Semi-natural habitats enhance bird diversity in intensively managed farmlands in North China

Agricultural intensification has caused substantial biodiversity loss in farmland worldwide. Although China's farmland accounts for a significant proportion globally, knowledge about farmland heterogeneity and biodiversity remains limited. We examined how semi-natural habitats and habitat heterogeneity affect bird diversity in the intensively managed, low-crop-diversity (wheat–maize rotation) farmland of Qihe County, Shandong Province, China. We applied a multi-scale approach that included patch-scale and transect-scale analyses at both local (100 m buffer) and broader local (200 m buffer) scales across 20 transects, with habitat data classified into eight types: cropland, woody vegetation, herbaceous vegetation, reed, bare ground, tomb (small, earthen mounds with spontaneous vegetation), water, and artificial infrastructure. Bird richness and abundance were recorded within 100 m on either side of each 500 m transect. At the patch scale, Semi-natural habitats—particularly tombs, woody vegetation, and reeds—supported higher bird richness and abundance. At both local and broader local scales, semi-natural habitats positively influenced bird richness, but their positive effect on abundance occurred only at the local scale; woody vegetation, herbaceous, and reed were most important locally, while at the broader scale, richness was mainly associated with woody vegetation, herbaceous, and bare ground. Habitat diversity (SHDI) positively affected species richness, edge density (ED) of semi-natural habitat had a positive effect on bird abundance, and mean patch size showed limited effects. These results indicate that biodiversity in intensively farmed landscapes can be enhanced through the management of semi-natural habitats and habitat heterogeneity, highlighting the importance of maintaining these habitats and improving landscape connectivity. • Semi-natural habitats enhance bird diversity at patch and transect scales. • At patch scale, tombs, woody vegetation, and reeds support higher bird diversity. • Reeds show consistent positive effects at both 100 m and 200 m scales. • Managing semi-natural habitats boosts biodiversity without cropland reduction.