Change of Vegetation Cover and Its Relationships with Climatic Factors in Large-area Eucalyptus Intro- duced Region of Yunnan

摘要

Taking Lancang County as a study area with a large area of eucalyptus introduction in Yunnan,spatiotemporal change characteristics of vegetation cover,as well as the relationships between Enhanced Vegetation Index( EVI) and climatic factors( temperature and precipitation) were analyzed by using the data of MODIS-EVI from 2005 to 2010. The results indicated that:( 1) The vegetation cover was overall good,and the annual average values of EVI were greater than 0. 395 and showed a slow increasing trend from 2005 to 2010 in study area; the monthly average values of EVI ranged from 0. 296 to 0. 538,and seasonal variability was obvious. Monthly average values of EVI usually fell to the lowest level in February and March,and reached the peak in July and August. From the perspective of space,average EVI over the years significantly varied in different towns of Lancang County. During 2005-2010,in 92. 534% area of total,vegetation coverage change were not obvious; in 7. 25% area of total,vegetation becoming better; only in 0. 02% area of total,vegetation cover were getting worse.( 2) Monthly average values of EVI were significantly correlated with monthly average rainfall in Lancang County. The maxima of monthly average EVI and rainfall appeared in August on summer,while the minima of monthly average EVI and rainfall appeared in February and January on winter respectively.( 3) Monthly average EVI was somewhat relative with monthly average temperature. The maxima of monthly average EVI and temperature appeared in June and August respectively,while the minima appeared in January and February respectively.