Research On Insect Community Structure And Biodiversity In Urban Green Space In Chengdu

From June to October 2020 and from May to October 2021,the methods of sweeping nets,net trapping,searching,visual inspection and vibrating off were used to investigate the insect community functional groups of three functional green spaces(Green lands of parks,Productive plantation area and Road green space)in Chengdu.The structure and biodiversity were investigated and analyzed,and the main results were as follows:1.A total of 66483 specimens were observed and collected in two years,belonging to974 species of 17 orders,148 families.Diptera,Hemiptera and Hymenoptera are not only the dominant groups of the three functional green spaces,but also the dominant groups of the entire urban green space in Chengdu.In the three habitats,the number of insect species and individuals from high to low are: Productive plantation area > Green lands of parks >Road green space;the individual numbers of insect subcommunities in the three habitats from high to low are: Phytophagous insects(Ph)> Neutral insects(Ne)> Predatory insects(Pr)> Parasitic insects(Pa)Among the 7 functional groups,leaf-eating,bud-eating,piercing-sucking,neutral and predatory insects are the dominant functional groups in the three green spaces;Parasitic species were the dominant functional in Road green space,and common functional in Park green space and Production green space.2.The results of functional group community characteristics showed that the functional group structure of insect communities in different green space types was relatively similar,and the population distribution was uniform and the degree of dispersion was basically the same.The richness,dominance and diversity of Road green space are the lowest,and the community structure is the simplest.In the whole urban green space,the richness of Ph is generally higher than that of Pa,Pr,and Ne;the overall trend of the temporal and dynamic changes of the functional group richness of insect communities in each green space is consistent,showing a trend of first increasing and then decreasing.The dominant taxa of each functional group in different green spaces in two years showed great changes with seasonal changes.The population dynamics of natural enemy insects and herbivorous insects did not have an obvious follow-up effect.The insect community structure of Park green space and Production green space is relatively similar.The two indicators of Ss/Si and Sn/Sp indicated that September and October were the most stable periods for insect communities in the three habitats.3.The results of principal component analysis showed that the dominant factors of green space with different functions were different,but the herbivorous and parasitic groups were the main components of the insect community among the four groups.The analysis of the space-time niche of each functional group showed that leaf-eating,bud-eating,and parasitic insects occupy obvious space-time advantages and make the most full use of the resources of each green space.Stem-boring insects with a single host plant and a small distribution range are at a disadvantage in the spatiotemporal niche.Except stem-boring insects,other herbivorous insects have high niche overlap with predatory and parasitic insects,and their populations have strong temporal and spatial synchronization,which can effectively control the outbreak of pests.The functional groups of the phytophagous subcommunity have a high niche overlap,and there is fierce competition for space-time resources among them.To sum up,the diversity of insect species in urban green space in Chengdu is relatively rich,the composition of insect communities in Park green space and Production green space is relatively similar,and the community structure of Road green space is the simplest.There was no significant difference in the structural characteristics of the functional groups of the three species of green insects,and the overall trend of the temporal changes of functional group richness was basically the same.Different green space dominant groups showed great changes with seasonal changes;the three kinds of green space herbivorous insects and natural enemy insect populations had strong temporal and spatial synchronization,which played a certain role in maintaining the stability of insect communities.Although the vegetation types,management modes and human disturbance of different green spaces all affect the species composition and diversity of insects,the insect community structure of different green space types is different,but all have high insect diversity.Therefore,rational planning of green space is crucial for green space management and biodiversity conservation.