RUI: Oak Regeneration: Roles for Fungi and Small Mammals

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Natural regeneration in oaks, particularly Oregon white oak, is poor. Few seedlings grow beyond a few years; saplings are rare. Oak roots depend on beneficial fungi in the form of mycorrhizas, modified roots that form a symbiotic association between the oak trees and the fungi. Fungi provide water and nutrients to trees; trees provide sugars to fungi. Many mycorrhizal fungi are species of truffles. Their spores cannot be dispersed by air because the fruiting bodies remain closed underground. So the problem for the oaks is two-fold: acorns must be dispersed away from the parent tree to avoid competition, and they require fungi to make mycorrhizas. One possibility is that small mammals eat the truffles and disperse the spores. The goal of this proposal is to determine the roles of fungi and small mammals in oak regeneration. The objectives are to (1) assess the availability of fungi for mycorrhizal formation at distances away from mature oaks; (2) measure the effect of absence of fungal sources on seedling growth, and (3) determine the potential of small mammals to disperse mycorrhizal fungi.The broader impacts of the proposed work include (1) engaging undergraduate students in research and (2) collaboration with land managers to preserve and regenerate oak habitat. Students will be responsible for parts of the project, and will present their work at scientific meetings. The PIs will communicate with applied scientists in environmental organizations and federal agencies, and with private land owners, attending meetings and conferences. They will give talks and provide handouts about oak ecology and management of oak habitat.