Ectomycorrhizal communities on pine and oak seedlings converge in the absence of canopy tree influence
G. C. WILLIAMS (1), R. Vilgalys (1). (1) Duke University, Durham, NC, U.S.A.
The succession of mycorrhizal fungi often mirrors plant succession, and ectomycorrhizal (EM) community composition may affect the outcome of competition among trees during late succession. Previously, a reciprocal transplant of white oak (<i>Quercus alba</i>) and loblolly pine (<i>Pinus taeda</i>) seedlings was conducted in paired plots of oak-dominated and pine-dominated forest. This study suggested that the fungal associations of adult trees determine which EM species are dominant in the soil and thus available for seedlings to associate with. Here, we investigate the degree to which adult trees influence the availability of EM fungi for seedlings by removing that influence. Soil was collected from oak- and pine-dominated stands and dried to kill off mature mycelium, leaving only the spore bank as a source of inoculum. Pine and oak seedlings were then planted in this soil in laboratory conditions. EM root tips were collected for molecular identification of fungal species based on ITS barcoding. Soil samples from field and laboratory conditions were also analyzed for fungal and bacterial diversity using 454 sequencing. We found a reduced influence of canopy type and a more pronounced influence of seedling identity when compared to the EM communities on seedlings planted in the field, suggesting that adult trees do alter the availability of fungi by promoting the growth of their preferred EM associates. The fungal and bacterial communities in the soil will also be discussed.
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