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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    Basisregistratie Ondergrond (BRO) Actualisatie bodemkaart : Herkartering van de veengebieden aan de flanken van de Utrechtse Heuvelrug
    Brouwer, Fokke ; Walvoort, Dennis - \ 2020
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 177) - 38
    Wageningen Environmental Research (WENR) has been in the process of updating the Soil Map of the Netherlands, scale 1:50,000, since 2010. The map distinguishes between various different soil units with peat layers in the upper horizons of the profile. The thickness of the peat is being reduced by oxidation and subsidence. To manage these peat soils it is important to have information on the thickness of the peat layer. This study has resulted in a peat thickness map for the peat soil areas around the Utrechtse Heuvelrug north of Utrecht and in the vicinity of Veenendaal and an updated soil map of these peat soil areas at scale 1:50,000.
    Expanding tropical forest monitoring into Dry Forests: The DRYFLOR protocol for permanent plots
    Moonlight, Peter W. ; Banda, Karina ; Phillips, O.L. ; Soussa Oliveira, Tony de; Veenendaal, E.M. - \ 2020
    Plants, People, Planet 2020 (2020). - ISSN 2572-2611 - p. 1 - 6.
    Understanding of tropical forests has been revolutionized by monitoring in permanent plots. Data from global plot networks have transformed our knowledge of forests’ diversity, function, contribution to global biogeochemical cycles, and sensitivity to climate change. Monitoring has thus far been concentrated in rain forests. Despite increasing appreciation of their threatened status, biodiversity, and importance to the global carbon cycle, monitoring in tropical dry forests is still in its infancy. We provide a protocol for permanent monitoring plots in tropical dry forests. Expanding monitoring into dry biomes is critical for overcoming the linked challenges of climate change, land use change, and the biodiversity crisis.
    Experimental light at night has a negative long-term impact on macro-moth populations
    Grunsven, Roy H.A. van; Deijk, Jurriën R. van; Donners, Maurice ; Berendse, Frank ; Visser, Marcel E. ; Veenendaal, Elmar ; Spoelstra, Kamiel - \ 2020
    Current Biology 30 (2020)12. - ISSN 0960-9822 - p. R694 - R695.

    Van Grunsven et al. experimentally test the long-term effects of artificial light on natural moth populations. In the initial two years there was no effect on populations, but in the latter three years population sizes were reduced compared with the dark controls. This shows that artificial light negatively affects moth populations.

    Tree seedling recruitment dynamics in forest-savanna transitions : Trait responses to vegetation controls mediate differential seedling establishment success of tree functional types
    Issifu, Hamza - \ 2020
    Wageningen University. Promotor(en): F. van Langevelde, co-promotor(en): E. Veenendaal; P. Vergeer. - Wageningen : Wageningen University - ISBN 9789463953887 - 211

    In the transition between tropical forests and savannas, forest may be lost to savanna-like vegetation or may occasionally encroach on savannas affecting climate and other benefits to humans. Vegetation in the forest savanna-transition of Ghana often appears stable, except in forests with significant human-induced deforestation where forests are being replaced by savanna-like vegetation. This phenomenon is still poorly understood, but may be explained by how changes in vegetation controls (e.g. fire and precipitation) affect recruitment of forest and savanna-transition tree seedlings differently. Savanna-transition species occur both in forest and humid savanna. I showed that high grass biomass in savanna both directly (via competition) and indirectly (via dry season fire) select for species which invest higher in belowground resource capture and carbohydrate storage. Lower precipitation decreases chances of tree seedling recovery from defoliation disturbance, but allocation trait differences between forest and savanna-transition tree species may explain relative stability of transition forests and the lack of success of true forest species in the forest-savanna transition.

