Abstract: The Qingtu Lake area at Minqin Qasis, Gansu Province, China belongs to the oasis-desert transition zone, and its ecological system is fragile and easy to develop into a desert. As dominant species of vegetation in the Qingtu Lake area, Haloxylon ammodendron, Nitraria tangutorum and Phragmites australis play an important role in the stability and healthy development of ecological system. Therefore, we selected the Qingtu Lake area as study area and took dominant species of the vegetation as the study objects. First, we applied object-oriented classification method with texture features to extract canopy breadth of Haloxylon ammodendron, Nitraria tangutorum and distribution area of Phragmites australis by high-resolution remote sensing image with a spatial resolution of 0.5 m (Worldview-2). Second, a model was established for the relationship between aboveground biomass and canopy breadth of Haloxylon ammodendron and Nitraria tangutorum and aboveground biomass and distribution area of Phragmites australis based on the field test data. Third, we estimated aboveground biomass of dominant species of vegetation with the model combined with the canopy area and distribution area in the Qingtu Lake area, which has achieved the conversion of aboveground biomass estimation of dominant species of vegetation from the “point” to the “area”.Results showed as follows: (1) Object-oriented classification method with texture features achieved good classification results, the overall Kappa coefficient was 87.9%,and the overall accuracy of 91.3%. (2) Total above ground biomass of the dominant of the vegetation in the study area was 3.17×10³ t, and the aboveground biomass of Haloxylon ammodendron,Nitraria tangutorum,Phragmites australis was 0.54×10³ t, 0.90×10³ t, 1.73×10³ t, respectively. Aboveground biomass was in the rank of Phragmites australis>Nitraria tangutorum>Haloxylon ammodendron. This paper could provide references for further study on ecological restoration and carbon reserve in Qingtu Lake area.

Key words: aboveground biomass, vegetation dominant species, Worldview-2, Qingtu lake