Wright, Clinton S.; Vihnanek, Robert E. 2013. Stereo photo series for quantifying natural fuels. Volume XIII: Grasslands, Shrublands, Oak-Bay Woodlands, and Eucalyptus Forests in the East Bay of California. Gen. Tech. Rep. PNW-GTR-xxx. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 39 p.

Four series of photographs display a range of natural conditions and fuel loadings for grassland, shrubland, oak-bay woodland, and eucalyptus forest ecosystems on the eastern slopes of the San Francisco Bay area of California. 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, East Bay Regional Park District, Tasmanian bluegum, Eucalyptus globulus, California laurel, California bay, Umbellularia californica, California live oak, coast live oak, Quercus agrifolia, coyotebrush, Baccharis pilularis.

COOPERATORS
This publication was developed by the USDA Forest Service, Pacific Northwest Research Station, Fire and Environmental Research Applications team with funding provided by the East Bay Regional Park District. The USDA Forest Service, Pacific Northwest Research Station provided funding to print this Report.

ACKNOWLEDGMENTS
Special recognition is due John Swanson, Steve Quick, John Hitchen, Sergio Huerta, Janet Gomes, Gordon Wiley, and Ken Blonski, East Bay Regional Park District for assistance selecting sites and providing logistical support. Jon Dvorak, Joe Restaino, Travis Fried, and Alex Lundquist, U.S. Forest Service, Pacific Northwest Research Station, Pacific Wildland Fire Sciences Laboratory, worked on this project in the field and in the laboratory. John Swanson, Carol Rice, Cheryl Miller, and Brad Gallup provided helpful reviews that improved the quality of the final product.

AUTHORS
Clinton S. Wright is a research forester and Robert E. Vihnanek is a supervisory forester, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Pacific Wildland Fire Sciences Laboratory, 400 North 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 in the grassland and shrubland series is shown on a single page, and includes wide-angle (16-24mm) and stereo-pair photographs and summaries of vegetation composition and structure. The shrubland series also includes general site information and summary vegetation information, as well as data describing the shrub, litter, and dead and down woody fuel components. Each oak-bay woodland and eucalyptus forest site is arranged to occupy two facing pages. The upper page contains a wide-angle (16-24mm) photograph and general site and stand information. The lower page includes the stereo-pair photographs and summaries of overstory structure and composition; understory vegetation structure and composition; and downed woody material loading and density by size class.

SITE AND STAND INFORMATION
The camera point of each site was located with a global positioning system receiver, and aspect and slope were measured with a compass and clinometer, respectively. Fuel type (LSA Associates 2009), an aggregation of many vegetation types determined from vegetation mapping done by the East Bay Regional Park District, and ecological community classification to the association level (Buck-Diaz et al. 2012, NatureServe 2013), based on the potential natural vegetation concept, were assigned for all sites. A list of the most common grass, forb, and shrub species is included. The listing of species was not meant to be a complete vegetation inventory and represents only a portion of the species richness of the sampled areas. For the two series with a tree component, crown closure at each site was measured with a forest densitometer (95 systematically located points). Tree composition and density were determined by a total inventory of the sample area for all trees greater than 4 in diameter at breast height (d.b.h.) and on twelve 0.005-ac (oak-bay woodlands and mature eucalyptus forest sites) or 0.002-ac (young eucalyptus forest sites) circular plots for all trees greater than 4 ft tall and less than or equal to 4 in d.b.h. (fig.1); trees less than 4.5-ft tall were considered seedlings. Seedling composition and density were also measured on twelve 0.005-ac circular plots.

VEGETATION>
Shrub, forb, and graminoid species coverage (along with litter coverage and mineral soil exposure) were estimated by using line intercept transects (Canfield 1941). Vegetation heights were measured at 25 points located systematically throughout the sample area. Vegetation biomass was determined by sampling square, clipped vegetation plots (twelve 10.76-ft2 plots for herbaceous species and six 43.06-ft2 plots for shrubs) located systematically throughout the sample area (fig. 1). All live and dead vegetation rooted within each square plot was clipped at ground level, sorted by lifeform, and returned to the laboratory for oven drying. Vegetation was oven dried at a minimum of 158 °F for at least 48 hours before weighing and determination of area loading.

