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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    Data from: Modelling mobile agent-based ecosystem services using kernel weighted predictors
    Goedhart, P.W. ; Lof, M.E. ; Bianchi, F.J.J.A. ; Baveco, J.M. ; Werf, W. van der - \ 2018
    conservation planning - biocontrol - natural pest control - pollination - source-sonk dynamics - kernel - landscape - statistical model - spatial distribution - spatial extent
    1. Agriculture benefits from ecosystem services provided by mobile agents, such as biological pest control by natural enemies and pollination by bees. However, methods that can generate spatially explicit predictions and maps of these ecosystem services based on empirical data are still scarce. 2. Here we propose a generic statistical model to derive kernel functions to characterize the spatial distribution of ecosystem services provided by mobile agents. The model is similar in spirit to a generalized linear model, and uses data of landscape composition and ecosystem services assessed at target sites to estimate parameters of the kernel. The approach is tested in a simulation study and illustrated by an empirical case study on parasitism rates of the diamondback moth Plutella xylostella. 3. The simulation study shows that the scale parameter of the exponential power kernel can be estimated with limited bias, whereas estimation of the shape parameter is difficult. For the case study the model provides biologically relevant estimates for the kernel associated with parasitism of Plutella xylostella. These estimates can be used to generate ecosystem service maps for existing or planned landscapes. The case study reveals that predictions can be sensitive to the parameter values for the width and shape of the kernel, and to the link function used in the statistical model. 4. In the last two decades numerous empirical studies assessed ecosystem services at target sites and related these to the surrounding landscape. Our method can take advantage of these data by estimating underlying kernels that can be used to map the spatial distribution of ecosystem services. However, empirical data that can discriminate between alternative kernel shapes remain critical.
    Quantifying the influence of geography and environment on the northeast Atlantic mackerel spawning distribution
    Brunel, Thomas ; Damme, Cindy J.G. Van; Samson, Melvin ; Dickey-Collas, Mark - \ 2018
    Fisheries Oceanography 27 (2018)2. - ISSN 1054-6006 - p. 159 - 173.
    density-dependence - generalised additive model - habitat suitability - mackerel - spatial distribution - spawning strategy
    Mackerel (Scomber scombrus) in the northeast Atlantic have shown changes in distribution at certain times of the year, which have impacted their exploitation and management. In this study, mackerel spawning habitat over 21 recent years was characterised using generalised additive modelling, based on spatial egg density data collected every third year during targeted ichthyoplankton surveys. Mackerel spawning distribution was found to depend primarily on geographical variables (coordinates and bottom depth), with preferred spawning locations on the shelf-edge from the north of the Iberian peninsula to the west of Scotland, with a maximum west of Ireland. Environmental drivers had a lesser influence on egg distribution. Dome shaped relationships were found with temperature and mixed layer depth, with respective optimum at 13°C and around –300 m. The model was used to reconstruct maps of the potential habitat (areas where conditions were suitable, but not necessarily used, for spawning). Little changes were observed over the years in the potential habitat, suggesting that the expansion of the egg distribution (realised habitat) was not triggered by changes in the environmental variables investigated. Little evidence was found for density-dependent habitat selection. There was a tendency for mackerel to make more use of areas of lesser suitability in years with large stock size (1992 and 2010). This pattern, however, broke down in 2013, when stock size was the highest, as spawning occurred very south and concentrated in the most suitable habitat.
