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Plant diversity effects on grassland productivity are robust to both nutrient enrichment and drought

Craven, Dylan, Isbell, Forest, Manning, Pete, Connolly, John, Bruelheide, Helge, Ebeling, Anne, Roscher, Christiane, van Ruijven, Jasper, Weigelt, Alexandra, Wilsey, Brian, Polley, H. Wayne
Philosophical transactions of the Royal Society B 2016 v.371 no.1694 pp. 20150277
drought, ecosystems, global change, grassland soils, grasslands, nutrients, plant available water, plant-water relations, soil nutrients, soil-plant interactions, soil-plant-atmosphere interactions, species diversity, Europe, North America
Global change drivers are rapidly altering resource availability and reducing biodiversity. Here, we evaluate the extent to which biodiversity influences the response of ecosystem productivity to increases or decreases in resource availability across grassland experiments. This was done using data from 16 grassland experiments across North America and Europe that manipulated both plant species richness and an essential resource: soil nutrients or water. We assessed the interaction between plant diversity and resource alteration as both positive interactions with diversity, e.g. more complete utilization of additional nutrients at high plant diversity, and negative interactions, e.g. the breakdown of complementarity for limiting resources, could be expected. Despite strong increases in productivity with nutrient addition and decreases in productivity due to water reduction, we found that resource alterations did not alter the strength of diversity effects on productivity. Standardizing for absolute productivity changes revealed a consistent yet weak and non-significant trend for diversity to buffer the effects of both drought and nutrient enrichment. The immutability of diversity effects indicates that diversity will remain an important regulator of grassland ecosystem productivity, regardless of changes in other global change drivers.