Modeling gross primary production and ecosystem respiration in a semiarid grassland of Mongolia
Modeling gross primary production and ecosystem respiration in a semiarid grassland of Mongolia
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DOI：
10.1080/00380768.2014.966043
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发表时间：
2015-01
影响因子：
2
通讯作者：
T. Nakano;M. Shinoda
中科院分区：
文献类型：
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作者：
T. Nakano;M. Shinoda
摘要我们构建了一个经验模型，在该模型中，总初级生产力（GPP）和生态系统呼吸（Reco）的速度计算使用气象，土壤和植物变量，根据我们以前的测量二氧化碳（CO2）通量在蒙古草原使用封闭室技术。在以前的研究中，我们使用透明和不透明的腔室测定GPP和Reco，并同时测量腔室内部和旁边的环境变量。这些测量使我们能够量化GPP和Reco率及其控制因素之间的直接和准确的关系。在2010年和2011年的生长季节，利用光合有效辐射，空气和土壤温度，蒸汽压赤字，土壤含水量的观测值和估计值的地上生物量从遥感植被指数计算的GPP，Reco和他们的差异净生态系统CO2交换（NEE）。模型性能进行了验证，通过比较模拟和观察到的NEE值使用涡度协方差技术。结果表明，该模式成功地再现了观测到的NEE的震级和季节变化，回归分析表明，在这两年的合理协议。在植物生长季节（5月至9月），GPP和Reco的累积速率在干旱年份（2010年）分别为200.3和210.5 g C m−2，在湿润年份（2011年）分别为342.3和300.1 g C m−2。这一结果表明，干旱是更有效地减少CO2吸收的植物比减少生态系统呼吸。因此，草地生态系统在2010年生长季是净碳源，2011年是净碳汇。
Abstract We constructed an empirical model in which the rates of gross primary production (GPP) and ecosystem respiration (Reco) were calculated using meteorological, soil and plant variables, based on our previous measurements of carbon dioxide (CO2) fluxes using a closed-chamber technique in Mongolian grasslands. In the previous studies, we determined GPP and Reco using transparent and opaque chambers and simultaneously measured the environmental variables inside and beside the chambers. These measurements allowed us to quantify direct and accurate relationships between the rates of GPP and Reco and their controlling factors. The GPP, Reco and their difference net ecosystem CO2 exchange (NEE) were computed in a semiarid grassland site of Mongolia for the growing seasons of 2010 and 2011 using observed values of photosynthetically active radiation, air and soil temperatures, vapor pressure deficit, soil water content and estimated values of aboveground biomass from a remotely sensed vegetation index. Model performance was validated by comparing the modeled and observed NEE values using an eddy covariance technique. Results showed that the model successfully reproduced the magnitude and seasonal variations of the observed NEE, and regression analysis showed reasonable agreement in both years. Cumulative rates of GPP and Reco during the plant-growing season (May − September) were 200.3 and 210.5 g carbon (C) m−2 in the dry year (2010) and 342.3 and 300.1 g C m−2 in the wet year (2011), respectively. This result indicates that drought was more effective in reducing CO2 uptake by the plant than in reducing ecosystem respiration. Consequently, the grassland ecosystem was a net carbon source during the growing season in 2010 and a net carbon sink in 2011.