Mechanisms for carbon stock driving and scenario modeling in typical mountainous watersheds of northeastern China

Abstract Watershed ecosystems play a pivotal role in maintaining the global carbon cycle and reducing global warming by serving as vital carbon reservoirs for sustainable ecosystem management. In this study, we based on the "quantity-mechanism-scenario" frameworks to evaluate carbon stocks in mid to high latitudes alpine watersheds in China and explored the mechanisms of climate change and land use influence on the ability of watershed ecosystems to store carbon. The results showed that the carbon stock of the watershed increased by about 15.9 Tg from 1980 to 2020. Vegetation, precipitation, land-use change, and economic production have the strongest explanatory power for carbon stocks. Under different climate scenarios, it was found that the SSP2-4.5 scenario had a significant rise in carbon stock from 2020 to 2050, roughly 24.1 Tg. This increase was primarily observed in the southeastern region of the basin, with forest and grassland effectively protected. Conversely, according to the SSP5-8.5 scenario, the carbon stock would decrease by about 50.53 Tg with the expansion of cultivated and construction land in the basin's southwest part. Therefore, given the vulnerability of mid to high latitudes mountain watersheds, global warming trends continue to pose a greater threat to carbon sequestration in watersheds. Our findings carry important implications for tackling potential ecological threats in mid to high latitudes watersheds in the Northern Hemisphere and assisting policymakers in creating carbon sequestration plans, as well as for reducing climate change.