International Research Fellowship Program: The Effect of Ecto-Mycorrhiza and Organic Acids on Weathering and CO2 Production in Forest Soils

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The International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four month research fellowship by Dr. Julie D. H. Spears to work with Dr. Ulla Lundstrom at Mid Sweden University in Sundsvall, Sweden.The goal of this project is to gain greater understanding of the controls on and ecosystem effects of ectomycorrhizal fungi (EM) weathering via low molecular weight organic acids (LMWOAs). It will address two major questions: (1) do high production and decomposition rates of LMWOAs explain the high evolution of CO2 sometimes observed from forest soils? (2) To what extent could trees get their supply of nutrients directly from mineral grains? The PI will study the impact of EM infection (P. involutus and Suillus sp.) on weathering rates (Si, Al, Ca, Mg and K release) of soils and pure minerals with Pinus sylvestris and Picea abies as host plants under sterile/non-sterile conditions. Weathering budgets for the soil including accumulation in seedlings will be constructed. LMWOAs and siderophores will be determined in solution. She will also evaluate CO2 production due to biodegradation of LMWOAs in forest soils under field and laboratory conditions. LMWOA concentrations in micropores will be estimated using a mechanistically based mathematical diffusion model. The contribution of EM fungi exudates will be calculated/estimated.Dr. Lundstrom's lab is one of the leaders in researching the impacts of soil mycorrhizae on forest soil chemistry.