Decaying logs and gap positions jointly maintain the structure and function of soil invertebrate community in a subalpine forest

Abstract

Background and aims

Soil invertebrates are an indispensable component of forest biodiversity, and play irreplaceable roles in carbon and nutrient cycling in forest ecosystems. Although decaying logs and canopy gaps might affect the structure and function of soil invertebrate community via multiple pathways, knowledge regarding the interactive effect of decaying logs and gap positions on soil invertebrate community is limited.

Methods

Minjiang fir (Abies faxoniana) logs of decay classes I, II, III, IV, and V were simultaneously incubated on the floor from the gap center to the closed canopy in an over-mature Minjiang fir forest. After a 6-year incubation, soil invertebrate communities in the litter and topsoil layers beneath and away from logs were investigated in the growing season.

Results

Soil invertebrate taxa compositions beneath logs differed from those away from logs. Invertebrate densities in the litter and topsoil were significantly higher in microhabitats away from logs than those beneath early- and highly-decayed logs. Meanwhile, the Shannon–Wiener index of invertebrate communities in the litter and topsoil was significantly higher beneath the middle-decayed logs. Furthermore, invertebrate densities and the Shannon–Wiener index in the litter and topsoil markedly increased from the gap center to the closed canopy. Additionally, densities of fungivores and detritivores beneath logs were markedly lower than those away from logs, and densities of fungivores and omnivores increased significantly from the gap center to the closed canopy.

Conclusion

Decaying logs and gap positions jointly mediate the structure and function of soil invertebrate communities, implying that reserving logs and intermediate gap disturbances are crucial for maintaining soil biodiversity in the subalpine forest.