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Increasing CO 2 from subambient to superambient concentrations alters species composition and increases above‐ground biomass in a C 3 /C 4 grassland
Author(s) -
Polley H. Wayne,
Johnson Hyrum B.,
Derner Justin D.
Publication year - 2003
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2003.00897.x
Subject(s) - biomass (ecology) , grassland , forb , ecosystem , nitrogen , grazing , agronomy , zoology , ecology , biology , environmental science , botany , chemistry , organic chemistry
Summary• The glacial‐to‐present increase in atmospheric CO 2 concentration is likely to have stimulated plant production, but experimental tests in natural ecosystems are lacking. • We measured above‐ground biomass production, plant nitrogen (N) accumulation, and species dynamics in a C 3 /C 4 grassland exposed for 4 yr (1997–2000) to a continuous gradient in CO 2 from 200–560 mol mol −1 . • Biomass increased with CO 2 concentration in 1997–99. Biomass increases ranged between 121 and 161 g m −2 per 100 mol mol −1 rise in CO 2 and were similar at subambient and superambient concentrations. Biomass responses to CO 2 were determined by different species or functional groups of species during different years. Increasing CO 2 accelerated a successional shift initiated by release from grazing in which C 3 forbs increased at the expense of a C 4 grass. Effects of CO 2 on tissue N concentration varied among species and functional groups, but CO 2 did not alter total N in above‐ground tissues. • Results imply that rising CO 2 has stimulated plant production and accelerated successional change and that grasslands will remain sensitive to rising CO 2 for several decades.