Changes of Grassland Vegetation Growth in Xilin Gol League over 10 Years and Analysis on the Influence Factors

Monitoring of grassland vegetation growth is an important part in grassland studies.It is helpful to acquire the grassland situation and has significance to environmental management and protection through analysis on the relationship between vegetation growth and meteorological factors.In this research,we obtained the spatial distribution of temperature and precipitation by using the ANUSPLIN spatial interpolation method and uses 16days,250m MODIS-NDVI data to build grassland vegetation growth index MGI(modified growth index),get the changes of Xilin Gol League grassland vegetation growth from 2001 to 2010,analyze the relationships between vegetation growth and temperature/precipitation,and reveal the hysteresis effect of precipitation.The results of this research showed:(1) spatially,the vegetation growth in east part is better than in central part and west part,in north part is better than in south part.Growth in 2003 is better than the other years,and 2001 is the worst year.(2) The correlation between MGI and precipitation of the three grasslands in Xilin Gol is significant,but the relation between MGI and temperature is week.Precipitation can explain 57.5% of desert grassland grow,75.2% of typical steppe grow and 63.7% of meadow prairie grow.So,we can say that vegetation growth performs better with the increase of precipitation.(3) Impact factor is different to grassland vegetation growth in different phrases,temperature limits the growth during early and late stage,precipitation is the main impact factor to growth during middle stage.Grassland vegetation grow has an obvious lag response,about 32-48 days.And we pointed out that lag response time is different in different grow stage,during early stage is 32days,during middle stage is 48days,and during late stage is 32days.