Ottmar, Roger D.; Vihnanek, Robert E. 1998. Stereo photo series for quantifying natural fuels. Volume II: black spruce and white spruce types in Alaska. PMS 831. Boise, ID: National Wildfire Coordinating Group, National Interagency Fire Center. 65 p.

Two series of single and stereo photographs display a range of natural conditions and fuel loadings in black spruce and white spruce ecosystem types in Alaska. Each group of photos includes inventory information summarizing vegetation composition, structure and loading, woody material loading and density by size class, forest floor depth and loading, and various site characteristics. The natural fuels photo series is designed to help land managers appraise fuel and vegetation conditions in natural settings.

Keywords: Woody material, biomass, fuel loading, natural fuels, black spruce, Picea mariana, white spruce, Picea glauca, boreal forest, Alaska.

COOPERATORS
This publication was developed by the USDA Forest Service, Pacific Northwest Research Station, Fire and Environmental Research Applications Group, under contract with the U.S. Department of the Interior.

ACKNOWLEDGMENTS
Special recognition is due Larry Vanderlinden, Fish and Wildlife Service; Jim Roessler, Bureau of Land Management, Alaska Fire Service; Arturo Frizzera and Martin Maricle, State of Alaska, Department of Natural Resources, Division of Forestry; and Al Yates, Ahtna Forest Products, Inc.

AUTHORS
ROGER D. OTTMAR is a research forester and ROBERT E. VIHNANEK is a supervisory forester, USDA Forest Service, Pacific Northwest Research Station, Pacific Wildland Fire Sciences Laboratory, 400 N 34th Street, Suite 201 Seattle, Washington  98103.

PHOTOGRAPH AND INFORMATION ARRANGEMENT
The photographs and accompanying data summaries are presented as single sites organized into two series. Each site contains a wide-angle (50 mm) view photograph, general site information, understory summary data, summaries of overstory structure and composition, forest floor depth, loading and constancy, and dead and down woody material loading and density by size class.

Figure 1--Photo series sample area layout. Forty random azimuth line transects (one at each point on the 30- and 150-foot arcs, and two at each point on the 60-, 90-, and 120-foot arcs) and 10-15 clipped vegetation plots (two to three per arc) were located within the sample area. Trees, shrubs and seedlings were inventoried on 12 systematically located sample plots.

SITE INFORMATION
The camera point of each site was located with a global positioning system (GPS) receiver using the WGS-84 datum. Elevations were derived from U.S. Geological Survey topographic maps. Cover type, an indicator of current vegetation composition, was assigned for each site (Eyre 1980). Vegetation type, corresponding to level IV in Viereck et al. (1992), is also noted as a measure of current vegetation composition. Major tree and tall shrub species present at a site are listed in order of abundance.¹ Soil type was determined from soil survey maps and descriptions (Rieger et al. 1979). Crown closure was measured with a spherical densiometer at 12 systematically located points in the sample area. The proportion of hardwood species present in the overstory is reported as a percentage of the total number of stems sampled in twelve 0.005-acre plots located systematically throughout the sample area (fig. 1). Total unit biomass is the sum of the understory biomass, aboveground mass, total forest floor loading, and total woody material loading on an area basis.²

1See below for a list of scientific and common species names used in this volume. 2All biomass and loading values are reported on an oven-dry basis.

UNDERSTORY
Understory vegetation was sampled in 12 square, clipped vegetation plots (2.69 square feet each) located systematically throughout the sample area (fig. 1). All low shrubs, grasses, and forbs growing within each square plot were clipped at ground level and returned to the laboratory for oven drying. Clipped understory vegetation was oven-dried at a minimum of 158 °F for at least 48 hours before weighing and determination of area loading. Tall shrubs and seedlings were censused and measured in, respectively, twelve 0.005-acre and 0.001-acre circular plots located systematically throughout the sample area (fig. 1). Tall shrub and seedling biomass values were calculated using allometric equations (Barney et al. 1978, Brown 1976, Roussopoulos and Loomis 1979, Telfer 1969).

OVERSTORY
Overstory trees were sampled in twelve 0.005-acre circular plots located systematically throughout the sample area; the overstory plots represented 43 percent of the total sample area (fig. 1). Tree measurement data were summarized by diameter at breast height (d.b.h.) size class and by tree status (all, live or dead).³ Ladder fuel height was defined as the height of the lowest live or dead branch material that could carry fire into the crown of the tree, while height to live crown was the height of the lowest live branches of the continuous tree canopy. Live crown mass (branches and foliage) and aboveground mass (crown and stem) values were calculated from species-specific allometric equations (Barney et al. 1978; Harding and Grigal 1985; Roussopoulos and Loomis 1979; Singh 1981, 1984; Yarie and VanCleve 1983).

