A rare episode of sexual reproduction in aspen (Populus tremuloides Michsx.) following the 1988 yellowstone fires

A widely held tenet of Rocky Mountain ecology is that trembling aspen (Populus tremuloides Michx.) reproduces almost exclusively by vegetative root sprouting. However, a rare episode of sexual reproduction in aspen occurred following the extensive Yellowstone fires in Wyoming (USA) in 1988. Great numbers of aspen seedlings became established in burned areas in 1989, apparently because of the unusual combination of high seed production, favorable weather conditions, and suitable substrate conditions that existed that year. The new aspen genets are elongating and are developing lateral root systems with numerous sprouts. Genetic diversity of seedling populations on the Yellowstone Plateau is greater than the diversity of mature clones that were sampled in northern Yellowstone National Park. Aspen has become established in many portions of the park where it was absent before the 1988 fires. Thus, we appear to be witnessing an unusual ecological event in which a widespread, ecologically important species has very rapidly expanded its geographic range and genetic variability in response to a large-scale natural disturbance.