Soil arthropods make an important contribution to litter decomposition in both indigenous and plantation forests

Declines in biodiversity can disrupt ecosystem functioning. Yet, for soil ecosystems, which are rich reservoirs of biodiversity, we have a limited understanding of the consequences of soil biodiversity loss to ecosystem functioning. We assessed soil arthropod diversity in South African Eucalyptus plantations and nearby indigenous forests and estimated the contribution of arthropods to litter breakdown with an arthropod suppression experiment over a 13-month period. Litter bags in tree plantations attracted significantly lower arthropod species richness and abundance, and assemblages with different species composition compared to those in indigenous forests. Overall litter decomposition did not differ between the two biotopes. In both biotopes, arthropods made a significant contribution to litter decomposition, increasing it by 12 %. These results show that the altered soil arthropod assemblages in plantations still support an important ecosystem function, and management aimed at conserving this biodiversity will benefit plantation soil resilience. Furthermore, maintenance of natural habitats is critical for conserving indigenous soil biodiversity in these landscape mosaics.