Key drivers of soil arthropod community shift across a subalpine forest series vary greatly with litter and topsoil layers

Soil arthropods play crucial roles in carbon and nutrient cycling in forest ecosystems. The structure and biodiversity of soil arthropod communities may vary considerably with forest succession and across soil layers due to changes in key drivers, which needs to be fully investigated. Arthropod communities in both litter and topsoil (0–5 cm) layers were simultaneously investigated in the subalpine deciduous broadleaved shrub (S1) and forest (S2), coniferous and broadleaved mixed forest (S3), and half-mature (S4), mature (S5), and overmature (S6) coniferous forests in Wanglang National Nature Reserve. The dominant taxa and common taxa in litter and topsoil layers shifted with forest succession. The litter layer had the most fungivores and saprophages, while the topsoil layer had the most saprophages. From S1 to S4, individual densities and functional groups of soil arthropod declined, then increased continuously. The Shannon-Wiener index, Pielou index, and Margalef index of arthropod communities in litter and topsoil layers declined from S1 (S2) to S4, then increased; for each functional group in the topsoil layer, these indices varied more significantly with forest succession than those in the litter layer. The structure and diversity of the soil arthropod community in the litter layer were significantly influenced by coarse woody debris stock, and those in the topsoil layer were significantly influenced by canopy density and the C/N ratio, based on RDA analysis. In conclusion, the key drivers of arthropod community shift with forest succession differed between litter and topsoil layers, which allowed arthropod communities to show different sensitivity to the environment change. This study contributes to an in-depth understanding of the ecological impact of forest succession changes on soil arthropods.