ALBERT

Description: Biodiversity is rapidly declining, and this may negatively affect ecosystem processes, including economically important ecosystem services. Previous studies have shown that biodiversity has positive effects on organisms and processes across trophic levels. However, only a few studies have so far incorporated an explicit food-web perspective. In an eight-year biodiversity experiment, we studied an unprecedented range of above- and below-ground organisms and multitrophic interactions. A multitrophic data set originating from a single long-term experiment allows mechanistic insights that would not be gained from meta-analysis of different experiments. Here we show that plant diversity effects dampen with increasing trophic level and degree of omnivory. This was true both for abundance and species richness of organisms. Furthermore, we present comprehensive above-ground/below-ground biodiversity food webs. Both above ground and below ground, herbivores responded more strongly to changes in plant diversity than did carnivores or omnivores. Density and richness of carnivorous taxa was independent of vegetation structure. Below-ground responses to plant diversity were consistently weaker than above-ground responses. Responses to increasing plant diversity were generally positive, but were negative for biological invasion, pathogen infestation and hyperparasitism. Our results suggest that plant diversity has strong bottom-up effects on multitrophic interaction networks, with particularly strong effects on lower trophic levels. Effects on higher trophic levels are indirectly mediated through bottom-up trophic cascades.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scherber, Christoph -- Eisenhauer, Nico -- Weisser, Wolfgang W -- Schmid, Bernhard -- Voigt, Winfried -- Fischer, Markus -- Schulze, Ernst-Detlef -- Roscher, Christiane -- Weigelt, Alexandra -- Allan, Eric -- Bessler, Holger -- Bonkowski, Michael -- Buchmann, Nina -- Buscot, Francois -- Clement, Lars W -- Ebeling, Anne -- Engels, Christof -- Halle, Stefan -- Kertscher, Ilona -- Klein, Alexandra-Maria -- Koller, Robert -- Konig, Stephan -- Kowalski, Esther -- Kummer, Volker -- Kuu, Annely -- Lange, Markus -- Lauterbach, Dirk -- Middelhoff, Cornelius -- Migunova, Varvara D -- Milcu, Alexandru -- Muller, Ramona -- Partsch, Stephan -- Petermann, Jana S -- Renker, Carsten -- Rottstock, Tanja -- Sabais, Alexander -- Scheu, Stefan -- Schumacher, Jens -- Temperton, Vicky M -- Tscharntke, Teja -- England -- Nature. 2010 Nov 25;468(7323):553-6. doi: 10.1038/nature09492. Epub 2010 Oct 27.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Georg-August-University Gottingen, Department of Crop Sciences, Agroecology, Grisebachstrasse 6, 37077 Gottingen, Germany. christoph.scherber@agr.uni-goettingen.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20981010" target="_blank"〉PubMed〈/a〉

Description: Plant diversity generally promotes biomass production, but how the shape of the response curve changes with time remains unclear. This is a critical knowledge gap because the shape of this relationship indicates the extent to which loss of the first few species will influence biomass production. Using two long-term (〉/=13 years) biodiversity experiments, we show that the effects of diversity on biomass productivity increased and became less saturating over time. Our analyses suggest that effects of diversity-dependent ecosystem feedbacks and interspecific complementarity accumulate over time, causing high-diversity species combinations that appeared functionally redundant during early years to become more functionally unique through time. Consequently, simplification of diverse ecosystems will likely have greater negative impacts on ecosystem functioning than has been suggested by short-term experiments.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reich, Peter B -- Tilman, David -- Isbell, Forest -- Mueller, Kevin -- Hobbie, Sarah E -- Flynn, Dan F B -- Eisenhauer, Nico -- New York, N.Y. -- Science. 2012 May 4;336(6081):589-92. doi: 10.1126/science.1217909.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Forest Resources, University of Minnesota, St. Paul, MN 55108, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22556253" target="_blank"〉PubMed〈/a〉

