Ottmar, Roger D.; Vihnanek, Robert E; Regelbrugge, Jon C. 2000. Stereo photo series for quantifying natural fuels. Volume IV: pinyon-juniper, sagebrush, and chaparral types in the Southwestern United States. PMS 833. Boise, ID: National Wildfire Coordinating Group, National Interagency Fire Center. 97 p.

Three series of single and stereo photographs display a range of natural conditions and fuel loadings in pinyon-juniper, sagebrush, and chaparral types in the Southwestern United States. Each group of photos includes inventory information summarizing vegetation composition, structure and loading, and as appropriate, 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, pinyon-juniper, pinyon pine, Pinus edulis, Pinus monophylla, juniper, Juniperus monosperma, Juniperus osteosperma, sagebrush, Artemisia, chaparral, coastal sage scrub.

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 Ken Kerr, Grand Canyon National Park; Jim Cunio, Royal Gorge Resource Area, Bureau of Land Management; Ed Skerjanec and Mike Smith, Pike-San Isabel National Forest; Robert E. Means, Elko Field Office, Bureau of Land Management.

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. At the time this research was conducted, JON C. REGELBRUGGE was an Ecologist, USDA Forest Service, Pacific Southwest Research Station, Riverside Fire Laboratory; he is currently a Lands and Resource Officer, USDA Forest Service, San Bernardino National Forest, San Jacinto Ranger District, P.O. Box 518, Idyllwild, CA 92549.

PHOTOGRAPH AND INFORMATION ARRANGEMENT
The photographs and accompanying data summaries are presented as single sites organized into three series. Each site contains the wide-angle (50 mm) photograph, general site information, shrub structure and composition data, and as appropriate, seedling information, summaries of overstory and understory vegetation structure and composition, 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
For all series the camera point of each site was located with a global positioning system (GPS) receiver using the WGS-84 datum. Elevation was derived from topographic maps or by using the GPS.

In the pinyon-juniper series, Society of American Foresters (SAF), and Society for Range Management (SRM) cover types, indicators of current vegetation composition, were assigned for each site (Eyre 1980, Shiflet 1994). Tree and litter coverage were estimated with a series of line intercept transects (Canfield 1941). Litter depth was measured at between 20 and 80 locations distributed randomly throughout the sample area, where litter was present. Litter loading was calculated from the above mentioned depth and cover data and bulk density values derived from field measurements. Total aboveground biomass includes litter and all live and dead woody material and vegetation.

In the sagebrush and chaparral series, the principal species occurring at a site are listed, although not necessarily in the order of abundance.¹ The listing of species is not meant to be a complete vegetation inventory and may represent only a portion of the actual species richness of the sampled areas. The SRM cover type was assigned for each site (Shiflet 1994). For the sagebrush series, total aboveground biomass includes litter and all live and dead woody material and vegetation. For the chaparral series, stand age, litter loading, and shrub composition are reported. Stand age is the time since the last fire occurred in the sample area as determined from historical records. Study sites in the chaparral series were sampled as part of several different studies. Therefore, the methodology differed somewhat among sites. Where reported (for coastal sage scrub sites CH 01–CH 03), litter loading was determined by collecting litter in three 43.06-square-foot sample plots located in and around the sample area. Shrub composition and density, where reported (for chamise chaparral sites CH 05–CH 08 and ceanothus mixed chaparral sites CH 12–CH 14, and CH 16), were determined by sampling in three 172.22-square-foot square plots located in and around the sample area.

1See below for a list of scientific and common species names used in this volume.

SEEDLINGS
Seedling composition, density, and loading were determined using twelve 0.005-acre circular plots representing 43 percent of the sample area for the pinyon-juniper series. An individual of a species regarded as a tree that was less than 4.5 feet tall was considered a seedling.

TREES
For the pinyon-juniper series, depending on stand density, overstory trees were sampled either in the entire sample area, or in twelve 0.005-acre circular plots located systematically throughout the sample area (fig. 1). Tree measurement data were summarized by basal diameter size class. Basal diameter was measured above the root collar. Height to crown was defined as the height of the lowest continuous live or dead branches of the tree canopy. Crown breadth was defined as the average of two crown diameter measurements: (1) maximum diameter, and (2) the widest point perpendicular to the maximum diameter. Crown area was calculated from crown breadth. Aboveground mass values (i.e., bole, branches, and foliage) were calculated from species-specific allometric equations (Meeuwig 1980, Miller et al. 1981, Clary and Tiedemann 1986, Weaver 1986, Grier et al. 1992).

