title: Resource colimitation governs plant community responses to altered precipitation.
abstract: Ecological theory and evidence suggest that plant community biomass and composition may often be jointly controlled by climatic water availability and soil nutrient supply. To the extent that such colimitation operates, alterations in water availability caused by climatic change may have relatively little effect on plant communities on nutrient-poor soils. We tested this prediction with a 5-y rainfall and nutrient manipulation in a semiarid annual grassland system with highly heterogeneous soil nutrient supplies. On nutrient-poor soils, rainfall addition alone had little impact, but rainfall and nutrient addition synergized to cause large increases in biomass, declines in diversity, and near-complete species turnover. Plant species with resource-conservative functional traits (low specific leaf area, short stature) were replaced by species with resource-acquisitive functional traits (high specific leaf area, tall stature). On nutrient-rich soils, in contrast, rainfall addition alone caused substantial increases in biomass, whereas fertilization had little effect. Our results highlight that multiple resource limitation is a critical aspect when predicting the relative vulnerability of natural communities to climatically induced compositional change and diversity loss.
authors.affiliation: Department of Environmental Science and Policy, University of California, Davis, CA 95616; Department of Ecology, University of Oulu, 90014 Oulu, Finland; anu.eskelinen@oulu.fi.
authors.forename: Anu
authors.initials: A
authors.lastname: Eskelinen
authors.affiliation: Department of Environmental Science and Policy, University of California, Davis, CA 95616.
authors.forename: Susan P
authors.initials: SP
authors.lastname: Harrison
mesh_terms: D017753:Ecosystem; D018521:Plant Physiological Phenomena; D011891:Rain; D012987:Soil; D014867:Water
chemical_list: D012987:Soil; D014867:Water
keywords: biodiversity; climate change; functional traits; low-productivity ecosystems; resource colimitation