Effects of Fruiting Plants on Frugivorous Bird Diversity Across Different Disturbed Habitats

Bird–plant interactions are critical for maintaining biodiversity and ecosystem function, and represent a key research focus in modern ecology. Using the line transect method, we surveyed bird diversity and collected plant trait data in four habitat types in the southern zone of Fujian’s Meihuashan National Nature Reserve during October–December 2021 and July–August 2022. This study investigated how plant traits (tree height, diameter at breast height (DBH), canopy density fruit amount) influence the diversity of frugivorous birds (species richness, abundance, Shannon–Wiener, Pielou, Simpson) across four disturbed habitats—villages (residential areas), bamboo forests (economic plantations), unguarded broad-leafed forests (wild forests), and nurtured broad-leafed forests (managed forests)—during both summer (breeding season) and autumn–winter (fruiting season). The key findings revealed that (1) significant correlations between plant traits and bird diversity were exclusive to the fruiting season, with no associations found in summer; (2) during autumn–winter, the key plant traits driving bird diversity varied distinctively by habitat: tree height and canopy density were paramount in villages; both habitat structure (canopy density) and fruit amount were important in bamboo forests, whereas in both broad-leafed forests, a combination of tree structure (height, DBH, canopy density) and fruit amount determined bird abundance; (3) a significant interaction between season and habitat was detected for community evenness, indicating that habitat type modulates the seasonal effects on community composition. This study underscores that in human-modified landscapes, conserving habitat structural complexity and key resource plants is crucial for sustaining frugivorous bird diversity and its ecological functions. Conservation strategies must account for seasonal dynamics to be effective.