Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

Records 1 - 20 / 111

  • help
  • print

    Print search results

  • export

    Export search results

  • alert
    We will mail you new results for this query: q=Kraker
Check title to add to marked list
Video monitoring of brown planthopper predation in rice shows flaws of sentinel methods
Zou, Yi ; Kraker, Joop De; Bianchi, Felix J.J.A. ; Telgen, Mario D. Van; Xiao, Haijun ; Werf, Wopke Van Der - \ 2017
Scientific Reports 7 (2017). - ISSN 2045-2322 - p. 42210 - 42210.
Immobilized preys are routinely used in agro-ecological exposure studies to quantify predation of pests under field conditions, but this method has not been validated. Our purpose was to determine the validity of using immobilized adults of the major rice pest Nilaparvata lugens, brown plant hopper (BPH), as sentinels. We used direct observation by video recording to determine the causal agents of removal of field exposed BPH sentinels with two experiments: 1) we recorded removal events of dead, immobilized BPH; and 2) we compared removal of (i) dead, immobilized BPH, (ii) live, immobilized BPH, and (iii) live, mobile BPH. Long-horned grasshoppers were responsible for most removals of dead, immobilized BPH, in both experiments. Predatory ground beetles removed most of the live, immobilized BPH, whereas frogs were the major predators of live, mobile BPH. Overall, we showed that removal of immobilized sentinel prey is not representative for predation of live, mobile prey, stressing the need for a critical assessment of commonly used sentinel methods. In addition, we found that frogs played the major role in predation of BPH in rice. As current strategies to enhance biocontrol of planthoppers in rice focus on arthropod natural enemies, this finding could have major implications.
Sustainable Forest Management as a potential integrative approach in international public policy
Mattei Faggin, Joana ; Offermans, A. - \ 2016
In: Sustainable Development Research at ICIS / Cövers, R., Kraker, J. de, Kemp, R., Martens, P., Lente, H. van, Maastricht : Universitaire Pers Maastricht - ISBN 9789461596475 - p. 189 - 201.
Deforestation negatively affects the provision of environmental services, and
consequently affects local populations’ livelihoods that depend on the use of forest
resources. Sustainable Forest Management (SFM) aims to use forest resources in such a
way as to provide environmental services while at the same time achieving economic
and social goals. Even though there is currently no forest convention in an international
public policy context, the SFM concept is included in several international public policy
forums. The present chapter analyses SFM in three United Nations Conventions (CBD –
on Biological Diversity, UNFCCC – on Climate Change, and UNCCD – to Combat
Desertification). The chapter concludes that SFM is a broad concept, and its
implementation specificities are addressed at a national policy scale, which is mainly
influenced by the sovereignty principle. Finally, we concluded that the SFM concept still
hardly touches upon the social dimension, compared to the economic and
environmental dimensions.
Modification and application of a leaf blower-vac for field sampling of arthropods
Zou, Yi ; Telgen, Mario D. van; Chen, Junhui ; Xiao, Haijun ; Kraker, Joop de; Bianchi, Felix J.J.A. ; Werf, Wopke van der - \ 2016
Journal of Visualized Experiments (2016)114. - ISSN 1940-087X
Arthropod abundance - Biodiversity - Environmental Sciences - Issue 114 - Natural enemy - Pest management - Rice - Suction sampling

Rice fields host a large diversity of arthropods, but investigating their population dynamics and interactions is challenging. Here we describe the modification and application of a leaf blower-vac for suction sampling of arthropod populations in rice. When used in combination with an enclosure, application of this sampling device provides absolute estimates of the populations of arthropods as numbers per standardized sampling area. The sampling efficiency depends critically on the sampling duration. In a mature rice crop, a two-minute sampling in an enclosure of 0.13 m2 yields more than 90% of the arthropod population. The device also allows sampling of arthropods dwelling on the water surface or the soil in rice paddies, but it is not suitable for sampling fast flying insects, such as predatory Odonata or larger hymenopterous parasitoids. The modified blower-vac is simple to construct, and cheaper and easier to handle than traditional suction sampling devices, such as D-vac. The low cost makes the modified blower-vac also accessible to researchers in developing countries.

