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Rhizodeposition stimulated by elevated CO 2 in a semiarid grassland
Author(s) -
Pendall Elise,
Mosier Arvin R.,
Morgan Jack A.
Publication year - 2004
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 - 10.1111/j.1469-8137.2004.01054.x
Subject(s) - grassland , biomass (ecology) , growing season , agronomy , ecosystem , primary production , environmental science , chemistry , zoology , biology , ecology
Summary• Rhizodeposition, or the addition of C from roots to soil C pools, is expected to increase if net primary production is stimulated and some excess C is allocated below‐ground. We investigated the effects of 5 yrs of elevated CO 2 on below‐ground C dynamics in a native, C 3 –C 4 grassland ecosystem in Colorado, USA. • Cylinder harvests following each growing season and monolith excavation at the end of the experiment provided data on root biomass, root C : N ratios, and root and soil δ 13 C values. We applied an isotopic mixing model to quantify new soil C inputs on elevated and ambient CO 2 treatments. • Root biomass increased by 23% and root C : N ratios increased by 26% after 5 yrs of elevated CO 2 . Species‐specific differences were found in root residence times, which ranged from 6 to 8 yrs. • Rhizodeposition was roughly doubled in elevated compared with ambient CO 2 chambers, at 83 ± 16 versus 35 ± 9 g C m −2 yr −1 over the last 4 yrs of the experiment ( t ‐test, P = 0.006). Net C sequestration will depend on how decomposition rates are altered by elevated CO 2 .