ALBERT

Description: Ecosystems exhibit surprising regularities in structure and function across terrestrial and aquatic biomes worldwide. We assembled a global data set for 2260 communities of large mammals, invertebrates, plants, and plankton. We find that predator and prey biomass follow a general scaling law with exponents consistently near (3/4). This pervasive pattern implies that the structure of the biomass pyramid becomes increasingly bottom-heavy at higher biomass. Similar exponents are obtained for community production-biomass relations, suggesting conserved links between ecosystem structure and function. These exponents are similar to many body mass allometries, and yet ecosystem scaling emerges independently from individual-level scaling, which is not fully understood. These patterns suggest a greater degree of ecosystem-level organization than previously recognized and a more predictive approach to ecological theory.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hatton, Ian A -- McCann, Kevin S -- Fryxell, John M -- Davies, T Jonathan -- Smerlak, Matteo -- Sinclair, Anthony R E -- Loreau, Michel -- New York, N.Y. -- Science. 2015 Sep 4;349(6252):aac6284. doi: 10.1126/science.aac6284. Epub 2015 Sep 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada. i.a.hatton@gmail.com. ; Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada. ; Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada. ; Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada. ; Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada. Tanzania Wildlife Research Institute, P.O. Box 661, Arusha, United Republic of Tanzania. ; Centre for Biodiversity Theory and Modeling, Experimental Ecology Station, CNRS, 09200 Moulis, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26339034" 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: While previous studies have evaluated the change in stability for the addition or removal of individual species from trophic food chains and food webs, we know of no study that presents a general theory for how stability changes with the addition or removal of trophic levels. In this study, we present a simple model of a linear food chain and systematically evaluate how stability—measured as invariability—changes with the addition or removal of trophic levels. We identify the presence of trophic cascades in the stability of species. Owing to top-down control by predation and bottom-up regulation by prey, we find that stability of a species is highest when it is at the top of the food chain and lowest when it is just under the top of the food chain. Thus, stability shows patterns identical to those of mean biomass with the addition or removal of trophic levels in food chains. Our results provide a baseline towards a general theory of the effect of adding or removing trophic levels on stability, which can be used to inform empirical studies.