Montana Field Guide

G314 is the primary, vegetated group above timberline throughout all the higher mountain ranges in the state, including the island ranges. It includes wind-scoured fellfields and dry to mesic, alpine turf communities dominated by graminoids and forbs. In contrast, G316 - Alpine Dwarf-Shrubland & Krummholz is characterized by sub-shrubs or krummholz growth forms and G520 - Alpine - Subalpine Herbaceous & Dwarf-Shrub Riparian & Wetland occupies wetter sites on the landscape. These alpine communities occur as low as 6,000ft in the northwest to over 11,000ft on the Beartooth Plateau in south-central MT. Alpine zones are characterized by a very cold climate and high amounts of snowfall during the winter and a very short growing season. At these elevations, the growing season typically ranges from 60 to 90 days and during this period, these areas are subject to windy conditions, high solar radiation and widely variable diurnal temperatures. Freezing temperatures and snow can occur throughout the summer months. Annual precipitation in these alpine environments typically ranges from 30-70 inches with significant amounts of that falling as snow during the majority of the year.

This group can largely be divided into Fellfields, which are dry, gravelly, wind-scoured areas such as ridgetops and windward slopes and saddles, and turf communities, which form on gentle to moderate upper slopes, flat ridges, basins, and gentle summit ridges where soil has become relatively stabilized and the soil moisture persists throughout most of the growing season. Turf communities are composed of a diversity of rhizomatous sedges, rushes, woodrushes, grasses and forbs that form a dense turf that is rarely greater than 12 cm (5 inches) tall. Depending on slope protection, soil development, snow depth, turf communities can range from dry to mesic. In contrast, most fell-field plants are adapted to a xeric environment and occur as singular plants among exposed rocks or within ribbons perpendicular to the slope. These species are typically cushioned, matted or succulent. Plant cover is low to moderate (15 to 50%) with exposed, rock and gravel constituting the remainder of cover. Throughout its range in Montana, this group mixes with talus and scree fields. Turf development may still be evident, but it is patchy and discontinuous due to high rock content and very shallow soil development.

This Group incorporates the Alpine Turf and the Alpine Fellfield Ecological Systems.

Alpine Zone; Vegetation Cover >15%; Short Growing Season; Graminoid and/or Forb Dominated; Shallow, Gravelly Soils; Fellfield Communities, Turf Communities.

This group occurs in all the higher elevation mountain ranges in Montana that have some herbaceous-dominated areas above treeline, including the island mountain ranges.

In Montana, G314 is confined to areas within or immediately adjacent to Level IV Ecoregions 15h (High Northern Rockies), 16h (High Idaho Batholith), 17h (Middle Rockies Alpine Zone) and 41b Canadian Rockies Crestal Alpine-Subalpine Zone.

In Montana, G314 occurs within these Major Land Resource Areas: 43A-Northern Rocky Mountains and 43B-Central Rocky Mountains.

Large Patch

In Montana, alpine turf and fellfield communities are well represented throughout the higher mountain ranges. Elevations range from as low as 6,000 ft in northwestern Montana to over 11,000ft on the Beartooth Plateau. At these elevations, the growing season typically ranges from 60 to 90 days and during the growing season, these areas are subject to windy conditions and widely variable diurnal temperatures. Freezing temperatures and snow can occur throughout the summer months. Annual precipitation in these alpine environments typically ranges from 30-70 inches with significant amounts of that falling as snow during the majority of the year.

Turf communities form on gentle to moderate upper slopes, flat ridges, basins, and gentle summit ridges where soil has become relatively stabilized and soil moisture persists throughout the majority of the growing season. During winter months, turf communities are subjected to very cold temperatures, high winds, and heavy accumulations of snow. Snowpack accumulation is dependent on topography and is higher in alpine basins whereas ridges and summits can be blown free of snow due to high winds and sublimation. Soils are derived from a variety of parent materials and can be acidic or calcareous. The A horizon is typically less than 10 cm deep. Soils are typically rocky or gravelly with good aeration and drainage.

