Abstract: To understand the dynamics of spatial pattern of darkling beetle communities at the small scale, we surveyed the darkling beetle community using pitfall in a desert grassland of alluvial fans in Helan Mountain from May to October 2019. Based on the geostatistical analysis, we divided the 200 m×200 m study area equally into 100 grid squares and analyzed the spatial autocorrelation, spatial heterogeneity, spatial distribution pattern, and its relationship with topographic factors of the darkling beetle community. A total of 1086 individuals belonged to 10 species and 7 genera were collected. Community composition of darkling beetle had significant spatial and temporal variation. The diversity index of the community was the highest in May and lowest in July. The spatial autocorrelation of dominant species had obvious seasonal fluctuation, with a significantly spatial positive correlation in May, September, and October. Communities of darkling beetle and the dominant species showed strongly spatial heterogeneous, which were mainly determined by structural factors. The ordinary Kriging interpolation showed that the gradient distribution of beetle communities was obviously different among seasons, being the simplest in summer. The results of the cross variogram showed that the spatial relationships between different dominant species groups were mostly positive, and were mainly regulated by structural factors. Results of the canonical correspondence analysis (CCA) showed that the slope and elevation significantly affected the distribution of darkling beetles. Our results showed that the spatial heterogeneity of the darkling beetle showed significant seasonal variation, and thus provided a basis for understanding the mechanism and biodiversity of ground-dwelling beetle community in a desert grassland of alluvial fans.

Key words: Tenebrionidae, spatial heterogeneity, spatial association, topographic factor, small scale, alluvial fans, Helan Mountain