Multilevel Impacts of Habitat Fragmentation on Plant Diversity and Structure in Urban Remnant Forests

Against the backdrop of ongoing global urbanization, understanding the impact of urban remnant forest fragmentation on plant diversity and community structure is crucial for developing effective biodiversity conservation and urban management strategies. This study investigated 30 remnant forest patches in the Guiyang metropolitan area of China, quantifying fragmentation indices at both patch and landscape scales to analyze how plant diversity and forest structure vary along a fragmentation gradient in interior and edge habitats. The results showed that edge habitats exhibited higher forest structural metrics (total basal area, dominant tree height, and total biomass), but their plant diversity was negatively affected by the clumpiness of surrounding impervious surfaces. In interior habitats, diversity was negatively influenced by edge contrast and clumpiness of impervious surface. In addition, forest structure was also negatively affected by the clumpiness of surrounding impervious surfaces and positively affected by patch area. Furthermore, significant positive relationships were detected between tree density and plant diversity, and the composition of understory vegetation (including saplings/seedlings, shrubs, and herbs) was significantly influenced by forest structural attributes. Based on these results, we recommend maintaining patch integrity, establishing buffer zones to reduce edge contrast, and controlling the contiguity of impervious surfaces around patches to sustain both plant diversity and forest structural complexity in urban remnant forests.