How tree diversity affects soil fauna diversity: A review

Our statistical analyses showed no evidence of any general trend for the effect of mixture either on earthworm or microarthropod diversity or on their abundance. Indeed, positive, negative and non-significant effects have all been reported. Nevertheless, the majority of the studies did find that increased tree richness or the introduction of broad-leaves had a positive effect. In addition, our review shows that soil organism abundance and diversity can be strongly affected by the presence of certain tree species and that the soil organism community structure is, in most cases, significantly affected by an increase in tree richness or by a mixing effect. Litter features appear to be important drivers of soil fauna community composition, while mixture effect seems to have less impact on soil biota. Soil fauna are directly affected by the physical characteristics (microhabitats) and chemical composition (resource quality) of the litter specific to each tree species. Soil communities are then indirectly affected by the subsequent humus characteristics. We conclude our review with some guidelines for forest management and further research.