| Biodiversity is the link between landscape pattern and ecosystem services,biodiversity plays an important role in the process of human survival and social sustainable development.In agricultural system,soil animal diversity has the functions of improving soil structure and properties,promoting material circulation and energy flow,inhibiting pests and diseases,and maintaining ecological balance.Soil fauna have short generational cycle,strong reproductive capacity,and are sensitive to changes in the surrounding environment.They can quickly reflect the changes of some environmental factors in the ecosystem.They are often used as environmental indicators in agricultural ecosystems.They are important biological indicators in ecosystem health assessment,ecosystem restoration and reconstruction,and biodiversity conservation.However,in recent years,due to the change of agricultural landscape pattern,the diversity of soil animals has declined and the ecological function of soil animals has been reduced.To explore the response of soil animal diversity and feeding activity to multi-scale landscape heterogeneity,we established a study area in Gongyi County,Henan Province,Which is a typical agricultural regionin the middle and lower reaches of the Yellow River.Twenty-four sample sites were set up in the study area.According to the geomorphological characteristics of each site,they were divided into three types: mountain,hill and river plain.The representative habitat types in each sample site were selected,including farmland(NT),plantation(RGL),natural forest(ZRL)or shrub(GC)for arthropod community investigation and biological feeding activity research.Soil fauna were sampled in spring(7-12 May)and summer(13-15 September)of 2017 using soil sampling rings and Tullgren funnels method.The spatial distribution of the composition and diversity of soil fauna community in different habitats and geomorphological areas,and the temporal dynamics in spring and summer were analyzed.Based on the landscape characteristic index(CONTAG)of different radius buffer zones(25 m,50 m,100 m,150 m,200 m,250 m,500 m)centered on 24 sample points,the characteristic scale of soil fauna response was studied and illustrated.The effects of multi-scale heterogeneity of habitats,landscapes andlandscapes on diversity and feeding activity of soil fauna were discussed.The main results are as follows:(1)There are significant differences in the composition and diversity of soil fauna communities in different habitats and geomorphological regions.In summer,6335 soil fauna were captured in mountainous area,belonging to 51 groups.There are endemic species in different habitats,among which shrubs can maintain more abundant endemic species than other three habitats.The diversity of soil fauna in different habitats showed that the number of shrubs was significantly higher than that in farmland,plantation and natural forest(P < 0.05),and the Margalef richness index also showed the same trend.The Margalef richness index of shrubs was significantly different from that of the other three habitats(P < 0.05).The Simpson index of farmland,plantation and natural forest was higher than that of shrubs,among which farmland,artificial forest and natural forest were higher than that of shrubs.Simpson index of plantation and shrub had significant difference,but there was no significant difference in Simpson index between natural forest and shrub(P >0.05).In addition,the number of groups,individuals and species richness index of plantation in the area were lower than those of farmland.The number of common groups in natural forest in hilly area is lower than that in farmland,plantation and shrub.The general trend of the groups is: plantation > farmland >shrub > Natural forest.There are endemic species of different groups between farmland and plantation habitats.The results of diversity analysis showed that the number of soil fauna and Margalef richness index in shrubs still showed their advantages.As a natural habitat,shrubs have higher vegetation coverage,richer species types and less disturbance from human activities than other three habitats.Therefore,shrubs have more prominent advantages in maintaining non-agricultural biodiversity.The dominant and common groups of farmland and plantation in the river plain are not significantly different.Rare groups are the main reasons for the differences between the two habitats.The individual number and diversity index of farmland were higher than those of plantation habitat,and the Shannon index of farmland and plantation had significant difference(P < 0.05).(2)Through the analysis of soil animal diversity characteristics in different geomorphological areas of the same habitat,it was found that the evenness index of mountain areawas significantly higher than that of river plain and hill in farmland and plantation;Shannon index of mountain area was significantly higher than that of hill area in natural forest;and the number of mountain area was significantly higher than that of hill area in shrub area.Mountain areas play an active role in maintaining soil animal diversity.(3)There are seasonal differences in the composition and diversity of soil fauna communities.The abundance and taxa of soil fauna in spring were higher than those in summer.In summer,there are some large soil arthropods,including Hymenoptera,Diptera and Lepidoptera,such as Scarabaeoidea,Drosophilidae and Gelechiidae,which are rare in spring.In addition,some taxa only appeared in summer,such as Calliphoridae,Chironomidae,Gelechiidae and Pselaphidae.The main reason for the higher abundance in spring than in summer is that the number dominance of the suborder Prostigmata is particularly obvious in spring.The diversity between spring and summer is generally higher in summer than in spring,which is typical in mountain shrubs and plain plantations.(4)Soil animal diversity responds differently to landscape heterogeneity,landscape heterogeneity and habitat heterogeneity at multiple scales.The correlation between landscape index and soil animal diversity index is the most significant in the 150 m buffer zone,so 150 m is the characteristic response scale of soil animal diversity.Multiscale analysis of soil animal diversity showed that landforms and habitats had significant impacts on soil animal diversity,and the interaction between habitats and landscapes had the most significant impact on soil animal diversity.In the multi-scale analysis of the influence of soil fauna feeding activity,it was found that it was mainly affected by landform and habitat scale.In addition,the feeding activity of soil fauna in hilly plantation was higher than that in farmland(P < 0.05),which was consistent with the results of soil fauna and Margalef richness index in hilly plantation and farmland.Although there was no significant difference in feeding activity between mountain and river plain,the feeding activity of soil animals in farmland was higher than that in plantation. |
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