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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    Author Correction: A global database for metacommunity ecology, integrating species, traits, environment and space
    Jeliazkov, Alienor ; Mijatovic, Darko ; Chantepie, Stéphane ; Andrew, Nigel ; Arlettaz, Raphaël ; Barbaro, Luc ; Barsoum, Nadia ; Bartonova, Alena ; Belskaya, Elena ; Bonada, Núria ; Brind’Amour, Anik ; Carvalho, Rodrigo ; Castro, Helena ; Chmura, Damian ; Choler, Philippe ; Chong-Seng, Karen ; Cleary, Daniel ; Cormont, Anouk ; Cornwell, William ; Campos, Ramiro de; Voogd, Nicole de; Doledec, Sylvain ; Drew, Joshua ; Dziock, Frank ; Eallonardo, Anthony ; Edgar, Melanie J. ; Farneda, Fábio ; Hernandez, Domingo Flores ; Frenette-Dussault, Cédric ; Fried, Guillaume ; Gallardo, Belinda ; Gibb, Heloise ; Gonçalves-Souza, Thiago ; Higuti, Janet ; Humbert, Jean Yves ; Krasnov, Boris R. ; Saux, Eric Le ; Lindo, Zoe ; Lopez-Baucells, Adria ; Lowe, Elizabeth ; Marteinsdottir, Bryndis ; Martens, Koen ; Meffert, Peter ; Mellado-Díaz, Andres ; Menz, Myles H.M. ; Meyer, Christoph F.J. ; Miranda, Julia Ramos ; Mouillot, David ; Ossola, Alessandro ; Pakeman, Robin ; Pavoine, Sandrine ; Pekin, Burak ; Pino, Joan ; Pocheville, Arnaud ; Pomati, Francesco ; Poschlod, Peter ; Prentice, Honor C. ; Purschke, Oliver ; Raevel, Valerie ; Reitalu, Triin ; Renema, Willem ; Ribera, Ignacio ; Robinson, Natalie ; Robroek, Bjorn ; Rocha, Ricardo ; Shieh, Sen Her ; Spake, Rebecca ; Staniaszek-Kik, Monika ; Stanko, Michal ; Tejerina-Garro, Francisco Leonardo ; Braak, Cajo ter; Urban, Mark C. ; Klink, Roel van; Villéger, Sébastien ; Wegman, Ruut ; Westgate, Martin J. ; Wolff, Jonas ; Żarnowiec, Jan ; Zolotarev, Maxim ; Chase, Jonathan M. - \ 2020
    Scientific Data 7 (2020)1. - ISSN 2052-4463

    Following publication of this Data Descriptor it was found that the affiliation of Oliver Purschke was stated incorrectly. The correct affiliations are stated below: Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 37, SE-223 62 Lund, Sweden Biodiversity, Department of Biology, Lund University, Sölvegatan 37, SE-223 62 Lund, Sweden This has been corrected in both the HTML and PDF versions.

    A global database for metacommunity ecology, integrating species, traits, environment and space
    Jeliazkov, Alienor ; Mijatovic, Darko ; Chantepie, Stéphane ; Andrew, Nigel ; Arlettaz, Raphaël ; Barbaro, Luc ; Barsoum, Nadia ; Bartonova, Alena ; Belskaya, Elena ; Bonada, Núria ; Brind’Amour, Anik ; Carvalho, Rodrigo ; Castro, Helena ; Chmura, Damian ; Choler, Philippe ; Chong-Seng, Karen ; Cleary, Daniel ; Cormont, Anouk ; Cornwell, William ; Campos, Ramiro de; Voogd, Nicole de; Doledec, Sylvain ; Drew, Joshua ; Dziock, Frank ; Eallonardo, Anthony ; Edgar, Melanie J. ; Farneda, Fábio ; Hernandez, Domingo Flores ; Frenette-Dussault, Cédric ; Fried, Guillaume ; Gallardo, Belinda ; Gibb, Heloise ; Gonçalves-Souza, Thiago ; Higuti, Janet ; Humbert, Jean Yves ; Krasnov, Boris R. ; Saux, Eric Le ; Lindo, Zoe ; Lopez-Baucells, Adria ; Lowe, Elizabeth ; Marteinsdottir, Bryndis ; Martens, Koen ; Meffert, Peter ; Mellado-Díaz, Andres ; Menz, Myles H.M. ; Meyer, Christoph F.J. ; Miranda, Julia Ramos ; Mouillot, David ; Ossola, Alessandro ; Pakeman, Robin ; Pavoine, Sandrine ; Pekin, Burak ; Pino, Joan ; Pocheville, Arnaud ; Pomati, Francesco ; Poschlod, Peter ; Prentice, Honor C. ; Purschke, Oliver ; Raevel, Valerie ; Reitalu, Triin ; Renema, Willem ; Ribera, Ignacio ; Robinson, Natalie ; Robroek, Bjorn ; Rocha, Ricardo ; Shieh, Sen Her ; Spake, Rebecca ; Staniaszek-Kik, Monika ; Stanko, Michal ; Tejerina-Garro, Francisco Leonardo ; Braak, Cajo ter; Urban, Mark C. ; Klink, Roel van; Villéger, Sébastien ; Wegman, Ruut ; Westgate, Martin J. ; Wolff, Jonas ; Żarnowiec, Jan ; Zolotarev, Maxim ; Chase, Jonathan M. - \ 2020