    Data from: Feeding preference as a main determinant of microscale patchiness among terrestrial nematodes
    Quist, C.W. ; Gort, G. ; Mulder, Christian ; Wilbers, R.H.P. ; Termorshuizen, A.J. ; Bakker, J. ; Helder, J. - \ 2017
    Wageningen University & Research
    nematode community - quantitative PCR - bio-indicators - spatial distribution - trophic group
    Soil biota are responsible for essential ecosystem services such as carbon storage, nutrient cycling and water retention. However, assessment of the condition of soil biota is hampered by an overwhelming level of diversity. With representatives in all trophic levels of the food web, nematode communities can be used as bio-indicators. Accurate assessment of nematode assemblages requires insight in the distribution of specimens with distinct food preferences. With the availability of taxon-specific quantitative-PCR assays, distribution patterns of multiple nematode groups can be investigated simultaneously. Here, microscale patchiness of 45 nematode taxa was studied on 12 sampling sites (each with four adjacent microplots) located on arable fields or semi-natural grasslands (‘system’), and on marine-, river clay or sandy soils (‘soil type’). From each microplot five composite samples were collected. Contrary to our expectations, an increase of the number of cores per composite sample did not result in more accurate measurements, and apparently the levels of microscale patchiness of the taxa are low compared to what has been reported for oligophagous plant-parasites. System and soil type did not affect microscale distribution. To investigate the level of patchiness in more detail, detection probability (DP) and variability of abundances were calculated. Common and widespread bacterivorous and fungivorous taxa had DP ≥ 90%, confirming low level of microscale patchiness. With DPs of 40-70%, predators and most omnivores showed degrees of local clustering. An overview of mean variabilities of abundances is presented that offers insight in how feeding preferences impact the microscale distribution both between and within trophic groups.
    De PerceelVerdeler: optimaal verdelen van de beschikbare mest op het melkveebedrijf
    Oenema, Jouke ; Verloop, Koos ; Hilhorst, Gerjan - \ 2017
    Wageningen : Wageningen UR Livestock Research (Rapport / Koeien & Kansen 78) - 25
    melkvee - melkveehouderij - rundveemest - kunstmeststoffen - ruimtelijke verdeling - dairy cattle - dairy farming - cattle manure - fertilizers - spatial distribution
    Impact of trophic ecologies on the whereabouts of nematodes in soil
    Quist, Casper W. - \ 2017
    Wageningen University. Promotor(en): J. Bakker, co-promotor(en): J. Helder. - Wageningen : Wageningen University - ISBN 9789463430814 - 129
    nematoda - spatial distribution - soil fauna - biota - trophic levels - food webs - soil ecology - soil biology - farming systems - soil types (ecological) - geostatistics - nematoda - ruimtelijke verdeling - bodemfauna - biota - trofische graden - voedselwebben - bodemecologie - bodembiologie - bedrijfssystemen - bodemtypen (ecologisch) - geostatistiek

    Soil life is highly diverse, and ecologically intricate due to myriad of biotic interactions that take place. Terrestrial nematodes have a high potential to serve as an effective and policy-relevant indicator group for ecosystem functioning and soil biodiversity. The work described in this thesis contributed to the robust mapping of nematode communities at scales relevant in both agronomic and environmental contexts. The overarching aim of the work described in this thesis was to contribute to a sound exploration of the potential of nematode communities as an indicator group for the biological condition of soils. Therefore, the distributions of a wide range of nematode taxa were studied, within and between trophic groups and in soils conditioned by various plant species and/or farming systems.

    In Chapter 2 nematode taxon-specific qPCR assays were used to pinpoint responses of nematode communities to invasive plant species Solidago gigantea in two invaded ecosystems: semi-natural grasslands and riparian floodplains. Nematode communities and fungal biomass were examined in adjacent invaded and uninvaded patches. The dominant presence of the invasive plant causes a decrease of plant species-richness and diversity, and an about twofold increase of fungal biomass. Only the density of a single group of fungivorous nematodes (Aphelenchoididea) increased, whereas the densities of two other, phylogenetically distinct lineages of fungivorous nematodes, Aphelenchidae and Diphtherophoridae, were unaffected by the local increase in fungal biomass. Apparently S. gigantea induces a local asymmetric boost of the fungal community, and only Aphelenchoididae were able to benefit from this change induced by the invasive plant.

