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温带草原生态系统与大气间的碳交换通量受到降水和土壤水分可利用性的强烈影响,时空变化显著.所以,整合卫星遥感和田间通量观测成为准确刻画中国北方内蒙古温带草原生态系统区域碳循环动态的重要基础.基于涡度相关通量观测系统提供的生态系统与大气间的碳交换通量数据,研究发现:对于内蒙古锡林郭勒温带草原试验站,遥感增强植被指数(EVI)与植被总初级生产力(GPP)的相关关系强于归一化植被指数(NDVI)与GPP的关系.因此,利用基于EVI的植被光合模型(VPM)对该站点的总初级生产力进行了遥感模拟,模型的输入包括增强植被指数,陆地表面水分指数(LSWI),平均空气温度(Ta)和光合有效辐射(PAR).对比2003年5月到2005年9月的涡度相关通量观测数据和模型模拟结果发现:植被光合模型可以准确模拟研究时间段内总初级生产力的季节动态(R2=0.903,N=111,p<0.0001);研究时间段内模拟的总初级生产力为641.5gC·m?2,仅高估了约6%,且植被光合模型模拟效果优于其他生产效率模型(比如:TURC,MODIS-PSN).因此,引进改进的植被指数(比如EVI和LSWI),植被光合模型可以成功模拟温带草原生态系统的总初级生产力,可能成为区域碳通量准确模拟的有效工具.
Therefore, the integration of satellite remote sensing and field flux observation has become an accurate description of the carbon sequestration flux in the temperate grassland ecosystem in northern China. Based on the data of carbon exchange flux between ecosystem and atmosphere provided by the system of eddy covariance related flux observation, the study found that for the temperate grassland experimental station of Xilingol Inner Mongolia, the values of EVI and total primary vegetation (GPP) is higher than that of normalized vegetation index (NDVI) and GPP.Therefore, the total primary productivity of this site was remotely sensed using the EVI-based model of vegetation photosynthesis (VPM), which included Enhanced vegetation index, LSWI, average air temperature (Ta) and photosynthetically active radiation (PAR) .Comparing the data of vorticity correlation flux from May 2003 to September 2005 and the model simulation results, Vegetation photosynthesis models accurately simulate the seasonal dynamics of total primary productivity over the study period (R2 = 0.903, N = 111, p <0.0001); the study period The total primary productivity of the simulation was 641.5gC · m -2, which was only about 6% overestimated, and the simulated photosynthetic model was superior to other production efficiency models (eg TURC, MODIS-PSN). Therefore, the improved vegetation index (Such as EVI and LSWI), vegetation photosynthesis models can successfully simulate the total primary productivity of temperate grassland ecosystems and may be an effective tool for accurate simulation of regional carbon fluxes.