Ectomycorrhizal communities and ecological restoration: Status and performance in urban conditions

Ecological restoration plans rarely take into consideration the soil community of microbial mutualists. One particular group of soil microbes, mycorrhizal fungi, is known to confer benefits to associating host plants and can even influence plant community structure. The primary objectives of this dissertation are to: (1) Determine whether ectomycorrhizal fungal (EMF) communities differ among disturbed candidate restoration sites and old-growth woodland reference sites; (2) Test whether common urban soil stressors alter EMF communities; and (3) Test the efficacy of commercial and field mycorrhizal inoculants for use in restoration projects. In each experiment, colonization by EMF of Quercus rubra (northern red oak) seedlings was used along with morphological and molecular sampling methods to measure EMF community characteristics. EMF abundance and species richness was significantly lower in disturbed site soils and community composition was significantly different from that of reference sites. A suite of urban fungal species was identified that occurred across several study sites. Several common urban soil stressors were found to lower EMF abundance or species richness, indicating that edaphic factors could be partially responsible for depauperate EMF communities of disturbed sites. Inoculation of oak seedlings planted at two disturbed sites failed to result in significant EMF colonization of the seedlings' root systems, showing that both commercial and field-collected inoculum might not be effective in restoring EMF communities to degraded sites. This research suggests that the soil EMF community should be addressed in woodland restoration projects and more work is necessary to determine how best to restore EMF communities.