Description: It remains unclear whether biodiversity buffers ecosystems against climate extremes, which are becoming increasingly frequent worldwide. Early results suggested that the ecosystem productivity of diverse grassland plant communities was more resistant, changing less during drought, and more resilient, recovering more quickly after drought, than that of depauperate communities. However, subsequent experimental tests produced mixed results. Here we use data from 46 experiments that manipulated grassland plant diversity to test whether biodiversity provides resistance during and resilience after climate events. We show that biodiversity increased ecosystem resistance for a broad range of climate events, including wet or dry, moderate or extreme, and brief or prolonged events. Across all studies and climate events, the productivity of low-diversity communities with one or two species changed by approximately 50% during climate events, whereas that of high-diversity communities with 16-32 species was more resistant, changing by only approximately 25%. By a year after each climate event, ecosystem productivity had often fully recovered, or overshot, normal levels of productivity in both high- and low-diversity communities, leading to no detectable dependence of ecosystem resilience on biodiversity. Our results suggest that biodiversity mainly stabilizes ecosystem productivity, and productivity-dependent ecosystem services, by increasing resistance to climate events. Anthropogenic environmental changes that drive biodiversity loss thus seem likely to decrease ecosystem stability, and restoration of biodiversity to increase it, mainly by changing the resistance of ecosystem productivity to climate events.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Isbell, Forest -- Craven, Dylan -- Connolly, John -- Loreau, Michel -- Schmid, Bernhard -- Beierkuhnlein, Carl -- Bezemer, T Martijn -- Bonin, Catherine -- Bruelheide, Helge -- de Luca, Enrica -- Ebeling, Anne -- Griffin, John N -- Guo, Qinfeng -- Hautier, Yann -- Hector, Andy -- Jentsch, Anke -- Kreyling, Jurgen -- Lanta, Vojtech -- Manning, Pete -- Meyer, Sebastian T -- Mori, Akira S -- Naeem, Shahid -- Niklaus, Pascal A -- Polley, H Wayne -- Reich, Peter B -- Roscher, Christiane -- Seabloom, Eric W -- Smith, Melinda D -- Thakur, Madhav P -- Tilman, David -- Tracy, Benjamin F -- van der Putten, Wim H -- van Ruijven, Jasper -- Weigelt, Alexandra -- Weisser, Wolfgang W -- Wilsey, Brian -- Eisenhauer, Nico -- England -- Nature. 2015 Oct 22;526(7574):574-7. doi: 10.1038/nature15374. Epub 2015 Oct 14.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology, Evolution and Behavior, University of Minnesota Twin Cities, Saint Paul, Minnesota 55108, USA. ; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany. ; Institute of Biology, Leipzig University, Johannisallee 21, 04103 Leipzig, Germany. ; Ecological and Environmental Modelling Group, School of Mathematics and Statistics, University College Dublin, Dublin 4, Ireland. ; Centre for Biodiversity Theory and Modelling, Experimental Ecology Station, Centre National de la Recherche Scientifique, Moulis 09200, France. ; Institute of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland. ; Department of Biogeography, BayCEER, University of Bayreuth, 95440 Bayreuth, Germany. ; Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), PO Box 50, 6700 AB Wageningen, The Netherlands. ; Department of Agronomy, Iowa State University, Ames, Iowa 50011, USA. ; Institute of Biology, Martin Luther University Halle-Wittenberg, 06108 Halle, Germany. ; Institute of Ecology, Friedrich Schiller University Jena, Dornburger Strasse 159, 07743 Jena, Germany. ; Department of Biosciences, Swansea University, Singleton Park, Swansea SA28PP, UK. ; USDA FS, Eastern Forest Environmental Threat Assessment Center, RTP, North Carolina 27709, USA. ; Ecology and Biodiversity Group, Department of Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. ; Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK. ; Disturbance Ecology, BayCEER, University of Bayreuth, 95440 Bayreuth, Germany. ; Institute of Botany and Landscape Ecology, Ernst-Moritz-Arndt University Greifswald, D-17487 Greifswald, Germany. ; Department of Botany, Faculty of Science, University of South Bohemia, Branisovska 31, 37005 Ceske Budejovice, Czech Republic. ; Institute for Plant Sciences, University of Bern, CH-3013 Bern, Switzerland. ; Department of Ecology and Ecosystem Management, School of Life Sciences Weihenstephan, Technische Universitat Munchen, 85354 Freising, Germany. ; Graduate School of Environment and Information Sciences, Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama, Kanagawa, 240-8501, Japan. ; Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, New York 10027, USA. ; US Department of Agriculture Agricultural Research Service, Grassland, Soil and Water Research Laboratory, Temple, Texas 76502, USA. ; Department of Forest Resources, University of Minnesota Twin Cities, Saint Paul, Minnesota 55108 USA. ; Hawkesbury Institute for the Environment, University of Western Sydney, Penrith, New South Wales 2753, Australia. ; UFZ Helmholtz Centre for Environmental Research, Community Ecology, 06120 Halle, Germany. ; Graduate Degree Program in Ecology and Department of Biology, Colorado State University, Fort Collins, Colorado 80523, USA. ; Bren School of Environmental Science and Management, University of California, Santa Barbara, California 93106 USA. ; Crop and Soil Environmental Sciences, Smyth Hall 0404, Virginia Tech, Blacksburg, Virginia 24061, USA. ; Laboratory of Nematology, Wageningen University and Research Centre, PO Box 8123, 6700 ES Wageningen, The Netherlands. ; Nature Conservation and Plant Ecology Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands. ; Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, Iowa 50011, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26466564" target="_blank"〉PubMed〈/a〉

