Study On Effects Of Anthropogenic Disturbance On Community Characteristics In Pollinators

With the rapid urbanization across China,the human disturbance has become one of the major factors affecting the agricultural ecosystem and its functions.Different degrees of human disturbance make different effects on the original living environment,species composition and competitiveness inside the pollinating insect community,and lead to different changes in the original niche characteristics of the dominant species in the community,thus resulting in varying degrees of changes in biodiversity level.Biodiversity in agricultural landscapes provides all ecosystem services such as pollination services,pest control,disease prevention,and food supply,which is also the key factor to maintain a stable ecosystem.Pollinating insects are the main pollinators and important part of the agroecosystem.Their pollination activities can compensate the time-space niche.Therefore,accurate evaluation of the effect of human disturbance on the pollinating insect community has drawn wide attention.Taking Gongyi city in Henan Province as the research area,this study has extracted data source with the resolution of 1m of Gongyi for manual visual interpretation.The research area can be divided into 7landscape types,including forest land,shrub,farmland,water area,highway,residential area,and other landscapes.Based on the classification of landscapes and actual conditions,the intensity of the disturbance with the landscapes has been classified as low level,middle level and high level according to the human disturbance index assignment table and the calculation formula of disturbance intensity.In the sample area with different levels of disturbance intensity,the intensity of the disturbance with landscapes is studied to obtain the human disturbance distribution map of Gongyi.In May 2017,the colors pan traps were used in this study to sample pollinating insects within Gongyi.Meanwhile,the method of sampling 1*1 m~2 of the Braun-Blanquet was adopted to investigate the plant communities surrounding the pollinating insects and analyze the effect of human disturbance on the species diversity of pollinating insects and on the niche of dominant pollinating insect species in different sample areas.This study used the GIS10.3 software to process and analyze the landscape data,the R software to analyze the species diversity data,the SPSS.20 to carry out cluster analysis of niche breadth,and the Excel platform software for mapping.The effects of different levels of disturbance intensity on pollinating insect communities were explored,with main findings as follows:(1)In this study,15,431 pollinating insects in 6 orders,Diptera,Hymenoptera,Coleoptera,Lepidoptera,Hemiptera and Thysanoptera,and 134 families were captured.Among them,6,471 dipterans,6,098 hymenopterans,and 1,141 coleopterans are the main pollinators,respectively accounting for 34.83%,32.82%,and 6.14%of the total number of insects captured.The rest pollinating insect species account for8.88%.Among the samples captured,the dominant pollinating insect species are Vespidae and Ceratopogonidae.The common species include Syrphidae,Calliphoridae,Mycetophilidae,Daphnia,Sarcophagidae,Vespidae,Apoidea,Braconid and Scarabaeus.(2)Among the three levels of disturbance intensity,there is a significant difference in the species diversity of pollinating insects(P<0.05).The ranking of species diversity of Diptera under different levels of human disturbance intensity is low level>high level>middle level.For Hymenoptera,the ranking of a diversity index is middle level>low level>high level,and the ranking of evenness index and diversity index both is middle level>high level>low level.The diversity index of Coleoptera is significantly reduced with the increasing disturbance intensity.(3)The niche breadth of different families of pollinating insects changes differently with the increasing disturbance intensity.In the Diptera community,Calliphoridae shows a lower niche breadth and a narrower adaption range with the increasing human disturbance,while Ceratopogonidae and Mycetophilidae show a higher niche breadth.The niche breadth of Daphnia and Syrphidae increases first and declines later with the increasing disturbance intensity.Under different levels of disturbance intensity,Vespidae,as the representative of Hymenoptera,always ranks top in niche breadth,and plays a critical role.The niche breadth of Apoidea increases with the increasing disturbance intensity,while that of Braconid shows opposite results.The niche breadth of Scarabaeus in Coleoptera is always seen at the bottom of the list.(4)The niche overlap value of different families of pollinating insects changes differently with the increasing disturbance intensity,but there is no significant correlation between niche breadth and niche overlap in pollinating insect species.In the Diptera community,the mean value of niche overlap of all species increases first and declines later with the increasing human disturbance intensity,and the niche overlap value of Ceratopogonidae,Syrphidae and Daphnia reaches the highest under the middle level of disturbance intensity.In the Hymenoptera community,the mean value of niche overlap of Vespidae and other species ranks as middle level>low level>high level,the niche overlap value of Braconid reaches the highest under middle level of disturbance,that of Apoidea keeps increasing with higher and higher disturbance intensity,and that of Scarabaeus in Coleoptera has few changes under low,middle and high level of disturbance intensity.