    In Chapter 3 the outcome is shown of a test whether farming system effects are mirrored in compositional changes in nematode communities. The long-term impact of three farming systems (conventional, integrated and organic) on nematode communities was investigated at the Vredepeel, an experimental farm in the southeastern part of The Netherlands. The results showed that organic farming causes specific shifts in nematode community composition, exceeding the usually large crop-related assemblage shifts. Strongest effects were observed for the (putative) bacterivore Prismatolaimus, which was relatively common in organic fields and nearly absent in conventional and integrated farming. A reverse effect was observed for Pristionchus; this necromenic bacterivore and facultative predator made up about 7 – 21% of the total nematode community in integrated and conventional farming, whereas it was nearly absent from organic fields. The observed farming system effects suggest that specific nematode taxa might be indicative for the impact of farming practices on soil biota. Knowledge of spatial distribution patterns of soil organisms with distinct trophic preferences will contribute to our understanding of factors that maintain and regulate soil biodiversity, and is essential information to design soil sampling strategies with predictable accuracies.

    Chapter 4 deals with microscale patchiness of 45 nematode taxa (at family, genus or species-level) in arable fields and semi-natural grasslands, on marine clay, river clay or sandy soils. Contrary to our expectations, an increase of the number of cores per composite sample above 3, did not result in more accurate detection for any of the taxa under investigation (range of number of cores per composite sample: 3, 6, 12 or 24). Neither system nor soil type did influence microscale distribution. The insights in the spatial distribution of nematodes at microscale presented here, sheds light on the impact of trophic preferences on the spatial distribution of individual nematode taxa, and will allow for the design of statistically sound soil sampling strategies.

    Chapter 5 shows belowground distribution patterns of 48 nematode taxa in 12 visually homogeneous fields (each 100 x 100 m) on three soil types (marine clay, river clay and sand) and two land-use types (arable and natural grasslands) across the Netherlands. Over 35,000 nematode-taxon specific qPCR assays allowed us to quantitative analyse nematode taxa at family, genus or species level in over 1,200 soil samples. A sampling scheme was optimized for Bayesian geostatistical analysis (Integrated nested Laplace approximations; INLA). Multivariate analysis show soil type and land-use related differences in the nematode community composition, which underline the effects of environmental filtering and niche partitioning of nematodes. All individual nematode taxa together show a wide range of degrees of spatial variabilities were found (expressed by the range-parameter and the spatial variance parameter (s2spatial). No general effects were detected of soil characteristics or nematode traits (cp-value, trophic group, weight) on the spatial distribution parameters. The relatively high percentages of unexplained spatial variability – 92.5% of the variation for the range-parameter and 74% for spatial variance (s2spatial) – point at a major role of stochasticity for variability of nematode densities within fields. This study adds empirical evidence that distribution patterns of terrestrial nematodes, in areas without noticeable gradients, are driven by neutral / stochastic processes, within the boundaries set by the environment.

    In the final Chapter 6, I discuss the opportunities and challenges of the use of molecular tools in soil ecological research, the impact of trophic preferences on the whereabouts of nematodes, the use of nematode communities as indicator for soil condition and how this might be developed and applied to facilitate more sustainable ecosystem management.

    Elbersen, Berien ; Groot, Hugo de; Staritsky, Igor ; Dees, Mattias ; Datta, Pawan ; Leduc, Sylvain - \ 2016
    Wageningen University and Research
    forest biomass - EFISCEN - Europe - Potential supply - spatial distribution
    European forests are considered a crucial resource for supplying biomass to a growing bio-economy in Europe. This study aimed to assess the potential availability of forest biomass from European forests and its spatial distribution. We tried to answer the questions (i) how is the potential forest biomass availability spatially distributed across Europe and (ii) where are hotspots of potential forest biomass availability located? The spatial distribution of woody biomass potentials was assessed for 2020 for stemwood, residues (branches and harvest losses) and stumps for 39 European countries. Using the European Forest Information SCENario (EFISCEN) model and international forest statistics, we estimated the theoretical amount of biomass that could be available based on the current and future development of the forest age-structure, growing stock and increment and forest management regimes. We combined these estimates with a set of environmental (site productivity, soil and water protection and biodiversity protection) and technical (recovery rate, soil bearing capacity) constraints, which reduced the amount of woody biomass that could potentially be available. We mapped the potential biomass availability at the level of administrative units and at the 10 km × 10 km grid level to gain insight into the spatial distribution of the woody biomass potentials. According to our results, the total availability of forest biomass ranges between 357 and 551 Tg dry matter per year. The largest potential supply of woody biomass per unit of land can be found in northern Europe (southern Finland and Sweden, Estonia and Latvia), central Europe (Austria, Czech Republic, and southern Germany), Slovenia, southwest France and Portugal. However, large parts of these potentials are already used to produce materials and energy. The distribution of biomass potentials that are currently unused only partially coincides with regions that currently have high levels of wood production. Our study shows how the forest biomass potentials are spatially distributed across the European continent, thereby providing insight into where policies could focus on an increase of the supply of woody biomass from forests. Future research on potential biomass availability from European forests should also consider to what extent forest owners would be willing to mobilise additional biomass from their forests and at what costs the estimated potentials could be mobilised. This dataset contains the data of the map presented in Figure 2A: Estimated spatial distribution of forest biomass availability according to the BASE potential (ton dry matter ha-1 land yr-1) at the grid (10x10 km) level.