SHRUB BIOMASS
Six shrub clip plots, as referenced above, were selected for sampling that were completely covered by shrub vegetation. A list of more than six sampling point locations was developed a priori and each point was evaluated in order until six suitable points were located. Shrub vegetation was separated into live and dead fractions for all six shrub clip plots and further separated into size classes (less than or equal to 0.25 in + foliage, 0.25-1.0 in, and greater than 1.0 in) for three of six shrub clip plots. After clipping and separation, each shrub category was weighed in the field. Three moisture content subsamples that were representative of the material in each field-weighed sample were collected in airtight containers, returned to the laboratory, and oven dried to determine moisture content. Adjustment to an oven-dry basis for each field-weighed shrub sample for each plot was made by multiplying the field-measured weight by the mean of the ratio of oven-dry weight:wet weight of the three moisture content subsamples from that plot. The dry weight average proportion of each status and size class category of the three fully separated samples was applied to the gross dry weight of the unseparated samples and multiplied by the proportion of the site that was covered with shrubs to estimate site loading by status and size class.

LITTER
Litter coverage (and mineral soil exposure) was measured by using the line intercept method (Canfield 1941), and is reported with site information for all but the shrubland series. Litter loading was estimated by collecting surface material in twelve systematically located 2.69-ft2 plots (except eucalyptus forest sites). Collected material was oven dried at a minimum of 158 °F for at least 48 hours before weighing and determination of area loading. Litter depth was calculated as the average of measurements taken every 5 ft between the 30- and 150-ft arcs on the five sample area layout lines (see fig. 1) for all sites. For eucalyptus forest sites, litter loading was estimated by multiplied the depth by a site-specific bulk density . Litter depth was calculated as an average of the depth only where litter was encountered during sampling (null values, or points where litter was absent, are not included in the average).

For the eucalyptus series, the loading of litter, bark, and branch material that had accumulated at the bases of some trees or groups of trees was estimated by measuring the gross volume of the basal accumulation, subtracting the portion of the bole volume of the trees growing out of the accumulation that was encapsulated by the volume of the accumulation to derive net volume, and applying an allometric relationship for predicting loading from net volume. Material in basal accumulations is in addition to woody material and litter measured on transects. The allometric relationship was generated by measuring and weighing 25 basal accumulations in areas adjacent to several of the sites sampled in this photo series.

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 (1980a). Transects of random azimuth starting at 45 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). Woody material in 1-, 10-, and 100-hour-and-larger size classes was tallied on transects that were 3, 10, and 30 ft long, respectively. The decay class and the actual diameter at the point of intersection were measured for all pieces greater than 3 in in diameter. All woody material less than or equal to 3 in 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 in the shrubland series was measured by collecting all 1- and 10-hour pieces in twelve 2.69-ft2 plots nested within the larger clipped vegetation plots. Collected woody material was oven dried at a minimum of 158 °F for at least 48 hours before weighing and determination of area loading.

SAPLINGS AND TREES
Overstory tree (i.e., trees greater than 4 in d.b.h.) composition and density were determined by a total inventory of the sample area. Sapling (i.e., trees less than or equal to 4 in d.b.h. and greater than 4.5 ft tall) composition and density were estimated by using twelve 0.005-ac circular plots located systematically throughout the sample area (fig. 1). Tree measurement data were summarized by d.b.h. size class and by tree status (all, live, or dead). Each stem was measured in cases where trees forked below 4.5 ft. 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. All height measurements were made by using a graduated pole (measurements less than 25 ft) or a laser rangefinder with an inclinometer.

SPECIES LIST
Scientific and common species names are from NRCS (2009). Species with a variable growth form may appear on both the shrub and tree lists.

LITERATURE CITED

Albini, F.A. 1976. Estimating wildfire behavior and effects. Gen. Tech. Rep. INT-30. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 92 p.