Responses of Flowering Dogwood (Cornus florida L.) Phytobiome under Prescribed Burn Management

Prescribed burn is a critical management tool that influences the physical structure and community composition of forest plants and their associated microorganisms (phytobiome). The phytobiome often plays an important role in reducing the occurrence of plant disease and increasing nutrient availability. The effects of prescribed burn on the phytobiome of native ecologically and economically important tree species, such as Cornus florida L. (flowering dogwood), are not well understood. The objective of this study was to use 16S rRNA gene and ITS2 region sequencing to evaluate shifts in bacterial and fungal communities of five different niches (soil, roots, bark, stem, and leaves) of C. florida following a prescribed burn. Responses of bacterial and fungal species richness and diversity were niche specific, with belowground niches (soil and roots) more affected than aboveground niches (bark, stem, and leaves). This is most likely due to differences in proximity of these niches to the burn. In response to the prescribed burn, the relative abundance of ectomycorrhizal species decreased in the root niche, whereas relative abundance of saprotrophic fungi increased. Furthermore, phytobiome richness and diversity differed between sample collection years, which can be attributed to annual variation in soil physicochemical properties, temperature, and humidity. Together, prescribed burns do have an effect on phytobiome communities. Longer-term studies following prescribed burns are needed to ascertain if these observed changes may have lasting consequences, for example on the stability of mycorrhizal symbioses in C. florida trees.