    Spatial distribution and habitat preference of harbour seals (Phoca vitulina) in the Dutch North Sea
    Aarts, Geert ; Cremer, Jenny ; Kirkwood, Roger ; Wal, Jan Tjalling van der; Matthiopoulos, Jason ; Brasseur, Sophie - \ 2016
    Den Helder : Wageningen Marine Research (Wageningen Marine Research rapport C118/16) - 43
    seals - phoca vitulina - spatial distribution - habitats - animal ecology - marine ecology - north sea - netherlands - zeehonden - phoca vitulina - ruimtelijke verdeling - habitats - dierecologie - mariene ecologie - noordzee - nederland
    Modelling population effects of juvenile offshore fish displacement towards adult habitat
    Wolfshaar, K.E. van de; Tulp, I.Y.M. ; Wennhage, H. ; Støttrup, J.G. - \ 2015
    Marine Ecology Progress Series 540 (2015). - ISSN 0171-8630 - p. 193 - 201.
    complex life-cycles - nursery grounds - spatial distribution - competition
    Recent studies of fish distribution patterns highlight shifts in the spatial distributions of particular life-stages. Focus has thus far been on changes in habitat use and possible drivers for these changes. Yet, small-scale shifts in habitat use of certain life stages may have profound consequences on population dynamics through changes in resource use and competition. To explore this, a conceptual stage-structured model was developed with 3 stages and 2 resources and allowing a move of large juveniles from the shallow to the deep habitat. Large juveniles compete with small juveniles in shallow waters and with adults in deeper waters. Alternative stable states occur, with one state dominated by small juvenile biomass and the other dominated by adult biomass.
    The model results show for both states that while large juvenile biomass responds to a change in time spent in the deep habitat, the biomass of small juveniles and adults is barely affected. Between the 2 states there is a profoundly different population response to increased fishing mortality. In the adult biomass dominated state, adult biomass is hardly affected while juvenile
    biomass increases until population collapse, with increased fishing. In the small juvenile dominated state, adult and small juvenile biomass decrease, and large juvenile biomass increases. This state persists at much higher fishing mortality than the adult biomass dominated state. This study highlights that safeguarding nursery functions in a changing environment requires monitoring of juvenile life-stages in a range of habitats and a spatially adaptive management strategy
    Cruise report hydroacoustic survey for blue whiting (Micromesistius poutassou) with F.R.V. Tridens (BWHTS) 23 March - 7 April 2015
    Scoulding, B.C. - \ 2015
    IJmuiden : IMARES (Report / IMARES Wageningen UR 15.008) - 20
    micromestistius poutassou - onderwaterakoestiek - noordoost atlantische oceaan - eu regelingen - visbestand - ruimtelijke verdeling - micromestistius poutassou - underwater acoustics - northeast atlantic - eu regulations - fishery resources - spatial distribution
    This survey is part of the ICES coordinated international hydro acoustic survey for blue whiting which is carried out yearly in March/April. The other participating countries are the Faroe Islands, Ireland, Norway and Russia. IMARES, Institute for Marine Resources & Ecosystem Studies, part of Wageningen University and Research, has participated in the international North-East Atlantic hydro acoustic survey for blue whiting since 2004. The survey is part of the EU Data Collection Framework. The aim of this survey is to provide an abundance estimate of the whole North-East Atlantic blue whiting population and to determine the spatial distribution at this time of year. This estimate is used as a tuning index by the ICES Working Group on Widely Distributed Stocks (WGWIDE) to determine the size of the population. In this report the results are presented of the survey west of Ireland, carried out by FRV “Tridens”. A secondary objective during the survey is to gather information on the distribution of non-commercial mesopelagic species.
