Calcium oxalate accumulation and soil weathering in mats of the hypogeous fungus Hysterangium crassum |
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| Authors: | Kermit Cromack Phillip Sollins William C Graustein Karen Speidel Allen W Todd Gody Spycher Ching Y Li Robert L Todd |
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| Institution: | 1. Department of Forest Science, School of Forestry, Corvallis, OR 97331, U.S.A.;2. Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, U.S.A.;3. US Forestry Sciences Laboratory, Corvallis, OR 97331, U.S.A.;4. Department of Geology and Geophysics. Yale University, New Haven, CT 06520, U.S.A.;5. Department of Agronomy and Institute of Ecology, University of Georgia, Athens, GA 30602, U.S.A. |
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| Abstract: | Fungal mats of Hysterangium crassum (Tul. and Tul.) Fischer occupied a mean of 9.6% of the upper 10 cm of soil developed under a 40–65 yr old stand of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in Oregon. This hypogeous basidiomycete exudes large amounts of oxalic acid, some of which precipitates with Ca in microscopic crystals of calcium oxalate, resulting in a mean CaC2O4 content of 82g m?2 for the entire soil. Soil oxalate concentration was significantly greater within fungal mats (P < 0.01) and soil pH was significantly lower (P < 0.01) than in soil adjacent to mats. The quantity of Ca present as CaC2O4 is 0.5 the amount of exchangeable Ca in the soil and exceeds the mass of Ca lost annually in runoff. Scanning electron micrographs show intense chemical weathering, attributable to oxalate attack, in the immediate vicinity of hyphae. X-ray diffraction patterns of clay indicate bulk weathering is more intense within the fungal mats than in adjacent uncolonized soil. |
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