Effect of tree mixture on Collembola diversity and community structure in temperate broadleaf and coniferous forests

Springtails (Collembola) are the most abundant arthropods in terrestrial ecosystems and, are considered as key indicators of organic matter turnover and soil functioning. Mixture of tree species are often regarded as a mean to improve tree growth, soil fertility and biodiversity. We compared alpha-diversity, taxonomic beta-diversity and functional diversity of Collembola of mixed forest stands to pure stands in two forest sites, a mountain and a lowland site composed of a coniferous and a deciduous species for effect on. We choose sessile oak (Quercus petraea) and Scot pine (Pinus sylvestris) in lowland, and beech (Fagus sylvatica) and silver fir (Abies alba) in mountain stands. In total 41 species Collembola were identified. We showed that richness and abundance in mixed stands were in between those found in the pure stands, with a more pronounced response of the soil fauna in lowland compared to mountain. In the lowland, Shannon diversity index followed the same pattern, and we found species richness from 6.3 to 11.7 mean species, and 4400 to 9000 ind.m(-2), dominated by epedaphic group. In the mountain, we found species richness from 7 to 9 mean species, and 6600 to 103,000 ind.m(-2), dominated by euedaphic group. Among the 12 soil and litter characteristics, many differs between sites and/or stand type. The best predictors of the model explaining differences in mean Collembola were litter chemical composition including the lignin to N ratio and C to N ratio. Soil characteristics, such as humus index, organic layer thickness or pH, was also a good predictors for some life-forms and one or the other site. In addition, mixture modified Collembola community structure with some species found only in the pure stands. Jaccard similarity index showed that mixture, even composed of different tree species, homogenized Collembola community structure. We conclude that mixture of tree species in temperate forests can locally increase Collembola diversity, but this management should not be generalized to maximize the beta-diversity.

Automated summary

The study found that mixture of tree species can increase the diversity of Collembola, and the soil fauna response differs between lowland and mountain sites.