    Ruimtelijke spreiding ammoniakemissies 2013
    Koeijer, T.J. de; Luesink, H.H. ; Kuhlman, J.W. ; Puister-Jansen, L.F. ; Hoogeveen, M.W. - \ 2014
    Den Haag : LEI Wageningen UR (Factsheet / LEI Wageningen UR 14-118b2) - 2
    ammoniakemissie - ruimtelijke verdeling - landbouw en milieu - bemesting - begrazing - ammonia emission - spatial distribution - agriculture and environment - fertilizer application - grazing
    Voor de NEC-richtlijn (National Emission Ceiling), GCN/GDN (Grootschalige concentratie- en depositiekaarten) en de PAS (Programmatische aanpak stikstof) monitort de Emissieregistratie de emissies van diverse stoffen. De landbouw levert met 85% de belangrijkste bijdrage aan de emissie van ammoniak. LEI Wageningen UR levert elke drie jaar de regionale emissie van ammoniak uit bemesting en beweiding. De ammoniakemissies worden met MAMBO berekend per gemeente.
    Ruimtelijke optimalisatie van voederstromen in de Peel : nieuwe landgebruiksvormen en clustering ten behoeve van regionale productie van veevoer
    Walsum, P.E.V. van; Galama, P.J. ; Roelsma, J. ; Cormont, A. ; Hack-ten Broeke, M.J.D. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2615) - 49
    melkveehouderij - milieueffect - krachtvoeding - rundveevoeding - voedergewassen - duurzaamheid (sustainability) - ruimtelijke verdeling - nutriëntenuitspoeling - duurzaam bodemgebruik - regionaal landbouwbeleid - veevoederindustrie - de peel - dairy farming - environmental impact - force feeding - cattle feeding - fodder crops - sustainability - spatial distribution - nutrient leaching - sustainable land use - regional agricultural policy - feed industry - de peel
    In een eerdere studie werd verkend in hoeverre het economische en milieutechnisch haalbaar zou zijn om in regio De Peel krachtvoervervangers regionaal te verbouwen. In de in dit rapport beschreven studie stelden we ons de vraag of ruimtelijke optimalisatie wel tot milieuwinst zou kunnen leiden en vervolgens hoe regionale voercentra kunnen bijdragen en op welke locatie deze zouden moeten liggen.
    Note on minimum space allowance and compartment height for cattle and pigs during transport
    Visser, E.K. - \ 2014
    Wageningen : Wageningen UR Livestock Research (Livestock research report 764) - 7
    dierenwelzijn - veevervoer - transport - rundvee - varkens - eu regelingen - dierlijke productie - diergezondheid - animal welfare - transport of animals - transport - cattle - pigs - eu regulations - animal production - animal health
    Graphical presentation of guidelines for minimum space allowances for cattle and pigs during transport.
