Forest Development Alters the Compositions and Structures of Soil Macrofauna Communities in Reclaimed Coastal Lands

Soil fauna is integral to facilitating material cycles, energy flows, and the conservation of biodiversity in terrestrial ecosystems. However, the impacts of forest development on the compositions and structures of surface soil macrofauna remain uncertain. Here, we assessed the dynamics in abundance and diversity of soil macrofauna across eight successional age stages of Metasequoia glyptostroboides tree plantations (7-, 16-, 21-, 26-, 31-, 36-, 41-, 46-year-old stands) in a reclaimed coastal land in China. The results revealed that the total abundance of soil macrofauna initially decreased during the young to near-mature stand period (7- to 31-year-old stands), whereas it increased along the age series, from the near-mature to overmature stand period (31- to 46-year-old stands). Specifically, the dynamics showed a U-shaped curve with stand development. Further, there was a significantly negative correlation between the Shannon-Wiener diversity index and the total abundance of soil macrofauna across this plantation chronosequence. The variations in abundance of detritivores were consistent with the total abundance of soil macrofauna during stand development. The abundance and diversity of the soil macrofauna were strongly correlated with the soil environment (e.g., soil organic carbon, litter biomass, and microbial biomass nitrogen). These findings highlight that the compositions and structures of soil macrofauna were significantly altered with M. glyptostroboides stand development. This provides important insights for studying the interconnection of above- and belowground plantation ecosystems toward their optimal management.