Fuelbed Input Definitions
A fuelbed file encapsulates over 100 variables, organized by stratum: general, canopy, shrub, herbaceous, wood, litter-lichen-moss, and ground fuel. Hover over stratum/ substratum titles and field column headers for helpful tooltips to guide you in your editing.
General stratum
The General stratum contains fuelbed descriptive data.
- Fuelbed number
Fuelbed number is an alphanumeric field to stand in as shorthand for fuelbed identification. When a copy of a selected fuelbed is added to the editor via the 'Customize' button, its number becomes the parent fuelbed's number + u1 (the 'u' indicating user fuelbed). The FB No. field is not editable in the webtool, though the user could edit the XML file saved to their computer to change the <fuelbed_number> tag value. FCCS reference fuelbeds use reserved number 0-1299. The Region 6 pathway fuelbeds are numbered in the 5,000s. We recommend included a string element in user fuelbed numbers to prevent confusion.
- Fuelbed name (open-ended text field)
For fuelbeds in the FCCS reference library, the name of each FCCS reference fuelbed begins with a list of the most important or diagnostic species in the vegetation type that the fuelbed defines. Species in the same stratum are separated by a hyphen (e.g., red spruce [Picea rubens Sargent]–balsam fir [Abies balsamea (L.) Mill.] forest), and those in different strata are separated by a slash (e.g., Douglas-fir [Pseudotsuga spp.]/oceanspray [Holodiscus sp.] forest). Vegetation type (forest, shrubland, grassland, etc.) is listed after the species names. Rename as needed.
- Fuelbed description (open-ended text field)
Fuelbed descriptions typically contain the geographic extent of a fuelbed, species commonly associated with the fuelbed, a description of applicable change agents, and any other information important to distinguishing that fuelbed from others. Replace text as needed.
- Other attributes
These assignments are used for fuelbed filtering and are optional for user fuelbeds. Update as needed.
- Bailey’s Ecoregion Division
- Vegetation form (conifer forest, broadleaf forest, mixed forest, shrubland, or grassland)
- Society of American Foresters cover type (Eyre 1980) or Society for Range Management (SRM) cover type (Shiflet 1994)
- Forest structural class (Hessburg et al. 2007)
- Change agent(s) (includes natural disturbances, silvicultural activities, and other human impacts such as fire exclusion and grazing)
Canopy stratum
The canopy stratum contains overstory, midstory, and understory tree data, snag data arranged by decay classes, and ladder fuels. Canopy inputs represent average values for the entire fuelbed as opposed to an individual tree.
- Trees
- Total canopy cover (number, 0-100): total percentage cover, by crown projection, of all trees including overstory, midstory, and understory canopy layers
- Overstory
- Cover: percentage cover by crown projection
- Height: tree height, from ground to top of canopy
- HLC: height to live crown, from ground to bottom of live canopy
- Density: number of stems per unit area
- DBH: tree diameter at breast height (~ 4.5 ft/1.4 m above ground)
- Species: Relative cover %
A list of most common species coupled with their relative percent among all the species. Relative cover percents must sum to 100.
- Midstory
- See field definitions for Overstory
- Understory
- See field definitions for Overstory
- Snags
- Class 1 snags with foliage
- Cover: percentage cover by crown projection (Class 1 w/ foliage only)
- Height: height from ground to top of canopy
- Height to Crown Base: height from ground to base of crown (Class 1 w/ foliage only)
- Density: number of stems per unit area
- DBH: snag diameter at breast height (~ 4.5 ft/1.4 m above ground)
- Species: Relative cover %
A list of most common species coupled with their relative percent among all the species. Relative cover percents must sum to 100.
- Class 1 snags w/out foliage
- Height: height from ground to top of snag
- Density: number of stems per unit area
- DBH: snag diameter at breast height (~ 4.5 ft/1.4 m above ground)
- Species: Relative cover %
A list of most common species coupled with their relative percent among all the species. Relative cover percents must sum to 100.
- Class 2 snags
- See field definitions for Class 1 snags w/out foliage
- Class 3 snags
- See field definitions for Class 1 snags w/out foliage
- Ladder fuels
- Vertical continuity: are ladder fuels vertically contiguous from surface to crown fuels (Y/N)?
- Type: most dominant ladder fuel type. Select from:
- Arboreal lichen
- Dead branches
- Climbing ferns/epiphytes
- Stringy/fuzzy bark
- Vines/liana
- Leaning snags
- Tree regeneration
Shrub stratum
Shrubs are low woody plants, generally with multiple stems. There is no clear distinction between tall shrubs and short broadleaf deciduous or evergreen trees, and FCCS allows you to define them as either. Primary and secondary layer shrubs can be delineated by height, shrub species groupings, or any other classification you choose. You can also choose to characterize all shrubs in the primary layer and leave the secondary layer empty.
