Spatial evaluation of the ecological value importance of national park in Yarlung Tsangpo Grand Canyon.

The Yarlung Tsangpo Grand Canyon (YTGC) region is one of China's vital gene banks of mountain biological species resources. It is also an experimental site for biologists worldwide to study how organisms differentiate in the exceptional environment of the plateau. Evaluating the importance of the ecological value and identifying extremely important regions to national parks to implement the strictest conservation is significant to protecting and preserving global biodiversity. YTGC as the study area, and a comprehensive evaluation model conformed to ecological value attributes was established: (i) evaluation of ecosystem service function, including water retention, soil and water conservation and biodiversity maintenance; (ii) evaluation of ecological vulnerability, including soil erosion and geological disasters; (iii) evaluation of ecological conservation, including Important Bird and Biodiversity Areas (IBAs), Global 200 Ecoregions (G200), Biodiversity Hotspots (BH), Endemic Bird Areas (EBAs) and Priority Areas for Biodiversity Conservation in China (PABCC). Identifying as extremely important, important, and general important regions, then mosaicked with the maximum value. The results show: first, the extremely important regions of ecosystem service are about 30,242.90 km (45.64%), distributed in most regions flowing southwest along the Yarlung Zangbo River. Second, the ecological vulnerability regions are about 26,561.65 km (40.06%), concentrated and contiguously distributed in the valley regions along the Yarlung Zangbo River and the high-altitude glacier-covered regions. Third, the extremely important regions for ecological conservation are mainly distributed in Milin County (39.86%) and Medog County (36.33%), which also presents a clustered distribution in the highly high mountains with apparent differentiation along the Yarlung Zangbo River valley in Milin County and the vertical natural belt centered on the Namjagbarwa and the Galabai Leifeng. Finally, we proposed that the integrated extremely important regions of ecological value should be divided into national parks for strict conservation; at the same time, it is also a reference for considering the construction of biodiversity conservation corridors when roads pass through the extremely important regions. This study presents a reliable and integrative method for effectively identifying conservation priority areas at small-medium scales, which can be applied to other PAs planning and management.