.02). Residents participating in focus group discussions indicated that IRS was considered a necessary nuisance and also may decrease the use of long-lasting insecticidal nets. Conclusion/Significance: Bendiocarb and microencapsulated pirimiphos methyl are viable alternatives for indoor residual spraying where resistance to pyrethroids and DDT is high and may assist in the management of pyrethroid resistance.
    Putting sustainable fisheries on the map? Establishing no-take zones for North Sea plaice fisheries through MSC certification
    Toonen, H.M. ; Mol, A.P.J. - \ 2013
    Marine Policy 37 (2013)1. - ISSN 0308-597X - p. 294 - 304.
    environmental governance - marine - area - management - knowledge - economy - impact
    Spatial approaches gain importance in the governance of marine practices and their environmental impacts. Harmful effects of fishing gear on marine habitats is seen as a considerable spatial conflict that needs to be resolved. One of the most severe measures is the instalment of ‘no take zones’. In the certification programme of the Marine Stewardship Council (MSC) this measure is considered to be a last resort. MSC provides a telling example of ‘informational governance’, that is, a mode of environmental governance wherein information plays a centripetal but often also contested role. Such governing through information is different from conventional state-led decision-making processes. This paper assesses the way informational processes in MSC have affected the settlement of the spatial conflict between plaice fisheries and sensitive habitats in the North Sea. It concludes that information is a formative force in bringing about sustainable fisheries but leads to different outcomes even if the target species and fishing methods are very much alike. This is due to the (nationally) specific informational interactions between non-state actors, especially fishermen and environmental Non-Governmental Organizations. Even though information in marine governance should be science-based, other information (brought in by these actors) is extremely relevant in designing spatial measures.
    Typology and indicators of ecosystem services for marine spatial planning and management
    Bohnke-Henrichs, A. ; Baulcomb, C. ; Koss, R. ; Hussain, S. ; Groot, R.S. de - \ 2013
    Journal of Environmental Management 130 (2013)11. - ISSN 0301-4797 - p. 135 - 145.
    economic valuation - biodiversity - coastal - goods - area - classification - conservation - benefits
    The ecosystem services concept provides both an analytical and communicative tool to identify and quantify the link between human welfare and the environment, and thus to evaluate the ramifications of management interventions. Marine spatial planning (MSP) and Ecosystem-based Management (EBM) are a form of management intervention that has become increasingly popular and important globally. The ecosystem service concept is rarely applied in marine planning and management to date which we argue is due to the lack of a well-structured, systematic classification and assessment of marine ecosystem services. In this paper we not only develop such a typology but also provide guidance to select appropriate indicators for all relevant ecosystem services. We apply this marine-specific ecosystem service typology to MSP and EBM. We thus provide not only a novel theoretical construct but also show how the ecosystem services concept can be used in marine planning and management.
    Characterizing regional soil mineral composition using spectroscopy and geostatistics
    Mulder, V.L. ; Bruin, S. de; Weyermann, J. ; Kokaly, R.F. ; Schaepman, M.E. - \ 2013
    Remote Sensing of Environment 139 (2013). - ISSN 0034-4257 - p. 415 - 429.
    spatial prediction - usgs tetracorder - regression - vegetation - carbon - model - area - attributes - variograms - variables
    This work aims at improving the mapping of major mineral variability at regional scale using scale-dependent spatial variability observed in remote sensing data. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and statistical methods were combined with laboratory-based mineral characterization of field samples to create maps of the distributions of clay, mica and carbonate minerals and their abundances. The Material Identification and Characterization Algorithm (MICA) was used to identify the spectrally-dominant minerals in field samples; these results were combined with ASTER data using multinomial logistic regression to map mineral distributions. X-ray diffraction (XRD) was used to quantify mineral composition in field samples. XRD results were combined with ASTER data using multiple linear regression to map mineral abundances. We tested whether smoothing of the ASTER data to match the scale of variability of the target sample would improve model correlations. Smoothing was done with Fixed Rank Kriging (FRK) to represent the medium and long-range spatial variability in the ASTER data. Stronger correlations resulted using the smoothed data compared to results obtained with the original data. Highest model accuracies came from using both medium and long-range scaled ASTER data as input to the statistical models. High correlation coefficients were obtained for the abundances of calcite and mica (R2 = 0.71 and 0.70, respectively). Moderately-high correlation coefficients were found for smectite and kaolinite (R2 = 0.57 and 0.45, respectively). Maps of mineral distributions, obtained by relating ASTER data to MICA analysis of field samples, were found to characterize major soil mineral variability (overall accuracies for mica, smectite and kaolinite were 76%, 89% and 86% respectively). The results of this study suggest that the distributions of minerals and their abundances derived using FRK-smoothed ASTER data more closely match the spatial variability of soil and environmental properties at regional scale.
