Alnus viridis subsp. crispa, mountain alder
Matthews, Robin F. 1992. Alnus viridis subsp. crispa, mountain alder. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/species-reviews/alnvirc
| Abbreviation | Common Name | Scientific Name | Classification | Status |
|---|---|---|---|---|
| Plants | ||||
| ALNVIRC | mountain alder | Alnus viridis subsp. crispa | Life Form: Plants/Shrub, Plants/Tree Kingdom: Plantae Class: Dicot Order: Fagales Family: Betulaceae Genus: Alnus | Fed. Protected: No Nativity: Native Invasiveness: Noninvasive |
Taxonomy
The currently accepted scientific name of mountain alder is Alnus viridis (Chaix) DC. subsp. crispa (Ait.) Turrill. Sitka alder, Alnus viridis subsp. sinuata (Regel) A. Love & D. Love, and Siberian alder, Alnus viridis subsp. fruticosa (Ruprecht) Nyman, are other subspecies of green alder (A. viridis) occurring in North America [31,64,67,68]. The subspecies interbreed where their ranges overlap [10,21,30,36,58].
Information presented in this text is for mountain alder.
Synonyms
- Alnus viridis (Villars) Lam. var. crispa (Michx.) House [65]
- A. crispa (Ait.) Pursh subsp. crispa [30]
Other Common Names
American green alder
General Distribution
Mountain alder is widely distributed throughout interior, central, and northern Alaska across the Yukon Territory and interior Canada to Labrador, Newfoundland, and Greenland. It extends south through New England and the Great Lakes States, and into the Pacific Northwest. Disjunct populations are documented in south-central Pennsylvania and west-central North Carolina [21,36,48,58].
States and Provinces
- United States: AK CA ME MA MI MN NH NY NC OR PA VT WA WI
- Canada: AB BC LB MB NB NF NT NS ON PQ SK YT
Site Characteristics
Mountain alder on the edge of a lake, northern Quebec, CA.
Mountain alder occurs at elevations from sea level to 6,600 feet (2,000 m) [21] on steep to level terrain. It occupies habitats ranging from open tundra to open conifer forests [18,20,57] but cannot withstand a dense overstory [24]. It can occur singly or in thickets along streams, lakeshores, coasts, bogs, or muskeg margins, and as an understory component in conifer forests [21,24]. Mountain alder is usually associated with some source of moisture, but is adapted to somewhat drier conditions than other alders [21]. The wetter sites are more favorable for high nitrogen-fixing activity [27]. Its shallow roots make it well adapted to the generally cold, harsh climate characteristic of sites which it inhabits, where the soil may be only shallowly thawed [8,24].
Soil textures range from sandy to gravelly or rocky; green alder often occurs on morainal soil left by retreating glaciers [21,24,58]. Soils supporting mountain alder in deglaciated areas are generally acidic (pH 5.0-6.5) [24,53].
Plant Communities
Mountain alder is a dominant or codominant in a variety of habitats. It may occur as an understory dominant in open conifer forests with black spruce (Picea mariana), white spruce (P. glauca), lodgepole pine (Pinus contorta), and jack pine (P. banksiana) overstories; and in open and closed deciduous forests with paper birch (Betula papyrifera), quaking aspen (Populus tremuloides), balsam poplar (P. balsamifera), and red alder (Alnus rubra) overstories. American green alder can dominate in shrub types (often with Salix spp.) and on open, moist tundra [5,13,20,55,57].
