Changes in mycorrhizal colonization and overall fungal communities across upland and wetland Acer forests of the Virginia Coastal Plain

Abstract

Arbuscular mycorrhiza (AM) are common in the roots of most plants and provide benefits such as enhanced uptake of soil nutrients and water when the environment limits these resources. Two primary factors proposed in the literature as limiting the extent of mycorrhizal colonization of wetland plants are: (1) the low oxygen environment; and (2) the level of available phosphorus. The present study evaluated AM colonization of maple (Acer) roots and the fungal community structure in paired upland/wetland locations in the Virginia Coastal Plain to determine if wetland conditions affected the root fungal community. The range of observed AM colonization, based on 60 samples collected on 11 dates covering 3 years, was from 4 to 55%. Overall, soil redox potential and available phosphorus concentration were not significant in explaining the difference in AM colonization of Acer roots. In fact, the site with the greatest percent colonization in this study was a wetland site. A comparison of fungal diversity between the pooled wetland site communities and the pooled upland site communities was conducted and the difference was significant (p = 0.003), but the upland sites exhibited the lower diversity. Communities from all sites were dissimilar. Geographic location exerted a greater effect over community structure than did upland versus wetland status. This study concludes that the forested wetland environments studied here neither limited AM colonization nor reduced the overall fungal community and in fact may present a more favorable environment for fungal diversity.