    On the importance of root traits in seedlings of tropical tree species
    Boonman, Coline C.F. ; Langevelde, Frank van; Oliveras, Imma ; Couédon, Jeremy ; Luijken, Natascha ; Martini, David ; Veenendaal, Elmar M. - \ 2020
    New Phytologist 227 (2020)1. - ISSN 0028-646X - p. 156 - 167.
    biomass allocation - root morphology - rooting depth - savanna - specific root length - tropical forest - vertical root distribution

    Plant biomass allocation may be optimized to acquire and conserve resources. How trade-offs in the allocation of tropical tree seedlings depend on different stressors remains poorly understood. Here we test whether above- and below-ground traits of tropical tree seedlings could explain observed occurrence along gradients of resources (light, water) and defoliation (fire, herbivory). We grew 24 tree species occurring in five African vegetation types, varying from dry savanna to moist forest, in a glasshouse for 6 months, and measured traits associated with biomass allocation. Classification based on above-ground traits resulted in clusters representing savanna and forest species, with low and high shoot investment, respectively. Classification based on root traits resulted in four clusters representing dry savanna, humid savanna, dry forest and moist forest, characterized by a deep mean rooting depth, root starch investment, high specific root length in deeper soil layers, and high specific root length in the top soil layer, respectively. In conclusion, tree seedlings in this study show root trait syndromes, which vary along gradients of resources and defoliation: seedlings from dry areas invest in deep roots, seedlings from shaded environments optimize shoot investment, and seedlings experiencing frequent defoliation store resources in the roots.

    Dairy & the Dutch - Dairy Development in Emerging Economies
    Lee, Jan van der; Bijman, Jos - \ 2019
    Take action: Welke maatregelen nemen we in Nederland tegen teken (en muggen)?
    Vliet, Arnold van - \ 2019
    Red LED streetlights make UK road bat-friendly
    Ramakers, J.J.C. ; Ferguson, K.B. ; Veenendaal, E.M. ; Visser, M.E. - \ 2019
    Variation in vegetation cover and seedling performance of tree species in a forest-savanna ecotone
    Issifu, Hamza ; Ametsitsi, George K.D. ; Vries, Lana J. De; Djagbletey, Gloria Djaney ; Adu-Bredu, Stephen ; Vergeer, Philippine ; Langevelde, Frank Van; Veenendaal, Elmar - \ 2019
    Journal of Tropical Ecology 35 (2019)2. - ISSN 0266-4674 - p. 74 - 82.
    Biomass allocation - canopy cover - drought survival - fuel load - root starch - seedling traits - soil properties - tropical trees

    Differential tree seedling recruitment across forest-savanna ecotones is poorly understood, but hypothesized to be influenced by vegetation cover and associated factors. In a 3-y-long field transplant experiment in the forest-savanna ecotone of Ghana, we assessed performance and root allocation of 864 seedlings for two forest (Khaya ivorensis and Terminalia superba) and two savanna (Khaya senegalensis and Terminalia macroptera) species in savanna woodland, closed-woodland and forest. Herbaceous vegetation biomass was significantly higher in savanna woodland (1.0 ± 0.4 kg m-2 vs 0.2 ± 0.1 kg m-2 in forest) and hence expected fire intensities, while some soil properties were improved in forest. Regardless, seedling survival declined significantly in the first-year dry-season for all species with huge declines for the forest species (50% vs 6% for Khaya and 16% vs 2% for Terminalia) by year 2. After 3 y, only savanna species survived in savanna woodland. However, best performance for savanna Khaya was in forest, but in savanna woodland for savanna Terminalia which also had the highest biomass fraction (0.8 ± 0.1 g g-1 vs 0.6 ± 0.1 g g-1 and 0.4 ± 0.1 g g-1) and starch concentration (27% ± 10% vs 15% ± 7% and 10% ± 4%) in roots relative to savanna and forest Khaya respectively. Our results demonstrate that tree cover variation has species-specific effects on tree seedling recruitment which is related to root storage functions.

    Compositional patterns of overstorey and understorey woody communities in a forest–savanna boundary in Ghana
    Armani, Mohammed ; Langevelde, Frank Van; Tomlinson, Kyle Warwick ; Adu-Bredu, Stephen ; Djagbletey, Gloria Djaney ; Veenendaal, Elmar M. - \ 2018
    Plant Ecology & Diversity 11 (2018)4. - ISSN 1755-0874 - p. 451 - 463.
    Forest–savanna boundary - overstorey - recruitment barrier - species composition - strata - zone of transition

