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Carbon accumulation, distribution and water use of Danthonia richardsonii swards in response to CO 2 and nitrogen supply over four years of growth
Author(s) -
LUTZE JASON L.,
GIFFORD ROGER M.
Publication year - 1998
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 - 10.1046/j.1365-2486.1998.00200.x
Subject(s) - microcosm , nitrogen , carbon fibers , agronomy , chemistry , soil water , zoology , botany , horticulture , environmental chemistry , biology , ecology , materials science , organic chemistry , composite number , composite material
Microcosms of Danthonia richardsonii (Cashmore) accumulated more carbon when grown under CO 2 enrichment (719 μL L –1 cf. 359 μL L –1 ) over a four‐year period, even when nitrogen availability severely restricted productivity (enhancement ratios for total microcosm C accumulation of 1.21, 1.14 and 1.29 for mineral N supplies of 2.2, 6.7 and 19.8 g N m –2 y –1 , respectively). The effect of CO 2 enrichment on total system carbon content did not diminish with time. Increased carbon accumulation occurred despite the development over time of a lower leaf area index and less carbon in the green leaf fraction at high CO 2 . The extra carbon accumulated at high CO 2 in the soil, senesced leaf and leaf litter fractions at all N levels, and in root at high‐N, while at low‐and mid‐N less carbon accumulated in the root fraction at high CO 2 . The rate of leaf turnover was increased under CO 2 enrichment, as indicated by increases in the carbon mass ratio of senesced to green leaf lamina. Microcosm evapotranspiration rates were lower at high CO 2 when water was in abundant supply, resulting in higher average soil water contents. The higher soil water contents at high CO 2 have important implications for microcosm function, and may have contributed significantly to the increased carbon accumulation at high CO 2 . These results indicate that CO 2 enrichment can increase carbon accumulation by a simple soil–plant system, and that any increase in whole system carbon accumulation may not be evident from snapshot measurements of live plant carbon.