Impact of active vegetation restoration and native vegetation on breeding bird communities in coastal wetlands under disturbance by reintroduced Père David’s deer

Coastal wetlands are crucial habitats for waterbirds, and saltmarsh vegetation provides breeding habitats for bird species. However, studies on the effects of saltmarsh vegetation degradation and reconstruction on bird diversity are limited. In Dafeng Milu National Nature Reserve, a Ramsar wetland, the reintroduced Père David's deer, Elaphurus davidianus, severely degrades native vegetation. Thus, the natural reserve has implemented vegetation restoration through artificial planting to promote the growth of native flora. To elucidate the impact of active vegetation restoration on the avian community, we conducted bird surveys in active restoration areas and nonintervention areas during the breeding seasons from 2022 to 2023. The results indicated that there was no significant difference in the species diversity of bird communities between the active restoration areas and the nonintervention areas; however, there were significant differences in the functional and phylogenetic diversity of bird communities. Landscape analysis based on indices and correlation testing revealed a significant correlation between habitat heterogeneity at the landscape level and the functional diversity of bird communities. A random forest model identifies landscape area and cohesion as important influencing factors. Our results highlight that in the context of plant degradation caused by Père David's deer in coastal wetlands, active vegetation restoration and the control of deer populations are conducive to enhancing avian diversity.