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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Plant species richness and functional groups have different effects on soil water content in a decade-long grassland experiment
Fischer, Christine ; Leimer, Sophia ; Roscher, Christiane ; Ravenek, Janneke ; Kroon, Hans de; Kreutziger, Yvonne ; Baade, Jussi ; Beßler, Holger ; Eisenhauer, Nico ; Weigelt, Alexandra ; Mommer, Liesje ; Lange, Markus ; Gleixner, Gerd ; Wilcke, Wolfgang ; Schröder, Boris ; Hildebrandt, Anke - \ 2018
Journal of Ecology (2018). - ISSN 0022-0477
biodiversity - functional groups - Jena Experiment - plant–soil–water relation - soil water content - spatial–temporal variability - species richness

The temporal and spatial dynamics of soil water are closely interlinked with terrestrial ecosystems functioning. The interaction between plant community properties such as species composition and richness and soil water mirrors fundamental ecological processes determining above-ground–below-ground feedbacks. Plant–water relations and water stress have attracted considerable attention in biodiversity experiments. Yet, although soil scientific research suggests an influence of ecosystem productivity on soil hydraulic properties, temporal changes of the soil water content and soil hydraulic properties remain largely understudied in biodiversity experiments. Thus, insights on how plant diversity—productivity relationships affect soil water are lacking. Here, we determine which factors related to plant community composition (species and functional group richness, presence of plant functional groups) and soil (organic carbon concentration) affect soil water in a long-term grassland biodiversity experiment (The Jena Experiment). Both plant species richness and the presence of particular functional groups affected soil water content, while functional group richness played no role. The effect of species richness changed from positive to negative and expanded to deeper soil with time. Shortly after establishment, increased topsoil water content was related to higher leaf area index in species-rich plots, which enhanced shading. In later years, higher species richness increased topsoil organic carbon, likely improving soil aggregation. Improved aggregation, in turn, dried topsoils in species-rich plots due to faster drainage of rainwater. Functional groups affected soil water distribution, likely due to plant traits affecting root water uptake depths, shading, or water-use efficiency. For instance, topsoils in plots containing grasses were generally drier, while plots with legumes were moister. Synthesis. Our decade-long experiment reveals that the maturation of grasslands changes the effects of plant richness from influencing soil water content through shading effects to altering soil physical characteristics in addition to modification of water uptake depth. Functional groups affected the soil water distribution by characteristic shifts of root water uptake depth, but did not enhance exploitation of the overall soil water storage. Our results reconcile previous seemingly contradictory results on the relation between grassland species diversity and soil moisture and highlight the role of vegetation composition for soil processes.