- Primary layer
- Cover: percentage cover by crown projection
- Height: mean height from ground to top of shrub layer
- Percent live: percentage of shrub biomass that is living
- Needle drape: is the needle drape sufficient to affect surface fire behavior? (Primary layer only)
- Loading (optional): shrub biomass per unit area
- Species: Relative cover %
A list of most common species coupled with their relative percent among all the species. Relative cover percents must sum to 100.
- Secondary layer
- See field definitions for Primary layer
Herb stratum
Nonwoody plants including grasses, sedges, forbs, and other herbaceous fuels. Primary and secondary layers can be delineated by height, species groupings (e.g., graminoids vs. forbs), or any other classification you choose. You can also choose to characterize all herbs in the primary layer and leave the secondary layer empty.
- Primary layer
- Cover: percentage cover by crown projection
- Height: mean height from ground to top of herb layer
- Percent live: percentage of herb biomass that is living
- Loading: herb biomass per unit area
- Species: Relative cover %
A list of most common species coupled with their relative percent among all the species. Relative cover percents must sum to 100.
- Secondary layer
- See field definitions for Primary layer
Wood stratum
All downed and dead woody material, including stumps and piles. Dead trees that are still standing are input in the snags category of the canopy stratum. Similarly, dead shrubs that are still rooted are input in the shrub stratum.
- Downed wood
Downed wood is comprised of woody debris (detached sticks, branches, and logs), classified by degree of decay and size, denoted by timelag class (defined as the time a fuel particle requires in order to reach 63% of its equilibrium moisture content).
- Sound wood
- FWD cover: percentage cover of fine woody debris (1-hr, 10-hr, and 100-hr timelag classes)
- FWD depth: mean depth of fine wood (1-hr, 10-hr, and 100-hr timelag classes)
- 1-hr: 1-hr timelag class (≤0.25 in/0.6 cm diameter) loading per unit area
- 10-hr: 10-hr timelag class (0.25-1 in/0.6-2.5 cm diameter) loading per unit area
- 100-hr: 100-hr timelag class (1-3 in/2.5-7.6 cm diameter) loading per unit area
- 1K-hr: 1,000-hr timelag class (3-9 in/7.6-22.9 cm diameter) loading per unit area
- 10K-hr: 10,000-hr timelag class (9-20 in/22.9-50.8 cm diameter) loading per unit area
- >10K-hr: >10,000-hr timelag class (>20 in/50.8 cm diameter) loading per unit area
- Species: Relative cover %
A list of most common species coupled with their relative percent among all the species. Relative cover percents must sum to 100.
- Rotten wood
Rotten wood is defined as partially decomposed wood debris with obvious signs of decay, such that the material falls apart when kicked. All material with a diameter less than 3 in/7.6 cm is considered sound; smaller rotten wood is generally too decayed to accurately sample.
- 1K-hr: 1,000-hr timelag class (3-9 in/7.6-22.9 cm diameter) loading per unit area
- 10K-hr: 10,000-hr timelag class (9-20 in/22.9-50.8 cm diameter) loading per unit area
- >10K-hr: >10,000-hr timelag class (>20 in/50.8 cm diameter) loading per unit area
- Species: Relative cover %
A list of most common species coupled with their relative percent among all the species. Relative cover percents must sum to 100.
- Stumps
Stumps are defined as the remaining portion of a tree stem after it has been sawn or broken. Broken-top, dead trees that are greater than breast height (4.5 ft/1.4 m) are generally considered to be snags and are recorded in the canopy stratum.
- Sound stumps
Bark intact; hard when kicked
- Height: mean stump height, measured from the ground to top of the stump
- Density: number of stumps per unit area
- Diameter: mean stump diameter
- Species: Relative cover %
A list of most common species coupled with their relative percent among all the species. Relative cover percents must sum to 100.
- Rotten stumps
Bark may or may not be intact; represents decay classes 3, 4, and 5; feels soft or punky when kicked
- See field definitions for Sound stumps
- Lightered/pitchy stumps
Rotten with resin-soaked heartwood; particularly common in Southeastern pine stands
- See field definitions for Sound stumps
- Piles
Piles are accumulations of downed wood, including natural fuel accumulations (“jackpots”), hand piles, and machine piles. Fuelbeds store piles data as pile groups (i.e., collections of piles of the same dimensions). More than one pile group can be specified to represent the piles in a fuelbed (e.g., 100 hand piles and 2 machine piles). The embedded pile calculator takes the following inputs used to estimate pile group volume, biomass, and emissions. See also Getting Started: Editing Piled Fuels.
