A Guide to Soil Quality Monitoring for Long Term Ecosystem Sustainability on Northern Region National Forests

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Forest Habitat Types of Montana
PRODUCTIVITY/MANAGEMENT AND SOIL EXCERPTS

[Excerpted from: Pfister, Robert D., Bernard L. Kovalchik, Stephen F. Arno, and Richard C. Presby. 1977. Forest habitat types of Montana. Gen. Tech. Rep. INT-34. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest & Range Experiment Station. 174 p.]

OTHER VEGETATION TYPES

Forested Scree Communities
(SCREE)

Soil—Slopes covered with rock fragments are variously referred to in the literature as talus, scree, or rock debris. We have chosen to use the broad sense of the term “scree”—that is, any slope covered with loose rock fragments (Fairbridge 1968). The term is derived from the Old Norse word “skritha” which literally means “landslide, or the rock that slides away under the foot” (Gary and others 1972). Many of these sites are treeless, but those with finer rock often support an open forest cover. Ecologically, such stands can be considered as topo-edaphic climaxes, where the vegetation reaches a quasi-equilibrium with the constantly shifting substrate.

Productivity/Management—SCREE is characterized by steep, unstable slopes, lack of soil development, stockability limitations, low site productivity, and regeneration difficulty. Uses of these sites should be restricted to those which occur naturally, such as use by wildlife. Hazards are too high and opportunities too low to attempt intensive management.

Bottomland Hardwood Forests

These riparian forests are dominated by species of Populus, Salix, Betula, and Alnus, and by arborescent shrubs including Cornus stolonifera, Sambucus coerulea, Sorbus scopulina, Acer glabrum, Crataegus spp., and Prunus spp. They extend along rivers from the mountain forests far out into semiarid grasslands. Because of periodic destructive flooding, along with changes in stream channels and sedimentation, climax is rarely approached, even though conifers may be present with the hardwoods. Despite frequent disturbance, relatively stable plant communities develop and are identifiable. Analysis is complicated because these riparian forests are heavily grazed and otherwise disturbed by man's activities. Only a few undisturbed stands remain, usually on islands in the major rivers.

Populus Tremuloides Stands

Pure stands of Populus tremuloides are found in the prairies immediately east of Glacier National Park. These self-perpetuating aspen stands are apparently the southward extension of the broad Canadian groveland found at the foot of the Rockies in Alberta and extending east across Alberta and Saskatchewan into southwestern Manitoba and adjacent Minnesota (Lynch 1955). Climax aspen stands apparently related to this groveland were noted in the current study as far south as Augusta (west of Great Falls). It is evident that the aspen groves have more soil moisture than the adjacent grassland (Lynch 1955). Conifers are at best marginally present in these situations and their reproduction may be prevented by abundant Populus and luxuriant undergrowth (Pfister 1972a). Small patches of climax aspen groveland may also occur to a limited extent farther south in Montana, near or east of the Continental Divide. Reed (1971), Wirsing (1973), and Hoffman and Alexander (1976) described three Populus tremuloides habitat types in Wyoming.

Juniperus Woodlands

Stands of essentially pure Juniperus scopulorum cover small areas on rocky, dry sites in the higher valleys near the Continental Divide. We noted such stands in the vicinities of Drummond, Butte, Whitehall, and in the northern part of the Madison Range, but did not sample them. These coniferous woodlands, found well below the forest proper, are apparently a northern extension of the Great Basin “Pinyon/juniper” zone.

Savanas

Coniferous forest and mountain grassland are by far the two most extensive vegetational formations in the Montana Rockies. The boundary between them is usually well-defined. Mueggler and Handl (1974 preliminary draft, USDA Forest Service, Intermountain Station) have made a classification of grassland and shrubland habitat types in the Montana Rockies.

Our forest classification includes all stands having a potential of at least 25 percent forest canopy. Areas having 5 to 25 percent crown canopy coverage potential are termed savannas—grassland with scattered trees (Penfound 1967). Such areas are not extensive, but if encountered, they should be checked against both the grassland and forest classifications. (Neither study specifically sampled savannas.)

Great Plains Forests

Non-Rocky Mountain forests in eastern Montana were only marginally covered in this classification. Sampling was restricted to Pinus ponderosa forests in the Ashland and Roundup vicinities. Stands in the Missouri River Breaks northeast of Lewistown were not sampled, although Mackie (1970) described them. Isolated areas of mountain forests not sampled include the Bearpaw and Little Rocky Mountains, and the Sweetgrass Hills in north-central Montana, and the northern end of the Bighorn Range near the Wyoming line. Hoffman and Alexander (1976) should be useful in the latter area.

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