    Modeling elephant-mediated cascading effects of water point closure
    Hilbers, J.P. ; Langevelde, F. van; Prins, H.H.T. ; Grant, C.C. ; Peel, M. ; Coughenour, M.B. ; Knegt, H.J. de; Slotow, R. ; Smit, I. ; Kiker, G.A. ; Boer, W.F. de - \ 2014
    Wageningen UR
    surface water - spatial distribution - Loxodonta africana - animal densities - savanna ecosystemsKruger National Park - mesoherbivores
    Wildlife management to reduce the impact of wildlife on their habitat can be done in several ways, among which removing animals (by either culling or translocation) is most often used. There are however alternative ways to control wildlife densities, such as opening or closing water points. The effects of these alternatives are poorly studied. In this paper, we focus on manipulating large herbivores through the closure of water points (WPs). Removal of artificial WPs has been suggested to change the distribution of African elephants, which occur in high densities in national parks in Southern Africa and are thought to have a destructive effect on the vegetation. Here, we modeled the long-term effects of different scenarios of WP closure on the spatial distribution of elephants, and consequential effects on the vegetation and other herbivores in Kruger National Park, South Africa. Using a dynamic ecosystem model, SAVANNA, scenarios were evaluated that varied in (1) availability of artificial WPs, (2) levels of natural water, and (3) elephant densities. Our modeling results showed that elephants can indirectly negatively affect the distributions of mesomixed feeders, mesobrowsers and some mesograzers under wet conditions. The closure of artificial WPs hardly had any effect during these natural wet conditions. Only under dry conditions the spatial distribution of both elephant bulls and cows changed when the availability of artificial water was severely reduced in the model. These changes in spatial distribution triggered changes in the spatial availability of woody biomass over the simulation period of 80 years and this led to changes in the rest of the herbivore community, resulting in increased densities of all herbivores, except for giraffe and steenbok, in areas close to rivers. The spatial distributions of elephant bulls and cows showed to be less affected by the closure of WPs than most of the other herbivore species. Our study contributes to ecologically informed decisions in wildlife management. The results from this modeling exercise imply that long-term effects of this intervention strategy should always be investigated at an ecosystem scale.
    The landscape at your service : spatial analysis of landscape services for sustainable development
    Gulickx, M.M.C. - \ 2013
    Wageningen University. Promotor(en): Peter de Ruiter, co-promotor(en): Jetse Stoorvogel; Kasper Kok. - S.l. : s.n. - ISBN 9789461736871 - 143
    ecosysteemdiensten - ruimtelijke verdeling - landschapselementen - gebiedsgericht beleid - cartografie - plattelandsplanning - scenario planning - multi-stakeholder processen - landschapsplanning - noord-brabant - intensieve veehouderij - grondwaterkwaliteit - zandgronden - de peel - ecosystem services - spatial distribution - landscape elements - integrated spatial planning policy - mapping - rural planning - scenario planning - multi-stakeholder processes - landscape planning - noord-brabant - intensive livestock farming - groundwater quality - sandy soils - de peel
    De mens beheert en verandert het landschap om diverse producten en diensten te verkrijgen en te versterken. Deze producten en diensten, landschapsdiensten genoemd, leveren een positieve bijdrage aan de maatschappij. Interacties tussen sociale (menselijke) en ecologische (natuurlijke) systemen maken de voorziening van Landschapsdiensten mogelijk. In het landschap zijn er synergiën en conflicten tussen diensten, waardoor keuzes gemaakt moeten worden, oftewel we hebben te maken met trade‐offs tussen diensten. De interactie tussen de systemen, samen met de ruimtelijke verwevenheid van de diensten zorgen voor hoge complexiteit. Kaarten van landschapsdiensten kunnen deze complexiteit, of een deel daarvan, helder weergeven en daardoor bijdragen aan een beter begrip van de interacties en bijkomende trade‐offs. Dit begrip helpt ons bij het voorkomen van conflicten tussen diensten en geeft ons betere mogelijkheden om gewenste diensten te versterken. Voornamelijk ruimtelijke planners en beleidsmakers hebben veel baat bij deze informatie. Geschikte kaarten van landschapsdiensten zijn daarom van groot belang. Meer onderzoek is nodig naar ruimtelijk relaties om zodoende landschappelijke elementen te identificeren die kunnen fungeren als indicatoren voor het karteren van landschapsdiensten. Voor de gemeenten Deurne en Asten zijn de landschapsdiensten moerashabitat, bosrecreatie, grondgebonden veehouderij en wandelrecreatie in kaart gebracht. Met behulp van veldwerk zijn voor 389 locaties de landschapsdiensten geïdentificeerd. Een ruimtelijke analyse gemaakt van de grondwaterkwaliteit in relatie tot landschappelijke elementen, landgebruik en landschapsdiensten. De studie is uitgevoerd voor het zuidelijk zandgebied in de regio de Peel in Nederland.
