Dynamics of regional vegetation changes under the disturbance of human activities: A case study of Xishuangbanna

Xishuangbanna in Yunnan province is a typical tropical rainforest area in China. With the socio-economic development, human activities have exerted strong impacts on pattern and dynamics of regional vegetation. By analyzing the trend of NDVI, the transfer matrix of land use and disturbance index(MGDI) based on MODIS data, we examined the dynamics of regional vegetation under human disturbance from 2000 to 2010 in this paper. We developed the disturbance index of human activities and found its correlations with vegetation characteristics via the Redundancy analysis. The results showed that the coverage of vegetation in the study area was generally high, and the SLOPE values of the trend of vegetation change were all greater than 0, and the vegetation tended to improve in general during period of 2000-2010. The transfer matrix of land use indicated that the main vegetation dynamics were the changes of evergreen broad-leaved forest and evergreen coniferous forest into plantation shrub, artificial garden or residential land. Based on the MODIS images, it can be seen that the MGDI distribution in Xishuangbanna was very uneven, and the MGDI of different land covers from 2000 to 2010 showed little difference. From the disturbance index of human activity, it can been seen that the disturbance intensity of human activity is higher at the edge than in the center, and the overall distribution was decentralized. The dynamics were related to the distribution scale and intensity of human activities. According to redundancy analysis, NDVI was highly correlated with human activities, while MGDI was not. In general, the long-term vegetation change under human disturbances could be reflected by using three methods used in this study. Through the construction of disturbance index of human activity, we can identify the spatial distribution of disturbance. Human activities especially tourism, infrastructure construction, agricultural activities and other disturbances cannot be ignored for the natural ecosystem of tropical rainforest in Xishuangbanna region.