How do different processes of habitat fragmentation affect habitat quality? – Evidence from China

Large-scale loss and fragmentation of natural habitats is one of the critical factors in the global decline of biodiversity. Habitat quality is the foundation for supporting biodiversity, so exploring the mechanisms by which habitat fragmentation affects habitat quality is important for biodiversity protection. However, little is known about the specific forms that various processes of habitat fragmentation affect habitat quality. Taking China as an example, the three processes of habitat fragmentation (the decrease in habitat area, the increase in habitat isolation, and the increase in habitat edge) and variations in habitat quality were quantitatively assessed from 2000 to 2020. On this basis, Pearson coefficients, Generalized Additive Model (GAM) and Geographical detector were employed to examine the linear-linear impacts of habitat fragmentation different processes on habitat quality. The results indicated that there was a clear trend of habitat fragmentation and degradation of habitat quality in 2000–2020. 56. 94%, 42. 33%, and 50. 89% of the area experienced the decrease in habitat area, the increase in habitat isolation, and the increase in habitat edge, respectively, and 63. 12% experienced degradation of habitat quality. All three of these habitat fragmentation processes result in a downward trend in habitat quality. However, the specific form of impacts of habitat fragmentation different processes on habitat quality showed non-linear characteristics. The decrease in habitat area and the increase in habitat isolation consistently had a significant negative influence on habitat quality, albeit with varying strengths at different segments. While the increase in habitat edge causes an overall decrease in habitat quality, the two have a more complex non-linear relationship, with response curves varied between positive and negative correlations. In addition, negative impacts on habitat quality are exacerbated when multiple habitat fragmentation processes occur simultaneously. These findings reveal the complex impacts of different habitat fragmentation processes on habitat quality and inform the development of more rational landscape planning and biodiversity conservation measures in China.