Abstract: Wavelet transform demonstrates that abiotic factors’ impact change with spatial scale, confirming a scale-dependent relationship between NDVI and factors that influence it. To elaborate these scale effects, NDVI transect data and abiotic variables—climatic and topographic—at the 32.5 degree north latitude on the Qinghai-Tibet Plateau in China, were analyzed at different spatial scales by using wavelet transform. The results show that climatic variables such as precipitation and temperature are not dominant factors of NDVI patterns at the less than 80 km scale, while significant wavelet coherency is observed at the more than 80 km scale in some ecoregions. As a differentiating factor, elevation affects NDVI patterns only at the local level in longitudinal range-gorge region at certain specific scales. Wavelet transform is an alternative approach to examining multiscale relationships between NDVI and abiotic factors.

Key words: NDVI, abiotic factors, scale-dependence, wavelet transform, Qinghai-Tibet Plateau