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Edaphic and biotic controls of ectomycorrhizal species diversity.
JONSSON, LENA1, DIGHTON, JOHN1, LUSSENHOP, JOHN2, KOIDE, ROGER3, 1 2 3
ABSTRACT- Heterogeneity of leaf litter species on the forest floor has been implicated in influencing the ectomycorrhizal fungal species composition of roots invading the litter. We are attempting to understand the factors within these litters that control mycorrhizal community structure by a series of experimental leaf litter manipulations and real-time measures of root growth and dynamics of mycorrhizal colonization. Using horizontally placed minirhizotron tubes in the field and in mesocosms, we are measuring the rate of growth of roots into leaf litter patches (pine, oak, huckleberry) placed over the tubes. Tubes in the field are colonized by roots of mature pitch pine and by seedlings in the mesocosms. During the first year of study, mesocosm images have been taken at weekly intervals. Analysis of 4066 root containing images shows significant differences in root abundance between leaf litter treatments, but no difference between replicate tubes. Root mass is greater in control (litter removed) than all leaf litters and pine litter has least roots. We are beginning to see the development of different ectomycorrhizal communities in the different litters, the taxonomy of which will be confirmed by molecular techniques. In addition to the influence of the leaf litter alone, in future years we plan to alter the faunal grazing pressure in one set of replicates to evaluate the effect on mycorrhizal colonization patterns.
KEY WORDS: ectomycorrhizae, leaf litter, diversity, community