    Background: Forest and savanna vegetation in the zone of transition (ZOT) contain distinct woody species due to fire, drought and herbivory barriers that constrain forest species from invading adjacent savannas and vice-versa. Little is known if these barriers cause divergence in species composition between the overstorey and understorey strata in these vegetation types. Aim: We investigated woody species composition across overstorey and understorey strata in the ZOT and explored the relationship between soil fertility and species composition patterns. Methods: We sampled overstorey and understorey woody species and determined soil nutrient concentrations in twenty-five 20 m × 20 m plots in a ZOT in Ghana. Results: Forest and savanna species dominated the overstorey and understorey of their respective environments. However, species composition was decoupled between the overstorey and understorey strata in both forest and savanna vegetations. Few savanna and forest species had individuals co-occurring in both overstorey and understorey such that ~65% of the dominant species was limited to only one stratum. Soil fertility had little effect on these patterns. Conclusion: These patterns indicate that, forest and savanna species face significant recruitment barriers in their respective environments, suggesting that requirements for juvenile establishment may differ from recruitments to the canopy layer.

    Colors of attraction: Modeling insect flight to light behavior
    Donners, Maurice ; Grunsven, R.H.A. van; Groenendijk, D. ; Langevelde, F. van; Bikker, J. ; Longcore, Travis ; Veenendaal, E.M. - \ 2018
    Journal of Experimental Zoology Part A: Ecological and Integrative Physiology 329 (2018)8-9. - ISSN 2471-5638 - p. 434 - 440.
    Light sources attract nocturnal flying insects, but some lamps attract more insects than others. The relation between the properties of a light source and the number of attracted insects is, however, poorly understood. We developed a model to quantify the attractiveness of light sources based on the spectral output. This model is fitted using data from field experiments that compare a large number of different light sources. We validated this model using two additional datasets, one for all insects and one excluding the numerous Diptera. Our model facilitates the development and application of light sources that attract fewer insects without the need for extensive field tests and it can be used to correct for spectral composition when formulating hypotheses on the ecological impact of artificial light. In addition, we present a tool allowing the conversion of the spectral output of light sources to their relative insect attraction based on this model.
    On the relationship between fire regime and vegetation structure in the tropics
    Veenendaal, Elmar M. ; Torello-Raventos, Mireia ; Miranda, Heloisa S. ; Sato, Naomi Margarete ; Oliveras, Imma ; Langevelde, Frank van; Asner, Gregory P. ; Lloyd, Jon - \ 2018
    New Phytologist 218 (2018)1. - ISSN 0028-646X - p. 153 - 166.
    alternative stable states - feedbacks - fire ecology - forest - savannah
    We assessed data from 11 experiments examining the effects of the timing and/or frequency of fire on tropical forest and/or savanna vegetation structure over one decade or more. The initial ‘control treatment’ in many such cases consisted of previously cleared land. This is as opposed to natural vegetation subject to some sort of endogenous fire regime before the imposition of fire treatments. Effects of fire on fractional foliar cover are up to 10-fold greater when clearing pre-treatments are imposed. Moreover, because many of the ‘classic’ fire trials were initialised with applied management questions in mind, most have also used burning regimes much more frequent and/or severe than those occurring in the absence of human activity. Once these factors are taken into account, our modelling analysis shows that nonanthropogenic fire regimes serve to reduce canopy vegetative cover to a much lower extent than has previously been argued to be the case. These results call into question the notion that fire effects on tropical vegetation can be of a sufficient magnitude to maintain open-type savanna ecosystems under climatic/soil regimes otherwise sufficient to give rise to a more luxurious forest-type vegetation cover.
    Effect of Vachellia tortilis on understory vegetation, herbaceous biomass and soil nutrients along a grazing gradient in a semi-arid African savanna
    Yadeta, Temesgen ; Veenendaal, Elmar ; Sykora, Karle ; Tessema, Zewdu K. ; Asefa, Addisu - \ 2018
    Journal of Forestry Research 29 (2018)6. - ISSN 1007-662X - p. 1601 - 1609.
