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.]

WETLAND COMMUNITIES

Deschampsia cespitosa/Caltha leptosepala c.t.
(DESCES/CALLEP; Tufted Hairgrass/Elkslip Marshmarigold)

Soils—Parent materials included alluvium, limestone, sandstone, basalt, and gneiss. Litter and duff depths averaged 0.6 and 0.4 inch. Coarse fragment content was consistently low, averaging only 3 percent, with traces of gravel and rock found on the surface. Bare soil exposure was as high as 20 percent, especially where pocket gopher (Thomomys talpoides) workings were extensive. Soil texture varied from clay to sandy clay with a sandy clay modal value. Soil reaction for calcareous substrates averaged 7.5 pH, while that for noncalcareous was only 5.8 pH. Mean organic matter content was 20 percent, mean total nitrogen was 0.57 percent, and C:N ratio was 15:1.

Productivity/Management—Total productivity ranged widely, from 621 to 3,197 lbs per acre with a mean of 1,820 lbs per acre. Graminoid productivity accounted for only 13 to 42 percent of the total. These productivity figures are likely underestimates because at least two sites were sampled prior to culmination of growth.

Carex scopulorum/Caltha leptosepala c.t.
(CARSCO/CALLEP; Holm’s Rocky Mountain Sedge/Elkslip Marsh Marigold)

Soils—All parent materials were characterized as alluvium, mostly volcanic-derived. Four of the five sites had fibrous peat at least 6 inches deep. Litter depths averaged 0.7 inch; we did not discriminate duff from peat. No coarse fragments were found in any of the profiles. Soil texture ranged from clay to sandy clay-loam with a modal value of clay loam. Soil reaction for the one calcareous site (pH = 5.9) was the lowest of any calcareous site sampled; however, the soils derived from volcanic alluvium showed no trend of lower pH values (6.0 average) than other wet or moist sites. The only slightly acid values indicated minerotrophic sites having more in common with fens than bogs (as this c.t. has been termed in the literature). Mean organic matter content was 25 percent, mean total nitrogen content was 0.70 percent, and C:N ratio was 17:1. Organic matter and nitrogen content were higher than in other wetland types and were equaled only by the DRYOCT/POLVIV turf.

Productivity/Management—Average productivity for this c.t. (2,277 lbs per acre) was higher, particularly in the graminoid component (1,720 lbs per acre), than that of any other study area c.t. However, the range (1,426 to 4,123 lbs per acre) overlaps with a number of moist or wet site types. We speculate that these values are underestimates, as sampling invariably occurred prior to phenological optima. A protected site at 10,230 ft in the Madison range had a total productivity of 4,123 lbs per acre, much higher than for comparable c.t.’s in the central Rockies (Briggs and MacMahon 1983; May and Webber 1982; Scott and Billings 1964).

Salix reticulata/Caltha leptosepala c.t.
(SALRET/CALLEP; Snow Willow/Marsh Marigold)

Soils—Both stands were developed on limestone but were notably low in coarse fragment content (<10 percent). Litter and duff depths were less than 0.5 inch. Modal soil texture was clay. Despite the wet conditions, soil reaction was typical for calcareous substrates (7.5 pH average). Mean organic matter content was 15 percent, mean total nitrogen was 0.40 percent, and C:N ratio was 24:1.

Productivity/Management—The wide range in productivity, 517 to 1,670 lbs per acre, despite the similarity of site parameters, is partly explained by the fact that the low-productivity site had experienced snow release just prior to sampling. The higher figure would be more typical for the c.t. The shrub fraction of total production was 56 and 78 percent.

Salix planifolia/Carex scopulorum c.t.
(SALPLA/CARSCO; Planeleaf Willow/Holm’s Rocky Mountain Sedge)

Soils—Parent material for the single sampled stand was gneiss-derived alluvium in which there were no coarse fragments. With the high moss and litter cover there was no exposed bare ground. The pH was 6.3. Cold, saturated substrates were associated with the accumulation of peat as exemplified by this stand.

Productivity/Management—Total productivity was 2,373 lbs per acre: 860,178, and 1,335 lbs per acre, for graminoids, forbs, and shrubs, respectively.

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