- Pile group id and name: Pile number (starting at 1) and name (optional)
- Number of piles per unit area
- Pile type: hand or machine (i.e., piles created using equipment)
- Pile shape: select from half sphere, paraboloid, half cylinder, half-frustum of cone, half-frustum of cone with rounded ends, half ellipsoid, irregular solid
- Pile dimensions: needed widths, heights, and lengths by shape
- Soil percent: percentage of pile volume that is soil (machine only)
- Packing ratio: percentage of pile volume that is wood (machine only)
- Pile composition: select from conifer or shrub (hand piles) or specify up to 2 dominant species with relative percents (machine piles)
- Pile quality: Rating of pile cleanliness (clean, dirty, or very dirty) to inform estimated PM emissions (machine only; hand piles are assumed to be clean)
Litter-Lichen-Moss (LLM) stratum
- Litter
Litter is the top layer of the forest floor (also called the O1 or Oi organic soil horizon) and is composed of loose debris of dead sticks, branches, twigs, and recently fallen leaves or needles; little altered in structure by decomposition.
- Cover: percentage of ground covered by litter
- Depth: mean depth of the top of the litter layer to the bottom, defined as the boundary between distinguishable litter and decomposed material (duff)
- Loading (opt.): mean biomass per unit area
- Arrangement: select from normal (somewhat compacted), fluffy (fresh fallen), or perched (on grass or forb)
- Litter type: Percent: relative covers by litter type (short needle pine, long needle pine, other conifer, broadleaf deciduous, broadleaf evergreen, palm fronds, grass)
- Lichen
Ground lichens (composite organisms (fungus, alga or cyanobacterium) forming crustlike or branching growths) occur on rocks, bare ground or low vegetation.
- Cover: percentage of ground covered by lichen
- Depth: mean depth of lichens
- Loading (opt.): mean biomass per unit area
- Moss
Low-growing bryophytes; usually occurring in moist habitats.
- Cover: percentage of ground covered by moss
- Depth: mean moss depth
- Type: select from sphagnum or other
- Loading (opt.): mean biomass per unit area
Ground Fuel stratum
- Upper duff
The upper portion of organic soil (also called the Oe horizon or fermentation layer) between the LLM stratum and mineral soil, containing partially decomposed organic matter in which tree needles, leaves, and other material are identifiable.
- Cover: percentage of ground covered by upper duff
- Depth: mean depth of layer (from bottom of the litter layer to the top of the lower duff layer (or mineral soil if no lower duff layer))
- Type: derivation material, select from dead moss and litter or fibric peat (sphagnum or sedge)
- Loading (opt.): mean biomass per unit area
- Lower duff
The lower portion of organic soil (also called the Oa horizon or humic layer) between the LLM stratum and mineral soil, containing mostly decomposed organic matter, much denser than the upper duff layer. Many fuelbeds have only a single, upper duff layer, but boreal and high-elevation forests often have two duff layers.
- Cover: percentage of ground covered by lower duff
- Depth: mean depth of layer (from bottom of upper duff to beginning of mineral soil)
- Type: derivation material, select from humus or muck (fully decomposed moss/litter) or humic peat (fully decomposed sphagnum/sedge)
- Loading (opt.): mean biomass per unit area
- Basal accumulations
Basal accumulations are twigs, bark pieces, litter, and duff that accumulate and form a deep organic layer surrounding the base of trees.
- Depth: mean depth of basal accumulations of ground fuels around tree trunks
- Radius: mean radius (distance from center to outer edge) of basal accumulations of ground fuels around tree trunks
- Density: number of trees with basal accumulations per unit area
- Type: select dominant basal accumulation type from bark slough, branches, broadleaf evergreen, broadleaf deciduous, grass, needle litter, or grass
- Loading (opt.): mean biomass per unit area
- Squirrel middens
Squirrel middens are mounds of cone scales and other cone debris accumulated over time from generations of squirrels extracting seeds from cones. The mounds are composed exclusively of organic matter that can burn for extended periods of time. They are generally found in boreal forests and are uncommon in the contiguous United States.
- Depth: mean height of squirrel middens
- Radius: mean radius (distance from center to outer edge) of squirrel middens
- Density: number of middens per unit area
- Loading (opt.): mean biomass per unit area
