Contrasting Effects of Wildfire and Ecological Restoration in Old-Growth Western Larch Forests

The scientific basis for restoration of fire-excluded western larch/mixed-conifer forests is not as well developed as that for dry fire-frequent forests. We compared the effects of wildfire and restoration (combined thinning and prescribed fire) in fire-excluded western larch forests. In 2012, the wildfire site had more, taller, and more diverse tree regeneration; greater volume of coarse woody debris (CWD); and greater spatial heterogeneity (including more area in large openings) than the restoration site. Management recommendations based on our results include the following: use more intense prescribed fire than was applied to the restoration site we studied; retain abundant CWD on-site after restoration treatment; and create occasional large openings to regenerate larch and emulate the spatial heterogeneity induced by natural wildfire. Our most important finding is the greater dynamism of the wildfire-affected site than of the restored site. At the wildfire site, tree populations are turning over faster, regenerating trees are growing faster, and more CWD is available for decomposition. These contrasting outcomes suggest that a conceptualization of forest restoration that emphasizes static, or at least equilibrium, conditions is not appropriate for western larch/mixed-conifer forests.