Detecting latitudinal variations in phenology over the northeast asia based on remote sensing vegetation index

Abstract

We aim to detect responses of carbon sinking of plants to temperature and precipitation gradient across mid-latitudes of northeast Asia. MODIS Leaf Area Index (LAI) data were used to detect patterns and variations in annual integrated vegetation index (S.integral) for nine land cover types during 2001-2011. A smoothing algorithm using asymmetric Gaussian model was applied to smooth LAI time-series and estimate the values of S.integral. The result shows that the S.integral of forests was larger than that of other types during last ten years. However, the latitudinal variation in S.integral of forests was less pronounced. For grasslands and savannas, the S.integral was more significantly influenced by precipitation rather than temperature. In general, the S.integral of all types showed a decline trend in the southernmost of the study area. Then it presented an increasing trend from 35°N to 41°N. Between 43°N and 61°N, the S.integral kept decreasing again except around 52°N.