No abstract

Forest managers have little information of the effects of common restoration treatments, thinning and burning, on dead woody material (DWM) dynamics in fire-suppressed forests. Fine woody debris (FWD; 0.6–29.9 cm), coarse woody debris (CWD; ≥30.0 cm), and snags (≥5 cm) were inventoried and mapped in eighteen 4 ha plots before and after applying thinning (overstory, understory, and no thinning) and burning (burn and no burn) treatments. The combination of burning and thinning reduced FWD and CWD quantity and mean piece size, removed highly decayed logs, and increased small (5.0–24.9 cm) snag recruitment. In contrast, thin-only treatments produced similar results but increased FWD and did not remove many small snags. There were no differences in DWM response between the two thinning treatments. Log and snag spatial patterns prior to and following treatment were similar. These results indicate that burning in combination with thinning is more effective at reducing surface FWD and CWD, and removing small trees than are burn-only and thin-only treatments. Although large snags and logs were consumed in the burn, long-term recruitment of these habitat structures relies on managers retaining large-diameter trees. Repeated burns need to be conducted after initial restoration treatments to understand natural patterns of DWM.

Heat content with and without ash was measured for foliage of three interior Pacific Northwest conifers (Pinus ponderosa, Pseudotsuga menziesii, and Abies grandis/concolor) in five locations in Oregon and Washington. Heat content with ash did not vary by species (20.47–20.59 MJ kg–1), but ash content did vary, so that heat content without ash varied by species. Heat content also varied by location but, due to confounding with season, these differences should be viewed with caution. Foliar heat content values averaged about 10% higher than those used for surface fuels in standard fire behavior fuel models. If heat content is included in future models of crown fire behavior, errors in using heat contents that are too low may have a larger impact than most errors in estimating foliar moisture content, but sources of error might be overwhelmed by other errors in estimating crown fire energy balance.