Background As ecologically fragile landscapes, the dry-hot valleys are characterized by a pronounced hydro-thermal conflict, making them key areas for national soil and water conservation efforts. Under the dual pressures of global climate change and intensified human activities, the supply of critical ecosystem services, such as water conservation and soil retention, has demonstrated a general declining trend in these regions. However, previous researches have predominantly focused on the mechanisms influencing soil retention at small scales, such as individual plots or hillslopes, while largely overlooking the broader issues of ecosystem service functions across various spatiotemporal scales and their future changes in response to climate change.

Methods This project aims to address this gap by investigating the complex dynamics of ecosystem services in the dry-hot valleys of Yunnan province. By integrating field observation experiments with advanced numerical simulations, the dynamics of water conservation, soil retention, and climate regulation services across various spatial and temporal scales will be quantified. This empirical data will be used to elucidate the core water-soil-sediment coupling processes and identify their dominant controlling factors under anthropogenic disturbances. Subsequently, a high-resolution integrated assessment model for these ecosystem services will be developed and validated. To forecast future scenarios, the model will be driven by climate projection data from the Coupled Model Intercomparison Project Phase 6 (CMIP 6) under a range of Shared Socioeconomic Pathways (SSPs), allowing for a robust analysis of potential future trajectories.

Results The expected outcomes of this project are to: 1) Elucidate the driving mechanisms of water-soil-sediment coupling processes, and then develop a high-resolution water-soil-sediment dynamic simulation model suitable for the dry-hot valleys. 2) Provide a detailed characterization of the spatio-temporal distribution and evolutionary patterns of key ecosystem services within the study area, and identify the synergetic and trade-off effects between different ecosystem services. 3) Generate high-resolution simulations of ecosystem service functions through the integrated assessment model, offering a powerful tool for regional ecological management. 4) Reveal the potential changes and responses of ecosystem service functions to different future climate and socio-economic development pathways through scenario-based projections, thereby identifying critical thresholds and areas of vulnerability in the dry-hot valleys of Yunnan province.

Conclusions This project can propose the enhancement pathways and optimization strategies tailored for the ecosystem services in the dry-hot valleys of Yunnan. By providing a comprehensive understanding of current and future ecosystem service dynamics, the findings can offer a vital theoretical basis and a methodological reference for promoting the sustainable development and ensuring the long-term ecological security of this fragile region and other similar ecosystems. The outcomes will directly support policymaking for ecological restoration and management.