Coarse Woody Debris in Douglas-Fir Forests of Western Oregon and Washington
Spies TA, Franklin JF, Thomas TB. 1988. Coarse Woody Debris in Douglas-Fir Forests of Western Oregon and Washington. Ecology. 69(6):1689-1702
Amounts and structural characteristics of coarse woody debris (CWD) were examined in relation to stand age and site moisture condition in 196 Pseudotsuga menziesii stands in western Oregon and Washington. Stands ranged from 40 to 900 yr old, and most if not all, originated after fire. In a chronosequence from the Cascade range, the amount of CWD followed a U-shaped pattern for stands 200 yr old) among site moisture classes. Dry sites averaged 72 Mg/ha moderate sites 137 Mg/ha, and moist sites 174 Mg/ha. The dynamics of CWD were modeled for three fire histories, each beginning with an initial fire in an old-growth stand but differing in number and severity of subsequent fires. All three models exhibited low values of CWD between 80 and 200 yr. The lowest and most prolonged minimum in CWD between 80 and 200 yr. The lowest and most prolonged minimum in CWD during succession occurred when additional fires burned early in succession, which probably happened preceding many stands in the southern Coast Range. The results of the study indicate that a steady-state condition in CWD may not be reached for >1000 yr, and that the nature and timing of disturbance play a key role in the dynamics of CWD in the dynamics of CWD in the region.
- Type
- Journal Article
- Authors
- Spies, Thomas; Franklin, Jerry; Thomas, Ted
- Units
- MORA
- Keywords
- coarse woody debris, decay rate, FIRE, old-growth stands, Pacific Northwest, Pseudotsuga menziesii, Succession