Montana Field Guide

Wetlands in this group are dominated by coniferous or deciduous trees growing on poorly drained soils that are saturated year-round or have seasonal flooding in the spring. Sites are poorly drained, mucky areas, and have standing water at least early in the growing season often with a mosaic of moving water and stagnant water. Sites may be dominated or co-dominated by one or more species including Subalpine Fir (Abies lasiocarpa), Engelmann Spruce (Picea engelmannii and Picea, x albertiana), Lodgepole Pine (Pinus contorta), Paper Birch (Betula papyrifera), Quaking Aspen (Populus tremuloides), Western Redcedar (Thuja plicata), and Western Hemlock (Tsuga heterophylla). Many sites occupied by these species are upland communities, but these forested sites are typified by soils that are saturated year-round and/or are seasonally flooded with an obligate wetland herbaceous understory. These forests are typically found on flat to gently sloping bottomlands often adjacent to low gradient, montane streams. They also occur adjacent to ponds, fens, wet meadows or marshes and may be found from valley bottoms to the lower subalpine. In Montana, this group occurs in mountainous areas on both sides of the Continental Divide.

This Group includes the Rocky Mountain Conifer Swamp Ecological System and portions of the Rocky Mountain Subalpine-Montane Riparian Woodland Ecological System.

Wetland Forest; Rocky Mountain Region; Montane and Subalpine Zones; Deciduous and Coniferous Trees; Seasonally, Vernally or Permanently Saturated Soils.

Typical Dominants: Subalpine Fir (Abies lasiocarpa), Engelmann Spruce (Picea engelmannii and Picea, x albertiana), Lodgepole Pine (Pinus contorta), Paper Birch (Betula papyrifera), Quaking Aspen (Populus tremuloides), Western Redcedar (Thuja plicata), Western Hemlock (Tsuga heterophylla)

In Montana, this group occurs in mountainous areas on both sides of the Continental Divide. East of the Divide in the island ranges of central Montana, it is likely restricted to the Belts, Snowies and Crazy Mtn and may be absent from drier ranges like the Bear’s Paw and Little Rocky Mountains.

In MT, G505 occurs within these Level III Ecoregions: 15 (Northern Rockies), 16 (Idaho Batholith), 17 (Middle Rockies) and 41 (Canadian Rockies).

In Montana, G505 occurs within these Major Land Resource Areas: 43A-Northern Rocky Mountains, 43B-Central Rocky Mountains, and 44A - Northern Rocky Mountain Valleys.

Small Patch

This system is dominated by coniferous trees on poorly drained soils that are saturated year-round or are subjected to seasonal flooding during spring months. These forests are found on flat to gently sloping lowlands often adjacent to low gradient montane streams. These wetland forests occur from valley bottoms to the lower subalpine. They can also occur on steeper slopes where soils are shallow over unfractured bedrock. Soils in these systems are poorly drained and can be organic peat or muck, but are more commonly mineral soils with an A horizon of 10 centimeters (4 inches) or less. Surface horizons usually have high organic matter, and redox depletions are found in moist subsoil. Water tables are typically within 50 centimeters (20 inches) of the soil surface throughout the year, with standing water in surface depressions. There may be both moving and stagnant water within these forests. These communities may occur as an ecotone between fens, wet meadows or marshes and mesic, upland coniferous forests. Some occurrences develop in spring-fed areas adjacent to lakes and ponds, but they are most often found on benches, toeslopes or valley bottoms along mountain streams.

This group is dominated by conifers or deciduous trees with an obligate wetland herbaceous understory on poorly drained soils that are saturated year-round or that have seasonal flooding in the spring. Sites may be dominated or co-dominated by Subalpine Fir (Abies lasiocarpa), Engelmann Spruce (Picea engelmannii and Picea, x albertiana), Lodgepole Pine (Pinus contorta), Paper Birch (Betula papyrifera), Quaking Aspen (Populus tremuloides), Western Redcedar (Thuja plicata), or Western Hemlock (Tsuga heterophylla). The understory is dominated by obligate wetland, herbaceous species. In many conifer-dominated swamps, the understory vegetation is characterized by a high cover of ferns and fern allies such as American ladyfern (Athyrium filix-femina), Woodfern (Dryopteris species), and Horsetail (Equisetum species). Common graminoids include Bluejoint Reedgrass (Calamagrostis canadensis), Beaked Sedge (Carex utriculata) and Softleaf Sedge (Carex disperma).

In Spruce- (Picea species) dominated swamps in the Flathead Valley, Skunk Cabbage (Lysichiton americanus) can form a nearly continuous cover in the understory. American ladyfern is often co-dominant on these sites. In other spruce-dominated occurrences, Field Horsetail (Equisetum arvense) or Rough Horsetail (Equisetum hyemale) and American ladyfern are frequently the dominant species in the understory. Forbs include Arrowleaf Groundsel (Senecio triangularis), Brewer’s Miterwort (Mitella breweri), Five Stamen Miterwort (Mitella pentandra), Bunchberry Dogwood (Cornus canadensis), Dwarf Red Blackberry (Rubus pubescens), Twisted Stalk (Streptopus amplexifolius), and Canada Violet (Viola canadensis) (Hansen et al. 1995). Orchids such as Round-leaved Orchis (Amerorchis rotundifolia), Sparrow’s Egg Ladyslipper (Cypripedium passerinum) and Small Yellow Ladyslipper (Cypripedium parviflorum) may occur on hummocks formed around base of trees and shrubs, especially in spruce swamps occurring adjacent to extremely rich fens. The shrub canopy may include Thinleaf Alder (Alnus incana), Water Birch (Betula occidentalis), Dwarf Birch (Betula nana) and Red-osier Dogwood (Cornus sericea).

In northwestern Montana, swamps of Western Redcedar (Thuja plicata) and Western Hemlock (Tsuga occidentalis) are largely confined to toeslopes and valley bottoms below 4,200 feet. In these swamps, Devil’s-club (Oplopanax horridus) is the dominant understory. Pacific Yew (Taxus brevifolia) is often present. The herbaceous understory includes Skunk Cabbage, American Ladyfern, Wild Ginger (Asarum caudatum), Foam Flower (Tiarella trifoliata), Starry False Solomon's-seal (Smilacina stellata), and Sweet-scented Bedstraw (Galium triflorum).

Subalpine Fir (Abies lasiocarpa) swamps are infrequent in Montana, but floristically, they are very similar to western red cedar swamps. This minor type occurs in colder areas between 3,900 to 5,000 feet in northwestern Montana (Pfister et al. 1977). However, subalpine fir-bluejoint reedgrass systems are common throughout Montana up to the subalpine elevations. Shrub cover is low and is usually represented by Alder (Alnus species). Bluejoint Reedgrass dominates the understory vegetation.

In Montana, this group includes 4 Alliances and 13 Associations within the National Vegetation Classification, which likely encompasses the diversity of these habitats within this group in the state.

Due to the high-water tables, the shallowly-rooted trees are susceptible to windthrow.

Sites should be managed to maintain hydrologic function. Wet soils are very vulnerable to compaction. Increased land use within 100 meters (328 feet) has been correlated with increased nutrient levels in peatlands in Montana, so setbacks should be 100 meters or greater to adequately protect these systems (Jones 2003).

Restoring hydrology on sites where water has been drained or the hydrology altered is critical for proper functioning and maintenance of the habitats.

G. Kittel and M.S. Reid (2015)

S. Mincemoyer, T. Luna, C. McIntyre, L. Vance

12/6/2024