Effects Of Different Land Use Types On Species Diversity And Functional Composition Of Collembola Community In Chongming Island

Chongming Island is located at the estuarine zone of the Yangtze River and has a unique geological and geomorphological landscape with essential regional function.The predominantly agricultural land use has a profound impact on vegetation composition,soil properties,and biodiversity,making the island’s ecological environment vulnerable.Collembola are one of the most abundant and diverse soil fauna,participate in important ecological processes such as litter decomposition and nutrient cycling,and sensitive to land use changes,but there is a lack of research on Collembola in Chongming Island,especially on their functional traits.Therefore,in this study,four types of land use,including wetland,cropland,woodland and plantation,with a total of 11 sites,were selected in the eastern area,central area and western area of Chongming Island,and Collembola were sampled in May and October 2021 in both above and below ground,while soil properties were measured.The obtained Collembola were sorted,counted,made into specimens and identified,what’s more,seven functional traits of Collembola were measured: Reproduction mode,Body shape,PAO,Ocelli number,Furcula length,Antenna/body length ratio and Body length.The analysis of species composition and diversity,functional composition,community structure and soil properties of Collembola communities under different land use types led to the following conclusions:1.A total of 8 families,20 genera and 38 species of Collembola were obtained in this study.The species diversity and species composition of Collembola communities differed significantly between land use types.Higher proportion of Entomobryidae in plantation.The Sminthurididae and Katiannidae were higher in the wetland,with a high proportion of Isotomidae in below ground of cropland.Differences of Collembola density between above and below ground has opposite trends in cropland and woodland,and the species number of Collembola was higher in woodland than in cropland.Cropland has significantly lower Shannon diversity index and Margalef richness index of Collembola community than the woodland(P<0.05),while the Simpson dominance index was significantly higher than the woodland(P<0.05).2.Land use patterns have a significant impact on the functional composition of Collembola.Collembola in cropland has longer furca and antenna length,and a more cylindrical body.A higher proportion of parthenogenesis in cropland,which may be more conducive to adapted the farm environment.The wetland has a high proportion of Collembola with spherical body,short body length and relatively long antenna length.3.Vertical differences in habitat also had a significant effect on Collembola community structure.The most abundant family in above-ground Collembola community was Entomobryidae,while the most abundant family in below-ground Collembola community was Isotomidae.Collembola community in the 0～5 cm below ground showed the highest species diversity that is the highest values of Shannon diversity index,Pielou evenness index and Margalef richness index,while the lowest Simpson dominance index.In addition,the transition from above ground to below ground was accompanied by an increase individuals with fewer Ocelli number,shorter Furcula length and lower Antenna/body length ratio in Collembola community,as well as an increase individuals with parthenogenesis.4.Differences in soil properties significantly affect the species and functional composition of the community.The most abundant species in above-ground Collembola community was Homidia socia and the most abundant species in below-ground Collembola community was Folsomia sp.1,both of which had a significant positive correlation with soil nutrients(total nitrogen,total phosphorus and total organic carbon).The higher soil moisture had a significant negative correlation with some species(P<0.05).such as Isomurus balteatus above ground and Folsomides sp.1,Hypogastrura sp.1 and Papirinus sp.below ground(P<0.05).The number of individuals with a spherical body shape increases significantly at higher moisture content and bulk density and lower total phosphorus content in wetland soils(P<0.05).In summary,the species composition,diversity and functional composition of Collembola community differed significantly among different land use types on Chongming Island(P<0.05),what’s more,vertical effects and soil properties in sites also had a significant impact on the structure of Collembola community(P<0.05).The results of this study enrich the collembolan research in Chongming,and provide a basis for the scientific and rational use of land in the island.