Abstract: The community structure and interspecific relationships are of great significance to understand community succession and stability. Pitfall method was used to survey grounddwelling beetle communities in a desert grassland of alluvial fan in Helan Mountain from May to October in 2019. A 200 m×200 m plot was equally divided into 100 quadrats. Based on 2×2 contingency table analysis, χ² test, association coefficient, Godron method, Spearman rank correlation coefficient and principal component analysis (PCA), the interspecific association and community stability of grounddwelling beetle species were analyzed. A total of 2324 individuals belonging to 52 species, 36 genera and 11 families were collected. Pterostichus gebleri was the dominant species, accounting for 44.28% of the total individuals. The composition of dominant species was different across different months. Individual abundance showed medium variation in May, but strong variation in other months. Species richness showed medium variation in May, July and August, but strong in other months. The coefficient of variation of individual abundance and species richness was the largest in September and October, respectively. The variance ratio results showed that there was a significant positive between the interspecific associations in all months. The results of χ² test, association coefficient, and Spearman rank correlation coefficient showed the species pairs ratio of the positive and negative association were greater than 1 from May to August, and less than 1 in September and October, respectively. The relationships between dominant species and other major species were basically the same across different months. There was no significant negative correlation among congeneric species pairs. The results of Godron method analysis showed that the ground-dwelling beetle community was generally at an unstable state, while the results of PCA showed that the recovery stability of beetle community had a clear succession sequence with seasons, showing a strong resilience. Our results could provide reference for the research on the mechanism underlying ground-dwelling beetle community assemblage in desert grasslands of alluvial fans.

Key words: ground-dwelling beetle, interspecific association, community stability, small scale, alluvial fan, Helan Mountain.