Effects of increased atmospheric CO2, temperature, and soil N availability on root exudation of dissolved organic carbon by a N-fixing tree (Robinia pseudoacacia L.)

被引:122
作者
Uselman, SM [1 ]
Qualls, RG
Thomas, RB
机构
[1] Univ Nevada, Dept Environm & Resource Sci, Reno, NV 89557 USA
[2] W Virginia Univ, Dept Biol, Morgantown, WV 26506 USA
关键词
CO2; enrichment; carbon storage; climate change; dissolved organic carbon; nitrogen fixation; root exudate;
D O I
10.1023/A:1004705416108
中图分类号
S3 [农学(农艺学)];
学科分类号
0901 ;
摘要
Root exudation has been hypothesized as one possible mechanism that may lead to increased inputs of organic C into the soil under elevated atmospheric CO2, which could lead to greater long-term soil C storage. In this study, we analyzed exudation of dissolved organic C from the roots of seedlings of the N-fixing tree Robinia pseudoacacia L. in a full factorial design with 2 CO2 (35.0 and 70.0 Pa) x 2 temperature (26 degrees and 30 degrees C during the day) x 2 N fertilizer (0 and 10.0 mM N concentration) levels. We also analyzed the decomposition rates of root exudate to estimate gross rates of exudation. Elevated CO2 did not affect root exudation of organic C. A 4 degrees C increase in temperature and N fertilization did, however, significantly increase organic C exudation rates. Approximately 60% of the exudate decomposed relatively rapidly, with a turnover rate of less than one day, while the remaining 40% decomposed more slowly. These results suggest that warmer climates, as predicted for the next century, may accelerate root exudation of organic C, which will probably stimulate rapid C cycling and may make a minor contribution to intermediate to more long-term soil C storage. However, as these losses to root exudation did not exceed 1.2% of the net C fixed by Robinia pseudoacacia, root exudation of organic C appears to have little potential to contribute to long-term soil C sequestration.
引用
收藏
页码:191 / 202
页数:12
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