Fire Intensity / Burn Severity
Recovery after fire
This review is focused on tree seedling regeneration for several reasons. First, a high mortality event, like a high- severity wildfire, kills the mature trees needed to maintain forest cover. When fire-caused mortality is minimal, we are less concerned about tree regeneration, but a high severity fire creates the need for tree regeneration if long-term for-est cover is desired. Second, high mature tree mortality limits seed availability for the regeneration of most species, especially those that are not serotinous. Third, young trees are more sensitive to soil temperature and drought than established trees (Jackson et al. 2009, Andrus et al. 2018). Older trees may persist through multiple droughts or other suboptimal conditions that kill immature trees. Finally, with changing fire regimes and the potential for increasing fre-quency of fires, seedlings are more vulnerable to death from subsequent surface fires than are established trees with thicker bark and crowns that may be further above the heat from flames (Agee 1993). We recognize that in many locations forests have increased in density or expanded into areas that were historically persistent meadows and shrublands, representing an unnatural condition where abundant tree regeneration may not be optimal or repre-sentative of the historical forest structure (then loss of for-ests may or may not be of concern). However, with drought, bark beetles, fires and other disturbances re-sulting in extensive mortality of large trees, the lack of tree regeneration remains a concern.