Avian Biodiversity Response Toward Ecological Restoration of Wetlands Through Farmland Abandonment Measures in the Sanjiang Plain, China

Large-scale agricultural development has led to a significant reduction in wetland areas, resulting in habitat fragmentation for birds and biodiversity loss. Recently, the implementation of farmland abandonment policies has helped in the restoration of wetland areas. In order to understand the ecological effects of farmland abandonment, this study investigated the bird communities in the Naoli River National Nature Reserve (NRNNR) in the Sanjiang Plain after abandonment. The field surveys (line transect and point count methods) of bird community diversity in the abandoned areas of the NRNNR showed 92 bird species from 37 families and 16 orders, including 4 species of national first-class protected birds and 17 species of national second-class protected birds (accounting for a combined 22.83%). Additionally, the bird community diversity displayed annual variation in individual and species richness over time, and the diversity indices order was 2019 > 2020 > 2018 > 2016 > 2015. Bird species richness and individual abundance were significantly higher in meadow habitats as compared to other habitat types. With prolonged restoration time after farmland withdrawal, the Pielou evenness index of bird communities significantly decreased, while the total number of individual birds significantly increased (p < 0.05). The abandoned time showed a positive impact on waterbird richness, while the longer abandoned duration led to higher waterbird richness. In conclusion, long-term ecological restoration measures revealed a significant enhancement in bird diversity over time.