Biomass-based Transpiration Water Consumption of Dominant Species of Vegetation Estimation in the Oasis of Lower Reaches of Heihe River

The research object of this study are the Tamarix ramosissima, Populus euphratica and Sophora which are the dominant species vegetation in lower reaches of Heihe River. Guided by the theories of Ecology Hydrology, Geobotany, Statistics theories and other disciplines, field investigation combined with remote sensing and spatial analysis methods were applied to study biomass and transpiration water consumption of dominant species of vegetation in study area. Firstly, biological characteristics of typical samples survey and biomass observation of dominant species of vegetation was made. The relational model of aboveground biomass and the ecological parameters(canopy area or coverage area) of dominant species of vegetation were constructed.Then, ecological parameters of dominant species of vegetation were obtained from high resolution satellite imagery Geoeye-1 which were classified by decision tree method to realize the spatial distribution estimation of aboveground biomass of dominant species of vegetation. Finally, the transpiration water consumption of dominant species of vegetation was estimated by the relationship between biomass and transpiration coefficient.According to the studying results, the spatial distribution characteristics of aboveground biomass and transpiration water consumption of 0-2 km, 2-5 km, 5-10 km and 10-15 km river buffer zone were analyzed.The spatial distribution pattern of transpiration water consumption was revealed. The following results were gotten. According to the classification result, the total canopy area of Tamarix ramosissima and Populus euphrat.ica are 2.44×102km2 and 3.61×10 km2 respectively. And the coverage area of Sophora alopecuroides is 4.28×102km2. The total biomass of dominant species of vegetation was 2.53×106 t. The distance to river on the biomass of dominant species of vegetation is significant. According to the experimental results of the transpiration coefficient of dominant species of vegetation. The total transpiration water consumption of dominant species of vegetation is 10.89×108 t. The propotion of Tamarix ramosissima, Populus euphratica and Sophora alopecuroides are 12.94%, 82.93% and 4.13% respectively.