The following large wood inventory protocol was provided by Mendocino Redwood Company (MRC) for use in interpreting their large wood data:

LWD was inventoried in watercourses during the stream channel assessment.  All “functional” LWD was tallied within the active channel and the bankfull channel for each sampled stream segment.  Functional LWD is that LWD which is providing some habitat or morphologic function in the stream channel (i.e. pool formation, scour, debris dam, bank stabilization, or gravel storage).  There is no minimum size requirement for functional LWD. The LWD is classified by tree species class, either redwood, fir (Douglas-fir, hemlock, grand fir), hardwood (alder, tan oak, etc.), or unknown (if tree species is indeterminable). Length and diameter were recorded for each piece so that volume could be calculated.

LWD associated with an accumulation of 3 pieces or more is recorded and the number of LWD accumulations in the stream survey reach is tallied.  LWD pieces are also assigned attributes if they fall into certain categories.  These categories are:  if the LWD piece is part of a living tree, root associated (i.e. does it have a rootwad attached to it), is part of the piece buried within stream gravel or the bank, or is the piece associated with a restoration structure. 

By assigning these attributes, the number of pieces in a segment which, for example, have a rootwad associated with the piece can be noted.  This is important as these types of pieces can have ecological benefits above that which a LWD piece alone may have. Pieces that were partially buried were noted, as calculated volume for these LWD pieces represents a minimum.  There may likely be a significant amount of volume that is buried that we cannot measure.  Also, these pieces are more stable in the channel during high flows.  The percentage of total pieces which are partially buried was calculated for each stream segment.  Some consideration was given as to what percentage (0-25%, 25-50%, 50-75% and 75-100%) of the LWD pieces in the stream were recently contributed (<10 years).  The LWD is further classified as a key LWD piece if it meets the following size requirement:

Table D-3.  Key LWD Piece Size Requirements (adapted from Bilby and Ward, 1989)

            Debris jams (>10 pieces) were noted and total dimensions of the jam recorded. This volume was calculated and added to total LWD volume with a correction factor of 50%.  In other words, 50% of the total volume of a debris jam was considered to be “air space.” Total number of pieces and number of key pieces were noted.  Species and dimensions were not recorded for individual pieces contained in debris jams.  All volume estimates and piece counts were separated in two groups, one not considering jams and one considering all LWD pieces in the segment, debris jams included.  The percentage of total volume and total pieces per segment which was contained in debris jams was also calculated.

The quantity of LWD observed is normalized by distance, for comparison through time or to other similar areas, and is presented as a number of LWD pieces per 100 meters. This normalized quantity, by distance, is performed for functional and key LWD pieces within the active and bankfull channel. The key piece quantity in the bankfull channel (per 100 meters of channel) is compared to the target for what would be an appropriate key piece loading.  The target for appropriate key piece loading is derived from Bilby and Ward (1989) and Gregory and Davis (1992) and presented in Table D-4. 

Table D-4.  Target for Number of Key Large Woody Debris Pieces in Watercourses of the Big River WAU.