    Scientific Data 7 (2020)1. - ISSN 2052-4463

    The use of functional information in the form of species traits plays an important role in explaining biodiversity patterns and responses to environmental changes. Although relationships between species composition, their traits, and the environment have been extensively studied on a case-by-case basis, results are variable, and it remains unclear how generalizable these relationships are across ecosystems, taxa and spatial scales. To address this gap, we collated 80 datasets from trait-based studies into a global database for metaCommunity Ecology: Species, Traits, Environment and Space; “CESTES”. Each dataset includes four matrices: species community abundances or presences/absences across multiple sites, species trait information, environmental variables and spatial coordinates of the sampling sites. The CESTES database is a live database: it will be maintained and expanded in the future as new datasets become available. By its harmonized structure, and the diversity of ecosystem types, taxonomic groups, and spatial scales it covers, the CESTES database provides an important opportunity for synthetic trait-based research in community ecology.

    Rapid risk assessment tool (RRAT) to assess exotic animal disease introduction risks
    Vos-de Jong, C.J. de; Petie, R. ; Klink, E.G.M. van; Swanenburg, M. - \ 2019
    Wageningen Bioveterinary Research
    Rapid risk assessment of exotic animal disease introduction
    Vos-de Jong, C.J. de; Petie, R. ; Klink, E.G.M. van; Swanenburg, M. - \ 2018
    Risks and opportunities of trophic rewilding for arthropod communities
    Klink, Roel van; WallisDeVries, Michiel F. - \ 2018
    Philosophical Transactions of the Royal Society B. Biological sciences 373 (2018)1761. - ISSN 0962-8436 - 8 p.
    grazing - insects - invertebrates - near-natural grazing - Oostvaardersplassen - restoration

    Trophic rewilding is a restoration strategy focusing on the restoration of trophic interactions to promote self-regulating, biodiverse ecosystems. It has been proposed as an alternative to traditional conservation management in abandoned or defaunated areas. Arthropods constitute the most species-rich group of eukaryotic organisms, but are rarely considered in rewilding. Here, we first present an overview of direct and indirect pathways by which large herbivores and predators affect arthropod communities. We then review the published evidence of the impacts of rewilding with large herbivores on arthropods, including grey literature. We find that systematic monitoring is rare and that a comparison with a relevant control treatment is usually lacking. Nevertheless, the available data suggest that when the important process of top-down control of large-herbivore populations is missing, arthropod diversity tends to decrease. To ensure that rewilding is supportive of biodiversity conservation, we propose that if natural processes can only partially be restored, substitutes for missing processes are applied. We also propose that boundaries of acceptable outcomes of rewilding actions should be defined a priori, particularly concerning biodiversity conservation, and that action is taken when these boundaries are transgressed. To evaluate the success of rewilding for biodiversity, monitoring of arthropod communities should be a key instrument.This article is part of the theme issue 'Trophic rewilding: consequences for ecosystems under global change'.

