Ottmar, Roger D.; Vihnanek, Robert E.; Wright, Clinton S. 2007. Stereo photo series for quantifying natural fuels. Volume X: sagebrush with grass and ponderosa pine-juniper types in central Montana. Gen. Tech. Rep. PNW-GTR-719. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 59 p.

Two series of single and stereo photographs display a range of natural conditions and fuel loadings in sagebrush with grass and ponderosa pine-juniper types in central Montana. 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, Missouri Breaks, mixed-conifer, ponderosa pine, Pinus ponderosa, creeping juniper, Juniperus horizontalis, Rocky Mountain juniper, Juniperus scopulorum, Douglas-fir, Pseudotsuga menziesii, mountain big sagebrush, Artemisia tridentata ssp. vaseyana, Wyoming big sagebrush, Artemisia tridentata ssp. wyomingensis.

COOPERATORS
This publication was developed by the USDA Forest Service, Pacific Northwest Research Station, Fire and Environmental Research Applications team in cooperation with the Bureau of Land Management, Central Montana Zone Fire Management, with funding provided, in part, by the Joint Fire Science Program.

ACKNOWLEDGMENTS
Special recognition is due Vinita Shea, Jennifer Walker, Karly Krausz, Gary Kirpach (Zone FMO), and Mitch Maycox, Bureau of Land Management, Lewistown Field Office; Brad Gillespie, Bureau of Land Management, Dillon Field Office; John Thompson, Bureau of Land Management, Butte Field Office; and Shannon Downey, Montana Department of Environmental Quality. David Wright, Nicole Troyer, Geoffrey Seymour, Brian Maier, Ann McCauley, Frank Archuleta, Steve Duex, Jennifer Prince, Jennifer Byington, Erin Kenney, and Christine Pachecco, USDA Forest Service, Pacific Northwest Research Station, Pacific Wildland Fire Sciences Laboratory worked on this project in the field and in the laboratory.

AUTHORS
Roger D. Ottmar and Clinton S. Wright are research foresters, and Robert E. Vihnanek is a supervisory forester, Pacific Wildland Fire Sciences Laboratory, 400 North 34th Street, Suite 201, Seattle, WA 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 (50mm) photograph and general site and stand information. The ponderosa pine-juniper series include information on understory vegetation, dead and down woody material loading and density by size class, and summaries of the overstory tree, sapling, and shrub structure and composition. The sagebrush with grass series also includes vegetation, litter, and woody material loading by size class. The ponderosa pine-juniper series also includes forest floor information along with juniper biomass and structure information.

SITE AND STAND INFORMATION
The camera point of each site was located with a global positioning system receiver using the WGS-84 datum. Aspect and slope were measured with a compass and clinometer, respectively. Ecological community classification (to the association level; NatureServe 2006), an indicator of current vegetation composition, was assigned for all sites. In addition, Society of American Foresters (SAF; Eyre 1980) and Society for Range Management (SRM; Shiflet 1994) cover type, indicators of current vegetation composition were assigned for all ponderosa pine-juniper and sagebrush with grass sites, respectively. Shrub, forb, and graminoid species coverage along with mineral soil exposure, was estimated by using line intercept transects (Canfield 1941). The listing of understory species was not meant to be a complete vegetation inventory and may represent only a portion of the actual species richness of the sampled areas.

For the ponderosa pine-juniper series, tree and seedling species present at a site are listed in order of abundance. Crown closure was measured with a forest densitometer (95 systematically located points). Tree and seedling composition and density were determined either by a total inventory of the sample area, or estimated by using twelve 0.005-acre circular plots; all trees less than 4.5 feet tall were considered seedlings.

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 12 clipped vegetation plots (two to three per arc) were located within the sample area. Trees, shrubs and seedlings were inventoried within the entire sample area or on 12 systematically located sample plots.

UNDERSTORY VEGETATION
Graminoid and forb heights were measured at 25 points located systematically throughout the sample area; shrub height was calculated as an average of all shrubs measured in 12 systematically located 0.005-acre circular plots. Understory vegetation biomass was determined by sampling 12 square, clipped vegetation plots (10.76 square feet each) located systematically throughout the sample area (fig. 1). All live and dead understory vegetation (except Juniperus spp.) within each square plot were clipped at ground level, separated, and returned to the laboratory for oven drying. Understory vegetation and other collected material was oven dried at a minimum of 158 °F for at least 48 hours before weighing and determination of area loading. Where present, Prunus virginiana was considered a shrub and measured in twelve 0.005-acre circular plots; biomass was calculated from a growth-form-based allometric equation (tall shrubs; Brown 1976).

