Browsing by Subject "plant diversity"

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    Plant diversity effects on grassland productivity are robust to both nutrient enrichment and drought
    (The Royal Society, 2016) Craven, Dylan; Isbell, Forest; Manning, Pete; Connolly, John; Bruelheide, Helge; Ebeling, Anne; Roscher, Christiane; Van Ruijven, Jasper; Weigelt, Alexandra; Wilsey, Brian; Beierkuhnlein, Carl; De Luca, Enrica; Griffin, John N; Hautier, Yann; Hector, Andy; Jentsch, Anke; Kreyling, Jürgen; Lanta, Vojtech; Loreau, Michel; Meyer, Sebastian T; Mori, Akira S; Naeem, Shahid; Palmborg, Cecilia; Polley, H Wayne; Reich, Peter B; Schmid, Bernhard; Siebenkäs, Alrun; Seabloom, Eric; Thakur, Madhav P; Tilman, David; Vogel, Anja; Eisenhauer, Nico
    Global change drivers are rapidly altering resource availability and biodiversity. While there is consensus that greater biodiversity increases the functioning of ecosystems, the extent to which biodiversity buffers ecosystem productivity in response to changes in resource availability remains unclear. We use data from 16 grassland experiments across North America and Europe that manipulated plant species richness and one of two essential resources—soil nutrients or water—to assess the direction and strength of the interaction between plant diversity and resource alteration on above-ground productivity and net biodiversity, complementarity, and selection effects. Despite strong increases in productivity with nutrient addition and decreases in productivity with drought, we found that resource alterations did not alter biodiversity–ecosystem functioning relationships. Our results suggest that these relationships are largely determined by increases in complementarity effects along plant species richness gradients. Although nutrient addition reduced complementarity effects at high diversity, this appears to be due to high biomass in monocultures under nutrient enrichment. Our results indicate that diversity and the complementarity of species are important regulators of grassland ecosystem productivity, regardless of changes in other drivers of ecosystem function.
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    Plant diversity effects on soil microbial functions and enzymes are stronger than warming in a grassland experiment
    (Ecological Society of America, 2015) Steinauer, Katja; Tilman, G David; Wragg, Peter Douglas; Cesarz, Simone; Cowles, Jane M; Pritsch, Karin; Reich, Peter B; Weisser, Wolfgang W; Eisenhauer, Nico;
    Anthropogenic changes in biodiversity and atmospheric temperature significantly influence ecosystem processes. However, little is known about potential interactive effects of plant diversity and warming on essential ecosystem properties, such as soil microbial functions and element cycling. We studied the effects of orthogonal manipulations of plant diversity (one, four, and 16 species) and warming (ambient, +1.5°C, and +3°C) on soil microbial biomass, respiration, growth after nutrient additions, and activities of extracellular enzymes in 2011 and 2012 in the BAC (biodiversity and climate) perennial grassland experiment site at Cedar Creek, Minnesota, USA. Focal enzymes are involved in essential biogeochemical processes of the carbon, nitrogen, and phosphorus cycles. Soil microbial biomass and some enzyme activities involved in the C and N cycle increased significantly with increasing plant diversity in both years. In addition, 16-species mixtures buffered warming induced reductions in topsoil water content. We found no interactive effects of plant diversity and warming on soil microbial biomass and growth rates. However, the activity of several enzymes (1,4-β-glucosidase, 1,4-β-N-acetylglucosaminidase, phosphatase, peroxidase) depended on interactions between plant diversity and warming with elevated activities of enzymes involved in the C, N, and P cycles at both high plant diversity and high warming levels. Increasing plant diversity consistently decreased microbial biomass-specific enzyme activities and altered soil microbial growth responses to nutrient additions, indicating that plant diversity changed nutrient limitations and/or microbial community composition. In contrast to our expectations, higher plant diversity only buffered temperature effects on soil water content, but not on microbial functions. Temperature effects on some soil enzymes were greatest at high plant diversity. In total, our results suggest that the fundamental temperature ranges of soil microbial communities may be sufficiently broad to buffer their functioning against changes in temperature and that plant diversity may be a dominant control of soil microbial processes in a changing world.