Techniques to restore aspen forests in the western U.S.

A series of case studies conducted in Colorado, Arizona, and Utah have shown that vegetative regenera- tion of declining aspen (Populus tremuloides Michx.) can be initiated through manipulations that provide three critical elements defined as the aspen regeneration triangle: 1) hormonal stimulation, 2) proper growth environment, and 3) sucker protection. Results of the studies used to formulate this treatment model are presented along with recommenda- tions for innovative treatments to restore aspen in landscapes where it is rare or in decline. Soils and site productivity, competition from other plants, and the potential impact of browsing animals upon new regeneration should all be considered. Choosing a course of action depends upon a careful evaluation of the size, vigor, age, and successional status of candidate aspen clones. Treatments may include doing nothing, removal of existing aspen trees, removal of competing vegetation, prescribed burning, mechanical root stimulation, and browse protection