Study on the relationship between human activities and spatial distribution changes of Tamarix in Ejina oasis

The impact of human activities is huge, and sometimes it´s irreversible, especially in the area of fragile ecological environment. So, understanding the extension and intensity of human activities is very essential for ecological restoration. Ejina oasis was selected as the study area, and Tamarix ramosissima, the dominant species in the study area, is the core of the study. According to investigation, the relationship models between aboveground biomass of Tamarix ramosissima and its morphological features (i.e., basal diameter and height, canopy perimeter) have been built. In addition, Land use/cover of the study area is classified using the method of the object-oriented classification with high resolution image (QuickBird). The distribution of Tamarix ramosissima is extracted from classification map and morphological feature (i.e., canopy perimeter) of Tamarix ramosissima is calculated in ArcGIS 9.2. Based on the relationship models and the distribution map of morphological features, the spatial distribution of aboveground biomass in the study area is estimated. The results can show that: (1) aboveground biomass of Tamarix ramosissima is 69644.7 t and biomass per unit area is 0.78 kg / m². The higher biomass appears along the banks of Heihe River due to the suitable habitat to the species. (2) total biomass amount of Tamarix ramosissima reduced by human activities is 9945.9 t during the ten years.