Selected indices of structure and function were used to evaluate the effect of differing soil thermal regimes on soil-permafrost-dominated (muskeg) and permafrost-free (north-slope) black spruce ecosystems in interior Alaska. The poorly drained, permafrost site displayed cooler soil temperatures and higher soil moisture content than were encountered on the well-drained north slope. Mineral soil nutrient pools generally were largest on the permafrost site. However, low soil temperature acted as a negative feedback control, suppressing soil biological activity, nutrient mineralization, and tree primary production to lower levels on the soil-permafrost-dominated site as compared with the permafrost-free site. Forty percent larger accumulation of tree biomass and 80% greater annual tree productivity occurred on the warmer site.
This study reports the fuel weight and biomass distribution in a 51-year-old lowland and a 55-year-old upland black spruce (Piceamariana [Mill.] B.S.P.) stand in interior Alaska. Biomass distribution is shown for overstory, standing and down dead tree components, herbaceous understory, and the moss layer. The lowland stand contained over 11000 stems/acre (27170 stems/ha) and 82 ft2 of basal area per acre (18.8 m2 of basal area per hectare), and the upland stand contained 6000 stems/acre (14820 stems/ha) and 96 ft2 of basal area per acre (22.0 m2 of basal area per hectare). Moss layers contributed 54.6 and 45.5 t/acre (120.1 and 100.1 metric t/ha) to biomass totals in the lowland and upland sites, respectively. Total biomass was 64.7 t/acre (142.3 metric t/ha) in the lowland site and 58.0 t/acre (127.6 metric t/ha) in the upland site.
Allometric relations for tree phytomass distribution on two black spruce (Piceamariana Mill. B.S.P.) sites in interior Alaska were developed and compared with entire unit area samples. Tree component mass equations provided R2 values ranging from a low of 0.24 to a high of 0.97, with the majority of values above 0.75. Equations were developed for foliage; live and dead cones; dead branch total, dead branch bark, dead branchwood; live branch total, live branch bark, live branchwood; bole total, bole bark, bole wood; and tree total. Regression equations were developed to predict tree height, distance from crown bottom to ground, crown width, and crown length using basal diameters. R2 values for these equations ranged from 0.89 to 0.20. Foliage comprised from 37% to 17% of the total mass for the lowland stand and 50% to 17% of the total tree mass in the upland stand for trees with a diameter class ranging from 0.32 to 7.94 cm. For these same diameter classes, the total bole mass ranged from 11% to 58% and 21% to 61% of the total mass in the lowland and upland stands, respectively. Comparisons of predicted total aboveground tree biomass, measured biomass, and an average-tree-per-diameter-class procedure showed the lowland site predictions were about 6% low and the upland site predictions were approximately 3% high. Using a second, all-tree component method of prediction, results were about 3% low for lowland sites and 4% low for upland sites. A method of prediction using an average stand diameter yielded differences ranging from 31% low for the lowland site to 45% low for the upland site.
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