Ottmar, Roger D.; Vihnanek, Robert E.; Wright, Clinton S. 1998. Stereo photo series for quantifying natural fuels. Volume I: mixed-conifer with mortality, western juniper, sagebrush, and grassland types in the interior Pacific Northwest. PMS 830. Boise, ID: National Wildfire Coordinating Group, National Interagency Fire Center. 73 p.

Four series of single and stereo photographs display a range of natural conditions and fuel loadings in mixed-conifer, western juniper, sagebrush, and grassland ecosystem types in the interior Pacific Northwest. 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, Douglas-fir, Pseudotsuga menziesii, grand fir, Abies grandis, ponderosa pine, Pinus ponderosa, western larch, Larix occidentalis, western juniper, Juniperus occidentalis, big sagebrush, Artemisia tridentata, mixed-conifer, grassland.

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 and the U.S. Department of Agriculture, Forest Service, Pacific Northwest Region.

ACKNOWLEDGMENTS
Special recognition is due Mike Hilbruner, USDA Forest Service, PNW Region; Tom Wordell, USDA Forest Service, Umatilla National Forest, Walla Walla Ranger District; John Robertson, USDA Forest Service, Umatilla National Forest; Dale Ekman, Bureau of Land Management, Prineville District; and Roger Trick, National Park Service, Whitman Mission National Historic Site.

AUTHORS
ROGER D. OTTMAR is a research forester, ROBERT E. VIHNANEK is a supervisory forester, and CLINTON S. WRIGHT is a research 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 four series. Each site contains a wide-angle (50 mm) view photograph, general site information, general stand information (in the case of the mixed-conifer series), summaries of overstory structure and composition, understory composition and loading, shrub structure and composition, and dead and down woody material loading and density by size class, as appropriate for the ecosystem type. For the grassland sites, all available data are reported as site information.

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, where reported, were derived from U.S. Geological Survey topographic maps. Slope and aspect were measured at the mixed-confer sites only. Major species present at a site are listed in order of abundance.¹ Cover type, an indicator of current vegetation composition, was assigned for each site (Eyre 1980, Shiflet 1994). Note that in the mixed-conifer series, the species list (tree species only) and cover type appear with the stand information. Plant association was determined using locally-appropriate classifications for all sites, where available, and follows the potential vegetation concept (Hopkins and Kovalchik 1983, Johnson and Clausnitzer 1992). Classifications reported in Franklin and Dyrness (1988) were used as the phytosociological authorities where local classifications were unavailable. Soil type, where reported, was determined from county soil survey maps (Soil Conservation Service 1983, 1985).

For the mixed-conifer series, woody fuel depth was calculated as the average high particle height of 10-hour fuels measured at three locations on each of 40 random azimuth line transects used for determining dead and down woody material loading and density (fig. 1).²  Similarly, litter and duff depth were calculated as the average of measurements taken along the line transects with loading calculated from bulk density values derived from field measurements.³

For the western juniper and sagebrush series, species cover values were based on canopy size data collected for all plants within the boundaries of twelve 0.005-acre shrub plots (fig. 1). For calculation purposes, we assumed that the canopies of individual plants did not overlap. Total aboveground biomass is the sum, on an area basis, of all living and dead biomass found in the sample area.

For the grassland series, grass, forb, shrub, litter, 1-hour, 10-hour, and 100-hour loadings were calculated as the average amount present in fifteen 2.69 square foot clipped vegetation plots located systematically throughout the sample area (fig. 1). Grass and forb heights are the averages from 25 systematically located points within the sample area. Shrub height, where noted, is the average of all shrubs within the sample area. Also noted are the dates of the photography and the most recent fire, if available.

1See below for a list of scientific and common species names used in this volume. 21-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. 3All biomass and loading values are reported on an oven-dry basis.

STAND INFORMATION
Stand information is reported only for the mixed-conifer series. As noted above (see "Site Information"), a species list and cover type are reported as stand information. Overstory tree, seedling, and sapling species composition and the percentage of dead standing trees were determined by sampling within the site (fig. 1). Twelve systematically located 0.005-acre circular plots comprised the overstory and sapling sample and represented 43 percent of the total sample area. Seedling density was estimated using twelve 0.001-acre circular plots nested within the overstory plots. Crown closure was measured with a spherical densiometer at 10 systematically located points in the sample area.