    Fishing activities on the Dogger Bank 2006-2011
    Bartelings, H. ; Hamon, K.G. ; Oostenbrugge, J.A.E. van - \ 2013
    The Hague : LEI, part of Wageningen UR (Memorandum / LEI : Research area Natural resources ) - 45
    visserij-ecologie - ruimtelijke verdeling - beschermingsgebieden - noordzee - visserij - vis vangen - fisheries ecology - spatial distribution - conservation areas - north sea - fisheries - fishing
    In 2008, the Minister of Agriculture, Nature and Food Quality notified four proposed Sites of Community In-terest (pSCIs) to the European Commission (for protection as Special Conservation Areas (SCAs) under the Habitats Directive). These areas are the Dogger Bank, Cleaver Bank, the Coastal Zone and the Vlakte van de Raan. The areas have been chosen, based on their specific habitats and ecological values. The objective of the current project is to give insight into the trends of the fishing activities of the Dutch and important foreign fleets (Belgian, German and UK) in the area of the Dogger Bank in the period 2006-2011. In the analyses attention is given to developments in effort, landings and economic value of the landings.
    Biomolecule substrate topography for inkjet printed structures
    Mujawar, L.H. - \ 2013
    Wageningen University. Promotor(en): Willem Norde, co-promotor(en): Aart van Amerongen. - S.l. : s.n. - ISBN 9789461735478 - 145
    microarrays - ruimtelijke verdeling - eiwitten - assays - porositeit - substraten - microarrays - spatial distribution - proteins - assays - porosity - substrates
    Designing food structures to enhance sensory responses
    Mosca, A.C. - \ 2012
    Wageningen University. Promotor(en): Tiny van Boekel, co-promotor(en): Markus Stieger; F. van de Velde. - S.l. : s.n. - ISBN 9789461732477 - 164
    sucrose - vet - sensorische wetenschappen - smaakgevoeligheid - smaak - zintuiglijke waarneming - ruimtelijke verdeling - gels - mechanische eigenschappen - zoetheid - sucrose - fat - sensory sciences - taste sensitivity - taste - organolepsis - spatial distribution - gels - mechanical properties - sweetness

    Background and Aim

    The current overconsumption of sugar, salt and fat has been linked to the incidence of health problems. For this reason, it is necessary to decrease the intake of these food components. In the context of reducing the contents of sugar, salt and fat in food products while maintaining sensorial quality, the aim of this thesis was to identify and understand the factors that affect the perception of taste and fat-related sensory attributes in semi-solid foods. To achieve this aim, the relationship between the spatial distribution of sucrose, the mechanical properties of semi-solid gels and the perception of taste was investigated in detail. In addition, the relationship between the spatial distribution of fat and the perception of fat-related sensory attributes was investigated.


    Model systems composed of layers of mixed agar-gelatin gels were used to control the spatial distribution of sucrose and fat. Layers varying in concentration of sucrose or oil-in-water emulsion droplets (i.e. fat) were combined to prepare gels with homogeneous and inhomogeneous distributions of sucrose and fat. A series of experiments were carried out using 2-Alternative Forced Choice (2-AFC) tests, line scale ratings and time-intensity analysis to investigate the effects of modulation of the spatial distribution of sucrose and modulation of the mechanical properties of gels on sweetness intensity. The relationship between the spatial distribution of tastants and consumer preference was investigated in different types of foods (e.g. semi-solid gels, breads and sausages). Furthermore, a Quantitative Descriptive Analysis (QDA) panel was carried out to investigate the effect of modulation of the spatial distribution of fat on the perception of fat-related sensory attributes.


    An inhomogeneous distribution of sucrose at large sucrose concentration differences enhanced sweetness intensity. The frequency of high-intensity discontinuous stimulation of taste receptors, which is related to the presence of tastant concentration differences in the mouth during oral processing, was identified as the driving factor for taste enhancement. The oral breakdown of semi-solid gels, which is affected mainly by fracture strain, and the mixing behavior of gel fragments formed upon breakdownwere shown to influence the frequency of receptor stimulation and, consequently, taste enhancement. Furthermore, the optimum frequency of high-intensity discontinuous stimulation required to maximize taste enhancement was shown to depend on the textural properties of the gel. These findings suggest that the spatial distribution of tastants and the mechanical properties (especially fracture strain) can be modulatedto maximize taste enhancement. Additionally, consumer preference was found to be maintained or increased in products containing tastants heterogeneously distributed in the food matrix.