    Basisregistratie Ondergrond (BRO) actualisatie bodemkaart : Herkatering westelijk veengebied Waterschap Drents Overijsselse Delta
    Vries, Folkert de; Brouwer, Fokke ; Walvoort, Dennis - \ 2018
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research report 2887) - 27
    De bodemkaart onderscheidt allerlei bodemtypen met veenlagen ondiep in het profiel. Door oxidatie en klink neemt de veendikte geleidelijk af. Voor het beheer van veengebieden is het van belang om inzicht te hebben in de veendiktes. Dit onderzoek heeft geresulteerd in een veendiktekaart voor het westelijk veengebied in Waterschap Drents Overijsselse Delta en een geactualiseerde bodemkaart, schaal 1 : 50 000, van dit veengebied.
    Effects of grazing management on biodiversity across trophic levels – The importance of livestock species and stocking density in salt marshes
    Klink, Roel van; Nolte, Stefanie ; Mandema, Freek S. ; Lagendijk, D.D.G. ; Wallis de Vries, Michiel ; Bakker, Jan P. ; Esselink, Peter ; Smit, Christian - \ 2016
    Agriculture, Ecosystems and Environment 235 (2016). - ISSN 0167-8809 - p. 329 - 339.
    Birds - Butterflies - Cattle - Flower-visiting insects - Horses - Plants - Vegetation - Wetland

    European coastal salt marshes are important for the conservation of numerous species of specialist plants, invertebrates, breeding and migratory birds. When these marshes are managed for nature conservation purposes, livestock grazing is often used to counter the dominance of the tall grass Elytrigia atherica, and the subsequent decline in plant species richness. However, it remains unclear what is the optimal choice of livestock species and stocking density to benefit biodiversity of various trophic levels. To fill this knowledge gap, we set up a triplicate, full factorial grazing experiment with cattle and horse grazing at low and high stocking densities (0.5 or 1 animal ha−1) at the mainland coast of the Dutch Wadden Sea. Here, we present the results after 4 years and integrate these with previously published results from the same experiment to assess effects of livestock grazing on various trophic groups. Stocking density affected almost all measured variables: high stocking densities favoured plant species richness and suppression of E. atherica, whereas low stocking densities favoured abundances of voles, pollinators and flowers. Densities of different functional groups of birds showed no significant response to the regimes, but tended to be somewhat higher under 0.5 horse and 1 cattle ha−1. Choice of livestock species had fewer and smaller effects than stocking density. Horse grazing was detrimental to vole density, and showed an interactive effect with stocking density for Asteraceae flower abundance. Multidiversity, a synthetic whole-ecosystem biodiversity measure, did not differ among regimes. These results are discussed in the light of other results from the same experiment. Because of these contrasting effects on different trophic groups, we advise concurrent application of different grazing regimes within a spatial mosaic, with the inclusion of long-term abandonment. High density horse grazing, however, is detrimental to biodiversity.

    Changing Expectations of Experts: The Symbolic Role of Ethics Committees
    Poort, Lonneke ; Bovenkerk, B. - \ 2016
    In: Symbolic Legislation Theory and Developments in Biolaw / van Klink, Bart, van Beers, Britta, Poort, Lonneke, Springer (Legisprudence Library ) - ISBN 9783319333632 - p. 269 - 287.
    Complex policy issues pose a conundrum for liberal democratic governments. Disagreement about complex policy issues can often be traced back to fundamental value differences and governments aim to avoid heavy political conflicts based on these, while at the same time they face the need for expedient decision making. One solution is to seek advice of or even defer decisions to expert committees, in particular ethics committees. In this paper, we focus on the role of ethics committees by putting the role of ethicists as experts up for discussion. We argue that governments and the public foster wrong expectations regarding the role and mandate of ethics committees. Normative expertise is essentially different from scientific expertise. Lumping them together has resulted in false expectations and an overvaluation of the role of various types of experts. It is therefore necessary to explicate the roles the various players have and to define what is to be expected from them.
