Objective Ecosystems play an important role in carbon fixation and oxygen release, which can effectively mitigate climate change. Carbon storage is an important index to measure the carbon sink capacity of ecosystems, which can provide a scientific basis for formulating carbon emission reduction strategies. However, the current research on the distribution of carbon storage mostly focuses on the influence of a single factor, and there are relatively few systematic discussions on the multi-factor synergy and its spatial differentiation. Therefore, this study systematically analyzes the spatial and temporal distribution pattern of carbon storage in the Xiaoxing'anling region of China and its driving mechanism of change, and evaluates its potential contribution to regional carbon balance management and carbon emission reduction targets.

Methods Aiming at the mechanism of multi-factors on the spatial differentiation of ecosystem carbon storage, this study used the land use data of 2000, 2010 and 2020 to estimate the carbon storage and its spatial distribution characteristics in the Lesser Khingan Mountains based on the InVEST model. The random forest model was used to screen important variables such as topography, meteorology and soil, and the geographical detector was selected to explore the main driving factors driving the spatial differentiation of carbon storage in the study area and explore its driving mechanism.

Results ①The spatial distribution of carbon stocks in the study area is characterized by the following factors. The land use types in the study area are mainly dominated by forest land (77%) and cropland (20%), and the change of land structure is obvious, which is manifested in the increase of cropland and construction land area, and the decrease of forest land and grassland area; ②The total amount of carbon stock in the study area has increased by 14.72% in the last 20 a, and the mutual transformation of cropland and forest land and grassland is the main reason for the decrease of carbon stock; ③The dominant factors in the spatial differentiation of carbon stocks were vegetation cover (0.254~0.278) and soil texture (0.146~0.168).

Conclusions Although the area of forest and grass in the Xiaoxing'anling Mountains has decreased in the past 20 years, which has weakened the carbon sink capacity of the ecosystem, the increase of carbon storage in local areas has covered up the reduction of local areas, reflecting that the study area has certain ecological restoration potential. However, human activities have led to greater pressure on regional carbon sink capacity, increasing the difficulty of carbon emission control. Therefore, although the study area has the ability of ecological restoration, in order to enhance the regional carbon sink function and alleviate the pressure of regional carbon emissions, the ecological protection and restoration measures in the study area should be continuously strengthened.