SHRUBS
Sites in the chaparral series were sampled as part of several different studies. Methodology, therefore differed somewhat among sites, but all methods allowed for the calculation of fuel loading by fuel components and plant species. All sites were located in stands with relatively homogeneous structure and species composition. Shrubs were collected on either three 172.22-square-foot plots (CH 05–CH 08, CH 12–CH 14, and CH 16), three 43.06-square-foot plots (CH 01–CH 03), or nine 43.06-square-foot plots (CH 04, CH 10, and CH 11) randomly located in and around the sample area to determine loading by species for 14 of 16 sites. Shrub loading by species was estimated based on site-specific regression equations and the dimensions of all plants occurring in either a 1,550.00-square-foot plot (CH 15), or a 4305.55-square-foot (CH 09) plot for the remaining two sites. All shrubs rooted within the 14 smaller plots were cut at ground level and weighed whole in the field immediately after cutting. Several individuals of each species, representing a range of sizes, also were separated into their component parts and returned to the laboratory for oven drying (185 °F to a constant moisture content) and weighing to determine moisture content and component fractions. Component fractions represent size classes that correspond to timelag fuel classes used in fire behavior modeling (see, for example, Burgan and Rothermel 1984).² Using ratio estimators for species-specific moisture content and component fractions, field weights were adjusted yielding ovendry loading by component on an area basis for each species.

2Woody material <=0.25 inch, 0.26-1.0 inch and 1.1-3.0 inches, and >3.0 inches in diameter corresponds to 1-, 10-, 100- and 1000-hour timelag fuels, respectively.

SELECTED SHRUB SPECIES
Individual plants of selected shrub species were measured in circular plots for the sagebrush and pinyon-juniper series. Selected species were those with a predominantly single-stem growth form and included Cercocarpus ledifolius, Purshia mexicana, and species in the genus Artemisia. In addition, limited data on species with a predominantly multi-stem growth form are reported in the sage series; such species include Krascheninnokovia lanata and species in the genus Chrysothamnus. The density and percentage of all stems that were dead is based on the number of plants rooted in 12 circular plots ranging from 0.0025-acre to 0.005-acre each. As with the trees, 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. In addition, the height, the proportion of crown that was dead in the stand, the cover, and the loading were estimated for the sagebrush series. The height is reported as the mean of all the heights of all individuals of a given species sampled. A visual estimate of the percentage of the dead portion of the crown of each plant sampled also was made and averaged to determine the dead crown proportion in the stand. Cover was estimated using line intercept transects (Canfield 1941). Loading for each species was estimated based on species-specific allometric equations (Uresk et al. 1977, Weaver 1986), with the exception of Artemisia nova which was clipped in twelve 10.76-square-foot clipped vegetation plots.

UNDERSTORY AND VEGETATION
Understory species coverage (all species coverage in the sagebrush series) was estimated using line intercept transects (Canfield 1941). Where species-specific coverage is not reported, understory vegetation coverage was estimated by lifeform category (shrub, forb, or graminoid) using the line intercept transects. Understory vegetation heights were measured at 25 points located systematically throughout the sample area. Understory vegetation biomass was determined by sampling 12 square, clipped vegetation plots (10.76 square feet each) also located systematically throughout the sample area (fig. 1). All live and dead vegetation within each square plot was clipped at ground level, separated, and returned to the laboratory for oven drying. Understory vegetation and other collected material were ovendried at a minimum of 158 °F for at least 48 hours before weighing and determination of area loading.

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). Where appropriate, 40 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). As with the shrub data for the chaparral series, woody material data are reported by size classes that correspond to timelag fuel classes used in fire behavior modeling. 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 (and the 10-hour and larger size classes for several of the sites in the sagebrush series) was determined by collecting, ovendrying, and weighing all pieces in twelve 10.76-square-foot sample plots. The decay class 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 (for the pinyon-juniper series) 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.

SPECIES LIST
Scientific and common species names are from NRCS (1999).

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.

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. 

Canfield, R.H. 1941. Application of the line interception method in sampling range vegetation. Journal of Forestry 39: 388-394. 

Clary, Warren P.; Tiedemann, Arthur R. 1986. Distribution of biomass within small tree and shrub form Quercus gambelii stands. Forest Science. 32(1): 234-242. 

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

Grier, Charles C.; Elliott, Katherine J.; McCullough, Deborah G. 1992. Biomass distribution and productivity of Pinus edulis-Juniperus monosperma woodlands of north central Arizona. Forest Ecology and Management. 50: 331-350. 

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. 

Meeuwig, R.O. 1979. Growth characteristics of pinyon-juniper stands in the western Great Basin. Res. Pap. INT-238. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 22 p. 

Miller, Elwood L.; Meeuwig, Richard O.; Budy, Jerry D. 1981. Biomass of singleleaf pinyon and Utah juniper. Res. Pap. INT-273. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 11 p. 

Natural Resources Conservation Service [NRCS]. 1999. The PLANTS database. Baton Rouge, LA: U.S. Department of Agriculture, National Plant Data Center. (https://plants.usda.gov/plants) 

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. 

Uresk, D.W.; Gilbert, R.O.; Rickard, W.H. 1977. Sampling big sagebrush for phytomass. Journal of Range Management. 30(4) : 311-314. 

Weaver, T. 1986. Estimation of Cercocarpus ledifolius biomass and leaf area index: three methods. Proceedings of the Montana Academy of Sciences. 46: 67-74.