| Due to the increasing demand for agricultural land,biodiversity in China has faced losses.Our goal in this study is to evaluate how agriculturalization influences bird communities.We conducted field surveys from October 2020-October 2021 in three different habitats: forest;agricultural land close to the forest;agricultural land far to the forest.In total,we surveyed bird communities in 180 plots and then repeated the survey for each plot in each season(spring,summer,autumn and winter).All plots were one of three different national nature reserves in Guangxi Zhuang Autonomous Region: Dayaoshan,Damingshan and Shiwandashan.The results are as follows:(1)The species accumulation curve of each habitat increased at a decreasing rate.The ratio of each habitat’s recorded species richness to the estimated species richness was larger than 60%,indicating that sufficient sampling was conducted.(2)We recorded 103 species belonging to 8 genera and 34 families in the forest,101 species belonging to 12 genera and 41 families in the AG-close,94 species belonging to 11 genera and 37 families in the AG-far.Similarity analysis indicated that species composition was more similar between the two agricultural habitats,and both were different from forests in different seasons.Agricultural plots far from the forest had on average the highest Shannon-Wiener diversity index,while forest plots had the lowest in different seasons.A total of 196 species,belonging to 14 genera and 54 families,were recorded in three different habitats,including 29 species of national Class II key protected wild animals.Passerine birds accounted for the highest proportion of recorded species,with 139 species accounting for 71%.In order of different types of bird residence,132 species of resident birds accounted for 67.35%,34 species of winter visitors accounted for17.35%,21 species of summer visitors accounted for 10.71%,9 species of passing migrants accounted for 4.59%.(3)The species and individual numbers of birds in forest,AG-close and AGfar were significantly different in each season.The results of the generalized linear mixed model indicated that the bird diversity in each plot per survey in both AGfar and AG-close was significantly higher than in forest but there was no difference between the two agricultural habitats.(4)The correlation analysis between species and individuals of birds of different habitat preferences in different habitats of forest,AG-close and AG-far showed that species were highly correlated with individuals.The diversity of birds of different habitat preferences in different habitats based on the generalized linear mixed model shows that: The number of species and individuals of forest interiors in the forest habitat were significantly higher than those in the two agricultural habitats,but there was no significant difference between AG-close and AG-far;The species and individuals of generalists and open species in two agricultural habitats were significantly higher than in the forest,and there was no significant difference between the two agricultural habitats;The species and individuals of waterfowl in AG-far were significantly higher than those in AG-close but waterfowl are not recorded in the forest.(5)The correlation analysis between species and individuals of birds of different diets in different habitats of forest,AG-close and AG-far showed that species were highly correlated with individuals.The diversity of birds of different diets in different habitats based on the generalized linear mixed model shows that:The species and individuals of carnivorous birds in two agricultural habitats were significantly higher than in the forest,those in the AG-far significantly higher than in the AG-close;There were no significant difference of species and individuals between two agricultural habitats,and granivores birds are not distributed in the forest;The species and individuals of honeyeaters in forest were significantly higher than those in two agricultural habitats,but there was no significant difference in species and individuals between two agricultural habitats;The species and individuals of insectivorous birds and herbivores were significantly higher in the two agricultural habitats than in the forest,but there was no significant difference between AG-close and AG-far;Frugivore birds were found only in forest habitats,but were not recorded in two agricultural habitats;The omnivores species was significantly higher in two agricultural habitats than in forests,but there was no significant difference between two agricultural habitats,and no significant difference in individuals of omnivores between two agricultural habitats,and also between AG-close and forests,but the individuals of omnivore in AG-far was significantly higher than forest.Conclusion: In terms of bird diversity in habitat preferences,forests play an irreplaceable role in maintaining the normal life history activities of species within forests and providing habitat for generalist,agricultural habitat provides an extremely important habitat and foraging environment for open species,generalist and waterfowl.In the diversity of different bird diets,carnivores,insectivores,granivores,omnivores,and herbivores showed a higher preference for agricultural habitat,and the diversity of carnivores was higher in AG-far with a higher degree of agriculture,granivores only choose to inhabit agricultural habitats,honeyeaters and frugivores only distributed in forests with dense vegetation and high shade,indicating that these two types of birds with different diets had extremely strict requirements on habitat.The results showed that although the diversity of birds in two agricultural habitats was higher than that in forest to some extent,but the similarity of bird communities in the forest and agricultural habitats was low and it was difficult to replace each other,indicating that different land-use types provided different environments for different birds to inhabit.Therefore,when the birds protection plan cannot partiality,should strengthen the protection of endemic to highly dependent on the forest,to maintain its rarity,for the food resources are relatively abundant,high degree of agricultural,human disturbance strong live birds in the agricultural habitat,suggests that in the process of agricultural land use,as much as possible to retain the original vegetation environment,especially in non-crop areas,Such as roads and around villages,creating conditions for agricultural bird diversity to be maintained. |