Description: There is a growing awareness that biodiversity not only drives ecosystem services but also affects evolutionary dynamics. However, different theories predict contrasting outcomes on when do evolutionary processes occur within a context of competition. We tested whether functional diversity can explain diversification patterns. We tracked the survival and diversification of a focal bacterial species ( Pseudomonas fluorescens ) growing in bacterial communities of variable diversity and composition. We found that high functional diversity reduced the fitness of the focal species and, at the same time, fostered its diversification. This pattern was linked to resource competition: High diversity increased competition on a portion of the resources while leaving most underexploited. The evolved phenotypes of the focal species showed a better use of underexploited resources, albeit at a cost of lower overall growth rates. As a result, diversification alleviated the impact of competition on the fitness of the focal species. We conclude that biodiversity can stimulate evolutionary diversification, provided that sufficient alternative niches are available.

Description: Aims Theory suggests that species perform best at intermediate densities, where density-dependent facilitation and antagonism are balanced, but empirical evidence is scarce, particularly in plants. In a self-incompatible perennial herb ( Saussurea nigrescens ), whose recruitment heavily relies on seed output, we test whether both intraspecific facilitation and antagonism significantly affect seed production, resulting in highest seed yield at an intermediate capitulum density. Methods Plots with different S. nigrescens densities were sampled in an Eastern Tibetan meadow during the growing season of 2012 to investigate the relationships between capitulum density and pollinator visitation rate, seed set ratio, parasite ratio, seed damage ratio, and capitulum size. Both simple linear and quadratic models were employed to determine the shape of relationships. Important Findings In line with general theory, hump-shaped relationships of capitulum density versus seed set ratio and number of florets per capitulum indicate intraspecific facilitation in sparse populations, which can be attributed to positive density-dependent pollinator visitation and the amelioration of detrimental physical factors. However, the proportion of seeds damaged by pre-dispersal predators increased monotonically with capitulum density, which may have—in combination with increased intraspecific competition for light and soil nutrients—resulted in density-dependent antagonism. Both positive and negative density-dependent agents acted simultaneously throughout the density range investigated and led to the highest seed yield at intermediate density levels in the Tibetan lotus. More efforts concurrently exploring the two effects are needed to facilitate understanding species abundance and community structure.

Description: Recent metaanalyses suggest biodiversity loss affects the functioning of ecosystems to a similar extent as other global environmental change agents. However, the abundance and functioning of soil organisms have been hypothesized to be much less responsive to such changes, particularly in plant diversity, than aboveground variables, although tests of this...

Description: Climate warming is predicted to alter species interactions, which could potentially lead to extinction events. However, there is an ongoing debate whether the effects of warming on biodiversity may be moderated by biodiversity itself. We tested warming effects on soil nematodes, one of the most diverse and abundant metazoans in terrestrial ecosystems, along a gradient of environmental complexity created by a gradient of plant species richness. Warming increased nematode species diversity in complex (16-species mixtures) plant communities (by ~36%) but decreased it in simple (monocultures) plant communities (by ~39%) compared to ambient temperature. Further, warming led to higher levels of taxonomic relatedness in nematode communities across all levels of plant species richness. Our results highlight both the need for maintaining species-rich plant communities to help offset detrimental warming effects and the inability of species-rich plant communities to maintain nematode taxonomic distinctness when warming occur.