Fellfields are wind-scoured areas that are often free of snow in the winter or at most, have a shallow snowpack. They occur on upper slopes, ridgetops, benches and saddles where the combination of exposure and wind subjects the vegetation to drying conditions and environmental stress, leading to less soil moisture during the growing season in contrast to the more mesic, turf communities. Soils on these windy, unproductive sites are shallow, stony, low in organic matter, and poorly developed; wind scouring often results in a gravelly pavement. Organic matter is only found in limited quantities within vegetation ribbons and patches of dwarf-shrubs. Soils can be acidic or calcareous depending upon the underlying parent material. Fellfields often have significantly less vascular plant cover than turf communities, mostly in the range of 15 to 50% with exposed, rock and gravel constituting the remainder of cover. The distinction between turf and fellfield communities is not always clearcut and when the two occur adjacent to each other, the transition from turf to fellfields may be gradual or relatively abrupt depending largely on topographic features.

Embedded within this group is a mosaic of alpine plant communities that vary in density and composition depending on soil development, snow retention, subterranean hydrology and localized topography. They can generally be categorized as either turf communities or fellfields. Turf communities are composed of a diversity of grasses, sedges, rushes and forbs that form an open to more often, dense plant community that is rarely greater than 5 inches tall. Depending on slope, soil development, wind exposure and winter snowpack, turf communities can range from dry to mesic. The more mesic expressions of turf communities form on gentle slopes and basins where subirrigation from permanent snow fields and higher levels of organic matter accumulation occurs in the soil. Common graminoid species in turf communities include grasses, such as Bluegrasses (Poa alpina, Poa fendleriana, Poa glauca, Poa secunda), Alpine Timothy (Phleum alpinum), Tufted Hairgrass (Deschampsia cespitosa), Fescues (Festuca idahoa and alpine relatives), Spike Fescue (Leucopoa kingii), Purple Reedgrass (Calamagrostis purpurascens), sedges (Carex phaeocephala, Carex obtusata, Carex scirpoidea, Carex spectabilis, Carex rupestris, Carex capillaris, Carex paysonis, Carex albonigra, Carex elynoides, Carex lachenalii, Carex haydeniana, and Carex nardina), and woodrush (Luzula spicata) (Cooper etal 1997). The presence and abundance of these species varies in part, geographically (north to south), topographically, by soil type and parent material, and by local moisture conditions.

Forb cover is usually less abundant than graminoid cover in alpine turf communities, though diversity can be high. A few common species include Blue-leaved Cinquefoil (Potentilla glaucophylla), Rocky Mountain Goldenrod (Solidago multiradiata), Moss Campion (Silene acaulis), Louseworts (Pedicularis spp), and Eschscholtz's Buttercup (Ranunculus eschscholtzii). In well-developed turf communities, forb diversity increases and can reach greater than 40% percent cover. Additional species include arnica (Arnica species), alpine pussytoes (Antennaria species), Subalpine Fleabane (Erigeron peregrinus), Large-flower Fleabane (Erigeron grandiflorus), Sibbaldia (Sibbaldia procumbens), Glacier Lily (Erythronium grandiflorum), Castilleja rhexiifolia, Western Anemone (Anemone occidentalis), Alpine Saint John’s Wort (Hypericum formosum), Mountain Deathcamas (Zigadenus elegans), Alpine Bistort (Polygonum bistortoides), and Viviparous Bistort (Polygonum viviparum). Southwestern Montana alpine turf communities often include forbs more common in the middle Rocky Mountain region such as Alpine Forget-me-not (Eritrichium nanum), Ross Avens (Geum rossii), Common Alp Lily (Lloydia serotina), and Sheep Cinquefoil (Potentilla ovina). Mat forming, sub-shrubs such as Arctic Willow (Salix arctica), Net-veined Willow (Salix reticulata) and Eight-petal Mountain-avens (Dryas hookeriana) may be present or abundant in turf communities. Moss and lichen cover is typically very low within well-developed turf.

