Wood on the forest floor is decomposed primarily by filamentous fungi. These fungi are uniquely adapted to metabolize recalcitrant yet carbon-rich wood, and they often produce the carboxylic anion oxalate instead of CO2 as a more energy-efficient product of carbon metabolism. Oxalate levels in wood are variable and depend largely on the species of fungus colonizing the wood. There is emergent interest in this physiological phenomenon because oxalate may create a significant sink for calcium imported from forest soils. Calcium is an extremely important plant nutrient and buffering ion, yet it is sensitive to depletion in over-harvested and acid-stressed forests. The dissertation project funded by this NSF Doctoral Dissertation Improvement Grant (DDIG) aims to quantify how environmental variables affected by existing forest management practices (wood species, temperature, and soil moisture) affect fungal competition, wood colonization, and subsequent oxalate and calcium accumulation. The research will incorporate a molecular approach (qPCR) to quantify competitive success among several fungal species with distinct oxalate production patterns as they simultaneously compete for woody substrate. This qPCR approach allows observations during decay to be linked directly to each test fungus in a more natural system. This data will be correlated with subsequent oxalate and calcium patterns in the degraded wood, and the overall potential for these treatment variables to affect wood calcium enrichment will be assessed. This research has direct application to forest woody debris management and has broader implications on the role of wood decomposition and fungal ecology in maintaining forest health.
