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

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Plant Community Classification for Alpine Vegetation on the Beaverhead National Forest, Montana
PRODUCTIVITY/MANAGEMENT AND SOIL EXCERPTS

[Excerpted from: Cooper, Stephen V.; Lesica, Peter; Page-Dumroese, Deborah. Rev. 1997. Plant Community Classification for Alpine Vegetation on the Beaverhead National Forest, Montana. Gen. Tech. Rep. INT-362. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 61 p.]

CUSHION PLANT COMMUNITIES

Carex rupestris/Potentilla ovina c.t.
(CARRUP/POTOVI; Curly Sedge/Sheep Cinquefoil)

Soils—Parent material was quartzite in one stand and limestone in the remaining seven stands. Bare ground and gravel covered 67 percent of the surface. Mean depths of litter and duff were both 0.1 inch Percent of coarse fragments ranged from 40 to 66 percent with a mean of 57 percent. Texture of the fine fraction varied from sandy clay to sandy clay-loam with a modal class of sandy clay-loam. Soil pH varied from 6.9 to 8.2 with a mean of 7.8; pH from the seven plots on limestone varied from 7.5 to 8.2 with a mean of 7.9; pH of the single plot on quartzite was 6.9. Mean organic matter content was 12 percent, mean total nitrogen was 0.34 percent, and C:N ratio was 32:1.

Productivity/Management—Graminoid productivity varied from 35 to 253 lbs per acre with a mean of 112 lbs per acre. Forb productivity ranged from 89 to 759 lbs per acre with a mean of 277 lbs per acre. Mean total productivity was 389 lbs per acre. Cushion plant productivity is difficult to measure; thus, the forb estimates are only rough approximations. However, this community type was among the least productive in our study area.

Geum rossii-Arenaria obtusiloba c.t.
(GEUROS-AREOBT; Ross’ Avens-Arctic Sandwort)

Soils—Parent materials were granite and quartzite. Bare ground and gravel covered 47 percent of the surface. Mean depths of litter and duff were both less than 0.1 inch. Percent of coarse fragments varied from 35 to 70 percent with a mean of 49 percent. Textural classes of the fine fraction ranged from sandy clay-loam to sand with a modal class of sandy loam. Soil pH ranged from 6.2 to 6.6 with a mean of 6.4. Mean organic matter content was only 8 percent, mean total nitrogen was 0.24 percent, and C:N ratio was 20:1. Soils had a sandier texture and lower levels of organic matter and nitrogen than most other community types sampled.

Productivity/Management—Graminoid productivity ranged from 0 to 118 lbs per acre with a mean of 41 lbs per acre. Forb productivity varied from 192 to 651 lbs per acre with a mean of 453 lbs per acre. Mean total productivity was 494 lbs per acre. Cushion plant productivity is difficult to measure; thus, the forb estimates are only rough approximations. The low total productivity reflects the small graminoid contribution.

Dryas octopetala/Carex rupestris c.t.
(DRYOCT/CARRUP; Mountain Avens/Curly Sedge)

Soils—Parent materials were limestone, granite, and quartzite, with limestone predominating. Bare ground and gravel covered 40 percent of the surface. Mean depths of litter and duff were both 0.1 inch. Percent of coarse fragments ranged from 33 to 54 percent with a mean of 42 percent. Texture of the fine fraction varied from sandy clay to sandy clay-loam, and modal texture was sandy clay. Soil pH ranged from 6.2 to 7.8 with a mean of 7.3. Mean organic matter content was 12 percent, mean total nitrogen was 0.34 percent, and C:N ratio was 36:1. Soils were erodible and often unstable. Sandy clay-loam soils that were derived from calcareous parent materials often showed evidence of frost churning.

Productivity/Management—Our estimates are based on only three stands, and two of these stands were on barren soils derived from partially metamorphosed limestone. These soils likely have unusual physiochemical properties that deter plant establishment and growth. Consequently, our production estimates for this type are probably low. Shrub productivity varied from 44 to 651 lbs per acre with a mean of 157 lbs per acre. Graminoid productivity ranged from 15 to 89 lbs per acre with a mean of 33 lbs per acre. Forb productivity varied from 8 to 148 lbs per acre with a mean of 43 lbs per acre. Total productivity averaged 233 lbs per acre.

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