Vegetation Net Primary Productivity Estimation in Zhuxi Small Watershed,Changting County of Fujian Province

He Jianan;Chen Zhibiao;College of Geographical Science,Fujian Normal University;

eroded granite red soil area;;CASA model;;soil erosion;;NPP estimation

At the moment,researches of ecosystem degradation in the eroded granite red soil areas of South China are focused on erosion simulation and prediction,soil degradation causes and aspects of ecological restoration and reconstruction.However,there is less concern on the study of vegetation net primary productivity of degraded ecosystem response.Based on meteorological data,Spot- 5 satellite remote sensing data and DEM( digital elevation model),it is constructed the Zhuxi Small Watershed CASA( Carnegie- Ames- Stanford Approach) model to estimate the NPP.The results show that: 1NPP distribution is at low level in the whole small watershed of Zhu Xi,with the average value of 24.04 g/( m~2·Mon),that the standard deviations is up to 9.78; 2after nearly 15 years of strong governance,the NPP value distribution on space in the Zhuxi watershed appeared as higher in the eastern and the western regions,and significantly improved in the central region,but the governance still need to be strengthened in some areas; 3stripped distribution of NPP,that the NPP value at 270 ~ 320 m is higher,with better ecological environment while the NPP value at 320 ~ 470 m is lower,with worse ecological environment.In addition,the NPP value at 470 ~ 680 m is the highest with good vegetation and better ecological environment; and 4 NPP value is high and evenly distributed in the economic land use such as woodland,garden and farmland,etc.Of which,the NPP values at the first- level land- use types are listed as farmland > grassland > woodland > garden > vacant land,and at the second- level land use types are listed as arable land > natural grassland > woodland > nursery > orchard > tea- fruit intercropping orchard > sparse woodland > desert grassland > slash.Since the human intervention footprint is obvious,the spatial variation of the NPP values at second- level land use types are listed as farmland > tea- fruit intercropping land >orchard > nursery > woodland > desert grassland > sparse woodland > slash.