Showing papers by "Volkmar Wolters published in 2017"

The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project

Abstract: The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.

Land-use type and intensity differentially filter traits in above- and below-ground arthropod communities

Abstract: Along with the global decline of species richness goes a loss of ecological traits. Associated biotic homogenization of animal communities and narrowing of trait diversity threaten ecosystem functioning and human well-being. High management intensity is regarded as an important ecological filter, eliminating species that lack suitable adaptations. Below-ground arthropods are assumed to be less sensitive to such effects than above-ground arthropods. Here, we compared the impact of management intensity between (grassland vs. forest) and within land-use types (local management intensity) on the trait diversity and composition in below- and above-ground arthropod communities. We used data on 722 arthropod species living above-ground (Auchenorrhyncha and Heteroptera), primarily in soil (Chilopoda and Oribatida) or at the interface (Araneae and Carabidae). Our results show that trait diversity of arthropod communities is not primarily reduced by intense local land use, but is rather affected by differences between land-use types. Communities of Auchenorrhyncha and Chilopoda had significantly lower trait diversity in grassland habitats as compared to forests. Carabidae showed the opposite pattern with higher trait diversity in grasslands. Grasslands had a lower proportion of large Auchenorrhyncha and Carabidae individuals, whereas Chilopoda and Heteroptera individuals were larger in grasslands. Body size decreased with land-use intensity across taxa, but only in grasslands. The proportion of individuals with low mobility declined with land-use intensity in Araneae and Auchenorrhyncha, but increased in Chilopoda and grassland Heteroptera. The proportion of carnivorous individuals increased with land-use intensity in Heteroptera in forests and in Oribatida and Carabidae in grasslands. Our results suggest that gradients in management intensity across land-use types will not generally reduce trait diversity in multiple taxa, but will exert strong trait filtering within individual taxa. The observed patterns for trait filtering in individual taxa are not related to major classifications into above- and below-ground species. Instead, ecologically different taxa resembled each other in their trait diversity and compositional responses to land-use differences. These previously undescribed patterns offer an opportunity to develop management strategies for the conservation of trait diversity across taxonomic groups in permanent grassland and forest habitats.

Trade-offs in arthropod conservation between productive and non-productive agri-environmental schemes along a landscape complexity gradient

Abstract: Productive and non‐productive agri‐environmental schemes (AES) were developed to support farmland biodiversity. This study compares arthropod predators between productive (organic farming) and non‐productive (sown flowering fields) AES along a landscape complexity gradient. We compared species richness, community composition and community weighted mean body sizes of 12 306 carabids and 4868 spiders in organically managed cereal fields and flowering fields along a landscape complexity gradient. These data were used to evaluate the conservation success of different AES types for a number of exclusive species, financial incentives and benefits for farmers. Carabids only responded to the AES type and their communities had higher species richness in flowering fields. Spider species richness increased with landscape complexity. Community composition differed between AES types for all predator groups, with the composition of ground‐dwelling spiders being additionally affected by landscape complexity. The mean body size of web‐building spiders decreased with landscape complexity and the mean body size of female spiders was larger in flowering fields. Both AES types can contribute to the conservation of predator communities. Species richness increased with non‐productive AES. Agrobiont species occurred more frequently in productive AES. The overall number of exclusive predator species was lower in flowering fields. We emphasise that there is an additive effect of establishing productive and non‐productive AES within the landscape, and a diverse mosaic of different AES types holds the greatest potential to provide a large regional species pool of arthropod predators, while simultaneously guaranteeing financial benefits for farmers from production and subsidies.

Adaptive food webs: stability and transitions of real and model ecosystems

Abstract: Presenting new approaches to studying food webs, this book uses practical management and policy examples to demonstrate the theory behind ecosystem management decisions and the broader issue of sustainability. All the information that readers need to use food web analyses as a tool for understanding and quantifying transition processes is provided. Advancing the idea of food webs as complex adaptive systems, readers are challenged to rethink how changes in environmental conditions affect these systems. Beginning with the current state of thinking about community organisation, complexity and stability, the book moves on to focus on the traits of organisms, the adaptive nature of communities and their impacts on ecosystem function. The final section of the book addresses the applications to management and sustainability. By helping to understand the complexities of multispecies networks, this book provides insights into the evolution of organisms and the fate of ecosystems in a changing world. Read more at http://www.cambridge.org/gb/academic/subjects/life-sciences/ecology-and-conservation/adaptive-food-webs-stability-and-transitions-real-and-model-ecosystems#TksrzH3K0CTvzWiI.99

Contrasting Pollination Efficiency and Effectiveness among Flower Visitors of Malva Sylvestris, Borago Officinalis and Onobrychis Viciifolia

