Decades of acid deposition have depleted Ca from northern forest soils, reducing availability for root uptake. Replenishment is in part due to fungi that concentrate and release cations through the wood decay process. The greater potential of wood decay fungi to restore Ca relative to other essential elements is due to their trace requirement for Ca, unlike the substantial requirement for N, P, K, and Mg. In decaying wood and organic soil, exchangeable divalent Ca cations are associated with carboxylic anions of decaying wood and as dicarboxylic acid salts. Within one decade of decay, Ca in spruce and maple wood had accumulated to levels present in soil humus where feeder roots absorb nutrients. The decayed wood residue had a low molar Al/Ca ratio, favorable for root uptake of Ca. As organic residue is fragmented and incorporated into soil, we expect Ca to become more available in these otherwise depleted forests.

Role of forest fungi in biogeochemical cycling of root-available calcium in forest soils

244th National Meeting (2012)

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