新疆20年生态系统净初级生产力研究

Research on NPP Changes of the Land Ecosystem in Xinjiang during 1981-2000

针对中国西部新疆干旱区特有的气候—植被特征,利用卫星遥感技术对干旱区进行光合作用植被和非光合作用植被区分和解析,通过对干旱覆被植被灌层结构解析,解决植被区系差异和环境背景干扰问题,并参考国际上GLO-PEM、CEVSA和CASA遥感——生态模型,借助生态遥感反演的物理分析,初步构建基于遥感与生态过程的适用于干旱区的光能利用率模型NPP-GPEM,并以新疆陆地生态系统为例,利用AVHRR/NOAA气象卫星遥感数据和气候资料估算了1981到2000年新疆陆地生态系统1km分辨率的年净第一性生产力,同时对之进行了时空变化探测分析.模拟检验结果精度较好,生态系统碳吸收的空间异质性特征明显.结果表明,利用干旱区植被生理特征的光能利用模型,模拟结果较为合理,为将NPP-GPEM模型应用到干旱区生态系统研究做了一定的探索,也试图为干旱区陆地生态系统碳循环研究提供新的思路.

Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation, non- photosynthetic vegetation, bare soil and water are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy function structure of arid land cover in order to avoid the disturbance of the differentiation of regional vegetation system and the environmental background. We developed a modified production efficiency model NPP-GPEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. The model referring to the GLO-PEM, CEVAS and CASA model was driven from remotely sensed observations. The model calculates not only the conversion efficiency of absorbed photosynthetically active radiation but also the carbon fluxes that determine net primary productivity （NPP）. We apply and validate the model in the land ecosystem in XinJiang in arid NPP-GPEM model. The results show that the improved NPP-GPEM model, considering the edu. cnphotosynthetical activation of heterogeneous functional vegetation, is in good agreement withfield measurements and the existing literature. An accurate agreement （R^2= 0.86, P〈0. 001） between estimates and ground-based measurement was obtained.