Impact intensities of climatic changes on grassland ecosystems in headwater areas

摘要

Rainfall and temperature are the direct driving factors that affect grassland ecosystem evolution. The study constructed the assessment model of the driving factors, temperature and rainfall, that exerted influence on the primary productivities of the grassland ecosystems in headwater areas, and used the model to quantitatively analyze the primary productivity variations of the grassland ecosystems in the headwater areas with the temperature and rainfall from those in the baseline year on the basis of the nearly forty year climatic data collected by the meteorological stations of Qumalai County, Maduo County, Yushu County and Nangqian County. The results show that over the forty-one years between 1962 and 2002, the rainfall among the climate dominated natural factors was the critical factor that caused the primary productivities of the grassland ecosystems to vary in the headwater areas. Moreover, the temperature was the limiting factor of the primary productivities of the grassland ecosystems in the headwater areas, which gently affect the primary productivities of grassland ecosystems in the headwater areas.