How Abundant are Root-Colonizing Fungi in Southeastern Louisiana's Degraded Marshes?

Despite earlier notions that fungi are not important in wetlands, it is becoming clear that root endophytes are abundant in wetlands and potentially can influence plant community dynamics. Little is known about the effects of wetland degradation on these fungi. We assessed two groups of root endophytes in a degrading marsh in southeast Louisiana that historically was a swamp forest dominated by Taxodium distichum (baldcypress) and Nyssa aquatica (water tupelo). We determined percent root colonization by arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) in each of 18 vascular plant species. Fungi were present in all species that were assessed. In general, monocots were primarily colonized by DSE, whereas dicots were primarily colonized by AMF. Taxodium distichum was heavily colonized by AMF, as was the non-native, invasive Chinese tallow (Triadica sebifera). This study is the first to show that wetland plants in a degraded marsh harbor abundant and diverse root endophytes. These fungi and their interactions with stressed plants may be important in effective management of degrading wetlands.