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

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Forest Habitat Types of Northern Idaho
PRODUCTIVITY/MANAGEMENT AND SOIL EXCERPTS

[Excerpted from: Cooper, Stephen V.; Neiman, Kenneth E.; Roberts, David W. Rev. 1991. Forest habitat types of northern Idaho: a second approximation. Gen. Tech. Rep. INT-236. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 143 p.]

OTHER VEGETATIVE TYPES

Productivity/Management—This classification treats the vast majority of forested environments in northern Idaho. Communities where recurring disturbance is part of the natural environment—for example, avalanche chutes or flood plains—have not been classified but could be included in future work at the community-type level, as is being done with wetlands for the Northern Region, USDA Forest Service (Pierce 1986).

Forested Scree Communities (SCREE)

Productivity/Management—The hazards and limited opportunities associated with these sites preclude intensive management; only natural or low-impact uses such as for wildlife, watershed, and recreation are appropriate.

Flood Plain and Riparian Communities

(No productivity/management or soil information included.)

Alnus sinuata Communities

Productivity/Management—In northern Idaho attempts to convert pure A. sinuata stands to coniferous forest have generally been failures. On drier sites an A. sinuata-conifer mosaic has responded favorably to low-acreage clearcuts and uneven-aged management. But wet sites have produced highly competitive pure stands of Alnus and other species. Shrub competition, and damage by pocket gopher and varying hares are major management considerations in all the A. sinuata community types. Research on the feasibility and effective techniques to convert these communities is needed before further conifer regeneration is attempted.

Alnus sinuata/Montia cordifolia h.t.
(ALSI/MOCO; Sitka alder/miner’s lettuce)

Soils—Parent materials vary from volcanic ash to highly weathered granites to glacial till of metasedimentary origin. Soils generally exceed 40 inches (1 m) in depth and often dry throughout the rooting zone by late July and August. Soil family classification is usually a Typic or Andic Cryumbrept or Andic Cryochrept. Textures tend to be coarse sands to sandy loams, and structure is usually single grain to weak granular. The pH varies from 4 to 5.5 and is generally 1.0 pH unit lower than that of adjacent conifer-occupied sites (see Other Studies section regarding successional status/genesis of these sites).

Productivity/Management—We know of no successful management attempt to establish conifers on these sites. Silvicultural treatments on Alnus-dominated sites should only be performed where it can be ascertained that Alnus is not the indicated overstory climax species. The highly “conifer-islands” intermixed with this type should receive immediate regeneration treatment following overstory removal. Among other problems within this h.t. are high population densities of pocket gophers and hares. ALSI/MOCO sites produce abundant browse and thermal and hiding cover for wildlife.

Other Studies—This h.t. has not been previously described. All communities wherein A. sinuata is virtually the sole upper canopy dominant have heretofore been considered secondary successional stages of conifer-dominated h.t.'s. However, the stands analyzed in the study indicate that Alnus sinuata has long been the canopy dominant, perhaps for a period of time sufficient to develop a soil horizonation different from adjacent conifer-dominated sites. At least two alternative hypotheses can be advanced to explain this A. sinuata site dominance: (1) Site properties (ostensibly those of the soil) are inherently unfavorable to conifer establishment; initial site differences are possibly accentuated by continued A. sinuata dominance. (2) Chance phenomena in stand development have resulted in A. sinuata site dominance which in turn has generated site modification favoring the continued dominance of A. sinuata. We speculate, seeing no evidence to the contrary, that A. sinuata will continue to occupy these sites to the virtual exclusion of conifers and thus consider them examples of long-term stable or climax vegetation (recognized at h.t. level). Although research is needed, this also appears to be the situation on certain Pteridium aquilinum-dominated sites.

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