    Defoliation and soil compaction jointly drive large-herbivore grazing effects on plants and soil arthropods on clay soil
    Klink, R. van; Schrama, M. ; Nolte, S. ; Bakker, J.P. ; Wallis de Vries, M.F. ; Berg, M.P. - \ 2015
    Ecosystems 18 (2015)4. - ISSN 1432-9840 - p. 671 - 685.
    salt-marsh - nitrogen mineralization - wadden sea - mountain pastures - grassland - collembola - management - diversity - growth - cow
    In addition to the well-studied impacts of defecation and defoliation, large herbivores also affect plant and arthropod communities through trampling, and the associated soil compaction. Soil compaction can be expected to be particularly important on wet, fine-textured soils. Therefore, we established a full factorial experiment of defoliation (monthly mowing) and soil compaction (using a rammer, annually) on a clay-rich salt marsh at the Dutch coast, aiming to disentangle the importance of these two factors. Additionally, we compared the effects on soil physical properties, plants, and arthropods to those at a nearby cattle-grazed marsh under dry and under waterlogged conditions. Soil physical conditions of the compacted plots were similar to the conditions at cattle-grazed plots, showing decreased soil aeration and increased waterlogging. Soil salinity was doubled by defoliation and quadrupled by combined defoliation and compaction. Cover of the dominant tall grass Elytrigia atherica was decreased by 80% in the defoliated plots, but cover of halophytes only increased under combined defoliation and compaction. Effects on soil micro-arthropods were most severe under waterlogging, showing a fourfold decrease in abundance and a smaller mean body size under compaction. Although the combined treatment of defoliation and trampling indeed proved most similar to the grazed marsh, large discrepancies remained for both plant and soil fauna communities, presumably because of colonization time lags. We conclude that soil compaction and defoliation differently affect plant and arthropod communities in grazed ecosystems, and that the magnitude of their effects depends on herbivore density, productivity, and soil physical properties.
    Effects of large herbivores on grassland arthropod diversity
    Klink, R. van; Plas, F. van der; Noordwijk, C.G.E. ; Wallis de Vries, M.F. ; Olff, H. - \ 2015
    Biological Reviews 90 (2015)2. - ISSN 1464-7931 - p. 347 - 366.
    ungrazed chalk grassland - ground beetle coleoptera - plant-species richness - grazing management - phytophagous insects - seminatural grasslands - community structure - tallgrass prairie - long-term - butterfly communities
    Both arthropods and large grazing herbivores are important components and drivers of biodiversity in grassland ecosystems, but a synthesis of how arthropod diversity is affected by large herbivores has been largely missing. To fill this gap, we conducted a literature search, which yielded 141 studies on this topic of which 24 simultaneously investigated plant and arthropod diversity. Using the data from these 24 studies, we compared the responses of plant and arthropod diversity to an increase in grazing intensity. This quantitative assessment showed no overall significant effect of increasing grazing intensity on plant diversity, while arthropod diversity was generally negatively affected. To understand these negative effects, we explored the mechanisms by which large herbivores affect arthropod communities: direct effects, changes in vegetation structure, changes in plant community composition, changes in soil conditions, and cascading effects within the arthropod interaction web. We identify three main factors determining the effects of large herbivores on arthropod diversity: (i) unintentional predation and increased disturbance, (ii) decreases in total resource abundance for arthropods (biomass) and (iii) changes in plant diversity, vegetation structure and abiotic conditions. In general, heterogeneity in vegetation structure and abiotic conditions increases at intermediate grazing intensity, but declines at both low and high grazing intensity. We conclude that large herbivores can only increase arthropod diversity if they cause an increase in (a)biotic heterogeneity, and then only if this increase is large enough to compensate for the loss of total resource abundance and the increased mortality rate. This is expected to occur only at low herbivore densities or with spatio-temporal variation in herbivore densities. As we demonstrate that arthropod diversity is often more negatively affected by grazing than plant diversity, we strongly recommend considering the specific requirements of arthropods when applying grazing management and to include arthropods in monitoring schemes. Conservation strategies aiming at maximizing heterogeneity, including regulation of herbivore densities (through human interventions or top-down control), maintenance of different types of management in close proximity and rotational grazing regimes, are the most promising options to conserve arthropod diversity.
