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.]

PINUS FLEXILUS SERIES

Soil—Sites are generally rocky with intermittent shallow duff accumulation (appendix D-1). Surface soils are shallow gravelly loams to gravelly silts, nearly neutral, and generally derived from limestone or other calcareous parent materials. Surface horizons are typically dark-colored, reflecting the strong influence of grasses and forbs on soil development.

Productivity/Management—Timber productivity is very low (appendix E-4) in the severe environments of this series. Site indexes of both Pinus flexilis and Pseudotsuga menziesii are very low, and stockability limitations are reflected by low basal areas in natural stands (appendix E-1). Old growth trees rarely reach 50 feet height (appendix E-2).

The forage value of the undergrowth for domestic stock or wildlife varies among the habitat types. The overstory may provide important escape cover for wildlife, especially on sites adjacent to grasslands.

Pinus flexilis seeds are large, and constitute an important food source for certain bird and rodent species.

Pinus flexilis/Agropyron spicatum h.t.
(PIFL/AGSP; limber pine/bluebunch wheatgrass)

Soil—We found this type only on sedimentary parent materials, primarily limestone and sandstone (appendix D-1). The average pH was high (7.1), reflecting the calcareous parent materials. Ground surfaces had averages of 18 percent exposed rock and 25 percent bare soil. Duff accumulation averaged only 1 cm on the remaining area.

Productivity/Management—Although these sites are often adjacent to heavily-grazed grasslands, domestic livestock do not use the PIFL/AGSP h.t. heavily. Low forage production and steep slopes limit potential for domestic grazing.

Pinus flexilis/Festuca idahoensis h.t.
(PIFL/FEID; limber pine/Idaho fescue)

Soil—More than one half the sample stands were on calcareous parent materials (appendix D-1). Surface soils were slightly basic on the calcareous substrates and neutral to acidic on other substrates. Textures were gravelly, ranging from sandy loams to silts. Moderate amounts of surface rock (12 percent) and bare soil (8 percent) were exposed in the FEID phase. Duff was shallow (1 cm) in both phases.

Productivity/Management—PIFL/FEID h.t. seems to be capable of supporting considerable use by domestic stock. However, use was light in the areas we sampled. Immediately north of the Montana border, Moss and Campbell (1947) found that heavy grazing of Festuca scabrella-dominated grasslands resulted in greatly decreasing the coverage of that species while increasing the coverage of Festuca idahoensis.

Pinus flexilis/Juniperus communis h.t.
(PIFL/JUCO; limber pine/common juniper)

Soil—Soils had high pH values (average 7.1), reflecting the predominance of calcareous parent materials (appendix D-1). Bare soil (1 percent) and rock exposure (4 percent) were less than, and duff accumulations (3 cm) were greater than in other habitat types in this series. Textures were gravelly loams to gravelly clay loams.

Productivity/Management—Timber productivity is low to very low (appendix E). Cattle use appears to be moderate. Our observations also indicate that mule deer make substantial use of the type from spring through fall.

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