Integrated optimization of border ecosystem services and risks: A multiscale exploration considering the past and future

The global ecological environment is undergoing a systemic crisis driven by the combined effects of accelerated urbanization and climate change, with the ecosystem imbalance exceeding planetary boundary threshold. Border regions, serving as the frontline for national security, remain understudied, with insufficient research on ecosystem security simulations. This study takes the Yunnan-Guangxi region of China's land border (YGCB) as a case study, coupling a series of regional disparity and spatiotemporal mapping models to identify and simulate ecosystem services and risks across multiple scales, thereby establishing a comprehensive optimization framework for ecological security zones. The results indicate that: (1) The ecosystem services and risks in the YGCB exhibited spatiotemporal heterogeneity and regional interactions. The ecosystem service index (ESI) initially increased but later declined, dropping from 0.3775 in 1990 to 0.3769. The ecosystem risk index (ERI) rose to 0.4063 by 2020. The spatiotemporal trade-off relationship between ESI and ERI revealed the coupled effects of karst terrain sensitivity and human activities in the cross-border economic zone. (2) Significant variations exist in border ecological security across different development scenarios. Under the integrated optimization of security stabilization scenarios, ecosystem service capacity is markedly improved, showing a 6.22 % increase compared to 2020 levels, while ecosystem risks are effectively mitigated with a 37.88 % reduction from 2020 baselines. (3) As the core zones of geo-economic and social development in the YGCB, the border trade ports and central towns remain critical regions requiring focused attention and governance in the systematic engineering of border ecological protection. Therefore, the establishment of a Global Border Eco-Security Network is called for to analyze ecosystem service-risk interactions across borders, scales, and elements, systematically addressing the “protection-development” challenge.