    Actualisatie bodemkaart veengebieden : deelgebied en 2 in Noord Nederland
    Vries, F. de; Brus, D.J. ; Kempen, B. ; Brouwer, F. ; Heidema, A.H. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2556)
    veengronden - bodem - bodemkarteringen - cartografie - kaarten - noord-nederland - peat soils - soil - soil surveys - mapping - maps - north netherlands
    De bodemkaart onderscheidt allerlei bodemtypen met veenlagen ondiep in het profiel. Door oxidatie en klink neemt de veendikte geleidelijk af. Hierdoor treedt er een verschuiving op in bodemtypen; moerige gronden veranderen in minerale gronden en veengronden in moerige gronden. Vanwege deze dynamiek bij gronden met dunne veenlagen dient de bodemkundige informatie periodiek geactualiseerd te worden. Alle veengebieden in Friesland en een deel van de veengebieden in Drenthe, Groningen en Overijssel zijn opnieuw in kaart gebracht. Het project heeft geresulteerd in een veendiktekaart en een geactualiseerde bodemkaart.
    Agro Vertrouwensindex
    Jukema, Gerben ; Jongeneel, Roel ; Dalhuisen, J. ; Jong, W. de; Osinga, K.J. ; Zeinstra, F. ; Galen, M.A. van; Breembroek, J. ; Klink, J. - \ 2013
    Wageningen Economic Research
    economic sectors - agricultural sector - agroindustrial sector - statistics - farm comparisons - farm development - farm results - farm surveys - agricultural economics - economic development
    De Agro vertrouwensindex geeft op reguliere basis een beeld van de stemming onder agrarische ondernemers in Nederland. Naast het sentiment van de ondernemers wordt ook gevraagd naar de ontwikkeling in enkele belangrijke bedrijfsfactoren, zoals kosten productie, opbrengstprijs, omzet en winst. Deze website geeft daardoor elk kwartaal een actueel inzicht in de stand van zaken in de agrarische sector en een vooruitblik op de korte en de wat langere termijn. Beleidsmakers en bedrijven hebben door de Agro vertrouwensindex een actueel, wetenschappelijk en representatief beeld van de sector in handen. Door de vooruitblik is het mogelijk in te spelen op ontwikkelingen en hier het beleid op af te stemmen. Inzicht in de impact van beleidsbeslissingen, wijzigingen in inkomens- of concurrentiepositie kunnen met deze agro vertrouwensindex worden gevolgd. Door coördinatie met vertegenwoordigers van het landbouwbedrijfsleven en kennisinstellingen uit verschillende EU-lidstaten onder de vlag van Copa-Cogeca, de Europese belangenorganisatie van land- en tuinbouw ondernemers en hun coöperaties, worden resultaten van de agro vertrouwensindex vergeleken met de ontwikkelingen in andere EU-lidstaten.
    Grazed vegetation mosaics do not maximize arthropod diversity: Evidence from salt marshes
    Klink, R. van; Rickert, C. ; Vermeulen, R. ; Vorst, O. ; Wallis de Vries, M.F. ; Bakker, J.P. - \ 2013
    Biological Conservation 164 (2013). - ISSN 0006-3207 - p. 150 - 157.
    Light to moderate grazing in grasslands can create vegetation mosaics of short grazed vegetation and tall ungrazed vegetation. These mosaics have been proposed to maximize plant and animal species richness, yet experimental evidence, especially regarding arthropods is scarce. This study compares abundance, richness and species composition of arthropods in grazed mosaics to those of homogeneous short and tall vegetation. We sampled arthropods on three German coastal salt marshes where grazing with three densities (high, moderate and none) was installed in 1989 on previously intensively grazed plots. Stable vegetation mosaics had developed under moderate stocking densities. We collected spiders, beetles, bugs and moth larvae by suction sampling in a stratified random sampling design. Treatments had caused large differences in plant composition after 20 years, which were reflected in the arthropod community. Most species showed a clear preference for either short or tall vegetation, but some species were most abundant in grazed mosaics. Arthropod richness and composition were similar in patches of short vegetation in moderately and highly stocked plots, while patches of tall vegetation were similar to ungrazed plots. Surprisingly, however, grazed mosaics were not richer in species than homogeneous tall vegetation, despite the co-occurrence of species from short, tall and mosaic vegetation. We conclude that, although arthropod richness of salt marshes is greatly enhanced when stocking density is decreased, this cannot substitute ungrazed marshes for conservation of arthropod diversity. However, long term cessation leads to the disappearance of several species, and therefore the possibilities of rotational grazing should be explored.