Can computer models be used for social learning? A serious game in water management
Wal, Merel M. Van der; Kraker, Joop de; Kroeze, Carolien ; Kirschner, Paul A. ; Valkering, Pieter - \ 2016
Environmental Modelling & Software 75 (2016). - ISSN 1364-8152 - p. 119 - 132.
Serious game - Simulation model - Social learning - Water management

Computer simulation models are increasingly used to support solving complex problems in natural resource management, with social learning as subsidiary goal of the solution process. In this research, a serious game on water management is used where participants receive feedback on consequences of their choices from an Integrated Assessment Meta Model. This study aims to determine if and how social learning takes place and explores the role of the model in social learning. Group discussions were qualitatively analysed to uncover and understand the mechanisms in this process. Results show that social learning took place in 10 of the 12 game sessions. Though model feedback was an important driver for social learning, social learning was driven most by the team's reflection on their perspective. We conclude that using a model can facilitate social learning in a serious-game setting, in particular in combination with reflection on teams' perspectives.

Modelling the impact of sanitation, population growth and urbanization on human emissions of Cryptosporidium to surface waters—a case study for Bangladesh and India
Vermeulen, L.C. ; Kraker, Dummy ; Hofstra, N. ; Kroeze, C. ; Medema, G.J. - \ 2015
Environmental Research Letters 10 (2015). - ISSN 1748-9326 - 13 p.
Cryptosporidium is a protozoan parasite that can cause diarrhoea. Human faeces are an important source of Cryptosporidium in surface waters. We present a model to study the impact of sanitation, urbanization and population growth on human emissions of Cryptosporidium to surface waters. We build on a global model by Hofstra et al (2013 Sci. Total Environ. 442 10–9) and zoom into Bangladesh and India as illustrative case studies. The model is most sensitive to changes in oocyst excretion and infection rate, and to assumptions on the share of faeces reaching the surface water for different sanitation types. We find urban centres to be hotspots of human Cryptosporidium emissions. We estimate that 53% (Bangladesh) and 91% (India) of total emissions come from urban areas. 50% of oocysts come from only 8% (Bangladesh) and 3% (India) of the country area. In the future, population growth and urbanization may further deteriorate water quality in Bangladesh and India, despite improved sanitation. Under our 'business as usual' ('sanitation improvements') scenario, oocyst emissions will increase by a factor 2.0 (1.2) for India and 2.9 (1.1) for Bangladesh between 2010 and 2050. Population growth, urbanization and sanitation development are important processes to consider for large scale water quality modelling.
Assessment of the Potential of Honeybees (Apis mellifera L.) in Biomonitoring of Air Pollution by Cadmium, Lead and Vanadium
Steen, J.J.M. van der; Kraker, J. de; Grotenhuis, J.T.C. - \ 2015
Journal of Environmental Protection 6 (2015)2. - ISSN 2152-2197 - p. 96 - 102.
The aim of our study was to explore whether honeybees (Apis mellifera L.) could be used as a reliable alternative to the standard mechanical devices for monitoring of air quality, in particular with respect to the concentration of the heavy metals cadmium (Cd), lead (Pb) and vanadium (V). We therefore tested whether the concentrations of these metals in adult honeybees and in ambient air were positively correlated, and whether differences in concentration between locations were similar for bees and air. On the basis of our measurements, conducted over a two-month period at three distinct locations in the Netherlands with each three replicate honeybee colonies placed next to mechanical monitoring devices, we concluded that a significant positive relationship between the concentrations in bees and in air could only be established for V. Also, only in the case of V, the differences between the three locations in mean concentration were similar for bees and air. Both outcomes were probably due to the relatively large range over which the concentrations of V varied, both in bees and in air, as compared to Cd and Pb. However, for V, as well as for Cd and Pb, the concentrations in ambient air were about two orders of magnitude below the established air quality standards. We therefore conclude that in the Netherlands, both variation and levels of the atmospheric concentrations of these metals are too low to establish a relationship between the concentration in bees and in air that is useful to present honeybees as an alternative to mechanical devices in monitoring of air pollution. However, in countries with larger variation and higher levels of the atmospheric concentrations of these metals, further exploration of the potential of honeybees in biomonitoring of air pollution may be worthwhile
