Disentangling the relationship between environmental drivers and productivity in subalpine wet grasslands

Shuqiao Zhang^1,2*Langlang Shu²Wendou Liu²Zizhi Wang²Wengui Wu²Shengxi Liao²

• ¹The University of Melbourne, Parkville, Australia
• ²Institute of Highland Forest Science, Chinese Academy of Forestry, Kunming, China

Analyzing the productivity of subalpine (2000-4000m) wet grasslands and their responses to environmental factors is essential for understanding the carbon cycle of terrestrial ecosystems, especially in the context of global climate change. We applied destructive sampling techniques, optimized grassland investigation, and employed multivariate modeling to investigate how different environmental variables influence grassland biomass. An 80-plot field-based dataset was established in a subalpine wet grassland. Wet grassland had the highest biomass among the six grassland types. Our findings reveal that plant biomass was the highest at 3400 to 3500 m elevation. Belowground and dominant species biomass accounted for 85% of the total productivity of subalpine wet grasslands. Vegetation-related variables, such as species richness, coverage , and root/shoot ratio, were the primary determinants of aboveground biomass, whereas soil properties were key regulators of belowground biomass. Although direct and indirect effects of landform and climatic factors influenced total biomass, the patterns of total and belowground biomass were consistent.Additionally, direct and indirect effects of landform and climate characteristics influenced total biomass. The results underscore the significant positive impact of vegetation cover, root-to-shoot ratio, and soil conditions on grassland productivity. Notably, soil organic carbon, water content, and the nitrogen-to-phosphorus ratio affected belowground biomass. These insights enhance our understanding of the intricate interactions between climate, soil, landform, and plant communities in influencing grassland biomass and highlight the importance of preserving plant diversity and maintaining optimal soil conditions in subalpine wet grasslands. lead to rich and diverse grassland resources. The grassland area is 8084 km 2 (72.09% of the study area), and the major grassland types include alpine meadows and alpine semi-swampy areas. Dominant plant species include Blysmus sinocompressus, Carex setschwanensis, Carex enervis, Carex tibetikobresia, Elymus nutans, Carex moorcroftii, and Carex muliensis.