Abstract:

The grassland ecosystem is an important resource for humans to cope with climate change. The Headwaters of the Three Rivers is an important area to study the status of grassland ecosystem due to its vulnerability and sensitivity. Based on the totally 45 measured grassland biomass with varied coverage in the headwaters, mainstreams and tributaries, this study analyzed the spatial distribution of biomass and the ratio in the southern source of the Yangtze River. The results indicated that the grassland biomass becomes lower when the location is closer to headwater (as elevation increases). The grassland above-ground biomass (AGB) ranged from 21.12 g/m² to 850.61 g/m², while belowground biomass (BGB) ranged from 50.34 g/m² to 6 810.68 g/m². The higher the grassland coverage, the more obviously the biomass decreased with increasing elevation. The ratio of grassland AGB to BGB was less than 0.5, and the higher the grassland coverage, the lower the ratio. The study explored the distribution of AGB and BGB and their ratios, which provided preliminary exploration and data accumulation for understanding the grassland status in the source region of the three rivers.

Key words: headwaters of the Yangtze River, Dangqu river system, above-ground biomass, below ground biomass, biomass partitioning, grassland status in the three-river sources