DEM based analysis of biomass carbon stock in Xilingol grassland

Grassland ecosystem, one of the most widespread ecosystems in terrestrial ecosystem, performs a vital function in the carbon cycle, livestock production, climate regulation, biodiversity maintaining and ecological environment protection. Biomass carbon stock is referred to the carbon in organic material produced from the vegetation photosynthesis that converts the solar energy into chemical energy. And the variation of biomass carbon stock at different topographical factor has been paid more and more attention because of its role in global changing. In this paper, the variations of aboveground biomass carbon stock estimated by CASA Model and Plants Withered Loss Model have been analyzed based on the 30m resolution DEM in Xilingol grassland. The main variations include the changes along with the elevation levels, slopes and the aspects. And it was found that the variation of aboveground biomass carbon stock in Xilingol grassland from 2002 to 2005 and 2005 to 2009 were mainly occurred in the level-2, level-3 and level-4, elevation of 800-1400m. From 2002 to 2005, the largest decrease of biomass carbon stock was existed on the level-3 elevation; however, there was the largest increment on the level-3 elevation from 2005 to 2009. From aspect analysis, we found that, from 2002 to 2005, reduction of biomass carbon stock on the no aspect area was largest, about 60% of the total change and there was also a slight decrease on half sunny slop, half shady slope and sunny slope. The increment of biomass carbon stock on the flat area was about 30% of total changed area. The slope analysis revealed that, from 2002 to 2005 and 2005 to 2009, changes of biomass carbon stock was mainly occurred in the flat, nearly flat area. From 2005 to 2009, there was the largest increment on the flat area, accounting for 50% of the total change area, and also had about 40% of reduction.