## 4 Discussion
### Strengths and Limitations  
The limited regional scope of previous studies has constrained our understanding of habitat quality changes and interregional interactions. For example, [PERSON] et al. [111] focused specifically on the influence of threat factors within a medium-sized region, which may result in an underestimation of the role of inter-regional factors. In addition, the findings of studies conducted in medium- and small-sized regions may be constrained in their generalizability. For example, [PERSON] et al. [112] observed that the impacts of threat factors in the Pochote River Basin exhibited considerable variation from areas in close proximity to the city center to those situated downstream. This finding highlights the limitations of localized studies in capturing broader ecological processes and inter-regional interactions.  
Regional protection strategies must be coordinated at the national scale to effectively influence habitat quality and inform conservation strategies. In particular, [PERSON] et al. [113] conducted a nationwide research project on habitat quality in Italy. This study successfully identified priority conservation areas and supported large-scale strategic conservation measures, which demonstrates the benefits of national-scale assessment. In consideration of the findings of the national-scale assessment presented in this study, we propose the following countermeasures for enhancing habitat quality with the objective of optimizing land use patterns and achieving sustainable development in China.  
In addition, long-term research provides a comprehensive understanding of habitat quality trends, particularly given the complex and dynamic nature of ecosystems. Long-term research, on the other hand, is much more appropriate for determining the direction and rate of change in habitat quality by analyzing and comparing data over several decades. This provides a more reliable foundation for large-scale ecological conservation and management.  
This research has several limitations that warrant further investigation. First, the assessment of habitat quality should incorporate a wider range of threat factors to enhance the rationality of factor selection. Second, this research considered solely the effect of land use on habitat quality, neglecting other essential ecological factors including soil and water conservation, the establishment of protected areas, and forest restoration processes due to data availability. Third, while distinguishing between planted and natural forests would be advantageous for a more comprehensive examination of habitat quality, these forest categories were not distinguished in this study due to data limitations. Existing national land cover datasets lack the necessary detail to consistently and accurately distinguish between these forest categories. Future research should incorporate multiple data sources to enable finer-scale forest classification. Finally, the large study area and model complexity led to difficulties in data collection and potential differences between projected and actual land use results. Future research could integrate additional spatial factors and policy conditions into multi-scenario simulations.  
Conservation incentives should be incorporated into future ecological projections for 2050. Policy instruments such as ecological compensation and green credits can promote sustainable practices in agriculture, forestry, and fisheries. Additionally, expanding protected areas and promoting afforestation could enhance biodiversity conservation. These factors would provide valuable insights for environmental protection measures.