Plant-soil feedbacks differ in intact and tornado-damaged areas of the southern Appalachian mountains, USA

Abstract

Plant-soil feedbacks (PSF) greatly influence forest community structure and diversity. However, it remains unknown how feedbacks change after disturbances. Biotic and abiotic changes reduce soil microbial diversity after a severe disturbance. These post-disturbance changes may create neutral PSF. We examine a) differences in performance of three seedlings of southern Appalachian tree species in same-species and different-species soil and b) whether the relationship differs between intact forest and wind-damaged patches, as well as c) test mycorrhizal colonization rate as a potential mechanism. In April 2011, a severe (EF-3) tornado damaged several thousand hectares of mature secondary mixed pine-oak forest in northeast Georgia, USA. In 2012, we collected soil from the base of mature trees in intact forest and in tornado-damaged patches. Three tree species seedlings were grown in same-species and different-species soil for three months. Height, biomass, and mycorrhizal colonization were compared. Results suggest that PSF are neutral to negative in intact forest. For Nyssa sylvatica Marsh., PSF were less negative in wind-damaged soils. Quercus alba L. exhibited the opposite response. Pinus strobus L. PSF did not differ with wind damage. We found that PSF may be changed by severe wind disturbance, but the nature of the changes depends upon species identity. Multiple soil mechanisms aside from mycorrhizal colonization likely drive disturbance-related PSF changes.