Ecological characteristics of forest remnants left by wildfire

Increased awareness of the key ecological role of natural disturbance in maintaining ecological integrity and function coupled with forest harvesting becoming a dominant disturbance process has lead to an increasing desire to study natural disturbance at multiple scales. The eventual goal is to design harvesting regimes that achieve the ecological conditions that are maintained in nature by natural disturbance. Legacies of natural disturbance such as unburned forest remnants left by wildfire commonly occur scattered throughout large wildfires. The objective of this dissertation is to develop a better understanding of the role of unburned forest remnants in providing ecological diversity and sources of natural conifer regeneration. Two separate studies were undertaken. The first study characterized remnant habitats and compared them to large contiguous patches of remnant free young, mature and old forest. The second study examined post-fire recruitment surrounding remnant patches of Douglas-fir. Remnants could be discriminated from other stand types based on measures of tree and snag density. Some remnants displayed a unique unevenaged lodgepole pine regeneration structure compared to other stand types. Differences between remnants and other stand types appear to stem from the influence of the wildfire through which they survived. Remnants displayed high variability in all ecological variables examined which appears to relate to the variable influence of wildfire on them. Remnants share many ecological characteristics with old forest and thus could provide some of the same functions. Douglas-fir remnants provide a positive influence on Douglas-fir recruitment in the post fire regenerating forest. Patches of mature forest left in managed cutovers could serve similar functions as wildfire remnants. However, selection and management criteria must be developed to ensure that the ecological characteristics of wildfire remnants are duplicated within these reserves. The alternate regeneration dynamics demonstrated by some remnants could provide a model for the development of an alternate silviculture system for lodgepole pine dominated stands. There are many limitations to our ability to incorporate characteristics of natural disturbance into managed forests. For instance, removal of the trees to make wood products restricts our ability to leave large numbers of standing snags. However, leaving patches of trees behind which emulate the ecological characteristics of island remnants is achievable and can bring us closer towards achieving ecological sustainability in the managed forest.