    Assessing farmers' interest in agroforestry in two contrasting agro-ecological zones of Rwanda
    Bucagu, C. ; Vanlauwe, B. ; Wijk, M.T. van; Giller, K.E. - \ 2013
    Agroforestry Systems 87 (2013)1. - ISSN 0167-4366 - p. 141 - 158.
    highland region - scaling-up - fodder - systems - kenya - diversity - adoption - shrubs - area
    Uptake and management of agroforestry technologies differs among farms in Rwanda and needs to be documented as a basis for shaping future research and development programs. The objective of this study was to investigate current agroforestry practices, farmers’ preferences, tree management and perspectives for agroforestry technologies. The study consisted of a combination of a formal survey, a participatory tree testing, farmer evaluation and focus group discussions in the Central Plateau (moderate altitude) and the Buberuka (high altitude) agro-ecological zones. A survey and a tree testing exercise with a range of species: (timber species—Eucalyptus urophyla, Grevillea robusta; legume shrubs - Calliandra calothyrsus, Tephrosia vogelii; and fruit species—Persea americana and Citrus sinensis) were carried out in Simbi (Central Plateau) and Kageyo (Buberuka) with farmers from different wealth status who received tree seedlings for planting, managing, and evaluating. Simbi had more tree species farm-1 (4.5) than Kageyo (2.9). Fruit trees occurred most frequently in Simbi. Grevillea robusta, Calliandra calothyrsus and Tephrosia vogelii were mostly established along contours, fruit trees in homefields and Eucalyptus urophyla trees in woodlots. Survival was better on contours for Grevillea robusta (58–100 %) and Calliandra calothyrsus (50–72 %). Tree growth was strongly correlated with the total tree lop biomass in Eucalyptus urophyla (R2 = 0.69). Grevillea robusta was most preferred in Simbi and Eucalyptus urophyla and Calliandra calothyrsus in Kageyo. The study provided information useful for revising the national agroforestry research and extension agenda and has important implications for other countries in the highlands of Africa
    Rarity in large data sets: Singletons, model values and the location of the species abundance distribution
    Straatsma, G. ; Egli, S. - \ 2012
    Basic and Applied Ecology 13 (2012)4. - ISSN 1439-1791 - p. 380 - 389.
    null hypothesis - long-term - richness - communities - dynamics - area
    Species abundance data in 12 large data sets, holding 10 × 103 to 125 × 106 individuals in 350 to 10 × 103 samples, were studied. Samples and subsets, for instance the summarized data of samples over years, and whole sets were analysed. Two methods of the binning of data, assigning abundance values to classes for histograms, have been applied in the past: bins of equal size and bins of exponentially increasing size (‘octaves’). A hump in a histogram with exponential bins does not represent a mode of primary, non-transformed abundance values, but of log transformed abundance values. A proper interpretation of the hump is given. Moreover, the extrapolation to the left of a histogram with exponential bins, below an abundance of unity, lifting a ‘veil’, hiding species present in the community but absent from the sample, is rejected. The literature is confusing at these points and, as a result, prevents a proper view on the species abundance distribution. Applying bins of equal size, modal values equalled or approached unity. The number of singletons increased with sample size in some data sets but decreased in others. However, singletons remain present in large samples, subsets or sets, in agreement with the results on modal values. The relatively high number of singletons in small samples is no artefact of undersampling. The mode at unity, that is at the left end of the species abundance distribution, independent of scale (sample, subset or set), is an important statistical property of the species abundance distribution. Our results may have implications for theory development in community ecology: the selection and/or development of an accurate species abundance model, and, connected to this, the formulation of improved assembly rules, and the selection and/or development of more precise species richness estimators.
    Total loss and distribution of nitrogen and phosphorus in the outdoor run of organic laying hens
    Dekker, S.E.M. ; Aarnink, A. ; Boer, I.J.M. de; Groot Koerkamp, P.W.G. - \ 2012
    British Poultry Science 53 (2012)6. - ISSN 0007-1668 - p. 731 - 740.
    egg-production systems - range - productivity - welfare - layers - house - area
    1. The objective of this study was to determine the level and variation of the total mass, and load of nitrogen (N) and phosphorus (P) excreted into the outdoor run of organic egg production systems. 2. Three egg production farms with an aviary system and an outdoor run were selected for this study. Four measurements, one per season, were executed on each farm. 3. Mean content of N and P of a manure dropping was 14·0¿g N¿kg-1 and 3·12¿g P¿kg-1, mean mass of a dropping was 6·36¿g and mean dry matter content of a dropping was 238¿g¿kg-1. Mean rate of excretion in the outdoor run was 2·99 droppings per hen per h. Mean percentage of hens outside during the time the outdoor run could be accessed was lowest on Farm 1 (1·7%), highest on Farm 2 (16·0%), and intermediate on Farm 3 (7·1%). 4. On all farms an exponential decrease of the number of hens and of the load of N and P with increasing distance from the hen house was found. Load of N exceeded the fertilisation standard (of 170¿kg¿ha-1¿y-1) in the region at a 0 to 19¿m distance from the hen house on Farm 1, 0 to 146¿m on Farm 2 and 0 to 52¿m on Farm 3. 5. It is concluded that the husbandry system should be redesigned to solve the problem of overloading, unwanted loss of N and P to the environment and loss of N and P from the organic production cycle.
