## 1 Introduction  
To combat the global challenge of ecosystem degradation and biodiversity reduction, nature reserves have become one of the most effective strategies to protect and restore natural ecosystems and biodiversity, widely accepted by governments worldwide. By 2021, up to 15.73% of global land area has been designated as nature reserves [1]. In order to support ecosystem management and scientific decision-making concerning nature reserves, quantitative assessment of ecosystem changes and protection effects has become a popular topic in ecological research [2]. Related studies can be summarized into two categories: assessments based on the biological community and on the ecosystem scale. Based on the scale of the biological communities, the protection effectiveness of nature reserves is usually evaluated by analyzing changes in protected species and their habitats [3; 4; 5; 6; 7]. Two categories can be summarized based on the assessment scope and key contents. One relies on the specific species and their habitat, which takes the changes in a single nature reserve as the assessment scope, and these cases mainly focus on the changes in species and population number, spatial distribution patterns and scope [5; 8; 9; 10; 11]. Another one takes the network of nature reserves and the potential distribution area of species populations as the assessment scope, focusing on the effectiveness and vacancy of specific species populations and their habitat protection [12; 13; 14]. Based on the ecosystem scale, the effectiveness evaluation mainly focuses on two aspects: the disturbance caused by human activities and the change in ecosystem quality. Firstly, regarding human disturbance, some effectiveness evaluations focus on limiting the coefficients of man-made damage, reducing human interference and changing land use patterns. Although the specific indicators differ in different research cases, the selected indicators mainly include land use or land cover change and ecological land area change [15; 16; 17; 18]. Other indicators that assess human interference include the human footprint and human activity stress indexes [19; 20; 21; 22], or landscape indexes such as the patch density, aggregation index, and development intensity index [23; 24; 25]. Secondly, regarding the change in ecosystem quality, vegetation indexes and net primary productivity are mainly used to evaluate the restoration or degradation of natural vegetation [26; 27; 28; 29]. The ecosystem quality index, based on vegetation parameters, is used to evaluate the protection effectiveness [30]. Nevertheless, these methods also have some limitations [31]. To compensate for the lack of spatial dimension information, some researchers compared the differences in ecological changes inside and outside the nature reserve from the ecosystem scale to evaluate the effectiveness of the nature reserve [32; 33; 34; 35; 36; 37; 26; 32; 33; 37], or by extending a certain buffer zone in the nature reserve to compare and analyze the differences inside and outside the nature reserve [15]. This paper comprehensively analyzes the changes in the ecosystem type, vegetation ecological quality and ecosystem services. Additionally, it evaluates the restoration of vegetation ecological quality and the stability of ecosystem services. In contrast to the use of a single indicator in traditional ecosystem assessments, this study proposes a multi-indicator evaluation system, which provides a more comprehensive approach. Furthermore, expanding the protected area to encompass the entire geographical unit enhances the comparability of the ecosystem change results. In order to promote natural ecosystem protection and enhance the capacity for sustainable development, the Chinese government issued and implemented the policy of main functional zones in 2010, designating some key ecological spaces as prohibited and restricted development zones. Actually, a prohibited development zone is called a nature reserve, and a restricted development zone is called a key ecological function zone.