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: 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: Aims Functional traits are supposed to play an important role in determining the colonization success of new species into established communities. Short-term experimental studies have documented higher resistance of more diverse grasslands against colonization by new species. However, little is known about which traits colonizers should have to successfully invade diverse plant communities in the longer term and how community history may modify the resistance of diverse communities against colonization. Methods In a grassland biodiversity experiment (Jena Experiment) established with different species richness (SR; 1, 2, 4, 8 and 16) and functional group (FG) number and composition (1 to 4; legumes, grasses, small herbs, tall herbs), we studied colonization of naturally dispersed species in split-plots (i) with different duration of weeding (never weeded, weeded for 3 or 6 years and then un-weeded for 1 year) and (ii) with different duration of colonization (7 years, 4 years and 1 year after cessation of weeding). Important Findings Resistance against colonization by new species declined with increased duration of weeding (on average 13, 17 and 22 colonizer species in 1-, 4- and 7-year-old communities, respectively). Communities established at low diversity accumulated more colonizer species with a longer duration of weeding than more diverse communities. Duration of colonization had only small effects on the number of colonizer species. Colonizers with early successional traits, i.e. annual life cycle, reproduction by seeds, small seeds, long-lived seeds and an earlier start of a longer flowering period, were favoured in species-poor newly established experimental plant communities (short duration of weeding) and early after cessation of weeding (short duration of colonization). A change from early- to mid-successional traits, i.e. taller growth, perennial life cycle, vegetative reproduction, characterized colonization at increased plant diversity and in communities with legumes or without grasses. Legume absence/grass presence and increased duration of weeding led to a shift in colonizer strategies from rapid nutrient uptake and cycling (higher specific leaf area) to nutrient retention and symbiotic N 2 fixation. Our study shows that non-random trait spectra of naturally dispersed colonizers encompass trade-offs between different functions (reproduction, persistence, growth) reflected in a change from early- to mid-successional traits at increasing plant diversity, with a longer duration of weeding and a longer time of colonization.

Description: More diverse communities have been shown to have higher and more temporally stable ecosystem functioning than less diverse ones, suggesting they should also have a consistently higher level of functioning over time. Diverse communities could maintain consistently high function because the species driving function change over time (functional turnover) or because they are more likely to contain key species with temporally stable functioning. Across 7 y in a large biodiversity experiment, we show that more diverse plant communities had consistently higher productivity, that is, a higher level of functioning over time. We identify the mechanism for this as turnover in the species driving biomass production; this was substantial, and species that were rare in some years became dominant and drove function in other years. Such high turnover allowed functionally more diverse communities to maintain high biomass over time and was associated with higher levels of complementarity effects in these communities. In contrast, turnover in communities composed of functionally similar species did not promote high biomass production over time. Thus, turnover in species promotes consistently high ecosystem function when it sustains functionally complementary interactions between species. Our results strongly reinforce the argument for conservation of high biodiversity.

Description: Aims Diversity–productivity relationships among herbaceous species have mostly been studied in grasslands, while less is known about diversity effects among weedy species with a short life cycle. Methods We studied diversity–productivity relationships, shoot density, size and allometry in experimental communities of different species richness (one, three, six, and nine species), functional group number (one to three functional groups: grasses, small herbs and tall herbs) and functional group evenness (even and uneven number of species per functional group) based on a pool of nine arable weed species with a short life cycle in a 2-year experiment. Important Findings Higher species richness increased above- and belowground biomass production in both years of the experiment. Additive partitioning showed that positive selection effects increased with increasing species richness and functional group number, while positive complementarity effects were greater when tall herbs were present. Relative yield totals were larger than 1 across all species richness levels but did not increase with species richness, which is consistent with constant positive complementarity effects. Community biomass production and diversity effects increased in the second year of the experiment, when communities achieved greater shoot densities and average shoot sizes. At the community level, varying productivity was mainly attributable to variation in mean shoot sizes. Tall herbs reached greater observed/expected relative yields (=overyielding) due to increased shoot sizes, underyielding of small herbs was mainly attributable to decreased shoot sizes, while grasses partly compensated for reduced shoot sizes by increasing densities. Shifts in community-level density–size relationships and changes in shoot allometry in favour of greater height growth indicated that a greater biomass at a given density was due to increased dimensions of occupied canopy space. We conclude that diversity effects are also possible among short-lived arable weed species, but selection effects through sizes differences among species are key for positive species richness–productivity relationships.

Description: Soil nitrogen mineralisation (Nmin), the conversion of organic into inorganic N, is important for productivity and nutrient cycling. The balance between mineralisation and immobilisation (net Nmin) varies with soil properties and climate. However, because most global-scale assessments of net Nmin are laboratory-based, its regulation under field-conditions and implications for real-world soil functioning remain uncertain. Here, we explore the drivers of realised (field) and potential (laboratory) soil net Nmin across 30 grasslands worldwide. We find that realised Nmin is largely explained by temperature of the wettest quarter, microbial biomass, clay content and bulk density. Potential Nmin only weakly correlates with realised Nmin, but contributes to explain realised net Nmin when combined with soil and climatic variables. We provide novel insights of global realised soil net Nmin and show that potential soil net Nmin data available in the literature could be parameterised with soil and climate data to better predict realised Nmin.