The boreal forests of interior Alaska cover approximately 110 million acres, and appear to be changing rapidly in response to warming temperatures. In 2014 the United States Forest Service’s Forest Inventory and Analysis (FIA) program in conjunction with the National Aeronautics and Space Administration’s (NASA) Goddard Space Flight Center carried out a pilot test of an interior Alaska inventory design. The pilot inventoried the forests in the Tanana River Valley of interior Alaska, covering 2.5 million acres. The field component of the inventory consisted of a systematic grid of 98 field-measured plots.
Results of the field plots indicate that black spruce (Picea mariana) was the most common forest type, covering 49 ± 5% of the forested land area. Most of the above-ground live tree biomass was found in birch (Betula neoalaskana) (18.0 ± 4.4 million tons) and black spruce (13.9 ± 2.7 million tons) forest types. However white spruce (Picea glauca) forest types had the highest tree biomass per acre. Black spruce forests had the lowest biomass per acre (8.8 ±2.8 tons acre-1). Most of the biomass of down woody materials (DWM) occurred on the birch forests. Birch (5.3 ± 1.6 tons acre-1) and aspen (5.8 ± 1.5 tons acre-1) forests had the highest DWM biomass per acre while black spruce forests (0.4 ± 0.1 tons acre-1) had the lowest. The majority of the total soil carbon (C) in the litter, organic and the top 1 inch of mineral soil occurred on black spruce (36%) and birch (23%) forests. Total soil C per acre was highest in black spruce forests (28 ± 2.6 tons acre-1) and lowest in aspen forests (14.9 ± 6.7 tons acre-1). Most of the ground cover of the non-vascular functional groups in the inventory unit was in the form of nitrogen fixing feather mosses (57 ±5%). In terms of total ecosystem (live tree, DWM, ground layer, and soil) C, soils were the largest pool (47- 84%), trees accounted for 13 - 47%, down woody materials accounted for 1 - 14%, and the ground layer accounted for 0- 7% of total ecosystem C. These results highlight the variability in forests in Alaska’s boreal forests and the importance of establishing an inventory in the region.