Return of the native facilitated by the invasive? Population composition, substrate preferences and epibenthic species richness of a recently discovered shellfish reef with native European flat oysters (Ostrea edulis) in the North Sea
Christianen, M.J.A. ; Lengkeek, W. ; Bergsma, J.H. ; Coolen, J.W.P. ; Didderen, K. ; Dorenbosch, M. ; Driessen, F.M.F. ; Kamermans, P. ; Reuchlin-Hugenholtz, E. ; Sas, H. ; Smaal, A. ; Wijngaard, K.A. Van Den; Have, T.M. Van Der - \ 2018
Marine Biology Research 14 (2018)6. - ISSN 1745-1000 - p. 590 - 597.
Ostrea edulis - facilitation - native oyster restoration - invasive alien species - North Sea - biodiversity
After being ecologically extinct for almost a century, the discovery of a shellfish reef with native European flat oysters (Ostrea edulis) in the Dutch coastal area of the North Sea by the authors of this study called for an extensive survey to better understand some of the key requirements for the return of the native oyster in coastal waters. We assessed habitat conditions, its potential for increasing biodiversity, and the role of substrate provision by other bivalves such as the invasive alien Pacific oyster (Crassostrea gigas). Using underwater visual census, O. edulis size-frequency distributions and attachment substrate was investigated, as well as the composition of the epibenthic community and substrata types inside quadrats that were distributed across the reef. This reef was found to be composed of native European flat oysters, invasive alien Pacific oysters and blue mussels (Mytilus edulis), alternated with sandy patches. The O. edulis population (6.8 ± 0.6 oysters m−2) consisted of individuals of different size classes. In quadrats with native and non-native oysters the number of epibenthic species was 60% higher compared to adjacent sand patches within the reef. Notably, our results showed that the native oyster predominantly used shell (fragments) of the invasive Pacific oyster as settlement substrate (81% of individuals). Our results optimistically show that conditions for native oyster restoration can be suitable at a local scale in the coastal North Sea area and suggest that the return of native oysters may be facilitated by novel substrate provided by invasive oysters at sites where their distribution overlap.
Data from: The effects of recent changes in breeding preferences on maintaining traditional Dutch chicken genomic diversity
Bortoluzzi, C. ; Crooijmans, R.P.M.A. ; Bosse, M. ; Hiemstra, S.J. ; Groenen, M. ; Megens, H.J.W.C. - \ 2018
Bantam - biodiversity - chicken - genetic diversity - molecular characterisation - traditional breed - Gallus gallus
Traditional Dutch chicken breeds are marginalised breeds of ornamental and cultural-historical importance. In the last decades, miniaturising of existing breeds (so called neo-bantam) has become popular and resulted in alternatives to original large breeds. However, while backcrossing is increasing the neo-bantams homozygosity, genetic exchange between breeders may increase their genetic diversity. We use the 60K SNP array to characterise the genetic diversity, demographic history, and level of inbreeding of Dutch heritage breeds, and particularly of neo-bantams. Commercial white layers are used to contrast the impact of management strategy on genetic diversity and demography. A high proportion of alleles was found to be shared between large fowls and neo-bantams, suggesting gene flow during neo-bantams development. Population admixture analysis supports these findings, in addition to revealing introgression from neo-bantams of the same breed and of phenotypically similar breeds. The prevalence of long runs of homozygosity (ROH) confirms the importance of recent inbreeding. A high diversity in management, carried out in small breeding units explains the high heterogeneity in diversity and ROH profile displayed by traditional breeds compared to commercial lines. Population bottlenecks may explain the long ROHs in large fowls, while repetitive backcrossing for phenotype selection may account for them in neo-bantams. Our results highlight the importance of using markers to inform breeding programmes on potentially harmful homozygosity to prevent loss of genetic diversity. We conclude that bantamisation has generated unique and identifiable genetic diversity. However, this diversity can only be preserved in the near future through structured breeding programmes.
Dataset for "Return of the native facilitated by the invasive? Population composition, substrate preferences, and epibenthic species richness of a recently discovered shellfish reef with native European flat oysters (Ostrea edulis) in the North Sea"
Christianen, M.J.A. - \ 2018
biodiversity - facilitation - invasive alien species - native oyster restoration - North Sea - Ostrea edulis
After being ecologically extinct for almost a century, the discovery of a shellfish reef with native European flat oysters (Ostrea edulis) in the Dutch coastal area of the North Sea by the authors of this study called for an extensive survey to better understand some of the key requirements for the return of the native oyster in coastal waters. We assessed habitat conditions, its potential for increasing biodiversity, and the role of substrate provision by other bivalves such as the invasive alien Pacific oysters. Using underwater visual census, O. edulis size-frequency distributions and attachment substrate was investigated, as well as the composition of the epibenthic community and substrata types inside quadrats that were distributed across the reef. This reef was found to be composed of native European flat oysters, invasive alien Pacific oysters (Magallana gigas) and blue mussels (Mytilus edulis), alternated with sandy patches. The O. edulis population (6.8_±_0.6_oysters_m-2) consisted of individuals of different size classes. In quadrats with native and non-native oysters the number of epibenthic species was 60_% higher compared to adjacent sand patches within the reef. Notably, our results showed that the native oyster predominantly used shell (fragments) of the invasive Pacific oyster as settlement substrate (81 % of individuals). Our results optimistically show that conditions for native oyster restoration can be suitable at a local scale in the coastal North Sea area and that the return of native oysters may be facilitated by novel substrate provided by invasive oysters at sites where their distribution overlap.
The significance of meaning. Why IPBES needs the social sciences and humanities
Jetzkowitz, Jens ; Koppen, C.S.A. van; Lidskog, Rolf ; Ott, Konrad ; Voget-Kleschin, Lieske ; Wong, Catherine Mei Ling - \ 2018
Innovation: The European Journal of Social Science Research 31 (2018)sup1. - ISSN 1351-1610 - p. S38 - S60.
biodiversity - ethics - foundations of biodiversity research - IPBES - methodology - science–policy interface - social sciences

The term “biodiversity” is often used to describe phenomena of nature, which can be studied without a reference to the socially constructed, evaluative, or indeed normative contexts. In our paper, we challenge this conception by focusing particularly on methodological aspects of biodiversity research. We thereby engage with the idea of interdisciplinary biodiversity research as a scientific approach directed at the recognition and management of contemporary society in its ecological embedding. By doing this, we explore how research on and assessments of biodiversity can be enhanced if meaning, aspiration, desires, and related aspects of agency are methodically taken into account. In six sections, we substantiate our claim that the discourse on biodiversity (including the IPBES (Intergovernmental science-policy Platform on Biodiversity and Ecosystem Services) debate) is incomplete without contributions from the social sciences and humanities. In the introduction, a brief overview of biodiversity’s conceptual history is provided showing that “biodiversity” is a lexical invention intended to create a strong political momentum. However, that does not impede its usability as a research concept. Section 2 examines the origins of the Convention on Biological Diversity (CBD) by way of sociological discourse analysis. Subsequently, it proposes a matrix as a means to structure the ambiguities and tensions inherent in the CBD. The matrix reemphasizes our main thesis regarding the need to bring social and ethical expertise to the biodiversity discourse. In Section 3, we offer a brief sketch of the different methods of the natural and social sciences as well as ethics. This lays the groundwork for our Section 4, which explains and illustrates what social sciences and ethics can contribute to biodiversity research. Section 5 turns from research to politics and argues that biodiversity governance necessitates deliberative discourses in which participation of lay people plays an important role. Section 6 provides our conclusions.

