Decomposition of red spruce and balsam fir boles in the White Mountains of New Hampshire

Decomposition rates for red spruce (Picearubens Sarg.) and balsam fir (Abiesbalsamea (L.) Mill.) boles on the forest floor were determined for midelevation forests of the White Mountains from a chronosequence of previously logged stands. Density changes in wood and bark were described using a negative exponential model, yielding decay constants of 0.033 and 0.029/year for spruce and fir wood, respectively. The two species were not statistically different in terms of mass loss. Bole diameter had no influence on the decay rate of red spruce. Fir boles in midelevation forests decayed significantly faster than those in high-elevation forests measured in another study. Net accumulation of N, P, Ca, and Mg occurred in the wood of both species. N accumulated in bark, but P, Ca, and Mg behavior was variable. Na and K behavior was similar in the wood and bark of both species, with Na release concomitant with mass loss, while K was lost faster than mass. C:N ratios declined, and N:P ratios converged on a value of ca. 20, in the wood and bark of both species.