Fellfield communities have a higher percentage of plants that are highly adapted to harsh, xeric environments. The vegetation often occurs as singular plants among exposed rocks or within ribbons perpendicular to the slope. These species are typically cushioned, matted or succulent, or grow as flat rosettes, often with thick leaf cuticles or a dense cover of hairs. Many of the cushion species are very long lived, and well adapted to limited water availability. Common fellfield species include yarrow (Achillea millefolium), Ross' Avens (Geum rossii), penstemon (Penstemon species), phacelia (Phacelia species), alpine sandwort (Minuartia obtusiloba), moss campion (Silene acaulis), Rocky Mountain Goldenrod (Solidago multiradiata), Phlox pulvinata, Asters (Symphyotrichum species) sky Pilot (Polemonium viscosum), Cut-leaf Daisy (Erigeron compositus), Draba (Draba species), Narrowleaf Arnica (Arnica angustifolia), Pussytoes (Antennaria species), Large-flower Fleabane (Erigeron grandiflorus), Sibbaldia (Sibbaldia procumbens), Blue-leaved Cinquefoil (Potentilla glaucophylla), Lousewort (Pedicularis species), elegant death camas (Zigadenus elegans), alpine bistort (Polygonum bistortoides), oval-leaf buckwheat (Eriogonum ovalifolium), viviparous bistort (Polygonum viviparum), and alpine forget-me-not (Myosotis alpestris).
Ribbons of nitrogen-fixing Eight-petal Mountain-avens (Dryas hookeriana), yellow sweetvetch (Hedysarum sulphurescens), shrubby cinquefoil (Dasiphora fruticosa), silver lupine (Lupinus argenteus), crazyweed (Oxytropis species) and milkvetch (Astragalus species) occur on slopes subject to downward movement due to frost heaving. These ribbons or stair-step vegetation patterns form perpendicular to the slope, accumulating litter within the mats. Other forbs can occur with the mats, singly or in small patches among the exposed rocks.

Cover of graminoids is usually lower than forb cover in fellfield communities, but often includes species such as Dunhead sedge (Carex phaeocephala), spike sedge (Carex nardina), curly sedge (Carex rupestris), northern single spike sedge (Carex scirpoidea), black and white sedge (Carex albonigra), alpine blue grass (Poa alpina), Sandberg’s bluegrass (Poa secunda), spike trisetum (Trisetum spicatum) and slender wheatgrass (Elymus trachycaulus). In southwestern Montana fellfield communities, other species such as blackroot sedge (Carex elynoides), Parry’s rush (Juncus parryi), fescue (Festuca idahoensis and alpine relatives), and spike fescue (Leucopoa kingii) become common (Cooper et al., 1999).

Mat-forming subshrubs such as arctic willow (Salix arctica), Net-veined Willow (Salix reticulata), are also found in fellfield communities and Kinnikinnick (Arctostaphylos uva-ursi) is often prevalent in these communities along the Rocky Mtn Front and in the island mountain ranges. Crustose and foliose lichen species form significant cover on exposed rocks. Fern allies such as lesser spikemoss (Selaginella densa) can be locally abundant in some areas. Several northern Rocky Mountain endemic species and species of concern inhabit alpine fell-field communities.

Alpine Fellfields and Turf communities are often bordered by subalpine forest krummholz mats and the upper elevational limit of subalpine forests. In Montana, whitebark pine (Pinus albicaulis) and subalpine fir (Abies lasiocarpa) are common in this zone. In scattered locations on north and east facing aspects, turf communities are bordered by alpine larch (Larix lyallii) forests.

In Montana, this group is represented by 18 Associations grouped into 4 Alliances, which likely covers the diversity of vegetation communities present in the state within this group.

High winds and desiccation, heavy snow loads, and harsh growing conditions dominate the alpine environment.

Due to the short growing season, and limited soil development, alpine turf and fellfield communities cannot support heavy levels of disturbance from activities such as grazing or foot traffic. Climatic warming and decreasing snowpack levels will alter the floristic composition and the distribution of species.

Disturbances in these habitats are often limited due to the remoteness of many sites. However, the short growing conditions and harsh environments make potential restoration of sites difficult and time-consuming.

K.A. Schulz 2015

S. Mincemoyer, L. Vance, T. Luna

11/7/2024