The missing pillar : Eudemonic values in the justification of nature conservation
Born, Riyan J.G. van den; Arts, B. ; Admiraal, J.G.A. ; Beringer, A. ; Knights, P. ; Molinario, E. ; Horvat, K.P. ; Porras-Gomez, C. ; Smrekar, A. ; Soethe, N. ; Vivero-Pol, J.L. ; Ganzevoort, W. ; Bonaiuto, M. ; Knippenberg, L. ; Groot, W.T. De - \ 2018
Journal of Environmental Planning and Management 61 (2018)5-6. - ISSN 0964-0568 - p. 841 - 856.
biodiversity - committed action - eudaimonia - life history interview - nature
The public justification for nature conservation currently rests on two pillars: hedonic (instrumental) values, and moral values. Yet, these representations appear to do little motivational work in practice; biodiversity continues to decline, and biodiversity policies face a wide implementation gap. In seven EU countries, we studied why people act for nature beyond professional obligations. We explore the motivations of 105 committed actors for nature in detail using life-history interviews, and trace these back to their childhood. Results show that the key concept for understanding committed action for nature is meaningfulness. People act for nature because nature is meaningful to them, connected to a life that makes sense and a difference in the world. These eudemonic values (expressing the meaningful life) constitute a crucial third pillar in the justification of nature conservation. Important policy implications are explored, e.g. with respect to public discourse and the encounter with nature in childhood.
Dataset supplementing Lichtenberg et al. (2017) A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes. Global Change Biology
Lichtenberg, Elinor M. ; Kennedy, Christina M. ; Kremen, Claire ; Batáry, Péter ; Berendse, F. ; Bommarco, Riccardo ; Bosque-Pérez, Nilsa A. ; Carvalheiro, Luísa G. ; Snyder, William E. ; Williams, Neal M. - \ 2017
agricultural management schemes - arthropod diversity - functional groups - landscape complexity - meta-analysis - evenness - biodiversity - organic farming - plant diversity
This dataset contains data and scripts that supplement the publication
Ecosysteemdiensten van bomen en groen in de stad
Hiemstra, J.A. - \ 2017
Wageningen : Groen Kennisnet
bomen - planten - biodiversiteit - ecosystemen - klimaat - luchtkwaliteit - regenwateropvang - stedelijke gebieden - trees - plants - biodiversity - ecosystems - climate - air quality - water harvesting - urban areas
Groen kost geld en de baten zijn slecht tastbaar. Het project 'Ecosysteemdiensten van boomkwekerijproducten' ontwikkelt instrumenten om de voordelen van groen beter te laten meewegen bij het nemen van beslissingen. Voordelen: verkoeling, luchtzuivering, waterberging en beleefbare biodiversiteit. In eerste instantie voor de productgroep bomen, later ook voor andere productgroepen.
Functional trait dissimilarity drives both species complementarity and competitive disparity
Wagg, Cameron ; Ebeling, Anne ; Roscher, Christiane ; Ravenek, Janneke ; Bachmann, Dörte ; Eisenhauer, Nico ; Mommer, Liesje ; Buchmann, Nina ; Hillebrand, Helmut ; Schmid, Bernhard ; Weisser, Wolfgang W. - \ 2017
Functional Ecology 31 (2017)12. - ISSN 0269-8463 - p. 2320 - 2329.
biodiversity - community ecology - competition - Jena experiment - trait-based experiment (TBE)
Niche complementarity and competitive disparity are driving mechanisms behind plant community assembly and productivity. Consequently, there is great interest in predicting species complementarity and their competitive differences from their functional traits as dissimilar species may compete less and result in more complete use of resources. Here we assessed the role of trait dissimilarities for species complementarity and competitive disparities within an experimental gradient of plant species richness and functional trait dissimilarity. Communities were assembled using three pools of grass and forb species based on a priori knowledge of traits related to (1) above- and below-ground spatial differences in resource acquisition, (2) phenological differences or (3) both. Complementarity and competitive disparities were assessed by partitioning the overyielding in mixed species communities into species complementarity and dominance effects. Community overyielding and the underlying complementarity and competitive dominance varied strongly among the three plant species pools. Overyielding and complementarity were greatest among species that were assembled based on their variation in both spatial and phenological traits. Competitive dominance was greatest when species were assembled based on spatial resource acquisition traits alone. In communities that were assembled based on species variation in only spatial or phenological traits, greater competitive dominance was predicted by greater differences in SLA and flowering initiation respectively, while greater complementarity was predicted by greater dissimilarity in leaf area and flowering senescence respectively. Greater differences in leaf area could also be linked to greater species complementarity in communities assembled based on variation in both phenological and spatial traits, but trait dissimilarity was unrelated to competitive dominance in these communities. Our results indicate that complementarity and competitive disparity among species are both driven by trait dissimilarities. However, the identity of the traits that drives the complementarity and competitive disparity depends on the trait variation among species that comprise the community. Moreover, we demonstrate that communities assembled with the greater variation in both spatial and phenological traits show the greatest complementarity among species. A plain language summary is available for this article.
Biodiversity and climate determine the functioning of Neotropical forests
Poorter, L. ; Sande, M.T. van der; Arets, E.J.M.M. ; Ascarrunz, N. ; Enquist, B.J. ; Finegan, B. ; Licona, J.C. ; Martinez-Ramos, M. ; Mazzei, L. ; Meave, J. ; Munoz, R. ; Nytch, C.J. ; Oliveira, A.A. de; Perez-Garcia, E.A. ; Prado-Junior, J.A. ; Rodriguez-Velazquez, J. ; Ruschel, A.R. ; Salgado Negret, B. ; Schiavini, I. ; Swenson, N.G. ; Tenorio, E.A. ; Thompson, J. ; Toledo, M. ; Uriarte, M. ; Hout, P. van der; Zimmerman, J.K. ; Pena Claros, M. - \ 2017
biodiversity - biomass - carbon - ecosystem functioning - forest dynamics - productivity - soil fertility - tropical forest - water
Tropical forests account for a quarter of the global carbon storage and a third of the terrestrial productivity. Few studies have teased apart the relative importance of environmental factors and forest attributes for ecosystem functioning, especially for the tropics. This study aims to relate aboveground biomass (AGB), biomass dynamics (i.e., net biomass productivity and its underlying demographic drivers: biomass recruitment, growth and mortality) to forest attributes (tree diversity, community-mean traits, and stand basal area) and environmental conditions (water availability, soil fertility and disturbance). We used data from 26 sites, 201 one-ha plots and >92,000 trees distributed across the Neotropics. We quantified for each site water availability and soil total exchangeable bases and for each plot three key community-weighted mean functional traits that are important for biomass stocks and productivity. We used structural equation models to test the hypothesis that all drivers have independent, positive effects on biomass stocks and dynamics. Of the relationships analysed, vegetation attributes were more frequently significantly associated with biomass stocks and dynamics than environmental conditions (in 67% versus 33% of the relationships). High climatic water availability increased biomass growth and stocks, light disturbance increased biomass growth, and soil bases had no effect. Rarefied tree species richness had consistent positive relationships with biomass stocks and dynamics, probably because of niche complementarity, but was not related to net biomass productivity. Community-mean traits were good predictors of biomass stocks and dynamics. Water availability has a strong positive effect on biomass stocks and growth, and a future predicted increase in (atmospheric) drought might, therefore, potentially reduce carbon storage. Forest attributes – including species diversity and community-weighted mean traits – have independent and important relationships with AGB stocks, dynamics, and ecosystem functioning, not only in relatively simple temperate systems, but also in structurally complex hyper-diverse tropical forests.
Greenery: more than beauty and health : A summary of the benefits of greenery on health, productivity, performance and well-being
Hiemstra, J.A. ; Vries, S. de; Spijker, J.H. - \ 2017
Wageningen : Wageningen University & Research - 6 p.
health - well-being - plants - trees - reconditioning - air quality - biodiversity - air conditioning - learning - labour - green roofs - green walls - gezondheid - welzijn - planten - bomen - herstellen - luchtkwaliteit - biodiversiteit - klimaatregeling - leren - arbeid (werk) - groene daken - groene gevels
Greenery in our living environment is beneficial for more than just our health and well-being. It facilitates water management and stimulates biodiversity in built-up areas, and it can also reduce the effects of noise pollution. Greenery also has a positive impact on the property value of homes and offices. This document provides general information on the benefits of greenery, supplementary to the detailed fact sheets on how greenery can improve health and well-being in Residential, Professional, Educational and Healthcare contexts.
Diversifying Food Systems in the Pursuit of Sustainable Food Production and Healthy Diets
Dwivedi, Sangam L. ; Lammerts van Bueren, Edith T. ; Ceccarelli, Salvatore ; Grando, Stefania ; Upadhyaya, Hari D. ; Ortiz, Rodomiro - \ 2017
Trends in Plant Science 22 (2017)10. - ISSN 1360-1385 - p. 842 - 856.
agro-ecosystems - biodiversity - carbon footprints - cropping system - diet × gene interaction - dietary diversity - evolutionary/participatory plant breeding - resource use-efficient crops