    Basal area cover - Grazing pressure - Inside/outside canopy - Soil moisture
    The spatial pattern and abundance of herbaceous vegetation in semi-arid savannas are dictated by a complex and dynamic interaction between trees and grasses. Scattered trees alter the composition and spatial distribution of herbaceous vegetation under their canopies. Therefore, we studied the effect of Vachellia tortilis on herbaceous vegetation composition, biomass and basal area, and soil nutrients on sites with varying grazing intensities in the central rift valley of Ethiopia. Data were collected on species composition, cover and biomass of herbs and grasses, and soil moisture and nutrient contents under light, medium, and heavy grazing pressures, both under the inside and outside of V. tortilis canopies. Species richness was similar in both locations but decreased with increased grazing. Only the overall biomass and herb cover were significantly greater under the canopy than outside, and overall biomass showed significant unchanging decline with increased grazing. However, vegetation cover was significantly greater on moderately grazed sites compared to low and heavily grazed sites. All soil variables were significantly higher under V. tortilis canopies than outside. Our findings suggest that V. tortilis has more effect on composition and diversity of herbaceous vegetation than on species richness, and that V. tortilis promotes the herbaceous layer biomass by reducing soil moisture loss and increasing soil fertility under the inside than outside the canopies. Therefore, we suggest that management practices should be directed on reducing pressure on V. tortilis by regulating grazing. Low to moderate grazing levels (i.e., a stocking rate less than 39.6 TLU ha −1 yr −1 ) seems to be tolerable to ensure sustainable conservation of the species in the study area in particular and in semi-arid savannas in general.
    Extending the baseline of tropical dry forest loss in Ghana (1984–2015) reveals drivers of major deforestation inside a protected area
    Janssen, Thomas A.J. ; Ametsitsi, George K.D. ; Collins, Murray ; Adu-Bredu, Stephen ; Oliveras, Imma ; Mitchard, Edward T.A. ; Veenendaal, Elmar M. - \ 2018
    Biological Conservation 218 (2018). - ISSN 0006-3207 - p. 163 - 172.
    Tropical dry forests experience the highest deforestation rates on Earth, with major implications for the biodiversity of these ecosystems, as well as for its human occupants. Global remote sensing based forest cover data (2000 − 2012) point to the rapid loss of tropical dry forest in South America and Africa, also, if not foremost, inside formally protected areas. Here, we significantly extend the baseline of tropical dry forest loss inside a protected area in Ghana using a generalizable change detection technique. The forest cover change detection is based on the normalized difference vegetation index (NDVI) derived from historical Landsat data (1984–2015). Field measurements were carried out in dry semi-deciduous forest and in the adjacent savanna and woodland. Estimates of the canopy area index and above ground woody biomass were related to NDVI derived from Landsat 8 data. The change detection indicated significant NDVI decrease in a large area initially covered by tropical dry forest, associated with deforestation. The peak in deforestation was found to have occurred between 1990 and 2002, hereafter, the conservation status of the area was improved. A combination of remote sensing data corroborated by secondary data sources provides evidence for the almost complete clearance of a tropical dry forest inside a strictly protected area, attributable to logging and land clearing for arable farming. The NDVI change detection also revealed NDVI increase in the adjacent woodlands from 2002 to 2015, demonstrating woody encroachment. Historical fire data from the MODIS burned area product indicate that the deforested area experienced a high frequency of anthropogenic burning since 2004, which may have caused further degradation and largely prevents forest regeneration. The results show the ongoing destruction of tropical ecosystems even within ostensibly protected areas and ask for the revision of protection and management strategies of such areas.
    Biofilm composition and threshold concentration for growth of Legionella pneumophila on surfaces exposed to flowing warm tap water without disinfectant
    Kooij, Dick van der; Bakker, Geo L. ; Italiaander, Ronald ; Veenendaal, Harm R. ; Wullings, Bart A. - \ 2017
    Applied and Environmental Microbiology 83 (2017)5. - ISSN 0099-2240
    Legionella pneumophila - Predominating biofilm bacteria - Threshold biofilm concentration - Warm tap water

