Study On Quantitative Estimation And Dynamic Change Of Vegetation Fractional Coverage In The Sanjiangyuan Region

Based on the sub-project "Geographic Information System of Ecological Environmental Remote Sensing Dynamic Monitoring in the Sanjiangyuan Region" of the Western Mapping Project from the State Bureau of Surveying and Mapping and the sub-project "Image Processing and Thematic Production" of the Application System Software Engineering of the Small Satellite Constellation for Environment and Disaster Monitoring and Forecasting from Ministry of Environmental Projection of the People's Republic of China, this paper established the remote sensing model of estimating vegetation fractional coverage in the Sanjiangyuan Region using MODIS-NDVI time-series data,MODIS-LAI time-series data and HJ-1 data. The vegetation fractional coverage (fc) from 2000 to 2009 was estimated quantitatively in the Sanjiangyuan Region. We analyzed the spatio-temporal variations of the fc during ten years and its drive factors, which provides basis for decision-making to scientifically manage and protect ecological environment in the Sanjiangyuan Region.The results were as follows:1) Based on the Pixel Unmixing Model and NDVI, the model for eastimating f。was established using the MODIS data and HJ-1 data. The parameters NDVIveg and NDVIsoil in the model was improved that suitable for this region. The accuracy of estimated fc using MODIS data in August,2008 was 87.72%, which indicates that the model is feasible to estimate the fc in this region.2) The vegetation fractional coverage of Maduo County on 30 August,2009 was estimated using HJ-1 data. Compared to the MODIS results, the accuracy of HJ-1 estimated f。was 96.62%, which indicates that it was feasible to estimate the vegetation fraction coverage using HJ-1 data.3) We analyzed the inter-annual variations trends using the year-maximization vegetation fractional coverage from 2000 to 2009. The results showed that the fc had fluctuantly changed in the past ten years and generally presented the degradation trend. The slope trend analysis indicated that the fc in the eastern part of the Sanjiangyuan Region had been increased in the ten years, while in the western part the f。showes decreased trend.4) The changes of landscape patterns were analyzed using the year-maximization vegetation fractional coverage in 2000,2004 and 2009. The results showed that the coverage fragmentation had been decreasing; the complicated degree of the distribution of the f。for different grades had been reduced and the area of high f。had been increasing.5) The policy changes, economic development, increased population, other social factors and human activities play more and more influence on the change of vegetation fractional coverage in the Sanjiangyuan Region. They are the most important drive factors in such a short period of time.