Increasing demand for nutritious, safe, and healthy food because of a growing population, and the pledge to maintain biodiversity and other resources, pose a major challenge to agriculture that is already threatened by a changing climate. Diverse and healthy diets, largely based on plant-derived food, may reduce diet-related illnesses. Investments in plant sciences will be necessary to design diverse cropping systems balancing productivity, sustainability, and nutritional quality. Cultivar diversity and nutritional quality are crucial. We call for better cooperation between food and medical scientists, food sector industries, breeders, and farmers to develop diversified and nutritious cultivars that reduce soil degradation and dependence on external inputs, such as fertilizers and pesticides, and to increase adaptation to climate change and resistance to emerging pests. Intensive industrial agriculture does not appear to be sustainable and does not contribute to a healthy human diet. Reduced consumption of livestock products and increased use of plant products are central to reducing food carbon footprints and healthy eating. Fundamental to better health is understanding gene–nutrient interactions in growth and development and in disease prevention; genomics and phenomics may assist selecting for nutritionally enhanced, resource use-efficient, and stress-resilient cultivars. A paradigm shift is occurring from the current production/productivity goals to developing nutritionally enhanced and resource use-efficient crops. There is growing notion that not all healthy diets are sustainable and not all sustainable diets are healthy, thus an integral system approach will be necessary to produce sufficient, safe, and nutritionally enhanced food.