    Legionella pneumophila in potable water installations poses a potential health risk, but quantitative information about its replication in biofilms in relation to water quality is scarce. Therefore, biofilm formation on the surfaces of glass and chlorinated polyvinyl chloride (CPVC) in contact with tap water at 34 to 39°C was investigated under controlled hydraulic conditions in a model system inoculated with biofilm-grown L. pneumophila. The biofilm on glass (average steady-state concentration, 23 ± 9 pg ATP cm -2 ) exposed to treated aerobic groundwater (0.3 mg C liter -1 ; 1 μg assimilable organic carbon [AOC] liter -1 ) did not support growth of the organism, which also disappeared from the biofilm on CPVC (49 ± 9 pg ATP cm -2 ) after initial growth. L. pneumophila attained a level of 4.3 log CFU cm -2 in the biofilms on glass (1,055 ± 225 pg ATP cm -2 ) and CPVC (2,755± 460 pg ATP cm -2 ) exposed to treated anaerobic groundwater (7.9 mg C liter -1 ; 10 μg AOC liter -1 ). An elevated biofilm concentration and growth of L. pneumophila were also observed with tap water from the laboratory. The Betaproteobacteria Piscinibacter and Methyloversatilis and amoeba-resisting Alphaproteobacteria predominated in the clones and isolates retrieved from the biofilms. In the biofilms, the Legionella colony count correlated significantly with the total cell count (TCC), heterotrophic plate count, ATP concentration, and presence of Vermamoeba vermiformis. This amoeba was rarely detected at biofilm concentrations of <100 pg ATP cm -2 . A threshold concentration of approximately 50 pg ATP cm -2 (TCC = 1 × 106 to 2 × 106 cells cm -2 ) was derived for growth of L. pneumophila in biofilms.

    Benefits and burdens
    Sluis, T. van der; Veenendaal, E.M. - \ 2017
    Data from: Response of bats to light with different spectra: light-shy and agile bat presence is affected by white and green, but not red light
    Spoelstra, K. ; Grunsven, R.H.A. van; Ramakers, Jip J.C. ; Ferguson, Kim B. ; Raap, Thomas ; Donners, Maurice ; Veenendaal, E.M. ; Visser, Marcel E. - \ 2017
    Wageningen University & Research
    light pollution - experimental light at night - bats - light colour
    Artificial light at night has shown a remarkable increase over the past decades. Effects are reported for many species groups, and include changes in presence, behaviour, physiology and life-history traits. Among these, bats are strongly affected, and how bat species react to light is likely to vary with light colour. Different spectra may therefore be applied to reduce negative impacts. We used a unique set-up of eight field sites to study the response of bats to three different experimental light spectra in an otherwise dark and undisturbed natural habitat. We measured activity of three bat species groups around transects with light posts emitting white, green and red light with an intensity commonly used to illuminate countryside roads. The results reveal a strong and spectrum-dependent response for the slow-flying Myotis and Plecotus and more agile Pipistrellus species, but not for Nyctalus and Eptesicus species. Plecotus and Myotis species avoided white and green light, but were equally abundant in red light and darkness. The agile, opportunistically feeding Pipistrellus species were significantly more abundant around white and green light, most likely because of accumulation of insects, but equally abundant in red illuminated transects compared to dark control. Forest-dwelling Myotis and Plecotus species and more synanthropic Pipistrellus species are thus least disturbed by red light. Hence, in order to limit the negative impact of light at night on bats, white and green light should be avoided in or close to natural habitat, but red lights may be used if illumination is needed.
    Data from: Artificial night lighting inhibits feeding in moths
    Langevelde, F. van; Grunsven, R.H.A. van; Veenendaal, E.M. ; Fijen, T.P.M. - \ 2017
    nocturnal light pollution - feeding behaviour - Lepidoptera - moth population declines - sublethal effect
    One major, yet poorly studied, change in the environment is nocturnal light pollution, which strongly alters habitats of nocturnally active species. Artificial night lighting is often considered as driving force behind rapid moth population declines in severely illuminated countries. To understand these declines, the question remains whether artificial light causes only increased mortality or also sublethal effects. We show that moths subjected to artificial night lighting spend less time feeding than moths in darkness, with the shortest time under light conditions rich in short wavelength radiation. These findings provide evidence for sublethal effects contributing to moth population declines. Because effects are strong under various types of light compared with dark conditions, the potential of spectral alterations as a conservation tool may be overestimated. Therefore, restoration and maintenance of darkness in illuminated areas is essential for reversing declines of moth populations.
    De lusten en de lasten: plan moet conflicten verminderen
    Sluis, T. van der; Veenendaal, E.M. - \ 2017
    Communities, Wildlife and tourism: a landscape planning approach for Chobe District and transboundary areas, Northern Botswana
    Sluis, T. van der; Veenendaal, E. ; Cassidy, L. - \ 2017
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