Abstract: It was important for understanding the reason of pasture degradation and recovering the grasslands ecological environments to analyze the impact of climate change on dry and wet conditions in typical grassland areas.The new factors,including potential evaporation amount,aridity index of ground surface and water budget,were calculated by using the Penman-Monteith equation,based on meteorological data from 25 stations during 1961 to 2008 in typical grassland areas.The temporal and spatial variation of dry and wet conditions of ground surface in typical grassland areas was analyzed,the relationship between meteorological factors and dry and wet conditions was discussed.The result showed that all the aridity indexes were above 2 during grass growing season in typical grassland areas,the water budget was more than 400mm.Dry and wet condition change temporal in typical grassland areas obviously,the severe water budget and high aridity index occurred during 1960s-1970s and 2001-2008,but not occurred during 1980s and 1990s.Precipitation and relative humidity were key factors to wet and dry conditions of ground surface in typical grassland areas(r>0.8),followed by sunshine duration(r>0.6),average temperature and average velocity.

Key words: Typical grassland, Typical grassland, Climate change, Dry and wet condition, Influence factors