Community ecology of Neotropical ticks, hosts, and associated pathogens
Esser, Heleen J. - \ 2017
University. Promotor(en): Herbert Prins; Frans Bongers, co-promotor(en): Patrick Jansen. - Wageningen : Wageningen University - ISBN 9789463436908 - 200
metastigmata - host specificity - host parasite relationships - biodiversity - species diversity - pathogens - size - community ecology - tickborne diseases - panama - tropics - hosts - gastheerspecificiteit - gastheer parasiet relaties - biodiversiteit - soortendiversiteit - pathogenen - grootte - gemeenschapsecologie - ziekten overgebracht door teken - tropen - gastheren (dieren, mensen, planten)

The ongoing loss of global biodiversity is unprecedented in both magnitude and pace, raising urgent questions as to how this loss will affect ecosystem functioning and human well-being. Control of infectious diseases has been proposed as an important ecosystem service that is likely to be affected by biodiversity loss. A negative relationship between biodiversity and disease risk could offer a win-win situation for nature conservation and human health. However, the generality of this relationship remains the subject of contentious debate. The aim of this thesis was to contribute to a better understanding of the interactions between ticks and their vertebrate hosts in a biodiversity hotspot, and how loss of biodiversity affects these interactions and ultimately, tick-borne disease risk. My study was unique in that I simultaneously considered and directly assessed broader communities of Neotropical wildlife, ticks, and tick-borne pathogens across an anthropogenic disturbance gradient.

Determining whether and how biodiversity loss affects tick-borne disease risk in tropical forests requires a thorough understanding of tick-host associations, which are a function of tick-host specificity as well as host biological and ecological traits. In chapter 2, I therefore quantified the degree to which adult ticks are host-specific in my study region: Panama. Using quantitative network analyses and phylogenetic tools with null model comparisons, I found that the adult life stages of most tick species were specific to a limited number of host species that were phylogenetically closely related. In Chapter 4 I showed that species assemblages of adult ticks became increasingly diverse on larger-bodied host species, indicating that adult ticks in Panama tend to select for large reproduction hosts.

In contrast to adult ticks, understanding the ecological interactions between immature ticks and their hosts in the tropics has long been hampered by a lack of morphological identification keys. Therefore, in Chapter 3, I describe the development of a DNA barcode reference library for the molecular identification of larvae and nymphs. This reference library was highly effective in species-level identification of immature ticks collected from birds (Chapter 3) and small mammals (Chapter 4 and 6). Several avian ecological traits were positively associated with tick parasitism, but the potential role of wild birds in tick-borne disease transmission seems to be limited in Panama. Immature ticks did not show any specificity to particular bird species or avian ecological traits (Chapter 3), and species assemblages of immatures ticks were equally diverse across a large number of host taxa (Chapter 4). This suggests that larvae and nymphs may feed more opportunistically than their adult counterparts.

High host specificity in adult ticks implies high susceptibility to tick-host coextinction, even if immature ticks feed opportunistically. In chapter 5, I tested this hypothesis by surveying tick and vertebrate host communities across a forest fragmentation gradient. Forest fragments consisted of previously connected islands and peninsulas in the Panama Canal and ranged 1000-fold in size. Abundance and species richness of ticks was positively related to that of wildlife, which in turn was related to the size of the forest fragment. Specialist tick species were only present in fragments where their specific reproduction hosts were captured by camera traps. Further, less diverse tick communities were dominated by a generalist tick species. These results indicate that loss of wildlife had cascading effects on tick communities through local host-parasite coextinction.

In Chapter 6, I studied how communities of wildlife, ticks, and tick-borne microbes changed along a more ‘typical’ disturbance gradient, in which forest fragments were embedded in an agricultural and sub-urban landscape, rather than surrounded by water. I found that wildlife community disassembly either diluted, amplified, or had no effect on infection prevalence in ticks, depending on the pathogen and degree of disturbance. However, hyperabundance of medium- to large-sized frugivores and herbivores (important reproduction hosts for adult ticks) in sites that lacked apex predators was related to exponential increases in tick density, negating any effect of reduced pathogen prevalence. Moreover, high tick species richness in these sites was related to high microbial and pathogen richness. High parasite diversity is thus a source of infectious diseases. When medium- to large-sized frugivores and herbivores also disappeared, densities of infected ticks declined, suggesting a non-linear relationship between biodiversity loss and tick-borne disease risk, in which initial loss of apex predators increases disease risk, but further loss of species decreases disease risk again.

