针对中困西部干旱区特有的气候-植被特征,利用卫星遥感混合像元分解技术对干旱区植被进行了光合作用植被和非光合作用植被区分和组分解析.尝试通过对干旱覆被植被灌层结构进行解析而解决因植被区系差异和环境背景干扰的问题.并参考国际上遥感—生态模型GLO-PEM和CASA.借助遥感生态反演的物理分析.初步构建起基于遥感与生态过程的干旱区适用的光能利用率模型NPP-PEM.并以中围西部干旱区喀什地区叶尔羌—喀什噶尔河流域山地-绿洲-荒漠生态系统为案例.利用AVHRR/NOAA气象卫星遥感数据和气候资料估算了1992年和1998年中同西部喀什地区叶尔羌-喀什噶尔河流域山地-绿洲-荒漠生态系统1km分辨率年净第一性生产力.并进行了变化探测分析。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.考虑了干旱植被生理特征和灌层结构的光能利用模型.模拟结果较为合理.也为引入其他生态模型应用到干旱区生态系统研究提供了借鉴.从而为干旱区陆地生态系统碳循环研究开辟了途径。
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 (PV), non-photosynthetic vegetation (NPV), bare soil and water are unmixed, using the remote sensing spectral mixture anaysis. We try the method to unmix the canopy funcation sturcture of arid land cover in order to avoid the differentiation of regional vegetation system and the disturbance of environmental background. We developed a modified production efficiency model NPP-PEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. The model referring to the GLO-PEM and CASA model was driven from remotely sensed observations. The model calculates not just the conversion efficiency of absorbed photosysnthetically active radiation but also the carbon fluxes that determine net primary productivity (NPP). We apply and validate the model in Kaxger and Yerkant river basins in arid western China. The NPP of the study area in 1992 and 1998 was estimated based on the NPP-PEM model. The results show that the improved PEM model, considering the photosysnthetical activation of heterogeneous functional vegetation, is in good agreement with field measurements and the existing literature. An accurate agreement (R^2 = 0.85, P 〈 0.001) between estimates and ground-based measurement was obtained.