摘要
Although soil respiration is the largest contributor to C flux from terrestrial ecosystems to the atmosphere, our understanding of its characteristics and carbon budget in alpine meadow is rather limited because of extremely geographic situation. This study was designed to examine soil CO<sub>2</sub> efflux characteristics of diurnal and seasonal variation, thus obtaining estimates of carbon balance of <em>Kobresia pygmaea</em> meadow in Qinghai-Tibet plateau. The results showed that the soil respiration of diurnal and seasonal rate changed little in growing season and was mainly affected by temperature, and single peak curve that showed afternoon appeared. Composite model which was set by soil respiration rate, soil moisture content and temperature (atmospheric temperature and soil temperature) could explain better the variations of soil respiration rate. The variation range of <em>Q</em><sub>10</sub> ranged from 1.28 to 2.34, which was sensitive to temperature in green-up period and late growth stage, and decreased in growth peak period. Meanwhile, during the growing seasons the observed amount of annual carbon fixation via primary production for <em>Kobresia pygmaea</em> meadow ecosystem was about 120.21 g C<span style="white-space:nowrap;">·</span>m<sup>-2</sup><span style="white-space:nowrap;">·</span>a<sup>-1</sup>. The carbon dioxide output via soil heterotrophic respiration was about 37.54 g C<span style="white-space:nowrap;">·</span>m<sup>-2</sup><span style="white-space:nowrap;">·</span>a<sup>-1</sup>. So carbon budget had more input than output. The <em>Kobresia pygmaea</em> meadow ecosystem has stronger potential to absorb carbon dioxide, it was a sink of atmospheric CO<sub>2</sub>, and the plant community had a net carbon gain of 82.67 g C<span style="white-space:nowrap;">·</span>m<sup>-2</sup><span style="white-space:nowrap;">·</span>a<sup>-1</sup>.
Although soil respiration is the largest contributor to C flux from terrestrial ecosystems to the atmosphere, our understanding of its characteristics and carbon budget in alpine meadow is rather limited because of extremely geographic situation. This study was designed to examine soil CO<sub>2</sub> efflux characteristics of diurnal and seasonal variation, thus obtaining estimates of carbon balance of <em>Kobresia pygmaea</em> meadow in Qinghai-Tibet plateau. The results showed that the soil respiration of diurnal and seasonal rate changed little in growing season and was mainly affected by temperature, and single peak curve that showed afternoon appeared. Composite model which was set by soil respiration rate, soil moisture content and temperature (atmospheric temperature and soil temperature) could explain better the variations of soil respiration rate. The variation range of <em>Q</em><sub>10</sub> ranged from 1.28 to 2.34, which was sensitive to temperature in green-up period and late growth stage, and decreased in growth peak period. Meanwhile, during the growing seasons the observed amount of annual carbon fixation via primary production for <em>Kobresia pygmaea</em> meadow ecosystem was about 120.21 g C<span style="white-space:nowrap;">·</span>m<sup>-2</sup><span style="white-space:nowrap;">·</span>a<sup>-1</sup>. The carbon dioxide output via soil heterotrophic respiration was about 37.54 g C<span style="white-space:nowrap;">·</span>m<sup>-2</sup><span style="white-space:nowrap;">·</span>a<sup>-1</sup>. So carbon budget had more input than output. The <em>Kobresia pygmaea</em> meadow ecosystem has stronger potential to absorb carbon dioxide, it was a sink of atmospheric CO<sub>2</sub>, and the plant community had a net carbon gain of 82.67 g C<span style="white-space:nowrap;">·</span>m<sup>-2</sup><span style="white-space:nowrap;">·</span>a<sup>-1</sup>.
作者
Yuejun Fan
Xiyun Chang
Deping Zhao
Xiangyang Hou
Xin Li
Yuejun Fan;Xiyun Chang;Deping Zhao;Xiangyang Hou;Xin Li(Grassland Research Institute of Chinese Academy of Agriculture Science, Hohhot, China;Qinghai Vocational and Technical College of Animal Husbandry and Veterinary Science, Xining, China;Northwest Institute of Plateau, Chinese Academy of Science, Key Laboratory of Restoration Ecology of Cold Area in Qinghai Province, Xining, China;Qinghai University, Xining, China)