The following publications classify mountain alder as a dominant shrub layer component:
- Forest community types of west-central Alberta in relation to selected environmental factors [13]
- Field guide to forest ecosystems of west-central Alberta [14]
- Classification, description, and dynamics of plant communities after fire in the taiga of interior Alaska [20]
- Vegetation types in northwestern Alaska and comparisons with communities in other Arctic regions [23]
- Reconnaissance of vegetation and soils along the Dempster Highway, Yukon Territory: I. Vegetation types [49]
- The Alaska vegetation classification [57]
Botanical Description
Mountain alder is a deciduous, ascending shrub usually reaching up to 10 feet (3 m) in height [18,30,48,58]. Occasionally, it may reach heights of 20 to 30 feet (6-9 m) [10,21]. Growth rates vary with site and location, but usually decrease at higher elevations [24,30]. Mountain alder often forms dense thickets [10,58,59]. The bark is yellowish-brown and twigs have sessile, pointed axillary buds [10,24]. Leaves are ovate or elliptic and glabrous above, but pubescent below. The margins are serrated with very fine teeth [4,18,30,48,58].
The roots of mountain alder are shallow and have nodules containing nitrogen-fixing microorganisms [8,10,21].
Raunkiaer Life Form (Raunkiaer 1934)
- Phanerophyte
Seasonal Development
The pistillate catkins of mountain alder emerge before or with the leaves in spring; staminate catkins are produced during the previous growing season [10,21,24,48]. Flowering takes place from May to June, with fruits maturing in July [24,58,61]. Cones ripen from mid-September to mid-November, depending on latitude and elevation, and seed dispersal takes place immediately thereafter [48,58,60]. The leaves do not turn color, but remain green until they are dropped in the fall.
Regeneration Processes
Mountain alder catkins.
Sexual reproduction: Mountain alder is monoecious [10,14,24]. The female catkins turn woody and conelike at maturity. The seeds are winged nutlets [48,58] that are dispersed by wind and water [21,37,45]. One study estimated mountain alder seed to be 40 percent viable [61].
Germination from seed on disturbed habitats is the primary form of reproduction for mountain alder [24,25]. The seeds invade and colonize bare mineral soil [24,37,60] in areas such as avalanche tracks, talus slopes, fresh alluvium, and soils left by retreating glaciers [24,58]. In interior Alaska, the frequency of occurrence of alder species is three times greater on bare mineral soil than on organic surfaces [60].
Vegetative reproduction: Mountain alder sprouts from the root crown if damaged or cut. Sprouting often occurs after mechanical site preparation [24] and natural disturbances such as avalanches [41] and fire [33,35,45,46].
Successional Status
Facultative Seral Species
Mountain alder is semi-shade tolerant [24,44] and is considered a pioneer or seral species [21,25,26]. It invades and inhabits terraces above the floodplain which are subject to occasional flooding [8,56], and is a pioneer on alkaline glacial outwash [59]. After fire, American green alder sprouts from the root crown and establishes by seed from plants in adjacent unburned areas [33,35,45]. The bare mineral soils created by these disturbances are prime sites for mountain alder. These shrubs provide shade that reduce soil temperatures, allowing spruce and other genera to establish [1,9].
Immediate Fire Effects
Mountain alder does not burn easily, and dense stands can sometimes prevent fire spread [35,45]. However, light- to moderate-severity fires can kill aerial portions, and high-severity fires can remove the organic layer and leave charred roots exposed, eliminating sprouting from underground parts [60].
Postfire Regeneration Strategy (Stickney 1989)
- Tall shrub, adventitious-bud root crown
- Initial-offsite colonizer (off-site, initial community)
Fire Adaptations
Mountain alder is considered a survivor species because it sprouts from basal or underground parts following fire [19,44]. Additionally, its wind-dispersed seeds quickly colonize bare mineral soils exposed by fire. Regeneration from sprouting and the establishment of seedlings allow mountain alder to reestablish at a fairly rapid rate following fire [11,12,45,46]. Mountain alder is very adaptable and is successful regardless of length of the fire cycle [44].
Plant Response to Fire
Mountain alder sprouts from the root crown following fire [33,35,45]. The sprouting response is usually immediate and generally results in an increased number of plants [35,45,58]. Mountain alder also reestablishes by seed dispersed from adjacent, unburned areas. Green alder is abundant in areas with a history of frequent fires. This nitrogen-fixing alder may be favored over other invading species by severe fires that remove the surface organic matter [42]. Alder invasion and persistence are favored by fire, but total recovery is slow [16,21,24]. One study in central Alberta showed prefire mountain alder cover to be 36 percent, while 1 year later it was only 4 percent [16]. Repeated fires near treeline and in wet sites can result in thickets of mountain alder [23].
