The mature age class: A stand is considered within the mature age class when the maj ority
of stocking (>70%) can be found as dominant sawlog trees (30-45 cm DBH). The stand age
should be > 55 years old.
Field Measurements
Each reference location had a cluster of three one-hectare blocks, containing stands
representing each of the three previously defined age classes. Each one-hectare block was sub-
divided into four randomly placed 400 m2 meaSurement plots. Tree height and DBH were
measured on all trees > 10 cm DBH. At least two of the dominant trees were cored at breast
height to determine stand age. Stand density (trees/ha), basal area (m2/ha) and standing volume
(m3/ha) were calculated from these data. In addition, the volume (m3/ha) of all snags and downed
woody debris (CWD) were also calculated. The equation used for tree and snag estimates was:
V = (0.000078539816*(DBH2))*tree height.
The volumes of downed logs were estimated with Smalian's metric equation:
V = [((D2) + (d2))*0.00003927]* log length (m),
where D = diameter large end (cm) and d = diameter small end (Wenger, 1984).
We adapted the system of five decomposition states for snags and downed woody debris used by
Spetich et. al. (1999). The decomposition descriptions translated to five levels of decomposition
deductions by percent (15, 30, 45, 60, and 75%; see Table 2-1).
Each 400 m2 plOt contained four smaller 1 m2 Subplots randomly placed within the larger
plot for understory sampling (Figure 2-3). Percent cover of each species was assessed using a
modified Daubenmire method incorporating eight different levels (Daubenmire, 1959). Coleman
rarefaction and the Shannon-Weiner diversity indices were calculated for each stand (Koellner
and Hersperger, 2004; Colwell, 2006).