A new study by Chinese scientists has advanced understanding of the mechanism and impact of permafrost collapse, particularly thaw slumps, on the alpine ecosystem of the Qinghai-Tibet Plateau, according to the Northwest Institute of Eco-Environment and Resources (NIEER) under the Chinese Academy of Sciences.

Conducted by NIEER researchers, this study evaluated the impact of thaw slumps on alpine grassland ecosystems via systematic field observations and analysis. Its findings have been published in the journal Catena, the NIEER said.

The Qinghai-Tibet Plateau is the world's largest high-altitude permafrost region, featuring a unique and fragile alpine ecosystem. In recent years, climate warming and changes in precipitation patterns have been accelerating the degradation of permafrost on this plateau, leading to the expansion of thaw slumps and other thermokarst landforms.

Thaw slumps significantly affect carbon and nitrogen migration processes, microbial community structure and alpine ecosystem functions. They do so by altering soil texture and moisture conditions.

Thaw slumps also enhance soil carbon pool release and strengthen the positive feedback effect of climate warming, according to Jiang Guanli, a researcher at the NIEER.

The NIEER researchers carried out this study to trace thaw slumps' path of regulation of the soil-vegetation feedback process.

They conducted the study in the Beiluhe and Fenghuoshan permafrost regions in the interior of the Qinghai-Tibet Plateau. Both these regions are situated at an altitude of over 4,600 meters above sea level. They selected four typical areas containing thaw slump landforms.

Researchers carried out vegetation surveys and soil sampling, obtained the gross primary productivity (GPP) of the alpine ecosystem, and systematically evaluated the impact of thaw slumps on the soil-vegetation-CO2 flux in these alpine ecosystems.

Their study results indicated that thaw slumps on the Qinghai-Tibet Plateau have triggered a sequential series of reactions from soil structure to ecosystem function, doing so by reshaping the surface microtopography.

Thaw slumps mainly affect the ecosystem function of the Qinghai-Tibet Plateau through the path of soil texture, soil moisture and soil substrate-vegetation-GPP. Incorporating patch-scale heterogeneity and slump age is therefore essential for forecasting the carbon dynamics of the Qinghai-Tibet Plateau, the study revealed.

Thaw slumps are among the main thermokarst landforms found on the Qinghai-Tibet Plateau. "Our study addressed the previous knowledge gap in permafrost collapse, particularly thaw slumps, on the plateau. This is of importance in better understanding and preserving the plateau ecosystem," said Jiang.

Jiang added that the study provides reliable measured evidence for understanding changes in carbon sinks on the plateau, by proposing and quantifying the chain of a specific influence path of thaw slumps on soil, vegetation and carbon sinks.

"Furthermore, the study proposes new ideas that will be helpful for more accurately assessing the Qinghai-Tibet Plateau in terms of dual carbon goals and the global carbon budget," Jiang explained.