Impacts of warming and elevated CO2 on a semi‐arid grassland are non‐additive,shift with precipitation,and reverse over time |
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| Authors: | K E Mueller D M Blumenthal E Pendall Y Carrillo F A Dijkstra D G Williams R F Follett J A Morgan |
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| Affiliation: | 1. Rangeland Resources Research Unit, Agricultural Research Service, United States Department of Agriculture, Fort Collins, CO, USA;2. Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia;3. Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia;4. Department of Botany, University of Wyoming, Laramie, WY, USA;5. Soil Plant and Nutrient Research Unit, Agricultural Research Service, United States Department of Agriculture, Fort Collins, CO, USA |
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| Abstract: | It is unclear how elevated CO2 (eCO2) 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 eCO2 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 eCO2 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 eCO2 and warming on C3 graminoids became increasingly positive and supra‐additive over time, reversing an initial shift toward C4 grasses. Soil resources also responded dynamically and non‐additively to eCO2 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. |
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| Keywords: |
Artemisia frigida
Bouteloua gracilis
C3 grass C4 grass climate change forb nitrogen plant productivity root biomass soil moisture |
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