基于遥感-生态过程的绿洲-荒漠生态系统净初级生产力估算

Estimation of net primary productivity of the oasis-desert ecosystems in arid west China based on RS-based ecological process

针对干旱区特有的气候-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光能吸收的估算问题,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ERDAS IMAGINE为平台,实现了模型可视化模型界面,可用于中国西部干旱区山地-绿洲-荒漠生态系统年净第一性生产力的估算。由于考虑了干旱植被生理特征和灌层结构的光能利用模型,模拟结构与原理更加合理完善,为引入其他生态模型应用或移植到干旱区提供借鉴,从而为中国干旱区陆地生态系统碳循环研究开辟了途径。

Arid and semiarid ecosystems show a spatially complex bio - geophysical structure. Based on the especial climate - vegetation characters in arid areas in northwest China, the fractional covers of photosynthetic vegetation （PV）, non - photosynthetic vegetation （NPV） and bare soil are analyzed by using the remote sensing spectral mixture analysis. The canopy function structure of arid land cover is analyzed so as to avoid the differentiation of regional vegetation systems and the disturbance of environmental background. A modified model, NPP - PEM, is developed based on the concept of radiation utilization efficiency of vegetation and referred the GLO - PEM and CASA models, and it is appropriate to estimate the net primary productivity of the oasis - desert ecosystems in arid areas at regional scale. Based on the physically analyzed results with RS - ecological conversion, the model is used to calculate the conversion efficiencies of absorbed photosynthetic active radiation and the carbon fluxes affecting the net primary productivity （NPP）. An interactive interface of NPP- PEM model is developed based on the ERDAS IMAGINE suite. The PEM module for ERDAS is suitable for application and validation in oasis - desert ecosystems in arid northwest China. Based on ecosystem process with remote sensing means, the modified PEM model is applicable to study the ecosystems in arid areas from the aspects of characterizing the carbon cycle and carbon flux over arid areas and monitoring the change of productivity of the mountain - oasis - desert systems.