Change Of Fractional Vegetation Cover In Northeast Asia From2000to2011

Fractional Vegetation Cover (FVC) is a underlying data for describing ecosystemand an important parameter for researches on the global change detection, hydrology,soil erosion etc. The Northeast Asia, as a critical ecological shelter of China and thesensitive area of global change, analyzing its change characteristics of fractionalvegetation cover has great significance. Combined with field observation data,Landsat TM/ETM+data and MODIS-NDVI data, technology of Remote Sensing,GIS spatial analysis and statistical analysis method, this paper discussed the algorithmseletion of fractional vegetation cover extraction at different scales, estimatedfractional vegetation cover from2000to2011in the Northeast Asia, and analyzed itsspatial-temporal variations characteristics. Based on these researches, some basicconclusions are drawn as follows.(1) The Spectral Mixture Analysis (SMA) model and the NDVI-based SMAmodel were compared based on Landsat-TM/ETM+data. The SMA model performedbetter for estimating fractional vegetation cover, especially in high NDVI valueregions. The influence of supersaturated NDVI value on FVC estimation based onMODIS-NDVI data also can be seen. The NDVI-based SMA, taking accumulatedfrequency of NDVI corresponding to5%and95%as parameters, performed well forestimating FVC in the entire Northeast Asia.(2) In the Northeast Asia, the FVC is higher in mountain regions while lower inplain totally, which decreases from south to north and from east to west. In the past12years, the FVC in the most areas was basically steady. The regions where FVCdeclined were mainly located in the Central Siberian Plateau, Yablonovyy khrebet inthe eastern of the Lake Baikal, and mid-eastern of the Inner Mongolia. The regionswhere FVC increased were mainly located in the Northeast Plain of China, the easternpart of the Mongolia Plateau and the eastern side of Altai Mountains.(3) The highest average annual maximum FVC was located in Japan, NorthKorea and South Korea, followed by Russia and China, the lowest is in Mongolia. In the past12years, the average annual maximum FVC increased slowly in China andMongoliawhile decreased in Russia, Japan and North Korea, and that was basicallysteady in South Korea. Totally, the change of FVC in all countries was not significant.(4) The annual maximum FVC of forest is the highest in the study area, and thatof tundra and grassland is the lowest. The annual maximum FVC of grasslandfluctuates most severely, followed by arable land. In the past12years, the FVC offorest vegetation declined significantly, while that of arable land which was mainlylocated in the Northeast Plain of China increased fastest. The vegetation activity forall cover types intensed significantly from April in the Northeast Asia, the growth rateof FVC for all vegetation types reached the fastest in May except arable land whichreached the fastest in June. The time of maximum annual FVC for arable land andgrassland lagged one month than other vegetations. All vegetation types withered inOctober, which indicates that growing season ends.(5) The FVC in the North-South Transact of the Northeast Asia changesobviously along the latitude. Except for arable land, the FVC of all vegetation typesincreases rapidly first, then decreases slowly from south to north. The occurance ofthe fastest growth rate of FVC in the mid-high latitude region is one month beforethan that in the low and high latitude regions.