    Intermittent stimulus presentation stabilizes neuronal responses in macaque area MT
    Klink, P.C. ; Oleksiak, A. ; Lankheet, M.J.M. ; Wezel, R.J.A. - \ 2012
    Journal of Neurophysiology 108 (2012)8. - ISSN 0022-3077 - p. 2101 - 2114.
    local-field potentials - primary visual-cortex - structure-from-motion - binocular-rivalry - ambiguous patterns - perceptual memory - attention - variability - adaptation - brain
    Klink PC, Oleksiak A, Lankheet MJ, van Wezel RJ. Intermittent stimulus presentation stabilizes neuronal responses in macaque area MT. J Neurophysiol 108: 2101-2114, 2012. First published July 25, 2012; doi: 10.1152/jn.00252.2012.-Repeated stimulation impacts neuronal responses. Here we show how response characteristics of sensory neurons in macaque visual cortex are influenced by the duration of the interruptions during intermittent stimulus presentation. Besides effects on response magnitude consistent with neuronal adaptation, the response variability was also systematically influenced. Spike rate variability in motion-sensitive area MT decreased when interruption durations were systematically increased from 250 to 2,000 ms. Activity fluctuations between subsequent trials and Fano factors over full response sequences were both lower with longer interruptions, while spike timing patterns became more regular. These variability changes partially depended on the response magnitude, but another significant effect that was uncorrelated with adaptation-induced changes in response magnitude was also present. Reduced response variability was furthermore accompanied by changes in spike-field coherence, pointing to the possibility that reduced spiking variability results from interactions in the local cortical network. While neuronal response stabilization may be a general effect of repeated sensory stimulation, we discuss its potential link with the phenomenon of perceptual stabilization of ambiguous stimuli as a result of interrupted presentation.
    Spike-Interval Triggered Averaging Reveals a Quasi-Periodic Spiking Alternative for Stochastic Resonance in Catfish Electroreceptors
    Lankheet, M.J.M. ; Klink, P.C. ; Borghuis, B.G. ; Noest, A.J. - \ 2012
    PLoS ONE 7 (2012)3. - ISSN 1932-6203 - 11 p.
    white-noise analysis - interspike intervals - binocular-rivalry - nervous-system - organs - responses - neuron - input - motoneurons - cells
    Catfish detect and identify invisible prey by sensing their ultra-weak electric fields with electroreceptors. Any neuron that deals with small-amplitude input has to overcome sensitivity limitations arising from inherent threshold non-linearities in spike-generation mechanisms. Many sensory cells solve this issue with stochastic resonance, in which a moderate amount of intrinsic noise causes irregular spontaneous spiking activity with a probability that is modulated by the input signal. Here we show that catfish electroreceptors have adopted a fundamentally different strategy. Using a reverse correlation technique in which we take spike interval durations into account, we show that the electroreceptors generate a supra-threshold bias current that results in quasi-periodically produced spikes. In this regime stimuli modulate the interval between successive spikes rather than the instantaneous probability for a spike. This alternative for stochastic resonance combines threshold-free sensitivity for weak stimuli with similar sensitivity for excitations and inhibitions based on single interspike intervals.
    Indigenous Land Governance in Bolivia. A Case Study in Law and Anthropology.
    Köhne, F.M. - \ 2011
    In: Law and Method / van Klink, B., Taekema, S., Tübingen : Mohr Siebeck (1 4) - ISBN 9783161506765 - p. 289 - 300.
    Spatial summation in macaque parietal area 7a follows a winner-take-all rule
    Oleksiak, A. ; Klink, P.C. ; Postma, A. ; Ham, I.J. van der; Lankheet, M.J.M. ; Wezel, R.J. van - \ 2011
    Journal of Neurophysiology 105 (2011)3. - ISSN 0022-3077 - p. 1150 - 1158.