For information on prescribed fire and postfire responses of many plant species, including mountain alder, see these Research Project Summaries:
- The effects of experimental fires in an Alaskan black spruce/feather moss community
- Forest floor and plant responses to experimental fires in an Alaskan black spruce/feather moss community
- Understory recovery after burning and reburning quaking aspen stands in central Alberta
Fire Regimes
For fire regime information, search FEIS for this species by entering the species name or acronym on the home page and selecting “Fire Regime” as the publication type.
Fire Management Considerations
No entry.
Federal Status
None
Other Status
No entry.
Importance to Wildlife and Livestock
Mountain alder generally is of low value as browse for big game, but it is consumed in small quantities by deer [24,25]. In some areas, however, it is utilized heavily by moose [3,15,52,54] and caribou [2,54].
Although mountain alder is a principal component in mountain goat foraging areas, goats do not browse it. The alder shrubs do, however, provide ground cover that lessens snow accumulation, making lady fern (Athyrium filix-femina) more accessible to mountain goats [29].
Muskrat, beaver, cottontail, and snowshoe hares feed on alder twigs and foliage [25]. Many birds eat alder seeds, buds, and catkins [25,54,58]. Mountain alder is an important component of white-tailed ptarmigan winter forage [58]. Alder can be an important secondary forage for livestock, especially cattle [21,54].
Palatability and Nutritional Value
The palatability of alder to big game and livestock is generally low [15,24,54].
Cover Value
Mountain alder often forms dense thickets which serve as cover for many wildlife species. Big game animals use alder for hiding and escape cover. Bird species use alder thickets for nesting, feeding, and roosting [25].
Value for Rehabilitation or Restoration of Disturbed Sites
The major value of mountain alder in rehabilitation is its ability to invade sterile soil and increase the organic matter content by nitrogen fixation [9,24]. Mountain alder can fix nitrogen at a rate of 18 to 55 pounds per acre (20-62 kg/ha) per year [24]. Soil fertility increases as the plant looses leaves and other parts and the nitrogen-containing materials become available to decomposer species in the soil [51]. The nitrogen content in soil after glaciation is at a maximum when inhabited by mature alder, but is slowly depleted as spruce (Picea spp.) takes over [53]. Alders contribute to the reduction of soil erosion [21,50,59] and help to stabilize alluvial deposits [50].
Mountain alder recovered well within 2 to 3 years after an oil spill near Norman Wells, Northwest Territories [59]. It was also noted for its ability to colonize tailings at the Discovery Mine, Northwest Territories [59].
Other Uses
Alder bark is very astringent and has been used medicinally by Native Americans. It has also been used in the tanning of leather and dyeing of textiles [21].
Alders (Alnus spp.) are used as a source of firewood in regions where fuels are scarce [21]. Native Americans in Alaska consider alder a prime fuel for smoking salmon [39].
Other Management Considerations
Mountain alder can be a major competitor of conifer seedlings following timber harvest. Dense thickets can prevent conifer establishment over large areas [24]. However, due to its nitrogen-fixing ability, alder can improve soil fertility [9,40,50]. It is also a nurse tree for conifers such as spruce (Picea spp.), pine (Pinus spp.), and Douglas-fir (Pseudotsuga menziesii) on nitrogen-deficient soils [50]. Some suggest that conifers should be established prior to the alder to ensure that conifer growth is not hindered [24].
Mountain alder is a key indicator species of productive lodgepole pine stands in subalpine regions in British Columbia [26].
When desired, alder stands can be established on cool, moist sites by direct seeding or planting 2- and 3-year-old seedlings. Nondormant seeds should be sown in the spring and dormant seeds in the fall. Unstratified alder seeds will germinate but at a slower rate than stratified seeds [59]. Overmature thickets cut in the spring or winter will rapidly regrow [25].
