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Impacts of warming and elevated CO 2 on a semi‐arid grassland are non‐additive, shift with precipitation, and reverse over time
Author(s) -
Mueller K. E.,
Blumenthal D. M.,
Pendall E.,
Carrillo Y.,
Dijkstra F. A.,
Williams D. G.,
Follett R. F.,
Morgan J. A.
Publication year - 2016
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/ele.12634
Subject(s) - grassland , biomass (ecology) , precipitation , ecosystem , arid , environmental science , global warming , ecology , growing season , climate change , plant community , agronomy , atmospheric sciences , biology , species richness , geography , meteorology , geology
It is unclear how elevated CO 2 ( eCO 2 ) and the corresponding shifts in temperature and precipitation will interact to impact ecosystems over time. During a 7‐year experiment in a semi‐arid grassland, the response of plant biomass to eCO 2 and warming was largely regulated by interannual precipitation, while the response of plant community composition was more sensitive to experiment duration. The combined effects of eCO 2 and warming on aboveground plant biomass were less positive in ‘wet’ growing seasons, but total plant biomass was consistently stimulated by ~ 25% due to unique, supra‐additive responses of roots. Independent of precipitation, the combined effects of eCO 2 and warming on C 3 graminoids became increasingly positive and supra‐additive over time, reversing an initial shift toward C 4 grasses. Soil resources also responded dynamically and non‐additively to eCO 2 and warming, shaping the plant responses. Our results suggest grasslands are poised for drastic changes in function and highlight the need for long‐term, factorial experiments.