This ecological system is widespread but patchy in distribution in upper montane to subalpine zones of the Montana Rocky Mountains, and east into mountain island ranges of central Montana. These are upper montane to subalpine forests where the dominance of lodgepole pine (Pinus contorta)is related to fire history, topo-edaphic conditions and nutrient-poor soils. Presence of this system is determined more by substrate than by other factors. The most notable occurrence of this system is in the West Yellowstone Basin and surrounding Yellowstone Highlands, such as the Madison Plateau. In this region of Montana, cold-air ponding and coarse, rhyolitic outwash obsidian sands are the major factors contributing to the extensive development of this system in southwestern Montana. Fire is infrequent in this system, averaging every 150-400 years in subalpine forests. Following stand-replacing fires, lodgepole pinewill colonize rapidly on sites that are too extreme for the establishment of other coniferous species, developing into dense, persistent, even-aged stands. Mature stands are primarily open, and develop past their initial even-aged structure to become a multi-aged structure. These stands last for longer intervals between disturbances than do conventional lodgepole pine-dominated stands.
forest and woodland, acidic, very shallow ustic soils, organic A horizon less than 10 cm, Pinus contorta
This system occurs in parts of the upper montane and subalpine elevations throughout the Montana Rocky Mountains. Elevation ranges from 975 to 2,743 meters (3,200-9,000 feet). Presence of this system is determined more by substrate than by other factors. In north-central Montana, it can be found on appropriate habitats with intrusive volcanics and very nutrient-poor soils within the Little Rocky Mountains near Zortman and the Big Snowy and Highwood island mountain ranges. The most extensive Montana expression of this system is the West Yellowstone Basin and the surrounding Yellowstone Highlands, such as the Madison Plateau. In this region of Montana, cold-air ponding and coarse, rhyolitic outwash obsidian sands are the major factors contributing to its extensive development.
Approximately 101 square kilometers are classified as Rocky Mountain Poor Site Lodgepole Pine Forest in the 2013 Montana Land Cover layers.
Grid on map is based on USGS 7.5 minute quadrangle map boundaries.
Blaine, Carbon, Cascade, Chouteau, Gallatin, Hill, Judith Basin, Meagher, Park, Phillips, Stillwater, Sweet Grass
This system generally occurs on dry to intermediate sites with a wide seasonal temperature range and long precipitation-free periods in summer. Snowfall is heavy and supplies the major source of soil water used for growth in early summer. The nutrient-poor soils include excessively well-drained pumice deposits; glacial till and alluvium on valley floors where there is cold air accumulation; warm and droughty shallow soils over fractured quartzite bedrock; and shallow moisture-deficient soils with a significant component of volcanic ash. Soils supporting these forests are typically well-drained, gravelly, coarse-textured, acidic, and rarely formed from calcareous parent materials.
These forests are dominated by lodgepole pine (Pinus contorta) withsparse undergrowth. At the closed canopy stage of stand development, undergrowth may be totally lacking. Some open stands with very sparse understories can experience a form of mixed-severity burning along downed logs when there are insufficient fuels between logs to carry fire. Depending on the arrangement and loading of logs to living trees, either mortality or fire-scarring may occur.
The shrub layer may be conspicuous to absent. Common species include bearberry (Arctostaphylos uva-ursi), snowbrush ceanothus (Ceanothus velutinus), twinflower (Linnaea borealis), creeping Oregon grape (Mahonia repens), antelope bitterbrush(Purshia tridentata), birch leaf spiraea (Spiraea betulifolia), Canadian buffaloberry (Shepherdia canadensis), dwarf huckleberry (Vaccinium caespitosum), grouse whortleberry (Vaccinium scoparium), snowberry (Symphoricarpos species) and currant (Ribesspecies).
Herbaceous layers are generally sparse, but can be moderately dense, and are typically dominated by perennial graminoids such as Columbia needlegrass (Achnatherum nelsonii), pinegrass (Calamagrostis rubescens), Geyer’s sedge (Carex geyeri), Ross’ sedge (Carex rossii), bottlebrush squirrel tail (Elymus elymoides), California oatgrass (Danthonia californica), blue wildrye (Elymus glaucus), and Idaho fescue (Festuca idahoensis). Common forbs include yarrow (Achillea millefolium), arnica (Arnica spp.), silky lupine (Lupinus sericeus), phlox (Phlox spp.), buckwheat (Eriogonum spp.), and beargrass (Xerophyllum tenax).
Establishment of lodgepole pine is episodic and linked to stand-replacing fire. Some open subalpine stands with very sparse understories often experience a form of mixed-severity burning. Trees with closed, serotinous cones appear to be strongly favored by stand-replacing fire, and allow rapid colonization of fire-cleared substrates (Burns and Honkala, 1990). These forests often exhibit a multi-aged population structure, with non-fire regeneration, and often exhibit a higher proportion of trees bearing non-serotinous cones. Trees with non-serotinous cones may predominate in these persistent or climax lodgepole pine forests. If serotiny is expressed in these stands, cone polymorphism exists and allows regeneration after non-fire disturbance. In some occurrences, stand-replacing fires within this system have occurred more frequently during the past 20 years.
Effects of fire, fire suppression, fuel accumulation, stand development, insects, and disease in these forests interact to control the establishment and maintenance of stands. In the absence of natural fire, periodic prescribed surface burns can be used to maintain this system.
Restoration strategies will depend largely on fire severity. Under favorable moisture conditions, seeds released from serotinous cones during the fire germinate on exposed mineral soil and disturbed duff the following spring. Fire creates a favorable seedbed by removing loose organic matter and exposing mineral soil or decomposed organic matter, which encourages germination. Thus, in light or moderately severe fires, additional restoration practices are not required. Early successional stages following fire in lodgepole pine forests are dominated by an undergrowth of forbs and to a lesser extent graminoids such as fireweed (Chamerion angustifolium), aster (Aster species), nettleleaf giant hyssop (Agastache urticifolia), and pinegrass (Calamagrostis rubescens).
M.S. Reid
L.K. Vance, T. Luna, S.V. Cooper
