Abstract: Uncovering the ecological effectiveness of nature reserve policies will help protect and manage nature reserves in the future. Taking Sanjiangyuan region as an example, we examined the impacts of the spatial layout characteristics of natural reserves on the ecological environment quality by constructing the dynamic degree of land use and land cover change index, and depicted the spatial differences of the ecological effectiveness of natural reserve policies both inside and outside the natural reserves. Combined with ordinary least squares and field survey results, we explored the influencing mechanism of nature reserve policies on ecological environment quality. The results showed that the ecological quality of the whole region of Sanjiangyuan had been improved significantly since the implementation of the nature reserve policies, and that the transformation of unused land into ecological land was the most important type of land use change for the ecological environment quality improvement. The ecological effectiveness of large-scale nature reserves with concentrated and contiguous distribution was obvious, while the ecological effectiveness of small-scale nature reserves with scattered distribution and close to the administrative boundaries was relatively small. Although the ecological effectiveness of nature reserves was better than that of non-reserved areas, the ecological improvement of nature reserves and the surrounding areas was synchronous. The nature reserve policy had significantly improved ecological environment quality by implementing ecological protection and restoration projects in nature reserves. Meanwhile, it had alleviated the pressure of farmers and herdsmen's activities on the ecological environment by taking measures such as grazing restriction and guiding conversion of industry and production. In the future, we should promote the construction of ecosystem integrity protection network system with National Park as the core, strengthen the integrated protection and linkage management of National Park and surrounding areas, and help farmers and herdsmen further broaden their livelihoods.

Key words: nature reserve, ecological environment quality, influencing mechanism, Sanjiangyuan region, land cover change index