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Montana Field Guide

Montana Field Guides

Red Alder - Alnus rubra

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Species of Concern
Native Species

Global Rank: G5
State Rank: S2S3
(see State Rank Reason below)
State Threat Score: No Known Threats
C-value:


Agency Status
USFWS:
USFS:
BLM:


 

External Links

State Rank Reason (see State Rank above)
Rare in Montana, where it occurs only in the extreme western portion of the state. The species is at the eastern end of its range in the state.
  •  Details on Status Ranking and Review
    Red Alder (Alnus rubra) Conservation Status Review
    Review Date = 06/01/2012
    View State Conservation Rank Criteria
    Population Size

    Score3 - Vey Small: Generally <2,000 individuals.

    Range Extent

    Score1 - Peripheral, Disjunct or Sporadic Distribution in MT: Widespread species that is peripheral, disjunct or sporadically distributed within MT such that it occurs in <5% of the state (<7,500 sq. miles or the combined area of Beaverhead and Ravalli Counties) or is restricted to 4-5 sub-basins.

    CommentPeripheral in northwest Montana

    Area of Occupancy

    Score2 - Low: Generally occurring in 4-10 Subwatersheds (6th Code HUC’s).

    Environmental Specificity

    Score1 - Moderate: Species is restricted to a specific habitat that is more widely distributed or to several restricted habitats and is typically dependent upon relatively unaltered, good-quality habitat (C Values of 5-7).

    Trends

    ScoreNA - Rank factor not assessed.

    Threats

    Score0-1 - Low to Medium.

    Intrinsic Vulnerability

    Score0-1 - Low to Moderate Vulnerability.

    Raw Conservation Status Score

    Score 7 to 9 total points scored out of a possible 16 (Rarity factors and threats only).

 
General Description
Tree to 20 m with gray bark. Twigs reddish with club-shaped buds. Leaf blades to 15 cm long, with revolute margins 1 to 2-times serrate, gray, pubescent and glandular below. Inflorescence borne on twigs of previous season. Fruit with wings to half as wide as nutlet (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Phenology
Catkins develop in March-April.

Species Range
Montana Range Range Descriptions

Native
 


Range Comments
In MT only in Sanders and Mineral counties; coastal AK and YK south to CA, east to ID and MT (Furlow 1997 in Fl. N. Amer. Vol. 3).

Observations in Montana Natural Heritage Program Database
Number of Observations: 14

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see mtnhp.org/models

Ecological Systems Associated with this Species

Stewardship Responsibility

Based on the Montana Natural Heritage Program's latest predicted habitat suitability model

Total species' range in Montana 11,186 km2 (3% of Montana)
Area predicted to have
some level of suitable habitat		 2,804 km2 (<1% of Montana)

Stewardship responsibility for the predicted area of suitable habitat can be broken down as follows

  Total Suitable Optimal Suitability Moderate Suitability Low Suitability
Federal 79% 5% 19% 55%
State 1% <1% <1% 1%
Local <1% <1% <1% <1%
Conservation Lands/Easements 2% <1% <1% 2%
Private/Tribal/Unknown 17% 2% 5% 10%

See the Habitat Suitability for Biodiversity task in Map Viewer for a more detailed look at stewardship responsibilities within a variety of local jurisdictions.


Threats or Limiting Factors
STATE THREAT SCORE REASON
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).

References
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Citation for data on this website:
Red Alder — Alnus rubra.  Montana Field Guide.  .  Retrieved on , from