Wildfire catalyzes upward range expansion of trembling aspen in southern Rocky Mountain beetle-killed forests

In this study, we assessed whether recent wildfires and spruce beetle outbreaks promoted upward range expansion of trembling aspen (Populus tremuloides) in the San Juan Mountains of southern Colorado. We assessed aerial imagery for presence/absence of aspen in the study area and ground truthed a subset of these points to compare the aerial imagery analysis with field records of aspen. From these data we determined the upper elevational limit of aspen in the study area before fire. We then conducted field surveys at and above the upper elevational limit of aspen in burned and unburned, but beetle killed areas and collected data on stand structure, surface cover, seedling density and microsite conditions associated with seedlings.  Â