In this thesis, I have quantified host-feeding relationships of adult and immature Neotropical ticks, many of which (in the case of larvae and nymphs) were largely unknown. I have shown that adult ticks tend to be highly host-specific, particularly to larger-bodied vertebrates, whereas immature ticks appear to have broader host-use patterns. I found that ticks are susceptible to local host-tick coextirpation, and that the relationship between biodiversity loss and tick-borne disease risk is non-linear. My results emphasize the importance of directly assessing host community composition and suggest that the presence of specific (reproduction) hosts are a more important factor than species richness per se for tick population and tick-borne disease dynamics.

Shifts of community composition and population density substantially affect ecosystem function despite invariant richness
Spaak, Jurg W. ; Baert, Jan M. ; Baird, Donald J. ; Eisenhauer, Nico ; Maltby, Lorraine ; Pomati, Francesco ; Radchuk, Viktoriia ; Rohr, Jason R. ; Brink, Paul J. van den; Laender, Frederik De - \ 2017
Ecology Letters 20 (2017)10. - ISSN 1461-023X - p. 1315 - 1324.
Algae - biodiversity - coexistence - community ecology - modelling - primary production

There has been considerable focus on the impacts of environmental change on ecosystem function arising from changes in species richness. However, environmental change may affect ecosystem function without affecting richness, most notably by affecting population densities and community composition. Using a theoretical model, we find that, despite invariant richness, (1) small environmental effects may already lead to a collapse of function; (2) competitive strength may be a less important determinant of ecosystem function change than the selectivity of the environmental change driver and (3) effects on ecosystem function increase when effects on composition are larger. We also present a complementary statistical analysis of 13 data sets of phytoplankton and periphyton communities exposed to chemical stressors and show that effects on primary production under invariant richness ranged from −75% to +10%. We conclude that environmental protection goals relying on measures of richness could underestimate ecological impacts of environmental change.

What determines plant species diversity in Central Africa?
Proosdij, Andreas S.J. van - \ 2017
University. Promotor(en): Marc Sosef, co-promotor(en): Jan Wieringa. - Wageningen : Wageningen University - ISBN 9789463436618 - 161
plants - biodiversity - species diversity - species - distribution - biogeography - central africa - biosystematics - tropical rain forests - modeling - planten - biodiversiteit - soortendiversiteit - soorten - distributie - biogeografie - centraal-afrika - biosystematiek - tropische regenbossen - modelleren

Planet Earth hosts an incredible biological diversity. Estimated numbers of species occurring on Earth range from 5 to 11 million eukaryotic species including 400,000-450,000 species of plants. Much of this biodiversity remains poorly known and many species have not yet been named or even been discovered. This is not surprising, as the majority of species is known to be rare and ecosystems are generally dominated by a limited number of common species.

Tropical rainforests are the most species-rich terrestrial ecosystems on Earth. The general higher level of species richness is often explained by higher levels of energy near the Equator (latitudinal diversity gradient). However, when comparing tropical rainforest biomes, African rainforests host fewer plant species than either South American or Asian ones. The Central African country of Gabon is situated in the Lower Guinean phytochorical region. It is largely covered by what is considered to be the most species-rich lowland rainforest in Africa while the government supports an active conservation program. As such, Gabon is a perfect study area to address that enigmatic question that has triggered many researchers before: “What determines botanical species richness?”.

In the past 2.5 million years, tropical rainforests have experienced 21 cycles of global glaciations. They responded to this by contracting during drier and cooler glacials into larger montane and smaller riverine forest refugia and expanding again during warmer and wetter interglacials. The current rapid global climate change coupled with change of land use poses new threats to the survival of many rainforest species. The limited availability of resources for conservation forces governments and NGOs to set priorities. Unfortunately, for many plant species, lack of data on their distribution hampers well-informed decision making in conservation.

Species distribution models (SDMs) offer opportunities to bridge at least partly this knowledge gap. SDMs are correlative models that infer the spatial distribution of species using only a limited set of known species occurrence records coupled with high resolution environmental data. SDMs are widely applied to study the past, present and future distribution of species, assess the risk of invasive species, infer patterns of species richness and identify hotspots, as well as to assess the impact of climate change. The currently available methods form a pipeline, with which data are selected and cleaned, models selected, parameterized, evaluated and projected to other areas and climatic scenarios, and biodiversity patterns are computed from these SDMs. In this thesis, SDMs of all Gabonese plant species were generated and patterns of species richness and of weighted endemism were computed (chapter 4 & 5).

Although this pipeline enables the rapid generation of SDMs and inferring of biodiversity patterns, its effective use is limited by several matters of which three are specifically addressed in this thesis. Not knowing the true distribution limits the opportunities to assess the accuracy of models and assess the impact of assumptions and limitations of SDMs. The use of simulated species has been advocated as a method to systematically assess the impact of specific matters of SDMs (virtual ecologist). Following this approach, in chapter 2, I present a novel method to simulate large numbers of species that each have their own unique niche.

One matter of SDMs that is usually ignored but has been shown to be of great impact on model accuracy is the number of species occurrence records used to train a model. In chapter 2, I quantify the effect of sample size on model accuracy for species of different range size classes. The results show that the minimum number of records required to generate accurate SDMs is not uniform for species of every range size class and that larger sample sizes are required for more widespread species. By applying a uniform minimum number of records, SDMs of narrow-ranged species are incorrectly rejected and SDMs of widespread species are incorrectly accepted. Instead, I recommend to identify and apply the unique minimum numbers of required records for each individual species. The method presented here to identify the minimum number of records for species of particular range size classes is applicable to any species group and study area.