3D.b.h. is measured 4.5 feet above the ground.

FOREST FLOOR
Surface material and duff depth were calculated as the average of between 90 and 120 randomly distributed measurements taken throughout the sample area. The depth for the different surface material and duff types (i.e., moss, lichen, conifer litter, hardwood litter, upper duff, and lower duff) was calculated as an average of material depth only where that type was encountered during sampling. Therefore, the depths reported for the different surface material and duff types are not unit-wide averages and, as such, are not additive. Loading was calculated from bulk density values derived from field measurements. Constancy indicates how consistently the various forest floor types occur in the sample area and is expressed as a percentage of the total number of measurements.

WOODY MATERIAL
Measurement techniques used for inventorying dead and down woody material were patterned after the planar intersect method outlined by Brown (1974) and described by Maxwell and Ward (1980). Forty transects of random azimuth starting at 25 systematically located points within the sample area were used to determine woody material loading and density (fig. 1). Woody material data are reported by size classes that correspond to timelag fuel classes (e.g., 1-hour, 10-hour and 100-hour fuels are defined as woody material 0.25 inch, 0.26-1.0 inch, and 1.1-3.0 inches, respectively) used in fire behavior modeling (see, for example, Burgan and Rothermel 1984). Woody material in 10-hour and 100-hour and larger size classes was tallied on transects that were 10 feet and 30 feet long, respectively. Woody material loading in the 1-hour size class (i.e., 0.25 inch in diameter) was assumed to be 60 percent of 10-hour loading based on field observations. The decay class (sound or rotten) and the actual diameter at the point of intersection were measured for all pieces >3 inches in diameter. All woody material <3 inches in diameter was considered sound. Woody material loading and woody material density were calculated from relationships that use number of pieces intersected and transect length (and wood specific gravity for loading) developed by Brown (1974) and Safranyik and Linton (1987), respectively.

41-hour, 10-hour and 100-hour fuels are defined as woody material <=0.25 inch, 0.26-1.0 inch and 1.1-3.0 inches, respectively.

SPECIES LIST
Scientific and common species names are from Hitchcock and Cronquist (1973), unless otherwise noted.

LITERATURE CITED

Barney, Richard J.; VanCleve, K.; Schlentner, Robert. 1978. Biomass distribution and crown characteristics in two Alaskan Picea mariana ecosystems. Canadian Journal of Forest Research 8: 36-41.

Brown, James K. 1974. Handbook for inventorying downed woody material. Gen. Tech. Rep. INT-16. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 24 p.

Brown, James K. 1976. Estimating shrub biomass from basal stem diameters. Canadian Journal of Forest Research 6: 153-158.

Burgan, Robert E.; Rothermel, Richard C. 1984. BEHAVE: fire behavior prediction and fuel modeling system--FUEL subsystem. Gen. Tech. Rep. INT-167. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 126 p.

Eyre, F.H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [+ map].

Harding, R.B.; Grigal, D.F. 1985. Individual tree biomass equations for plantation-grown white spruce in northern Minnesota. Canadian Journal of Forest Research 15: 738-739.

Maxwell, Wayne G.; Ward, Frank R. 1980. Guidelines for developing or supplementing natural photo series. Res. Note PNW-358. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 16 p.

Rieger, Samuel; Schoephorster, Dale B; Furbush, Clarence E. 1979. Exploratory soil survey of Alaska. [Place of publication unknown]: U.S. Department of Agriculture, Soil Conservation Service. 213 p. [+ maps].

Roussopoulos, Peter J.; Loomis, Robert M. 1979. Weights and dimensional properties of shrubs and small trees of the Great Lakes conifer forest. Res. Pap. NC-178. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 6 p.

Safranyik, L.; Linton, D.A. 1987. Line intersect sampling for the density and bark area of logging residue susceptible to the spruce beetle, Dendroctonus rufipennis (Kirby). Inf. Rep. BC-X-295. Victoria, BC: Canadian Forestry Service, Pacific Forestry Centre. 10 p.

Singh, T. 1981. Biomass equations for ten major tree species of the prairie provinces. Inf. Rep. NOR-X-242. Edmonton, AB: Environment Canada, Canadian Forest Service, Northern Forestry Research Centre. 35 p.