Spatial and Temporal Dimensions of the Rhizopogon Spore Bank

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Ectomycorrhizal (EM )spore banks are a fundamental,but poorly studiedcomponent,of plant-fungal community ecology.EM spore banks can providethe inoculum necessary for tree recruitment following severe disturbance andmay facilitate tree invasion into bordering non-forested areas.Rhizopogon speciesare the most abundant component of spore banks in many western NorthAmerican pinaceous ecosystems,and in some forest-border settings they appearto be virtually the entire spore bank.This proposal is focused on understandingthe spatial and temporal dynamics of Rhizopogon spore banks in the context ofcyclic fire and pine regeneration.A conceptual model for these interactions isproposed,and five specific hypotheses related to the model are tested.Thesehypotheses focus on differences in spore longevity and spore dispersal amongRhizopogon species,and on differences in mode and frequency of dispersal withinmature-forests and post-fire forests.Measured parameters include:i)spatialpattern of the spore shadow in forest border zones,ii)current dispersal rates andmodes into these zones,iii)spore longevity of three key Rhizopogon species andiv)longevity of complex native spore banks.Hypotheses will be tested bycombining the techniques of bioassays,molecular ecology,large-scale spatialsampling,and seed bank ecology.The work addresses a crucial,but essentiallyunstudied,component of community ecology (i.e.,EM spore banks),andprovides an analogous system in which to test ideas developed for plant seedbanks.The broader impacts of this work are its direct relationship to forestregeneration and expansion;the ability to predict the spatial and temporal extentof the EM spore banks will provide forest managers with a rational way to assessthe likelihood of EM inoculum in highly disturbed systems.