The range size or prevalence is an important plant feature that is used in IUCN Red List classifications. It is commonly computed as the Extent Of Occurrence (EOO) and Area Of Occupancy (AOO). Currently, these metrics are computed using methods based on the spatial distribution of the known species occurrences. In chapter 3, using simulated species again, I show that methods based on the distribution of species occurrences in environmental parameter space clearly outperform those based on spatial data. In this chapter, I present a novel method that estimates the range size of a species as the fraction of raster cells within the minimum convex hull of the species occurrences, when all cells from the study area are plotted in environmental parameter space. This novel method outperforms all ten other assessed methods. Therefore, the current use of EOO and AOO based on spatial data alone for the purpose of IUCN Red List classification should be reconsidered. I recommend to use the novel method presented here to estimate the AOO and to estimate the EOO from the predicted distribution based on a thresholded SDM.

In chapter 4, I apply the currently best possible methods to generate accurate SDMs and estimate the range size of species to the large dataset of Gabonese plant species records. All significant SDMs are used here to assess the unique contribution of narrow-ranged, widespread, and randomly selected species to patterns of species richness and weighted endemism. When range sizes of species are defined based on their full range in tropical Africa, random subsets of species best represent the pattern of species richness, followed by narrow-ranged species. Narrow-ranged species best represent the weighted endemism pattern. Moreover, the results show that the applied criterion of widespread and narrow-ranged is crucial. Too often, range sizes of species are computed on their distribution within a study area defined by political borders. I recommend to use the full range size of species instead. Secondly, the use of widespread species, of which often more data are available, as an indicator of diversity patterns should be reconsidered.

The effect of global climate change on the distribution patterns of Gabonese plant species is assed in chapter 5 using SDMs projected to the year 2085 for two climate change scenarios assuming either full or no dispersal. In Gabon, predicted loss of plant species ranges from 5% assuming full dispersal to 10% assuming no dispersal. However, these numbers are likely to be substantially higher, as for many rare, narrow-ranged species no significant SDMs could be generated. Predicted species turnover is as high as 75% and species-rich areas are predicted to loose many species. The explanatory power of individual future climate anomalies to predicted future species richness patterns is quantified. Species loss is best explained by increased precipitation in the dry season. Species gain and species turnover are correlated with a shift from extreme to average values of annual temperature range.

In the final chapter, the results are placed in a wider scientific context. First, the results on the methodological aspects of SDMs and their implications of the SDM pipeline are discussed. The method presented in this thesis to simulate large numbers of species offers opportunities to systematically investigate other matters of the pipeline, some of which are discussed here. Secondly, the factors that shape the current and predicted future patterns of plant species richness in Gabon are discussed including the location of centres of species richness and of weighted endemism in relation to the hypothesized location of glacial forest refugia. Factors that may contribute to the lower species richness of African rainforests compared with South American and Asian forests are discussed. I conclude by reflecting on the conservation of the Gabonese rainforest and its plant species as well as on the opportunities SDMs offer for this in the wider socio-economic context of a changing world with growing demand for food and other ecosystem services.