Control: In the Caribou Forest Region of British Columbia, ripping apart clumps of alder with V-shaped or straight-blade plows has been successful at setting back the alder enough to establish a softwood crop [24]. When applied as stump, basal, or foliage sprays, 2,4,5-T or 2,4-D control alder effectively [25,40].
Table A1— Forest and range ecosystems, Bureau of Land Management (BLM) physiographic regions, Kuchler plant associations, Society for American Foresters (SAF) forest cover types, and Society for Rangeland Management (SRM) rangeland cover types in which this species occurs.
Forest and Range Ecosystems (Garrison et al. 1977)
- FRES10 White - red - jack pine
- FRES11 Spruce - fir
- FRES15 Oak - hickory
- FRES17 Elm - ash - cottonwood
- FRES18 Maple - beech - birch
- FRES19 Aspen - birch
- FRES20 Douglas-fir
- FRES22 Western white pine
- FRES23 Fir - spruce
- FRES24 Hemlock - Sitka spruce
- FRES26 Lodgepole pine
- FRES28 Western hardwoods
BLM Physiographic Regions (Bernard and Brown 1977)
- 1 Northern Pacific Border
- 2 Cascade Mountains
Kuchler Plant Associations (Kuchler 1964)
- K001 Spruce - cedar - hemlock forest
- K002 Cedar - hemlock - Douglas-fir forest
- K003 Silver fir - Douglas-fir forest
- K004 Fir - hemlock forest
- K008 Lodgepole pine - subalpine forest
- K012 Douglas-fir forest
- K013 Cedar - hemlock - pine forest
- K015 Western spruce - fir forest
- K025 Alder - ash forest
- K081 Oak savanna
- K093 Great Lakes spruce - fir forest
- K094 Conifer bog
- K095 Great Lakes pine forest
- K096 Northeastern spruce - fir forest
- K099 Maple - basswood forest
- K101 Elm - ash forest
- K102 Beech - maple forest
- K106 Northern hardwoods
- K107 Northern hardwoods - fir forest
- K108 Northern hardwoods - spruce forest
SAF Cover Types (Eyre 1980)
- 1 Jack pine
- 5 Balsam fir
- 12 Black spruce
- 13 Black spruce - tamarack
- 14 Northern pin oak
- 15 Red pine
- 16 Aspen
- 17 Pin cherry
- 18 Paper birch
- 21 Eastern white pine
- 22 White pine - hemlock
- 23 Eastern hemlock
- 24 Hemlock - yellow birch
- 25 Sugar maple - beech - yellow birch
- 26 Sugar maple - basswood
- 27 Sugar maple
- 30 Red spruce - yellow birch
- 31 Red spruce - sugar maple - beech
- 32 Red spruce
- 33 Red spruce - balsam fir
- 35 Paper birch - red spruce - balsam fir
- 37 Northern white-cedar
- 38 Tamarack
- 39 Black ash - American elm - red maple
- 60 Beech - Sugar maple
- 62 Silver maple - American elm
- 107 White spruce
- 108 Red maple
- 201 White spruce
- 202 White spruce - paper birch
- 203 Balsam poplar
- 204 Black spruce
- 205 Mountain hemlock
- 206 Engelmann spruce - subalpine fir
- 207 Red fir
- 210 Interior Douglas-fir
- 215 Western white pine
- 217 Aspen
- 218 Lodgepole pine
- 221 Red alder
- 222 Black cottonwood - willow
- 223 Sitka spruce
- 224 Western hemlock
- 225 Western hemlock - Sitka spruce
- 226 Coastal true fir - hemlock
- 227 Western redcedar - western hemlock
- 228 Western redcedar
- 229 Pacific Douglas-fir
- 230 Douglas-fir - western hemlock
- 251 White spruce - aspen
- 252 Paper birch
- 253 Black spruce - white spruce
- 254 Black spruce - paper birch
SRM Rangeland Cover Types (Shiflet 1994)
- No entry.
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