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标题：Increased Turnover but Little Change in the Carbon Balance of High-Arctic Tundra Exposed to Whole Growing Season Warming
其他标题：Increased Turnover but Little Change in the Carbon Balance of High-Arctic Tundra Exposed to Whole Growing Season Warming
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作者：Fleur L. Marchand ; Ivan Nijs ; Hans J. de Boeck 等
期刊名称：Arctic, Antarctic, and Alpine Research
印刷版ISSN：1523-0430
电子版ISSN：1938-4246
出版年度：2004
卷号：36
期号：3
页码：298-307
DOI：10.1657/1523-0430(2004)036[0298:ITBLCI]2.0.CO%3B2
摘要：Tundra ecosystems constitute large stocks of carbon and might therefore, if climate warming releases CO 2 , induce positive feedback and amplify temperature increase. We studied the effect of a 2.5°C temperature increment, induced by controlled infrared irradiation, on various components of the carbon balance of a High Arctic tundra ecosystem at Zackenberg in Northeast Greenland (74°N, 21°W) over the 1999 growing season. Gross photosynthesis ( P gross ), belowground respiration ( R soil ), and canopy respiration ( R canopy ) were regularly determined with closed dynamic CO 2 exchange systems, and the whole-growing season C-balance was reconstructed by relating these components to potentially controlling factors (green cover, soil moisture, radiation, soil and canopy temperature, and thawing depth). Thawing depth and green cover increased in heated plots, while soil moisture was not significantly affected. P gross increased 24.2%, owing to both a green cover and a physiological influence of warming. Belowground respiration was enhanced 33.3%, mainly through direct warming impact and in spite of lower Q 10 in the heated plots; the factors controlling R soil were day of the year and soil moisture. R canopy did not differ significantly between treatments, although green cover was higher in the heated plots. This tundra ecosystem acted as a relatively small net sink both under current (0.86 mol CO 2 m −2 ) and heated (1.24 mol CO 2 m −2 ) conditions. Nevertheless, turnover increased, which was best explained by a combination of direct and indirect temperature effects, and delayed senescence.