Long-term afforestation efforts increase bird species diversity in Beijing, China

Bird communities are important components of biodiversity and provide terrestrial ecosystems with multiple functions. The impact of long-term afforestation and rapid urbanization on bird species diversity (BSD) is of interest and has attracted increasing attention from biologists, government officials and the public. This study focused on patterns of BSD and changes in forest coverage in an Asian mega-city (Beijing). Forest coverage in Beijing increased moderately from 1.3% (in 1949) to 21.26% (in 2003), and rapidly from 21.26% (in 2003) to 41% (in 2014). Natural types of land cover (i.e., woodland, grassland and water) increased from 55.25% (9070.29 km2) in 1985-63.41% (10411.16 km2) in 2013, while anthropogenic types (i.e., cultivated land, construction land and unutilized land) decreased from 44.75% to 36.59% based on remote sensing data. Three sets of BSD records were obtained from the published literature, revealing a species diversity of 344 in 1987, 375 in 1994, and 430 in 2014. Approximately 15% of bird species were endemic and 80% were migratory. From 1987-2014, Beijing gained 81 bird species (37 species disappeared while 118 species appeared), which could be a result of the progressive increase in forest coverage. The changes in BSD may be affected by long-term afforestation efforts and rapid urbanization, along with meteorological factors. This study sheds some light on the effects of afforestation and urbanization on biodiversity.