    Photosynthetic thermotolerance of woody savanna species in China is correlated with leaf life span.
    Zhang, J.L. ; Poorter, L. ; Hao, G.Y. ; Cao, K.F. - \ 2012
    Annals of Botany 110 (2012)5. - ISSN 0305-7364 - p. 1027 - 1033.
    valley-savanna - heat tolerance - fluorescence - evolution - calcium - stress - plants - area - consequences - temperatures
    Background and Aims Photosynthetic thermotolerance (PT) is important for plant survival in tropical and sub-tropical savannas. However, little is known about thermotolerance of tropical and sub-tropical wild plants and its association with leaf phenology and persistence. Longer-lived leaves of savanna plants may experience a higher risk of heat stress. Foliar Ca is related to cell integrity of leaves under stresses. In this study it is hypothesized that (1) species with leaf flushing in the hot-dry season have greater PT than those with leaf flushing in the rainy season; and (2) PT correlates positively with leaf life span, leaf mass per unit area (LMA) and foliar Ca concentration ([Ca]) across woody savanna species. Methods The temperature-dependent increase in minimum fluorescence was measured to assess PT, together with leaf dynamics, LMA and [Ca] for a total of 24 woody species differing in leaf flushing time in a valley-type savanna in south-west China. Key Results The PT of the woody savanna species with leaf flushing in the hot-dry season was greater than that of those with leaf flushing in the rainy season. Thermotolerance was positively associated with leaf life span and [Ca] for all species irrespective of the time of flushing. The associations of PT with leaf life span and [Ca] were evolutionarily correlated. Thermotolerance was, however, independent of LMA. Conclusions Chinese savanna woody species are adapted to hot-dry habitats. However, the current maximum leaf temperature during extreme heat stress (44·3 °C) is close to the critical temperature of photosystem II (45·2 °C); future global warming may increase the risk of heat damage to the photosynthetic apparatus of Chinese savanna species.
    A comparison between urban livestock production strategies in Burkina Faso, Mali and Nigeria in West Africa
    Amadou, H. ; Dossa, L.H. ; Lompo, D.J. ; Abdulkadir, A. ; Schlecht, E. - \ 2012
    Tropical Animal Health and Production 44 (2012)7. - ISSN 0049-4747 - p. 1631 - 1642.
    agriculture - management - farmers - systems - crisis - area
    We undertook a comparative analysis of (peri-)urban livestock production strategies across three West African cities. Using a semi-structured questionnaire, livestock-keeping households (HH) were interviewed in Kano/Nigeria (84 HH), Bobo Dioulasso/Burkina Faso (63 HH) and Sikasso/Mali (63 HH). Questions covered livestock species kept, herd sizes and structure, feeds used, manure management, livestock marketing and production constraints. Sheep and goats dominated (p¿¿0.05), but the proportion of HH heads with a long-term experience in UPA activities was higher in Kano and in Bobo Dioulasso than in Sikasso (p¿
    Market-oriented conservation governance: The particularities of place
    Roth, R.J. ; Dressler, W.H. - \ 2012
    Geoforum 43 (2012)3. - ISSN 0016-7185 - p. 363 - 366.
    neoliberalism - biodiversity - paradigm - africa - space - area
    Conservation policy and practice is increasingly turning towards market-based interventions to reconcile the growing conflicts between environmental conservation and rural livelihood needs. This short introductory paper to the special issue on ‘‘market-oriented conservation governance’’ critically investigates the growing commitment to markets as a means of meeting conservation objectives and livelihood security. We distinguish market oriented conservation from neoliberal conservation and argue for a grounded, empirically rich investigation into the passive and active promotion of markets in conservation landscapes – analysis which pays attention to how and why certain markets are promoted by ENGOs, governments and private sector, as well as how rural people negotiate livelihoods and markets when adjusting to conservation pressures. Such an approach takes seriously how the particularities of place, from local harvests to trans-local trade, shape market-oriented conservation in practice and expose the messiness of such ventures. The range of papers in this special issue show how neither neoliberal nor market-based interventions in conservation are uniform in character, impact and outcome, and that while identifying the patterns and logic behind these processes remains crucial, the basis for understanding how markets inform conservation, must be done by drawing on empirical data that speaks clearly to how actors variously engage the logic of market-driven conservation in terms of their histories and contemporary realities. We argue that doing so makes it possible to understand not only what is ‘new’ about contemporary market-oriented conservation but also its continuities with earlier forms of command and control conservation
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