Study On The Effects Of Landscape Heterogeneity On The Diversity Of Pollinators In The Mountainous Region

Biodiversity is a guarantee for the existence of human society,and is also one of the key factors supporting the ecosystem function.Meanwhile,biodiversity play a major role in maintaining the sustainable agriculture landscape.Landscape heterogeneity is the variability of landscape elements in the spatial structure,and it affects the function and process of the ecosystem,such as energy flow,species flow,water flow,pest transmission and soil fertility.In recent years,with the increase of human population and intensive agriculture,the landscape structure has been greatly simplified,which results in the sharp decline of biodiversity.Insects are diverse,abundant and the most important pollinators for many crops to ensure crop production and food security.However,the exotic species invasion,climatic and environmental change and the intensive land utilization threaten the diversity of pollinators.In this study,we explored the effects of landscape heterogeneity on the diversity of pollinators in mountainous areas of western Henan Province.First,we extracted Google Earth data sources with 1 m resolution in the study area for artificial visual interpretation,and divided it into natural and semi-natural area(orchard,woodland,grassland and bare land),water area(river,reservoir,pond and ditch),artificial area(urban land,constructing land,rural land,road,and industries land)and agricultural area(farmland).Second,landscape heterogeneity was studied in seven spatial scales of 100,250,350,500,750,1000 and 1200 m radius around each sites.Colors pan traps were used to sample the pollinators both in the spring and autumn of 2016.The vegetation communities were also investigated in each plot.The effects of landscape heterogeneity on pollinator communities and the seasonal dynamic characteristics of pollinators at different special scales were analyzed.We used ArcGIS 10.2 and Fragstats 4.1 to calculate landscape variables,and analyze the effect of landscape structure on pollinator insect communities using multiple linear regression and nonlinear regression models in Past v3.10 to.Additionally,the relationship between pollinator insect communities composition and environmental variables was analyzed using RDA in R 3.1.3.The results showed that(1)A total of 46,092 insects were captured in spring and autumn.Among them,40,464 were pollinating insects,belonging to 85 families of 6 orders(Lepidoptera,Hymenoptera,Diptera,Thysanoptera,Coleoptera and Hemiptera).The main orders were Diptera(18274,45.16%),Hymenoptera(16737,41.36%),Coleoptera(3460,8.55%)and Lepidoptera(1088,2.69%).The dominant families included Vespidae and Anthomyiidae(23.08%).The individuals of Bombyliidae,Gyrinidae,Drosophilidae,Hydrophilidae,Halictidae,Tachinidae,Andrenidae,Calliphoridae,Chalalcididae,Sphecidae,Syrphidae,Apidae,Colletidae,Agromyzidae,Cantharidae and Cynipidae accounted for 54.74% together.Other rare families were 22.18%.(2)In general,the Shannon diversity,Pielou evenness and Margalef richness of pollinating insects were the highest in hilly,followed by valley plain,and the lowest in farmland.The diversity of pollinators in hilly areas was significantly different between the mountain and valley plains(P<0.05),and the dominance in mountainous areas was significantly higher than that of hills(P<0.05).(3)Pollinating insect communities were affected by seasons,and the pollinator communities varied among habitat types greatly,which led to the change of species composition,distribution and life characteristics.The range of S?rensen similarity coefficient and Jaccard similarity coefficient ranged from 62.32% to 72.34% and 45.26% to 56.67%,respectively,and both of them showed that the similarity of pollinating insect communities in mountainous areas is the highest,followed by hills,while the similarity of pollinating insect communities in valley plains was low in spring and autumn.With the change of seasons,the important values of Anthomyiidae in spring and autumn were the highest,followed by Vespidae.(4)The composition of the pollinator communities in the hilly areas was significantly different from that in the mountainous areas and valley plains(P<0.05),but there was no significant difference between the mountainous areas and valley plains.Among the seven environmental factors studied,only coverage of trees and altitude had significant effects on pollinator insect communities diversity(P<0.05).Lepidoptera,Hymenoptera and Diptera were positively correlated with altitude,and were negatively correlated with tree layer coverage,but Coleoptera was negatively correlated with altitude.(5)The relationship between biodiversity and landscape heterogeneity varied at different spatial scales.In the study area,the patch density decreased with the increase of the special scales,but both patch richness and Shannon's diversity showed the opposite trend,and the contagion index without significant difference.The correlation between pollinator insect diversity and landscape index was the highest in the 500 m.There was a significant correlation between the patch density and the abundance,richness,diversity and dominance index of pollinating insects(P<0.05).Moreover,the patch richness and the diversity and evenness of pollinating insects were correlated significantly(P<0.05).In summary,in order to maintain the diversity of pollinating insects,it is critical to protect the natural and semi-natural areas,but not to excessively expand the agricultural areas and artificial areas.However,it may be beneficial for pollinators to appropriately increase the interference.