FOREST FLOOR INFORMATION
For the ponderosa pine-juniper series, litter and duff depth were calculated as the average of measurements taken every 5 feet between the 30- and 150-foot arcs of the three center transects for a total of 75 measurements (fig. 1). The depth of the litter and duff was calculated as an average of the depth only where litter or duff was encountered during sampling (null values, or points where litter or duff were absent, are not included in the average). Therefore, the depths reported for litter and duff are not unit-wide averages, and do not necessarily sum to total depth. Loading was calculated from depth and bulk density values derived from field measurements or through collection of material in twelve 10.76-square-foot plots.¹ Constancy, an indicator of how consistently the various forest floor components occur in the sample area, is expressed as a percentage of the total number of measurements. The amount of exposed mineral soil at each site for the ponderosa pine-juniper series can be estimated by subtracting the constancy of the total forest floor from 100 percent. For the sagebrush with grass series, litter loading was determined through collection of material in twelve 10.76-square-foot plots.

1Forest floor bulk density values used for each material type appear under "Notes to Users" for each series.

SELECTED SHRUB SPECIES
For the sagebrush with grass series, individual plants of selected shrub and tree species were measured in circular plots or, if shrub density was low, in the entire sample area. Selected tree and shrub species included Pseudotsuga menziesii, Juniperus scopulorum, Artemisia tridentata, and Sarcobatus vermiculatus. The density and percentage of all stems that were dead is based on the number of plants rooted in circular plots ranging from 0.0001-acre to 0.005-acre each (or in the entire sample area if shrub density was low). Crown area was calculated from crown breadth (i.e., the average of the maximum crown diameter, and the widest point perpendicular to the maximum crown diameter). Basal diameter was measured above the root collar. Height is given as the average and maximum height of all sampled individuals of a given species. Cover was estimated by using line intercept transects (Canfield 1941). Pseudotsuga menziesii biomass was estimated by using species-specific allometric equations (Brown 1978) and includes the mass of foliage and branches less than 3 inches diameter. Shrub biomass was determined by sampling 12 square clipped vegetation plots located systematically throughout the sample area.

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 used in fire behavior modeling (see, for example, Burgan and Rothermel 1984).² 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. The decay class and the actual diameter at the point of intersection were measured for all pieces >3 inches in diameter. All woody material less than or equal to 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 loading in the 1-hour size class (and the 10-hour and 100-hour size classes for many of the sites) was determined by collecting, oven drying, and weighing all pieces in twelve 10.76-square-foot plots. When woody material >3 inches in diameter was scarce, a total inventory within the sample area was conducted to determine loading and density estimates. Measurements were taken to determine log volume, and wood specific gravities were applied to the volume to calculate loading.

2>1-, 10-, 100- and 1000-hour timelag fuels are defined as woody material <=0.25 inch, 0.26-1.0 inch, 1.1-3.0 inches, and >3.0 inches in diameter, respectively.

SAPLINGS AND TREES
Overstory tree and sapling composition and density were determined either by a total inventory of the sample area, or were estimated by using twelve 0.005-acre circular plots located systematically throughout the sample area (fig. 1). Tree measurement data were summarized by diameter at breast height (d.b.h.)³ size class and by tree status (live, dead, or all trees). The two most abundant tree species for each size class are listed with their relative density. Height to crown base (reported as ladder fuel height in previous photo series volumes) was defined as the height of the lowest, continuous live or dead branch material of the tree canopy, and height to live crown was defined as the height of the lowest continuous live branches of the tree canopy. Live crown mass (branchwood and foliage) was calculated from species- and size-specific allometric equations (Brown 1978, Jenkins et al. 2003). Juniperus scopulorum with a single-stemmed form was considered a tree.

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

JUNIPER BIOMASS
Juniperus scopulorum and J. horizontalis in the Missouri Breaks region of central Montana have a diverse morphology, from prostrate shrub to tree form, and are reported to hybridize (Fassett 1944, 1945), making them difficult to identify to the species level. Therefore, all juniper with a multi-stemmed form were combined, regardless of species, and characterized by height class to distinguish between the low stature juniper form (= 3 feet tall) and the more upright form (> 3 feet tall). Biomass was collected in six systematically located 10.76-square-foot plots for each height class represented at each site. All juniper vegetation that occupied the space defined by a vertical projection of the plot edges was clipped, separated into live and dead components, and weighed. A subsample of plots was further separated into size classes including foliage and live and dead fine twigs less than or equal to 0.25 inch, 0.26- to 1.0-inch twigs, and greater than 1.0 inch diameter stem and branch material. Biomass for each height class was calculated by multiplying the square footage occupied by each size/status class and the average loading per square foot for that size/status class for each site.

SPECIES LIST
Scientific and common species names are from NRCS (2006).

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