Assessment of ecological importance of the Qinghai-Tibet Plateau based on ecosystem service flows

Assessments of ecological importance based on static indexes that do not consider service flows frequently underestimate the importance of the Qinghai-Tibet Plateau as a "source". On the basis of natural environmental characteristics, this study selected six type of ecosystem services for evaluation, including water retention, soil retention, carbon sequestration, biodiversity conservation, sandstorm prevention, and tourism. According to the attributes of each ecosystem service flow, we calculated the flow length and traffic accessibility indexes, using Arc GIS hydrological module and kernel functions separately, to comprehensively analyse the ecological importance levels of the Qinghai-Tibet Plateau. Results showed that after considering the service flows, the ecologically important zone shifted to the core area of the Three River Source Region, such as Zadoi County located in the Tanggula Mountains. The area of extreme importance is mainly distributed in the Yarlung Zangbo River basin, Tanggula Mountains, Hengduan Mountains, and Qilian Mountains, which accounts for 31.7% of the Qinghai-Tibet Plateau, providing approximately 60% of the ecosystem services and having extremely high protection efficiency and protection value. By introducing ecosystem service flow indexes, this study confirmed the ecological importance of core source areas such as the Tanggula Mountains, weakened the space bias caused by not considering the spatial transfer of ecosystem services, and provided technical support for optimizing ecological protection strategies and coordinating regional development.