Measuring Social Learning in Participatory Approaches to Natural Resource Management
Wal, M.M. van der; Kraker, J. de; Offermans, A. ; Kroeze, C. ; Kirschner, P. ; Ittersum, M.K. van - \ 2014
Environmental Policy and Governance 24 (2014)1. - ISSN 1756-932X - p. 1 - 15.
natuurlijke hulpbronnen - hulpbronnenbeheer - sociaal leren - participatief management - klimaatverandering - governance - natural resources - resource management - social learning - participative management - climatic change - cultural theory - stakeholder participation - climate-change - sustainability - perspectives - framework - dilemmas
The role of social learning as a governance mechanism in natural resource management has been frequently highlighted, but progress in finding evidence for this role and gaining insight into the conditions that promote it are hampered by the lack of operational definitions of social learning and practical methods to measure it. In this article, we present a simple and flexible method to measure social learning, whether it has occurred and to what extent, among stakeholders in natural resource management. The method yields measurements of social learning that are visual, quantitative and qualitative. First, we elaborate our definition of social learning as a convergence of perspectives and outline how stakeholder perspectives in natural resource management can be described with Cultural Theory. Next, we provide a generic description of the method, followed by two examples illustrating its application to the domains of water and land management. Finally, we discuss relative strengths and weaknesses of the method and how it could be applied to improve our understanding of factors that contribute to social learning.
Prevalence of Extended-Spectrum Beta-Lactamase-producing Enterobacteriaceae in humans living in municipalities with high and low broiler density
Huijbers, P.M.C. ; Kraker, M. de; Graat, E.A.M. ; Hoek, A.H.A.M. van; Santen, M.G.M. ; Jong, M.C.M. de; Duijkeren, E. van; Greeff, S.C. de - \ 2013
Clinical Microbiology and Infection 19 (2013)6. - ISSN 1198-743X - p. E256 - E259.
escherichia-coli - volunteers - resistance - poultry - genes
Prevalence of, and risk factors for, carriage of extended-spectrum ß-lactamase (ESBL) -producing Enterobacteriaceae were determined for 1025 Dutch adults in municipalities with either high or low broiler densities. Overall prevalence of ESBL carriage was 5.1%. The hypothesis that individuals in areas with high broiler densities are at greater risk for ESBL carriage was rejected, as the risk was lower (OR = 0.45; p 0.009) for these individuals. Owning a horse increased the risk (OR = 4.69; p =0.0001), but horse owners often owned multiple species of companion animals. Routes of transmission from animals to humans in the community, and the role of poultry in this process, remain to be elucidated.
Prevalence of Extended-Spectrum ß-Lactamases in Humans Living in Municipalities with High or Low Broiler Density
Huijbers, P.M.C. ; Kraker, M. de; Graat, E.A.M. ; Hoek, A.H. van; Santen, M.G. van; Huijsdens, X.W. ; Duijkeren, E. van; Jong, M.C.M. de; Greeff, S.C. de - \ 2012
In: Proceedings of the 3rd American Society for Microbiology conference on Antimicrobial Resistance in Zoonotic Bacteria and Foodborne Pathogens in Animals, Humans, and the Environment, Aix-en-Provence, France, 26-29 June 2012. - Aix-en-Provence, France : - ISBN 9781555818630 - p. 17 - 17.
Spatial and temporal variation of metal concentrations in adult honeybees (Apis mellifera L.)
Steen, J.J.M. van der; Kraker, J. ; Grotenhuis, J.T.C. - \ 2012
Environmental Monitoring and Assessment 184 (2012)7. - ISSN 0167-6369 - p. 4119 - 4126.
heavy-metals - bees - contamination - products - pollen
Honeybees (Apis mellifera L.) have great potential for detecting and monitoring environmental pollution, given their wide-ranging foraging behaviour. Previous studies have demonstrated that concentrations of metals in adult honeybees were significantly higher at polluted than at control locations. These studies focused at a limited range of heavy metals and highly contrasting locations, and sampling was rarely repeated over a prolonged period. In our study, the potential of honeybees to detect and monitor metal pollution was further explored by measuring the concentration in adult honeybees of a wide range of trace metals, nine of which were not studied before, at three locations in the Netherlands over a 3-month period. The specific objective of the study was to assess the spatial and temporal variation in concentration in adult honeybees of Al, As, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, Ti, V and Zn. In the period of July-September 2006, replicated samples were taken at 2-week intervals from commercial-type beehives. The metal concentration in micrograms per gram honeybee was determined by inductive coupled plasma-atomic emission spectrometry. Significant differences in concentration between sampling dates per location were found for Al, Cd, Co, Cr, Cu, Mn Sr, Ti and V, and significant differences in average concentration between locations were found for Co, Sr and V. The results indicate that honeybees can serve to detect temporal and spatial patterns in environmental metal concentrations, even at relatively low levels of pollution. Keywords: Metals . Bioindication . Pollution . Honeybee
