Monitoring On The Comprehensive Benefit Of Coastal Protective Forests In Pingtan County

Coastal protective forests construction is a significant measure to mitigate the deterioration of ecological environment in coastal areas, make up for the ecological fragility of coastal zones, improve the ability of resisting natural disasters, improve the living environment of people in coastal areas and guarantee sustainable development of agriculture. It has a rather significance to achieve the monitoring on the Comprehensived benefit of coastal protective forests. The study uses Geomatics and achieves the extraction of temporal and spatial distribution thematic information of coastal protective forests in Pingtan County, drawing on the remote sensing images of different periods, survey data and various statistics data. At the same time, it builds a comprehensive benefit monitoring model using the monitoring indicators which could reflect the benefit of coastal protective forests, and then achieves the monitoring on the comprehensive benefit.The main conclusions are as follows:(1) According to the land classification system determined by Ministry of Land and Resources and the actual situation of the study area, it develops the land use and forest type classification system. Through field investigation, supported by related basic datum and the images of different periods, it extracts the temporal and spatial distribution thematic information of coastal protective forests. It shows the main changing trend of the land-use types is that the areas of sand, farmland and unused land have been decreased, while the residents and woodland have been increased, of which the changes of residents is large and followes by the woodland. And the area of waters remaines basically unchanged.(2) Taking the comprehensive benefit monitoring on the coastal protection forests in as the object, according to the principle of indicators selection, referencing research results of others as well as accessibility of indicators, it chooses soil erosion modulus, vegetation cover, bare sand area proportion, forest productivity, gross domestic product (GDP) as indicators for monitoring, to build an Comprehensive indicators system of effective monitoring.(3) Using of USLE equation, through the obtaining of the thematic maps of these factors in the equation and the database, it calculates the soil erosion modulus, and gets the soil erosion thematic map of Ping tan County in 1986 and 2003. The results show that: Soil and Water Conservation is in good condition in Pingtan County, the proportion of micro-erosion and light-erosion reaches 91.909% out of the total area in 2003. The area of high-erosion declines and the quality is beeing improved.(4) It uses the hybrid spectral analysis approach to do the study of the proportion of bare sand. The results show that the first four components images are figuring to diffenent types after MNF transform and the correlation of the four components is small. It selects farmland, woodland, sand, water and the residents as the major endmembers, decomposes the mixed-pexels after which the RMS value is less than 5%, which offers a better result.(5) Taking vegetation cover, soil erosion intensity and soil moisture as the factors of monitoring forest productivity, it determines the weight of each factor, calculates composite index using the weighted index. Using the raster database of forest climate productivity generated, taking the comprehensive index as a correction factor, it calculates the forest productivity raster data of Pingtan County, and establishes a database.(6) According the spatial relationship between GDP of different industries and land-use types, followed by the "no land-use no GDP" principle, it takes the farmland, woodland, waters, residents as the main land-use types while the GDP spatializing. Using GDP/(number of grids), it obtains the GDP of uint grid. The maps of GDP spatializing show that GDP of unit water grid is the most which has increaed to 25.491 thousand yuan from 3.008 thousand yuan in 1986, while the GDP of unit farmland grid has a bit of increace and there is nearly no change in the woodland and residents.(7) Selecting forest productivity, gross domestic product (GDP), bare sand proportion, vegetation cover and soil erosion modulus as indicators for monitoring, through data standardization and the determination of weights, it builds a model of comprehensive benefit monitoring, and makes a comprehensive analysis of the benefit generated by the coastal protective forests in Pingtan County. The results show that the proportion of better than middle efficiency grade was 79.67% in 1986, and in 2003 reaches 99.58%.