Spatial and Temporal Fractional Vegetation Coverage Variations in Chongqing Based on MODIS Data

Vegetation,as one of the most important part of terrestrial ecosystems,has a great impact on the global climate change and hydrological cycles. A useful indicator to evaluate the vegetation condition in land surface is the fractional vegetation coverage(FVC). In this research,the MODIS data from 2000 to 2014 year was employed to derive FVC basing on dimidiate pixel model,and then its change trend and intensity were analyzed using unitary linear recursive analysis and standard deviation. The result showed that:(1) The average FVC in Chongqing was 65.24% over the past 15 years and it was 67.48% in 2014a.(2) The FVC was highest in northeast,middle slanting east and south,and followed by that in the west of Chongqing,while the lowest was found in main urban city.(3) The quantity of FVC fluctuated but was with an increasing trend of 5.88%in total since 2000 a,and the average rate of change was 0.42% per year. Besides,the FVC in 91.03% of the study areas improved with varying degree,and the regions occupied by moderate improvements accounted for 64.30%.(4) Taking each district as an observational cell,it displayed a different change trend of FVC. However,all trends maintained upward,and the highest average annual rate of growth was the Yuzhong district,Changshou District,Banan District,and Hechuan district.