民勤绿洲-荒漠过渡带梭梭人工林净碳交换及其影响因子

基于涡动相关系统观测的民勤绿洲荒漠过渡带梭梭人工林生态系统通量资料,定量分析了2018年生长季(5—10月)碳通量变化特征及其影响因子,为民勤梭梭人工林生态系统碳源/汇的评估提供基础数据.结果表明: 生长季净碳交换量在日尺度上呈对称的“U”型曲线变化;在季节尺度上,呈双峰曲线变化规律,各月均为碳汇,总固碳量为34.38 g C·m^-2,且9月固碳量较高,为12.31 g C·m^-2,7月最低,为0.89 g C·m^-2.白天生态系统净碳交换随光合有效辐射的增加而增加,符合直角双曲线关系,但当饱和水汽压差大于2.5 kPa时,增加程度减弱.生态系统呼吸与气温呈较好的指数关系,其温度敏感性系数为1.7.整个生长季期间,白天和夜间的净碳交换量均与土壤温度呈显著相关

Net carbon exchange and its driving factors of Haloxylon ammodendron plantation in the oasis-desert ecotone of Minqin,China

Carbon fluxes in a Haloxylon ammodendron plantation in the oasis-desert ecotone of Minqin was measured using an eddy covariance system. To provide scientific data for carbon source/sink assessment, we quantitatively analyzed the characteristics of CO₂ flux and its driving factors in the growing season from May to October, 2018. The results showed that the trend of daily net carbon exchange in the growing season followed a symmetrical “U” shape curve. As to seasonality, bimodal curve was obvious. The plantation ecosystem was a carbon sink every month. The total carbon sequestrated was 34.38 g C·m^-2, with the peak of 12.31 g C·m^-2 in September and the lowest value of 0.89 g C·m^-2 in July. The net carbon exchange in this ecosystem increased during the daytime with the increasing photosynthetically active radiation, consistent with the Michaelis-Menten rectangular hyperbola change. When the vapor pressure deficit was greater than 2.5 kPa, the increasing trend tended to flat. Ecosystem respiration increased exponentially with temperature, with temperature sensitivity being 1.7. Net carbon exchange in either day or night was significantly correlated with soil temperature through the whole growing season.