Framework Construction and Application of Gross Ecosystem Product (GEP) in the Three-River-Source National Park (TRSNP) in China

Assessing the value of ecosystem products over time can reflect the effectiveness of ecosystem protection and serve as a measurable indicator in national park management. This study focuses on the Three-River-Source National Park (TRSNP), located in the Tibetan Plateau, the “Water Tower of China”. We developed an accounting system for ecosystem products in the TRSNP and assessed their value for 2015 and 2020. Key findings include the following. (1) The validation of the system’s scientific basis with a comprehensive indicator framework covering material products, regulating services, and cultural services. (2) The total value of ecosystem products in TRSNP increased by 31.19% from 2015 to 2020. Driven by policies such as grazing bans and the restoration of grasslands, the value of material products saw a decrease during the same period, while the value of regulating services experienced an increase. Notably, among the regulating services, the value associated with soil conservation emerged as the highest. (3) The value of regulating services varies across different regions due to the influences of land use types and soil erosion types. Among these, the value of regulating services per unit area is highest in the Lancang River source region, followed by the Yellow River source region, and the value was the lowest in the Yangtze River source region. (4) Recommendations include enhancing the value of agricultural and animal husbandry products to increase the overall agro-pastoral income, focusing on soil protection and restoration in the Yangtze and Yellow River source regions, and exploring strategies for the trading of ecological resource rights for soil retention in the Lancang River source region. This research offers a pertinent case study for ecosystem product value assessment, contributes a scientific ecological protection effect evaluation system for TRSNP, and provides a relevant scientific basis for the management of TRSNP.