Short‐term variation of CO2 flux in relation to environmental controls in an alpine meadow on the Qinghai‐Tibetan Plateau
Short‐term variation of CO2 flux in relation to environmental controls in an alpine meadow on the Qinghai‐Tibetan Plateau
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DOI：
10.1029/2003jd003584
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发表时间：
2003-11
影响因子：
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通讯作者：
Song Gu;Yanhong Tang;Mingyuan Du;Tomomichi Kato;Ying-nian Li;X. Cui;Xingquan Zhao
中科院分区：
文献类型：
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作者：
Song Gu;Yanhong Tang;Mingyuan Du;Tomomichi Kato;Ying-nian Li;X. Cui;Xingquan Zhao
[1]青藏高原高寒草甸生态系统可能在区域碳循环中发挥重要作用。为探讨生态系统中CO2通量及其与环境控制的关系，在海拔3，250 m的高寒草甸上，利用开放路径系统测量了CO2、H2O和能量通量的涡动相关。2001年8月9日至31日期间，生态系统CO2净流入量（Fc）平均为8.8 g m（-2）d（-1），最大值为15.9 g m（-2）d（-1），最小值为2.3 g m（-2）d（-1）。在研究期间，白天Fc平均为16.7 g m（-2）day（-1），范围为10.4 g m（-2）day（-1）至21.7 g m（-2）day（-1）。对于相同的光合光子通量密度（PPFD），总CO2吸收（Gc）显着高于阴天比晴天。然而，平均每日Gc是晴天高于阴天。在高PPFD条件下，随着气温从10 ℃升高到23 ℃，Fc降低。昼夜温差越大，汇越强。生态系统白天平均水分利用效率（WUEe）为8.7 mg（CO2）（g H2O）（-1）; WUEe值范围为5.8 - 15.3 mg（CO2）（g H2O）（-1）。WUEe随水汽压亏缺的减小而增大。在研究期间，每日平均体重为0.20，范围为0.19至0.22，与每日Fc呈负相关。我们的测量结果提供了一些关于青藏高原温带高寒草甸生态系统CO2交换的第一个证据，这对于评估温带草原生态系统的碳收支和碳循环过程是必要的。
[1] The alpine meadow ecosystem on the Qinghai-Tibetan Plateau may play a significant role in the regional carbon cycle. To assess the CO2 flux and its relationship to environmental controls in the ecosystem, eddy covariance of CO2, H2O, and energy fluxes was measured with an open-path system in an alpine meadow on the plateau at an elevation of 3,250 m. Net ecosystem CO2 influx (Fc) averaged 8.8 g m(-2) day(-1) during the period from August 9 to 31, 2001, with a maximum of 15.9 g m(-2) day(-1) and a minimum of 2.3 g m(-2) day(-1). Daytime Fc averaged 16.7 g m(-2) day(-1) and ranged from 10.4 g m(-2) day(-1) to 21.7 g m(-2) day(-1) during the study period. For the same photosynthetic photon flux density (PPFD), gross CO2 uptake (Gc) was significantly higher on cloudy days than on clear days. However, mean daily Gc was higher on clear days than on cloudy days. With high PPFD, Fc decreased as air temperature increased from 10degreesC to 23degreesC. The greater the difference between daytime and nighttime air temperatures, the more the sink was strengthened. Daytime average water use efficiency of the ecosystem (WUEe) was 8.7 mg (CO2)(g H2O)(-1); WUEe values ranged from 5.8 to 15.3 mg (CO2)(g H2O)(-1). WUEe increased with the decrease in vapor pressure deficit. Daily albedo averaged 0.20, ranging from 0.19 to 0.22 during the study period, and was negatively correlated with daily Fc. Our measurements provided some of the first evidence on CO2 exchange for a temperate alpine meadow ecosystem on the Qinghai-Tibetan Plateau, which is necessary for assessing the carbon budget and carbon cycle processes for temperate grassland ecosystems.