Spatio-Temporal Variations and Drivers of Carbon Storage in the Tibetan Plateau under SSP-RCP Scenarios Based on the PLUS-InVEST-GeoDetector Model

Abstract

Enhancing carbon storage in terrestrial ecosystems has become a key strategy for mitigating climate change. The Tibetan Plateau holds a pivotal position in achieving carbon neutrality, with the structural pattern of its land use types directly impacting the region’s ecosystem carbon storage capacity. However, there is still a lack of understanding of the spatial distribution of carbon storage in their ecosystems. This study targeted the Tibetan Plateau, utilizing land use data from 2000 to 2020, and employed the Patch-generating Land Use Simulation (PLUS) model to project land use patterns for 2030. By integrating future climate change projections, this study forecasted land use under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios. The Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model was employed to quantify carbon storage from 2000 to 2030, while the GeoDetector model was used to explore the driving influences of factors such as the Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Leaf Area Index (LAI), Net Primary Productivity (NPP), population density, and road network density on carbon storage. The results revealed that: (1) Grassland predominated the land use types on the Tibetan Plateau, with most types having a stability of over 70%, whereas significant changes were observed in the western Tibet Autonomous Region and southern Xinjiang Uygur Autonomous Region. (2) Carbon storage on the Tibetan Plateau generally followed a tendency towards an initial decrease followed by an increase, with an average annual reduction of 50,107,371.79 Mg. The SSP1-2.6 scenario demonstrated the most substantial increase in carbon storage, being 18 times the natural trend, while the SSP5-8.5 scenario indicated the largest decrease. (3) Over the two decades, NDVI emerged as the most influential driver of carbon storage on the Tibetan Plateau, which was maintained at around 0.4, with the interaction between NDVI and NDWI exerting the strongest driving force, which was maintained at around 0.45. The conversion to forestland and grassland was the primary factor accounting for the change in carbon storage. Based on these results, despite the absence of empirical carbon density data, the SSP1-2.6 scenario could be regarded as a reference pathway for carbon storage changes on the Tibetan Plateau. Solely focusing on enhancing carbon storage by converting low-carbon land uses to high-carbon land uses is misguided; sustainable development represents the optimal approach for augmenting carbon storage on the Tibetan Plateau.