Pulse-labeling studies of carbon cycling in arctic tundra ecosystems: Contribution of photosynthates to soil organic matter

被引:19
作者
Loya, WM [1 ]
Johnson, LC
Kling, GW
King, JY
Reeburgh, WS
Nadelhoffer, KJ
机构
[1] Kansas State Univ, Div Biol, Manhattan, KS 66506 USA
[2] Univ Michigan, Dept Biol, Ann Arbor, MI 48109 USA
[3] Univ Calif Irvine, Dept Earth Syst Sci, Irvine, CA 92697 USA
[4] Marine Biol Lab, Ctr Ecosyst, Woods Hole, MA 02543 USA
[5] Michigan Technol Univ, Sch Forestry & Wood Prod, Houghton, MI USA
关键词
soil organic matter; microbial biomass; roots; photosynthates; Arctic tundra; C-14-labeling;
D O I
10.1029/2001GB001464
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
[1] To increase our understanding of carbon (C) cycling and storage in soils, we used C-14 to trace C from roots into four soil organic matter (SOM) fractions and the movement of soil microbes in arctic wet sedge and tussock tundra. For both tundra types, the proportion of C-14 activity in the soil was 6% of the total C-14-CO2 taken up by plants at each of the four harvests conducted 1, 7, 21, and 68 days after labeling. In tussock tundra, we observed rapid microbial transformation of labile C from root exudates into more stable SOM. In wet sedge tundra, there appears to be delayed or indirect microbial use of root exudates. The net amount of C-14 label transferred to SOM by the end of the season in both tundra types was approximately equal to the amount transferred to soils 1 day after labeling, suggesting that transfer of C-14 tracer from roots to soils continued through the growing season. Overall, C inputs from living roots contributes 24 g C m(-2) yr(-1) in tussock tundra and 8.8 g C m(-2) yr(-1) in wet sedge tundra. These results suggest rapid belowground allocation of C by plants and subsequent incorporation of much of this C into storage in the SOM.
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页数:8
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