关键词: 气温；降水；物候；NPP；物种多样性；植被覆盖度；土壤

Abstract:

This paper analyzed the characteristics of climate changes in major grassland areas of China during recent 50 years. It also elaborated the research findings about the effect of temperature and precipitation changes on main grassland ecological system in China. The paper summarized the effect of climate changes on the vegetation spatial and temporal pattern of major grassland areas in china. In the past 50 years, the temperature of grassland areas in China was generally rising, while the changes of precipitation had larger time and space differences. The majority research results indicated that the effect of temperature rise on plant phenology had a great uncertainty, and its effect on the net primary productivity (NPP) of grassland vegetation had regional differences. Temperature rise would accelerate the decomposition of carbon in soil, and reduce the plant species diversity. Meanwhile, precipitation increase would make the plant phenology period in advance, prolong its growing season, raise grassland NPP, and improve species richness. But the vegetation growth had a certain hysteresis to the variation of precipitation. Different combination of temperature and precipitation had different influences on the vegetation growth. Temperature rise and precipitation increase could increase grassland vegetation coverage. Generally speaking, climate change could promote the growth of vegetation in glassland areas in China. But in certain region, it might suppress vegetation growth. The paper suggested under future climate change condition to combine the macro and micro aspects, to systematically analyze the sensitivity and vulnerability of grassland ecosystem in China, and to strengthen the comprehensive study on grassland ecosystem, so as to reduce the uncertainty of research results.

Key words: temperature, precipitation, phenology, NPP, species diversity, vegetation coverage, soil