LAUSR

Abstract Farmland is one of the most important ecosystems in the world, providing foods and habitats for humans as well as many wild animals. However, biodiversity in farmlands has been substantially impacted by the intensification of agriculture and changes in landscape. Increasing either the area of natural and semi-natural habitat or the proportion of biodiversity-friendly crops could potentially mitigate the decline of biodiversity, but at the same time they would affect the agricultural economic output and were not widely applied. To date, some studies have focused on whether crops or cropland heterogeneity has a positive impact on biodiversity, but the results were inconsistent and it is difficult to summarize the relationship between farmland heterogeneity and farmland biodiversity in general. Meanwhile, few papers have studied the differences in bird diversity among small-scale agriculture in China. We conducted a year-long field survey on the Chengdu Plain to explore the relationships of landscape composition and the heterogeneity of cropland and non-cropland with bird diversity and community structure across different seasons. Using generalized linear models (GLM) and generalized least squares (GLS) for data analysis, our results showed that bird diversity is positively correlated with natural woodlands but negatively correlated with commercial forests. Both crop and non-crop landscape compositional heterogeneity affect bird diversity and community structure, especially during the non-breeding season, as many high-altitude birds come down to the farmland for foraging. Both bird diversity and community structure are influenced by cropland configurational heterogeneity, but seldomly influenced by non-cropland configurational heterogeneity. We propose to maintain the area of natural habitat and increase the area of mixed commercial forests by replacing monocultures. Diversified crop and non-crop types with a reasonable layout could conserve farmland biodiversity and maintain the stability of local ecosystems. More research on landscape heterogeneity in small-scale agriculture is needed to provide better understanding of the relationship between the agricultural landscape and bird diversity.