    Fat-related mouthfeel attributes, such as spreadable and melting, were enhanced by an inhomogeneous distribution of fat at large fat concentration differences. The presence of high-fat zones on the surface of the model system was shown to maximize the enhancement of attributes related to fat. Therefore, the enhancement of fat-related attributes seems to be driven by the presence of high-fat zones preferably on the surface of the product rather than by the presence of fat concentration differences within the product.


    The combined effects of modulation of the spatial distribution of tastants and fat and modulation of the mechanical properties can be applied in the development of low-sugar, low-salt and low-fat food products with improved taste quality.

    Modeling patterns of farm diversification in a Dutch landscape
    Pfeifer, C. - \ 2011
    Wageningen University. Promotor(en): Arie Oskam, co-promotor(en): Jetse Stoorvogel; Marthijn Sonneveld; Roel Jongeneel. - [S.l. : S.n. - ISBN 9789085858416 - 144
    diversificatie - landbouwbedrijven - nevenactiviteiten - multifunctionele landbouw - landbouw - landschap - besluitvorming - plattelandsontwikkeling - ruimtelijke verdeling - gelderse vallei - nederland - diversification - farms - ancillary enterprises - multifunctional agriculture - agriculture - landscape - decision making - rural development - spatial distribution - gelderse vallei - netherlands
    In agrarische landschappen zijn het de beslissingen van de agrariërs die medebepalend zijn voor zowel het aanbod als de kwaliteit van de voortgebrachte landschapsdiensten. Het doel van dit proefschrift is inzicht te verschaffen in de ruimtelijke patronen van bedrijfsdiversificatie en na te gaan hoe deze patronen mogelijk in de toekomst zouden kunnen veranderen. De studie richt zich op de Gelderse Vallei
    Duurzame ontwikkeling van de veehouderij in Limburg
    Baltussen, W.H.M. ; Smeets, P.J.A.M. ; Tacken, G.M.L. - \ 2010
    Den Haag : LEI Wageningen UR (Alterra-rapport 2094) - ISBN 9789086154654 - 67
    veehouderij - duurzaamheid (sustainability) - ruimtelijke verdeling - milieueffect - volksgezondheid - attitudes - samenleving - landbouwbeleid - duurzame veehouderij - landbouw als bedrijfstak - limburg - livestock farming - sustainability - spatial distribution - environmental impact - public health - attitudes - society - agricultural policy - sustainable animal husbandry - agriculture as branch of economy - limburg
    Provinciale Staten van Limburg wil inzicht in de belangrijke aspecten om te komen tot een duurzame ontwikkeling van de veehouderij in de provincie Limburg. Op basis van feiten en cijfers over de economische betekenis van het veehouderijcomplex in Limburg, de invloed van de veehouderij op milieu en volksgezondheid en de mening van Limburgers over de veehouderij is met verschillende direct betrokkenen nagedacht over de gewenste duurzame ontwikkeling en hoe deze gerealiseerd kan worden.
    Distribution maps for the North Sea fisheries; Methods and application in Natura 2000 areas
    Oostenbrugge, J.A.E. van; Bartelings, H. ; Buisman, F.C. - \ 2010
    Den Haag : LEI, part of Wageningen UR (Report / LEI : Research area Natural resources ) - ISBN 9789086154593 - 122
    natura 2000 - visserij-ecologie - ruimtelijke verdeling - databanken - noordzee - natura 2000 - fisheries ecology - spatial distribution - databases - north sea
    In the study presented here a database was developed with spatial distribution pattern of fishing effort, catches and catch values of the Dutch and non-Dutch fisheries in the Dutch section of the North Sea. Distribution maps were produced on the basis of this database. In addition, estimates were made of the value of different fisheries in areas designated by the Netherlands as Natura 2000 areas.
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