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Northern Research Station
One Gifford Pinchot Drive
Madison, WI 53726
(608) 231-9318
(608) 231-9544 TTY/TDD

Down Woody Materials



Coarse Woody Debris (CWD) Dead pieces of wood including downed, dead tree and shrub boles, large limbs, and other woody pieces that are severed from their original source of growth or are leaning more than 45 degrees from vertical. For decay classes 1-4, CWD transect diameter must be > 3.0 inches (7.6cm), for decay class 5 the transect diameter must be > 5.0 inches (12.7 cm).

Decay Class Qualitative assessment of stage of decay (5 classes) of coarse woody debris based on visual assessments of color of wood, presence/absence of twigs and branches, texture of rotten portions, and structural integrity.

Down Woody Debris (DWD) See down woody material.

Down Woody Material (DWM) Woody pieces of trees and shrubs that have been uprooted (no longer supporting growth) or severed from their root system, not self-supporting, and are lying on the ground. Previous named down woody debris (DWD).

Duff A soil layer dominated by organic material derived from the decomposition of plant and animal litter and deposited on either an organic or a mineral surface. This layer is distinguished from the litter layer in that the original organic material has undergone sufficient decomposition that the source of this material (e.g., individual plant parts) can no longer be identified.

Fine Woody Debris (FWD) Dead branches, twigs, wood splinters 0.1 to 2.9 inches (0.3 - 7.4 cm) in diameter.

Forest Floor The entire thickness of organic material overlying the mineral soil, consisting of the litter and the duff (humus).

Fuel bedDown woody material fuel complex measured from top of duff layer to the highest piece of woody debris found at the transect point.

1000+ hour Fuels Coarse Woody Debris with a transect diameter ³ 3 in (7.6 cm).

100 hour Fuels Fine Woody Debris with a transect diameter between 1 in and 2.9 in (2.5 - 7.4 cm).

10 hour Fuels Fine Woody Debris with a transect diameter between 0.25 in and 0.9 in (0.6 - 2.3 cm).

1 hour Fuels Fine Woody Debris with a transect diameter less than 0.24 in (0.6 cm).

Litter Undecomposed or only partially decomposed organic material that can be readily identified (e.g., plant leaves, twigs, etc.).

Residue Pile Density In reference to CWD residue piles, the density of the volume (as defined by the corresponding shape code dimensions) of the slash pile occupied by actual CWD.

Residue Pile Shape The shape of each CWD residue pile coded as one of four shapes: half-section sphere, half-cylinder, half-frustum of cone, or irregular solid.

Residue Piles Piles and windrows of CWD created by human activity or natural causes in cases where CWD tally is physically impossible (i.e. large wind throws).

Transect Diameter The diameter of a piece of down woody material at the point of intersection with a transect.

Unless stated otherwise, all definitions are from the USDA Forest Service Indicator Advisor Band.




Last Modified: 02/06/2007