Verder vergroenen, verder verbreden : naar een effectieve bijdrage van het Europees landbouwbeleid en beleid voor agrarisch natuurbeheer aan groene opgaven
Doorn, Anne van; Westerink, Judith ; Nieuwenhuizen, Wim ; Melman, Dick ; Schrijver, Raymond ; Breman, Bas - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2822) - 75
duurzame landbouw - vergroening - milieubeheer - beschermde soorten - klimaatverandering - biodiversiteit - landbouwbeleid - conservering op het bedrijf - sustainable agriculture - greening - environmental management - protected species - climatic change - biodiversity - agricultural policy - on-farm conservation
This report explores in what way greening and enhancing sustainability of agriculture could be best supported within the CAP: by greening of direct payments (1 st pillar) or by contracts for agri-environmental management (2 nd pillar). Additionally it is explored for which goals it would be meaningful to implement a collective approach for agri-environmental management, next to the current objectives of the support of internationally protected species. The most relevant issues in the Netherlands concerning the sustainable management of natural resources, climate change and biodiversity are the point of departure of the analysis. For a couple of issues it is analysed which objectives can be best reached with which measures and instruments within the CAP.
Off-stage ecosystem service burdens : A blind spot for global sustainability
Pascual, Unai ; Palomo, Ignacio ; Adams, William M. ; Chan, Kai M.A. ; Daw, Tim M. ; Garmendia, Eneko ; Gómez-Baggethun, Erik ; Groot, Dolf de; Mace, Georgina M. ; Martín-López, Berta ; Phelps, Jacob - \ 2017
Environmental Research Letters 12 (2017)7. - ISSN 1748-9318
biodiversity - cross-scale interactions - ecosystem assessments - global sustainability - IPBES - IPCC - teleconnections
The connected nature of social-ecological systems has never been more apparent than in today's globalized world. The ecosystem service framework and associated ecosystem assessments aim to better inform the science-policy response to sustainability challenges. Such assessments, however, often overlook distant, diffuse and delayed impacts that are critical for global sustainability. Ecosystem-services science must better recognise the off-stage impacts on biodiversity and ecosystem services of place-based ecosystem management, which we term 'ecosystem service burdens'. These are particularly important since they are often negative, and have a potentially significant effect on ecosystem management decisions. Ecosystem-services research can better recognise these off-stage burdens through integration with other analytical approaches, such as life cycle analysis and risk-based approaches that better account for the uncertainties involved. We argue that off-stage ecosystem service burdens should be incorporated in ecosystem assessments such as those led by the Intergovernmental Platform on Biodiversity and Ecosystem Services and the Intergovernmental Panel on Climate Change. Taking better account of these off-stage burdens is essential to achieve a more comprehensive understanding of cross-scale interactions, a pre-requisite for any sustainability transition.
Ontwikkeling epifauna, infauna en kreeften (T0, T1, T2) op een ecologisch aantrekkelijke vooroeverbestorting (Schelphoek, Oosterschelde) : monitoring Building for Nature proefvak Schelphoek
Tangelder, Martijn ; Ooijen, Tim van; Kluijver, Mario de; Ysebaert, Tom - \ 2017
Den Helder : Wageningen Marine Research (Wageningen Marine Research rapport C039/17) - 69
fauna - oosterschelde - milieumonitoring - zeekreeften - mariene sedimenten - kalksteen - zandsteen - macrofauna - substraten - oesters - biodiversiteit - eastern scheldt - environmental monitoring - lobsters - marine sediments - limestone - sandstone - substrates - oysters - biodiversity
Rijkswaterstaat voert vooroeverbestortingen uit op het deel van de dijk dat onder water ligt in de Oosteren Westerschelde. Dit is nodig om de stabiliteit van de dijk en daarmee de waterveiligheid te kunnen blijven garanderen. Eerst werd hierbij alleen op veiligheidsdoelen gelet. Nieuw inzicht is dat je door gebruik van bepaalde materialen ook de natuur kunt faciliteren, dit principe wordt ‘Building for Nature’ genoemd. In 2014 is bij de oostelijke strekdam van locatie Schelphoek in de Oosterschelde een bestorting van zeegrind uitgevoerd. In het oorspronkelijke ontwerp was een basis van staalslakken voorzien, maar bij de uitvoering van het werk is vanwege beperkte beschikbaarheid van staalslakken voor zeegrind gekozen. Op het zeegrind zijn riffen van twee verschillende typen breuksteen gestort: kalksteen en zandsteen. Er is gekozen voor deze aangepaste bestorting om de ecologische meerwaarde van dit ontwerp te kunnen onderzoeken. Doel van dit onderzoek is om de rekolonisatie en ontwikkeling van hardsubstraatsoorten (epifauna) en soorten die leven in het sediment (infauna), en het voorkomen van kreeften op de nieuwe bestorting van kalksteen, zandsteen en zeegrind bij de locatie Schelphoek gedurende twee jaar na bestorting te volgen (T1-2015 en T2-2016) en te vergelijken met de situatie voor bestorten (T0-situatie in 2014).
Gezondheidseffecten onder de loep : weldadig groen
Spijker, J.H. ; Vries, S. de - \ 2017
Stadswerk (2017)6. - ISSN 0927-7641 - p. 34 - 36.
gezondheid - warmtestress - temperatuur - kwaliteit - beplantingen - biodiversiteit - stedelijke gebieden - bevolking - stressfactoren - sociaal welzijn - klimaat - health - heat stress - temperature - quality - plantations - biodiversity - urban areas - human population - stress factors - social welfare - climate
Groen speelt een sleutelrol bij een gezonde leefomgeving. De gezondheidseffecten spelen op diverse manieren, maar vooral door de stressverlagende effecten van groen en de hittedempende werking op warme dagen. Het is daarbij wel belangrijk om niet alleen naar de kwantiteit maar ook naar de kwaliteit van het groen te kijken.
Research for AGRI Committee : preserving agricultural soils in the EU - Study
Berge, H.F.M. ten; Schroder, J.J. ; Olesen, Jørgen Eivind ; Giraldez Cervera, J.V. - \ 2017
Brussels : European Parliament - ISBN 9789184609550 - 135 p.
soil management - soil quality - european union - soil organic matter - biodiversity - agriculture - organic farming - bodembeheer - bodemkwaliteit - europese unie - organisch bodemmateriaal - biodiversiteit - landbouw - biologische landbouw
This study explains how threats to soils and soil services are linked to agricultural soil management, how threats can be mitigated, and which barriers complicate this. It highlights trade-offs and synergies that exist between different interests affected by soil management, such as climate change mitigation, water and air quality, biodiversity, food security and farm income. Conservation of peatland and extensive agro-forestry systems, and protecting soils against sealing, erosion and compaction are ranked as highest priorities. Potential policy elements are suggested.
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