Recent concern regarding the potential decline of aspen in the western United States has sparked interest in whether the species can be effectively regenerated. RMRS researchers and their partners at Utah State University quantified the response of regenerating aspen stems to silvicultural treatments conducted over the past decade in southern Utah. A suite of variables describing stand structure and composition, stand vigor, physiographic factors, herbivore pressure, and treatment types were measured to predict the possible controls on aspen regeneration.
Aspen regeneration was most strongly related to browsing pressure, the presence of aspen in the understory prior to treatment (advance regeneration), and site preparation technique. Secondary predictors included elevation, site index, and overstory conditions, which are generally characteristics of stand vigor.
Management recommendations from this research include the need to recognize the strong primary control that browsing pressure exerts on aspen regeneration. The level of herbivory should be assessed before treatment by measuring the height of advance reproduction. The most effective site preparation techniques, broadcast burning and browsing reduction, will directly reduce browsing pressure, assuming ungulate populations are not too large. Any management targeting timely and effective aspen regeneration should incorporate monitoring and (or) controlling browsing pressure, both before and after treatment.