Aboveground Biomass Estimation Of Populus Euphratica And Tamarix Community With Remote Sensing In The Lower Reaches Of Tarim River

Taking field survey data, GPS location data, monitoring data of water level and the satellite image acquired in2010a, taking ecology, forestry and statistics as theoretical basis, taking Populus euphratica and Tamarix distributed between Yinsu and Ka’erdayi section in the lower reaches of Tarim River, using "3S" technology and mathematical statistical methods, analyzed the growth response of Populus euphratica and Tamarix to water supply, and the biomass of them and its space distribution pattern. The main conclusion are as followings:In Ka’erdayi section where the Populus euphratica distributed farthest:After the water transferring from2000a, the growth of tree-ring took on the type of unimodal curve. Before2004a, the growth of tree-ring demonstrated the time and scope of response to water transferring. After2008a, the differences of growth in tree-ring were not significant; The volume after the water supply was higher than that before water supply, and the volumes were significantly different among the distance to river in each time quantum; After the water supply, the groundwater level firstly quickly increased, and then decreased gradually. The growth of volume was well corresponded to the changes of groundwater, and showed a type of increase-decrease-slight increase curve. We concluded that water in the river and groundwater are the key factors to determine the growth of volume of Populus Euphratica.After water supply, the basal diameter of sprouting upright growth increased with increasing age, while there was no regularity in the upright growth sprouted before the water supply. According to the field survey data of standard branches and shrub crown of Tamarix, established the power function model with the following formula w=2.007(d2h)0.837which was best for estimating the biomass of single branch of Tamarix, its accuracy reached89.92%, single cluster biomass estimation model of Tamarix built taking crown area as variable was best, and its accuracy was80.54%.According to the survey data of first-class branch of Populus euphratica, Using mathematical statistics methods established the models for estimating the biomass of Populus euphratica branches and crown biomass, the result shows that:the equation model S=125.546(D2L)0.654which by using D2L as parameter was best to estimate the biomass of first-class branch, while the best equation model used to estimate crown biomass was established taking crown area as parameter. Both of them can be applied to estimate the biomass within300m distance to river, the accuracy of them was93.75%and87.01%respectively, but both of them must be modified when they are used in the range of600m to1500m distance to river, and the accuracy of them was86.04%and84.32%respectively after modified.Correlation analysis between biomass and characteristic parameters of ALOSimage showed that:the biomass of Populus euphratica and Tamarix showed positive markedly relation to each vegetation index, while showed negatively correlated with green, red and near-infrared wavelength of ALOS image. The inverse element function model with the following formula Y=-87.246-166.977/MSAVI was best for estimating the biomass of Populus euphratica, while the model with the formula Y=-2856.59+3562.16*RVI-2239.89*SAVI was best to estimate the biomass of Tamarix.The total area of study area is3021.20km2, Populus euphratica being40.64km2, and Tamarix area394.63km2. Based on the field investigation biomass data, taking ALOS satellite image as data source, using supervised classification method to estimate the biomass of Populus euphratica and Tamarix in the study area, the result shows that:the area of Populus euphratica which biomass is between0to30t/hm2, between30to60t/hm2, between60to90t/hm2and between90to120t/hm2is0.62km2,29.88km2,8.80km2and1.34km2respectively. While the area of Tamarix which biomass is between0to3t/hm2, between3to6t/hm2, between6to9t/hm2and between9to12t/hm2is210km2,133.41km2,33.88km2and17.34km2respectively, The Populus euphratica and Tamarix with the higher biomass distributed on the both sides of the river.