OVERSTORY
Overstory trees were sampled in 12 circular plots (0.005 acre each) located systematically throughout the sample area (fig. 1), for both forested series (mixed-conifer and western juniper). Tree measurement data were summarized by size class (either diameter at breast height [d.b.h.] or height).⁴

For the mixed-conifer series, tree data were further summarized by tree status (all, live, or dead). 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 continuous live branches of the tree canopy. Live crown mass values (i.e., live branches and foliage) for the mixed-conifer series were calculated from allometric equations (that use tree d.b.h.) developed by Brown (1978) for conifer species in the interior Western United States.

For the western juniper series, crown breadth was defined as the average of the diameter of the crown at the maximum width and the widest point perpendicular to the maximum width. Crown mass (live branches, dead branches and foliage) and aboveground mass (crown mass and stem mass) were calculated from allometric equations (that use crown volume) developed by Gholz (1980) for western juniper in central Oregon.

4D.b.h. is measured 4.5 feet above the ground.

SHRUB DATA
Shrubs were measured for the western juniper and sagebrush series only. The species, basal diameter, height, maximum crown width, and the widest point perpendicular to the maximum crown width of all sagebrush (Artemisia tridentata) and bitterbrush (Purshia tridentata) plants within twelve 0.005-acre shrub plots were noted (fig. 1). The crown area was calculated for each plant and averaged to determine the mean crown area.

UNDERSTORY OR VEGETATION AND BIOMASS DATA
Depending on density, understory vegetation was sampled in 10 to 15 square, clipped vegetation plots (2.69 square feet each) located systematically throughout the sample area (fig. 1). All shrubs (except sagebrush and bitterbrush), grasses, and forbs growing within each square plot were clipped at ground level and returned to the laboratory for oven drying. For the western juniper, sagebrush, and grassland series, moss, litter, duff, 1-hour, 10-hour and 100-hour fuels, if present, also were collected in the square clipped vegetation plots. Note that woody material loading (i.e., 1-hour, 10-hour and 100-hour fuels) is reported in the woody material section for the western juniper and sagebrush series. Understory vegetation and other collected material were oven-dried at a minimum of 158 °F for at least 48 hours before weighing and determination of area loading.

For the western juniper and sagebrush series, sagebrush (Artemisia tridentata) and bitterbrush (Purshia tridentata) biomass values were calculated using allometric equations (Uresk et al. 1977, Vora 1988). All other shrub biomass values are based on clipped vegetation plots. Shrub height is the average rabbitbrush (Chrysothamnus spp.) height measured at up to 25 systematically located points within the sample area. Sagebrush (Artemisia) and bitterbrush (Purshia) heights, however, are averages of all sagebrush and bitterbrush heights, respectively, within the twelve 0.005-acre shrub plots.

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 in 1-hour, 10-hour, and 100-hour and larger size classes was tallied on transects that were 3.3 feet, 10 feet, and 30 feet long, respectively. The decay class (sound or rotten) and the actual diameter at the point of intersection was 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. 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).

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

LITERATURE CITED

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. 1978. Weight and density of crowns of Rocky Mountain conifers. Res. Pap. INT-197. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 56 p.

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].

Franklin, Jerry F.; Dyrness, C.T. 1988. Natural vegetation of Oregon and Washington. Corvallis, OR: Oregon State University Press. 452 p.

Gholz, H.L. 1980. Structure and productivity of Juniperus occidentalis in central Oregon. American Midland Naturalist 103(2): 251-261.

Hitchcock, C. Leo; Cronquist, Arthur. 1973. Flora of the Pacific Northwest. Seattle, WA: University of Washington Press. 730 p.

Hopkins, William E.; Kovalchik, Bernard L. 1983. Plant associations of the Crooked River National Grassland. R6 Ecol 133-1983. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 98 p.

Johnson, Charles G.; Clausnitzer, Rodrick R., Jr. 1992. Plant associations of the Blue and Ochoco Mountains. Tech. Pap. R6-ERW-TP-036-92. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Region, Wallowa-Whitman National Forest. 207 p.

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.

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.

Shiflet, Thomas N., ed. 1994. Rangeland cover types of the United States. Denver, CO: Society for Range Management. 152 p. Soil Conservation Service. 1983. Soil survey of Morrow County area, Oregon. U.S. Department of Agriculture. Soil Conservation Service. 1985. Soil survey of Union County area, Oregon. U.S. Department of Agriculture.

Uresk, D.W.; Gilbert, R.O.; Rickard, W.H. 1977. Sampling big sagebrush for phytomass. Journal of Range Management 30(4): 311-314. Vora, Robin S. 1988. Predicting biomass of five shrub species in northeastern California. Journal of Range Management 41(1): 63-65.