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Feedback from plant species change amplifies CO 2 enhancement of grassland productivity
Author(s) -
Polley H. Wayne,
Jin Virginia L.,
Fay Philip A.
Publication year - 2012
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2012.02735.x
Subject(s) - primary production , forb , grassland , perennial plant , environmental science , soil water , productivity , vegetation (pathology) , ecosystem , plant community , agronomy , biomass (ecology) , ecology , soil science , biology , ecological succession , medicine , macroeconomics , pathology , economics
Abstract Dynamic global vegetation models simulate feedbacks of vegetation change on ecosystem processes, but direct, experimental evidence for feedbacks that result from atmospheric CO 2 enrichment is rare. We hypothesized that feedbacks from species change would amplify the initial CO 2 stimulation of aboveground net primary productivity ( ANPP ) of tallgrass prairie communities. Communities of perennial forb and C 4 grass species were grown for 5 years along a field CO 2 gradient (250–500 μL L −1 ) in central Texas USA on each of three soil types, including upland and lowland clay soils and a sandy soil. CO 2 enrichment increased community ANPP by 0–117% among years and soils and increased the contribution of the tallgrass species S orghastrum nutans (Indian grass) to community ANPP on each of the three soil types. CO 2 ‐induced changes in ANPP and S orghastrum abundance were linked. The slope of ANPP ‐ CO 2 regressions increased between initial and final years on the two clay soils because of a positive feedback from the increase in S orghastrum fraction. This feedback accounted for 30–60% of the CO 2 ‐mediated increase in ANPP on the upland and lowland clay soils during the final 3 years and 1 year of the experiment, respectively. By contrast, species change had little influence on the ANPP ‐ CO 2 response on the sandy soil, possibly because S orghastrum increased largely at the expense of a functionally similar C 4 grass species. By favoring a mesic C 4 tall grass, CO 2 enrichment approximately doubled the initial enhancement of community ANPP on two clay soils. The CO 2 ‐stimulation of grassland productivity may be significantly underestimated if feedbacks from plant community change are not considered.