A classification system is presented for the grasslands and shrublands of the mountainous western third of Montana. The classification utilizes the habitat type concept and is based upon potential natural vegetation. Data on plant species and environment from 580 relatively undisturbed stands were analyzed to form the classification. Twenty-nine habitat types occurring in 13 climax series are defined and described. A diagnostic key utilizing indicator plant species is provided for field identification of the habitat types. Vegetation composition, distribution, and environment of each habitat type are described in the text. Tables are provided for detailed comparisons. Management related information on forage productivity, composition changes with grazing, and range management practices is summarized for each type.

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Partial reduction of competition from surrounding vegetation more than doubled the total herbage and tripled the number of flower stalks produced the following year by bluebunch wheatgrass (Agropyron spicatum). Elimination of competition resulted in a sixfold increase in herbage production and a tenfold increase in number of flower stalks. The relative depressant effects of clipping were significantly reduced by concurrent reductions in competition. The beneficial effects of partial reduction of competition offset the adverse effects of heavy clipping, and elimination of competition more than offset the effects of extreme clipping. Number of flower stalks is a more sensitive indicator of vigor than total herbage production. Average flower stalk and foliage culm lengths are not useful indicators of vigor.

Stand age and sucker reproduction was measured in 713 aspen-dominated forest plots on nine National Forests in Utah, southeastern Idaho, and western Wyoming. About 95% of the quaking aspen (Populus tremuloides Michx.) stands are dominated by mature or over-mature trees. Almost one-sixth are in the 120-year or older age class and can be expected to deteriorate rapidly. The oldest aspen measured was 222 years. Stands in central and southern Utah are generally older than those in southeastern Idaho and western Wyoming. A fourth of the stands had more than 2,000 suckers per acre; half had fewer than 800 per acre. Approximately a third of the essentially pure (i.e., not invaded by conifers), mature or over-mature stands may experience regeneration problems because they contain less than 500 suckers per acre. A decision model is presented that will assist managers in identifying stands that require direct management intervention to ensure their survival as aspen-dominated communities. West J. Appl. For. 4(2):41-45, April 1989.

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