Exacerbating or mitigating landscape fragmentation: Exploring the role of topographic heterogeneity in shaping landscape patterns in China

Abstract

Topography provides the physical basis for landscape pattern formation. It also constrains how landscapes evolve. Understanding whether natural terrain exacerbates or mitigates landscape fragmentation is essential for revealing the mechanisms behind landscape change. This study used a mean change-point method to identify the optimal scale for topographic analysis. It then introduced evaluation models for the Relief Degree of Land Surface (RDLS) and the Landscape Fragmentation Index (LFI). A generalized additive model (GAM) was applied to examine the nonlinear association between RDLS and LFI. The results revealed that, first, in low-relief areas, terrain exerts a weak constraint effect, leading to rising fragmentation as RDLS increases. Second, moderate relief functions as a spatial barrier, isolating human activity and preserving landscape integrity. Third, in highly rugged terrain, even with limited human interference, natural topography alone can divide the landscape into disconnected patches, producing a natural fragmentation effect. Fourth, terrain also plays a guiding role: when steep relief compresses usable space, human activities concentrate in flatter or transformable areas, enhancing spatial continuity and reducing fragmentation. These findings uncover the specific mechanisms through which topography shapes landscape patterns, clarifying its multiple functions in either exacerbating or mitigating fragmentation. They provide valuable insights for differentiated land-use planning and sustainable ecological governance in complex terrain regions.