In Montana, this ecological system occurs on the east side of the Continental Divide, north to about the McDonald Pass area, and along the Rocky Mountain Front. This system is associated with a dry to submesic continental climate regime with annual precipitation ranging from 51 to 102 centimeters (20-40 inches), with a maximum in winter or late spring. Winter snowpacks typically melt off in early spring at lower elevations. Elevations range from valley bottoms to 1,980 meters (6500 feet) in northern Montana and up to 2,286 meters (7500 feet) on warm aspects in southern Montana. It occurs on north-facing aspects in most areas, and south-facing aspects at higher elevations. This is a Douglas-fir (Pseudotsuga menziesii) dominated system without any maritime floristic composition. Fire disturbance intervals are as infrequent as 500 years, and as a result, individual trees and forests can attain great age on some sites (500 to 1,500 years). In Montana, this system occurs from lower montane to lower subalpine environments and is prevalent on calcareous substrates. Common understory shrubs include common ninebark (Physocarpus malvaceus), common juniper (Juniperus communis), Rocky Mountain juniper (Juniperus scopulorum), birch-leaf spiraea (Spiraea betulifolia), snowberry (Symphoricarpos species), creeping Oregon grape (Mahonia repens) and Canadian buffaloberry (Shepherdia canadensis). The Douglas-fir/pinegrass (Calamogrostis rubescens) type is the most ubiquitous association found within this system in Montana.
Forest and Woodland, aridic soils, foothill to montane elevations, moderate persistence (100-500 yr) interval
This system extends north into Montana on the east side of the Continental Divide to McDonald Pass and along the Rocky Mountain Front. It occurs throughout the Beaverhead Mountains.
Approximately 9,795 square kilometers are classified as Rocky Mountain Montane Douglas-fir Forest and Woodland in the 2013 Montana Land Cover layers.
Grid on map is based on USGS 7.5 minute quadrangle map boundaries.
Big Horn, Broadwater, Carbon, Cascade, Deer Lodge, Gallatin, Glacier, Granite, Jefferson, Judith Basin, Lewis and Clark, Meagher, Missoula, Park, Pondera, Powell, Ravalli, Silver Bow, Stillwater, Sweet Grass, Teton, Wheatland
East of the Continental Divide, this ecosystem forms a forest belt on cold, dry to mesic sites in the montane zone. It is found on moderately dry mountain slopes and benches. It generally occurs on gravelly soils with good aeration and drainage and a neutral to slightly acidic pH. This system is subjected to a dry to sub-mesic continental climate. Individual trees and forests can attain great age on some sites (500-1500 years), due to mixed severity fire regimes. It often occurs at the lower treeline immediately above valley grasslands, or sagebrush steppe and shrublands.
This system is dominated by Douglas-fir (Pseudotsuga menziesii) forests. Limber pine (Pinus flexilis) can co-occuron calcareous substrates, and lodepole pine (Pinus contorta) is often frequent in these stands at higher elevations. Engelmann spruce (Picea engelmannii) is found in some stands within the upper montane zone, occurring just below or intergrading with whitebark pine (Pinus albicaulis) forests. Common understory shrubs include common ninebark (Physocarpus malvaceus), common juniper (Juniperus communis), Rocky Mountain juniper (Juniperus scopulorum) birch-leaf spiraea (Spiraea betulifolia), snowberry (Symphoricarpos species), creeping Oregon grape (Mahonia repens) and Canadian buffaloberry (Shepherdia canadensis). Dwarf huckleberry (Vaccinium caespitosum) or mountain huckleberry (Vaccinium membranaceum) are foundon colder, mesic sites. Common graminoids include pinegrass (Calamagrostis rubescens), Ross’ sedge (Carex rossii), and Geyer’s sedge (Carex geyeri). Bluebunch wheatgrass (Pseudoroegneria spicata) and Idaho fescue (Festuca idahoensis) are often common on sites adjacent to upper elevation montane grasslands. The Douglas-fir/pinegrass (Camogrostis rubescens) type is the most ubiquitous association found within this system in Montana. Common forbs within these forests include yarrow (Achillea millefolium), lanceleaf arnica (Arnica latifolia), pussytoes (Antennaria racemosa), wild strawberry (Fragaria virginiana), twinflower (Linnaea borealis), and beargrass (Xerophyllum tenax).
This system experiences 100- to 500-year fire disturbance intervals, but can be more frqeuent in some stands. Douglas-fir regenerates well following fire and is tolerant of repeated, low-intensity surface fires. In the absence of disturbance, Douglas-fir is the only species that continues to regenerate under shaded conditions, and becomes dominant in undisturbed stands. Pre-settlement fire regimes may have been characterized by frequent, low-intensity ground fires that maintained relatively open stands. Under present conditions, the fire regime is mixed severity and more variable, with stand-replacing fires more common, and the forests are more homogeneous. With vigorous fire suppression, longer fire-return intervals are now common, and multi-layered stands provide fuel "ladders," making these forests more susceptible to high-intensity, stand-replacing fires. In some areas, these forests have been priorities for timber harvesting and grazing. In recent years, these forests have been subjected to prolonged periods of drought, creating conditions where stands are susceptible to outbreaks of Douglas-fir tussock moth (Orgyia pseudotsugata) and Douglas-fir bark beetle (Dendroctonus pseudotsugae).
In the absence of natural fire, periodic prescribed burns can be used to maintain this system.
Post-fire Douglas-fir forest restoration strategies will depend largely on the severity of the fire. Because these forest recover well following light to moderate intensity burns, restoration practices are not necessary. Severely burned sites on steep slopes will require sediment retention and erosion control actions before and during restoration.
M.S. Reid
L.K. Vance, T. Luna
