The effect of introduced canopy tree species on the soil microbial community in a montane tropical forest

Within a single site in the Kohala Forest Reserve, Hawai`i, we examined the composition and diversity of soil microbial communities under four introduced (Cryptomeria japonica, Casuarina equisetifolia, Araucaria columnaris, and Eucalyptus sp.) and one native (Metrosideros polymorpha) canopy tree species, as well as pasture. Terminal restriction fragment length polymorphism (T-RFLP) analysis of soil bacteria, fungi and archaea indicated that soil under the native M. polymorpha had the highest richness and greatest number of unique terminal restriction fragments, whereas Eucalyptus and pasture sites had the lowest richness. The soil microbial community differed significantly between Eucalyptus and M. polymorpha, but not between the other three introduced species and M. polymorpha. The Eucalyptus microbial community was more similar to an adjacent deforested pasture site than to other forested stands. Soil pH was the environmental variable that best correlated with the variation in soil microbial community composition between tree species (r=0.89, p<0.001). * Corresponding author. E-mail: [email protected]