基于过程模型的泰国热带森林碳通量动态模拟解析

Dynamic Analysis of Carbon Flux of Tropical Forest in Thailand Based on Process Model

本研究收集整理泰国SKR站2001-2003年热带季节性常绿林CO2垂直梯度浓度和气温、降水等气象数据集,耦合并改进NCEAS模型,在月尺度上模拟季节气候变率下热带森林碳源-汇的收支过程。结果表明:(1)泰国SKR监测站热带森林表现为较明显的雨热同期现象,雨季(4-10月)降水量占全年的90%以上,温度在4-5月达到峰值。干季与雨季的CO_(2)浓度存在明显的差异,呈现雨季低、干季高;垂直方向上,CO_(2)浓度随高度的增加而降低。(2)降水量影响是SKR监测站热带森林的生产力变化的主要因素,改进后的NCEAS模型能够较准确地模拟月尺度森林的NPP;6-7月是改进后的NCEAS模型模拟热带森林的月NPP的最佳时间尺度。(3)构建的模型具有较高的拟合精度:r=0.69,RMSE=14.93 gC·m^(-2)·月。似然函数值RMSE对活化能Ea及凋落物质量M0不敏感,在参数分布区间内都有低似然值取值;扩散系数k敏感,在参数取值0.4时存在极值,表示k是影响热带森林CO2通量变化的主要影响因子。综上所述,在基于生态系统过程的碳通量模拟研究中,森林内部向大气边界层的CO2扩散过程是森林生态系统碳通量变化的主要影响因子。

CO_(2) vertical gradient concentrations,and meteorological data sets of temperature and precipitation in the tropical seasonal evergreen forest were collected from 2001-2003 at the SKR station in Thailand.and They were compiled,and the NCEAS model was coupled and improved to simulate tropical forest carbon source-sink income and expenditure processes under seasonal climate variability on a monthly scale.The results showed that the tropical forest in SKR monitoring station presented an obvious phenomenon of coincidence of rainfall with high temperature.The precipitation in the rainy season(April to October)accounted for more than 90% of the total annual precipitation,and the temperature came to the peak from April to May.CO_(2) concentration was obviously different in the two seasons,high in the rainy season and low in the dry season,and it decreased with the increase of vertical height.Precipitation was the major factor of tropical forest NPP in the SKR monitoring station.The improved NCEAS model can simulate the monthly NPP of the tropical forest more accurately.June−July was the best temporal scale for the improved NCEAS model to simulate the monthly NPP of tropical forests.The constructed model has a high fitting accuracy:r=0.69,RMSE=14.93 gC·m^(−2)·month.The likelihood function value RMSE is not sensitive to activation energy Ea and litter mass M0,and has low likelihood values in the parameter distribution interval.The diffusion coefficient k is sensitive,and there is an extreme value when the parameter is 0.4,indicating that k is the main influencing factor that affects the change in the CO_(2) flux of the tropical forest.It is concluded that in the simulation of carbon flux based on ecosystem process the diffusion process of CO_(2) from the interior forest to the atmospheric boundary layer is the main influencing factor of carbon flux change of forest ecosystem.