Blue landscape fragmentation and ecosystem health in river source regions: A case of Sanjiangyuan National Park, China

Sanjiangyuan National Park (SNP) is a significant river source region in Asia, and its coupled relationship between blue landscape fragmentation (BLF) and ecosystem health (EH) has far-reaching impacts on water ecological security in Asia. The study quantified the spatio-temporal evolution characteristics of BLF and EH from 1993 to 2023, combining the landscape index with the VORS (Vigor-Organization-Resilience-Service) model, while the spatial correlation mechanism was revealed. The results demonstrated that: (1)BLF exhibited substantial type and spatial differentiation, with wetland and glacier retreat being the most pronounced, and the fragmentation degree of the Yangtze River source region exceeding that of the Yellow River and the Lancang River source region. (2) Prior to 2003, the absence of regulatory measures resulted in the proliferation of "Sick" areas, while subsequent to 2013, the implementation of conservation policies fostered the progressive recuperation of EH, culminating in an increase in the proportion of "Very healthy" areas to 27.61 % in 2023. (3)The correlation analysis between BLF and EH further indicated the existence of negatively driven core areas in the SNP, with the driving intensity fluctuating over time. The study innovatively provides a spatial targeting basis for ecological restoration in the plateau national parks, meanwhile, suggesting prioritizing the control of vulnerable nodes in the blue landscape system and strengthening land tenure management mechanisms to cope with the overlapping effects of climate change and anthropogenic disturbances.