| Ground-dwelling beetles are sensitive to habitat changes and play an important role in maintaining biodiversity and ecosystem function.The desert grassland of the alluvial fan at the eastern piedmont of Helan Mountain is a transition section of Helan Mountain-Yinchuan plain ecosystem,the ecosystem is very fragile,and the research on the spatial distribution characteristics of surface beetle diversity and its relationship with environmental factors in this region is obviously lacking.In this study,three plots(CQK1,CQK2 and CQK3)of 200m×200m were set along an elevation gradient in the alluvial fan desert grassland of Chaqikou,Helan Mountain.The corresponding altitude is 1515m,1417m and 1252m,respectively,the investigation time is from May to October 2019,once a month,each time the trap is placed in the wild 7 daysThe community structure of surface beetle community was investigated,and the spatial distribution characteristics of the diversity of surface beetle community and its relationship with environmental factors were discussed.The aim of this study was to provide a scientific basis for further study on the evolution of beetle community and its key role in habitat restoration in the desert grassland of Helan Mountain.The main results and conclusions of this study are as follows:1.A total of 5819 individuals belonged to 78 species,54 genera and 14 families were collected.Among them,the dominant species were Pterostichus gebleri and Microdera kraatzi kraatzi,Protaetia brevitarsis,Anatolica pandaroides and Anatolica planata 3 species are secondary advantages,Harpalus salinusetc.12 belong to common species.The species composition of CQK1 and CQK2 ground-dwelling beetle communities was more similar.Activity peak period in June to August of ground-dwelling beetles,and the number of individuals in each of them was CQK3>CQK2>CQK1,number of species and Margalef richness index were CQK2>CQK1>CQK3,The size order of Shannon-Wiener diversity index and Pielou evenness index were CQK1>CQK2>CQK3,Simpson diversity index was CQK3>CQK1>CQK2.2.The spatiotemporal dynamic analysis of ground-dwelling beetles at small scale showed that the spatial autocorrelation and community space heterogeneity of beetles had obvious seasonal volatility.The highest proportion of positive spatial autocorrelation was found among beetles communities of CQK1 in May,CQK2 in August and CQK3 in August.Species interpretation was highly spatial correlation and was controlled by major structural factors.Pterostichus gebleri and Microdera kraatzi showed positive spatial correlation between the other species and controlled by structural factors.The results of semi-variance function fitting showed that structural factors were the main factors that caused the spatial pattern of the beetle community in a different month.Ordinary Kriging interpolation showed that the beetles in the three plots in May showed a uniform distribution of high density,and an obvious mosaic distribution of high and low density patches in other months.3.Studies on the relationship between the spatial distribution of beetle community diversity and environmental factors showed that elevation(E),vegetation coverage(VC),soil phosphorus content(P),slope aspect(SA),slope gradient(S),soil bulk density(SBD),plant diversity(PD),soil water content(SWC)and plane curvature(PLC)were the main factors affecting the spatial distribution of beetle community diversity.Different environmental factors had different effects on the spatial distribution of beetle community diversity from different plots.GAM showed that the number of beetle individuals and species in CQK1 were positively correlated with topography humidity index(TWI)and slope aspect(SA),respectively.In CQK2,there was a positive correlation between the number of beetle species and altitude.The individual of beetles in CQK3 was positively correlated with plant height(VH),plant coverage(VC)and profile curvature(PRC),the number of species is positively correlated with plant species richness(PSR). |
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