    lateral intraparietal area - primary visual-cortex - neuronal responses - complex cells - attentional modulation - selective attention - stimulus - v4 - representation - normalization
    While neurons in posterior parietal cortex have been found to signal the presence of a salient stimulus among multiple items in a display, spatial summation within their receptive field in the absence of an attentional bias has never been investigated. This information however, is indispensable when one investigates the mechanisms of spatial attention and competition between multiple visual objects. To examine the spatial summation rule in parietal area 7a neurons, we trained rhesus monkeys to fixate a central cross while two identical stimuli were briefly displayed in a neuron's receptive field. The response to a pair of dots was compared with the responses to the same dots when they were presented individually. The scaling and power parameters of a generalized summation algorithm varied greatly, both across neurons and across combinations of stimulus locations. However, the averaged response of the recorded population of 7a neurons was consistent with a winner-take-all rule for spatial summation. A control experiment where a monkey covertly attended to both stimuli simultaneously suggests that attention introduces additional competition by facilitating the less optimal stimulus. Thus, an averaging stage is introduced between approximately 200 and 300 ms of the response to a pair of stimuli. In short, the summation algorithm over the population of area 7a neurons carries the signature of a winner-take-all operation, with spatial attention possibly influencing the temporal dynamics of stimulus competition, that is the moment that the 'winner' takes 'victory' over the 'loser' stimulus
    A Company perspective on Innovation Brokering: The case of Food Valley Organization
    Klink, K. ; Fortuin, F.T.J.M. ; Batterink, M.H. ; Omta, S.W.F. - \ 2010
    Aanpassen management voor minder antibiotica
    Smolders, E.A.A. - \ 2010
    V-focus 7 (2010)4. - ISSN 1574-1575 - p. 24 - 26.
    melkveehouderij - antibiotica - veterinaire producten - reductie - geneesmiddelen - volksgezondheid - landbouwbeleid - dairy farming - antibiotics - veterinary products - reduction - drugs - public health - agricultural policy
    De maatschappij krijgt steeds meer moeite met de nadelen van antibiotica voor de volksgezondheid: resistente bacteriën, die niet meer op de gebruikelijke geneesmiddelen reageren. De ministers Verburg en Klink willen daarom in 2013 een reductie van het antibioticagebruik van 50 procent en uitkomen op het niveau van 1999. Kan het gemiddelde melkveebedrijf met 50 procent minder toe?
    At what spatial scale do high-quality habitats enhance the diversity of forbs and pollinators in intensively farmed landscapes?
    Kohler, F. ; Verhulst, J. ; Klink, R. van; Kleijn, D. - \ 2008
    Journal of Applied Ecology 45 (2008)3. - ISSN 0021-8901 - p. 753 - 762.
    agri-environment schemes - managing ecosystem services - plant-species richness - agricultural landscapes - european countries - field boundaries - seed dispersal - ditch banks - biodiversity - communities
    1. Over the last decades, biodiversity in agricultural landscapes has declined drastically. Initiatives to enhance biodiversity, such as agri-environment schemes, often have little effect, especially in intensively farmed landscapes. The effectiveness of conservation management may be improved by scheme implementation near high-quality habitats that can act as a source of species. We evaluated up to what distance high-quality habitats (nature reserves and artificially created flower-rich patches) affect the diversity of forbs and pollinators in intensively farmed landscapes of the Netherlands. 2. We surveyed forbs, inflorescences, bees and hover flies and estimated pollination services in transects along ditch banks extending 300 m from four nature reserves forming small islands in landscapes dominated by agriculture. 3. In a separate experiment, we surveyed inflorescences, bees and hover flies in 1500 m long transects on farmland adjacent to five newly introduced flower-rich patches and in five control transects. 4. Species density of forbs declined over the first 75 m and species density and abundance of hover flies declined over the first 125 m beyond the nature reserves. Beyond these distances, no further declines were observed. The effects of flower-rich patches were spatially limited. The species density and abundance of bees and hover flies were significantly enhanced in the flower-rich patch, but only the abundance of hover flies was enhanced up to 50 m beyond the patch. 5. Synthesis and applications. In intensively farmed areas, remnant high-quality habitats sustain more abundant and diverse pollinator and forb communities than the surrounding countryside. They do enhance biodiversity on nearby farmland but increases are spatially restricted (<150 m) and relatively small. These habitats may therefore function only as dispersal sources for ecological restoration sites or agricultural fields under extensification schemes that are located in close proximity. Habitat restoration in intensively used farmland should therefore be implemented preferentially in the immediate vicinity of high-quality habitats. In the short term, newly created flower-rich habitats are no alternative to pre-existing seminatural habitats for the promotion of pollinators on nearby farmland
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