‘The lived experience of climate change’: creating open educational resources and virtual mobility for an innovative, integrative and competence-based track at Masters level
Terwisscha van Scheltinga, C.T.H.M. ; Wilson, Gordon ; Abbott, Dina ; Kraker, Joop de - \ 2011
International Journal of Technology Enhanced Learning 3 (2011)2. - ISSN 1753-5255
This paper explores a new integrative approach to climate change education at Masters level. Drawing on the authors’ involvement in a European Union Erasmus project, it is argued that the diversity of knowledge(s) on climate change are a source of active/social learning. The wide variety of disciplinary, sectoral and lived experiential (both individual and collective)knowledge(s) are all considered legitimate in this exercise, the aim of which is to construct new interdisciplinary knowledge from their boundary interfaces. We further argue for a corresponding pedagogy based on developing transboundary competences – the ability to engage in social learning and action through communicative engagement across knowledge boundaries. We acknowledge that the challenges for enacting transboundary competence are considerable when it requires mobility across epistemological, even ontological, boundaries. The challenges are further compounded when the communicative engagement across space and time requires virtual mobility which is ICT-enabled. Nevertheless, meeting them is a normative goal, not only for this expanded, integrative approach to climate change education, but also for a global resolution of climate change itself.
De idylle van een SLOAP : Space Left Over After Planning
Dam, R.I. van - \ 2009
Topos : periodiek over landschapsarchitectuur, ruimtelijke planning en sociaal-ruimtelijke analyse 19 (2009)3. - ISSN 1572-302X - p. 32 - 35.
woningen - huisvesting - eigendom - dwellings - housing - ownership
Krakers wonen vaak op de meest fantastische plekken, zoals oude forten, monumentale panden, oude boerderijtjes, kloosters of treinloodsen. Het komt voor dat krakers zich vestigen in minder fantasievolle plekken als een "jaren '80 flat", maar er lijkt wel een voorkeur uit te gaan naar plekken met karakter. Hoe zit dat nou? Een visie op de kraker anno 2010, vlak voor een nieuw overheidsbeleid t.a.v. leegstand, waar een kraker geen woonrecht meer heeft.
Models as social learning tools in participatory integrated assessment
Kraker, J. de; Kroeze, C. ; Kirschner, P. - \ 2009
Valuation of ecosystems and ecosystem services
Leemans, R. - \ 2007
In: Ecosystems and Human Well-being, Textbook 1 / de Kraker, J., Heerlen : Open Universiteit Nederland - p. 55 - 77.
Integrated management of ecosystems
Hein, L.G. - \ 2007
In: Ecosystems and Human Well-being, Textbook 2 / de Kraker, J., Heerlen : Open Universiteit Nederland - p. 33 - 60.
Nature policy across Europe - between trends and traditions
Zouwen, M.W. van der; Kraker, J. - \ 2007
In: Ecosystems and Human Well-being, Textbook 2 / de Kraker, J., Heerlen : Open Universiteit - p. 63 - 94.
The Millennium Ecosystem Assessment: linking ecosystem science and policy
Leemans, R. ; Kraker, J. de - \ 2007
In: Ecosystems and Human Well-being, Textbook 1 Heerlen : Open Universiteit Nederland - p. 79 - 104.
Valuation of ecosystems and ecosystems services
Leemans, R. - \ 2007
In: Ecosystems and Human Well-being, Texbook 1 / de Kraker, J., Heerlen : Open Universiteit Nederland - p. 55 - 77.
Practical ecosystem assessment
Metzger, M.J. ; Kraker, J. de - \ 2007
In: Ecosystem and Human Well-being, Electronic Workbook / de Kraker, J., Heerlen : Open Universiteit Nederland - p. 1 - 15.
Enige beschouwingen over ligging, aanleg en gebruik van binnenlandse vaarroutes in Nederland tot in de 15e eeuw
Vervloet, J.A.J. - \ 2007
In: Landschap in ruimte en tijd / Beenakker, J.J.J.M., Horsten, F.H., de Kraker, A.M.J., Renes, J., Amsterdam : Aksant - ISBN 9789052602707 - p. 384 - 397.
waterwegen - transport over water - rivieren - geschiedenis - nederland - middeleeuwen - romeinse rijk - waterways - water transport - rivers - history - netherlands - middle ages - roman empire
In deze bijdrage wordt over de ontsluiting te water een overzicht gegeven: waar lagen de waterwegen, welke werden gegraven en wanneer werden ze in gebruik genomen. Het betreft de Romeinse periode en de Middeleeuwen
Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

 
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.