Scale-location specific analysis of temporal vegetation coverage in China

Abstract

China has been the study area for this paper. In this paper, we took series of MODIS Enhanced Vegetation Index (EVI) products from 2001 to 2012 to create the temporal vegetation coverage (TVC) as indication factor of vegetation cover. Then we selected a latitudinal transect along the latitude 30°N and used the continuous wavelet variance to test the characteristic scale of vegetation distribution with the wavelet coherency to detect the multi-scale relationship between vegetation cover with the effect factors through the continuous wavelet transform. It was shown that: (1) The study area is divided into multiple nested pattern levels which are larger river effect pattern, physiognomy effect pattern and the macro structure of Chinese Three Gradient Terrains. (2) In the scales of 0–300km, vegetation cover were greatly influenced by factitious factors; In the 300–600km scales, a major scale characteristic, vegetation cover has been influenced by elevation, temperature, land use/cover and factitious factors, and vegetation heterogeneity is greatly strong on this scale; In the scales of 600–1,200km, vegetation cover is intensity influenced by climate factors. (3) Elevation plays an important role to vegetation cover. At low elevation area, vegetation cover increases with elevation growth, while it appears the reverse relation in high elevation area. In the west area, the correlation between vegetation cover and precipitation is negative, while vegetation cover and temperature presents a strong positive correlation. In the whole eastern area, this relationship is not as strong as in western area, and in the mountains or hilly area, temperature and vegetation cover has a positive correlation. (4) Artificial factors show some inhibitory effects of vegetation cover that the vegetation coverage is relatively poor in the area with intensive human activities.