Drivers, Trade-offs and Synergies of Ecosystem Services in Ecological Security Barrier Zones: Implications for...

Nyingchi, as a critical ecological security barrier zone, its ecosystem services (ES) faced unprecedented disturbances and risks due to climate change and human activities. This study aimed to identify the primary drivers, trade-offs and synergies of ES in Nyingchi, thereby providing a scientific basis for spatially differentiated ecological conservation and management in the region. This study evaluated six ES in Nyingchi from 2000 to 2023, including water yield (WY), habitat quality (HQ), water conservation (WC), carbon storage (CS), water purification (WP) and soil conservation (SC). Standardized distance equivalence (SDE) and structural equation modeling (SEM) were employed to examine the spatial heterogeneity and drivers of ES, respectively. Coupling coordination model (CCM) and self-organizing maps (SOM) were introduced to assess trade-offs and synergies among ES. Results indicated: (1) High-value regions for the six ES were concentrated in the southern region. SDE results indicated that the center of most ES exhibited a spatial evolution pattern shifting toward the northwest excluding HQ. (2) Climatic and vegetation factors were confirmed to be the primary drivers of most ES. (3) In the southern regions with high vegetation cover, synergistic relationships among ES predominated. In contrast, trade-off relationships were more prevalent in the farmland and barren areas of the west and northwest. (4) Furthermore, 3000 m elevation served as a critical threshold: above this altitude, all ES relationships gradually transitioned from synergistic to trade-off patterns. This study provided data support and theoretical guidance for synergistically advancing ecosystem management and sustainable economic development in the region.