Abstract: Biotic pollination is an important factor for ecosystem functioning and provides a substantial ecosystem service to human food security. Not all flower visitors are pollinators, however, and pollinators differ in their pollination performances. In this study, we determined the efficiencies of flower visitors to the plant species Malva sylvestris , Borago officinalis and Onobrychis viciifolia by analysing stigmatic pollen deposition. We further calculated pollinator effectiveness by scaling up single-visit pollen deposition using visitation frequency. Flower-visitor groups differed in their efficiencies at the single-visit level and not all of them deposited more pollen compared to unvisited stigmas. Bumblebees tended to be most efficient in depositing pollen per single visit across the three plant species. Due to the by far highest visitation frequencies, Apis mellifera showed the highest effectiveness in depositing pollen per hour for M. sylvestris and B. officinalis , but not for O. viciifolia , for which the Bombus lapidarius complex was both the most frequent and the most effective pollinator group. Hence, the most frequent flower visitors were most effective in our study. For non-dominant pollinator groups, however, visitation frequencies contributed disproportionally to pollinator effectiveness. Thus, combining pollen deposition per single-visit with visitation frequency is necessary to reveal true pollinator performance and to better understand flower-visitor interactions. PLEASE NOTE: Supplementary files to this article can be found in the left menu of this website.

Global metawebs of spider predation highlight consequences of land-use change for terrestrial predator-prey networks

Abstract: Land-Use Change and Terrestrial Predator–Prey Networks Land-use change, here defined as the conversion of one land-use type into another (e.g., forest to arable land), affects biodiversity and biotic interactions worldwide (Sala et al., 2000). Although there has been large regional variation in the extent of agricultural expansion and abandonment in Europe in the past 50 years (Rabbinge and van Diepen, 2000), there has been a general trend that forest has expanded at the expense of agricultural land (Kankaanpaa and Carter, 2004; Rounsevell et al., 2006). The patterns have been similar in North America the past decades (Smith et al., 2010). Globally, particularly in developing countries, the general pattern has instead been agricultural expansion (Smith et al., 2010), threatening forest ecosystems (DeFries et al., 2010; Lambin and Meyfroidt, 2011; but see Angelsen, 2010). In fact, models predict an increase of cropland between 10 and 25% up to 2050, mainly due to agricultural expansion in developing countries (Schmitz et al., 2014). Natural and semi-natural non-forest ecosystems are primarily threatened by a conversion to pasture land (Schmitz et al., 2014) or by cultivation with biofuels (Havlik et al., 2011). Climate change is an important additional driver of land-use conversion, as the range of crop species contract or expand (Olesen and Bindi, 2002) and as forests adapt to changing climatic conditions (Spittlehouse and Stewart, 2004). In the past, effects of land-use change were often exclusively assessed by their impact on species richness (Tilman et al., 2001). Today, it has increasingly become evident that we need metrics that capture additional features of biological communities to understand consequences of land-use change on ecosystem functions and the provision of ecosystem services (Tylianakis et al., 2007; Diehl et al., 2013). Trophic interactions that link species in food webs are important components that modulate functions provided by biological communities (Laliberte and Tylianakis, 2010; Tylianakis et al., 2010; Thompson et al., 2012). For example, the loss of large apex predators from an ecosystem due to anthropogenic disturbance may cascade through the food chain and lead to drastic effects on primary producers (Estes et al., 2011). Predator populations are often severely affected by anthropogenic disturbances (Attwood et al., 2008). Consequently, the conversion from one major land-use type into another may alter predator–prey interactions (Ives et al., 2005) and the provision of predator-mediated ecosystem services such as the control of agricultural pests (conservation biological control; Barbosa, 1998). (Less)

Ein zukunftsfähiger Gesellschaftsvertrag mit der Landwirtschaft: Plädoyer für eine neue Agrarpolitik

Abstract: Dieses Policy-Paper ist das wichtigste Ergebnis des ZA-NExUS-Projekts, das wissenschaftlich basierte Optionen fur die kunftige Ausgestaltung der Agrarpolitik aus der Perspektive des Natur- und Umweltschutzes formulieren sollte. Es wurde im Januar 2017 auf einer Pressekonferenz mit der damaligen Bundesministerin Dr. Barbara Hendricks der Offentlichkeit vorgestellt. Ausgehend vom Konzept eines zukunftsfahigen Gesellschaftsvertrags mit der Landwirtschaft wird eine neue Architektur der Agrarpolitik mit folgenden Kernelementen vorgeschlagen: Pramien fur Landschaftsvielfalt und fur Basismasnahmen im Agrarumwelt- und Klimaschutz, regionale Agrarumwelt- und Klimaschutzprogramme, ein Kooperationsprogramm Natur und Landwirtschaft sowie ein effektives Ordnungsrecht. Hinzu kommt ein Innovationsprogramm zur Entwicklung von Mehrwertmarkten fur umweltfreundliche Produkte durch Verbraucherkommunikation, praxisorientierte Forschung und Beratung.