Aboveground biomass, surface area, and production relations of red fir (Abiesmagnified) and white fir (A. concolor)

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Abstract
Aboveground live biomass, surface area, and net production have been estimated in two 0.36-ha stands each of white fir (Abies concolor), red fir (Abies magnifica), and mixed red and white fir in Sequoia National Park in the southern Sierra Nevada of California. Estimates are based on regressions developed from dimension analysis of 12 individuals of each fir species harvested in the adjacent Sequoia National Forest. The white fir forests are the largest and most productive of the several fir forests measured. The net production values of 1630-2200 g .cntdot. m-3 year-1 are 1.3-2.7 times higher than for red or mixed fir forests and are at the high end of values reported from other highly productive coniferous forests of the western United states. The high productivity of these forests is attributable in part to the high proportion of aboveground biomass in leaves (4%), which remain on branches for up to 24 years or more, coupled with a high tolerance to shading. Production per unit leaf area is comparable to productive coast redwood and ponderosa pine stands. The biomass of white fir forests (59-97 kg .cntdot. m-2) is in the range of other coniferous forests of the Pacific Northwest. The red fir forests are lower in height, smaller in biomass (40-67 kg .cntdot. m-2), and lower in production (810-1030 g .cntdot. m-2 .cntdot. year-1), consistent with the higher elevation and greater climatic stresses of their typical habitats. In growth form, the two species are similar, with red fir showing a more rapid increase in leaf biomass with stem or sapwood diameter increase than white fir and greater bark production. All-sided leaf area indices of 15-21 m2 .cntdot. m-2 for white fir and 17-25 m2 .cntdot. m-2 for red fir are similar to values reported for mixed fir forests of comparable rainfall in Oregon.