Comparison of ground arthropod diversity in the Picea crassifolia forest and the alpine steppe on the northern slope of the Qilian Mountains

AbstractThe forest–steppe zone of the Qilian Mountains displays a mosaic of habitats, comprising Picea crassifolia forest (PCF) and alpine steppe (AS), at mid‐elevation. This mosaic has a significant impact on the distribution and response pattern of ground arthropod diversity to increases in elevation. The present study was conducted in the Dayekou watershed, situated on the northern slope of the Qilian Mountains. The investigation of ground arthropods employed pitfall trapping techniques during the period between July and August 2021 in PCF and AS habitats with varying elevation gradients. The results demonstrated significant differences in the ground arthropod assemblage between the PCF and AS habitats. Altitudinal variations were also found to influence the compositions of ground arthropods in both habitat types. However, the abundance and diversity of ground arthropods were markedly higher in PCF habitats than in AS habitats. Furthermore, trends in the evenness index of ground arthropods across vegetation habitats were inversely related to trends in abundance and diversity. Among the 12 identified major families of ground arthropods, three (Lithobiidae, Phalangiidae and Staphylinidae) were predominantly associated with PCF habitats, while five (Lycosidae, Arcypteridae, Lygaeidae, Formicidae and Carabidae) were primarily found in AS habitats. The capture rates of the remaining four families varied little between the two habitat types. The results of a co‐occurrence network analysis of these 12 major ground arthropod families indicated that, evolutionarily, predatory arthropods in PCF habitats were closer to other arthropod taxa than were those in AS habitats, suggesting a more complex community structure of ground arthropods in PCF habitats. Additionally, the results of a redundancy analysis indicated that the tree canopy density, shrub cover, herbaceous cover and species richness were the primary factors influencing the assemblage of ground arthropods in both PCF and AS habitats; collectively, these factors accounted for 75.9% of the observed variation in ground arthropod populations. In conclusion, the distribution patterns of ground arthropods on the northern slopes of the Qilian Mountains were found to be significantly influenced by changes in vegetation type, whereas variations in altitude within the same vegetation type appeared to have a lesser effect on these patterns.