Community Field Guide
Scientific Name:
Artemisia tripartita / Festuca campestris Shrub Herbaceous Vegetation
Common Name:
Threetip sagebrush / rough fescue Shrub Herbaceous Vegetation
Community Description
Summary:
This type is a minor component of landscapes generally dominated by Artemisia tridentata ssp. vaseyana in both eastern Washington and western Montana. These are generally arid sites with annual precipitation of 20-60 cm; in Washington elevation ranges between 1100 and 3000 feet whereas its highly circumscribed Montana distribution ranges between 4200 and 4600 feet. In Washington this type is found on northerly aspects where loess soils cap basalt and granite. In Montana this type is found in glaciated landscapes where glacial till derived from metamorphic Belt Series rock predominates, and it occurs on gentle slopes of all aspects. It is possibly more abundant in British Columbia and Alberta. Artemisia tripartita, characteristically less than 2 feet tall, dominates the shrub layer, typically ranging in canopy cover from 10-40%. In Washington, Artemisia tridentata and Purshia tridentata, and in Montana Rosa woodsii, are the shrubs regularly present. On most sites, especially those only lightly grazed, Festuca campestris is by far the dominant herb (canopy cover ranging from 10-60%), but on the most mesic sites its cover can be approached by that of Achnatherum richardsonii (= Stipa richardsonii) and/or Achnatherum occidentale (= Stipa occidentalis). On more intensively grazed sites Festuca idahoensis cover (or that of other graminoids) approaches or exceeds that of Festuca campestris. Forb diversity is moderate to high; in Montana, Potentilla gracilis, Geranium viscosissimum, Lupinus sericeus, Eriogonum umbellatum and Antennaria microphylla dominate this layer. Washington occurrences contrast with those of Montana by having a well-developed soil crust of mosses, lichens and algae.
Range:
This community is recorded from three counties of north-central Washington State and one county within west-central Montana, but it quite probably extends into the dry interior of British Columbia. It is uncommon within its range.
Dynamics:
Artemisia tripartita is well known to stump-sprout following fire, and it could be hypothesized that its current dominance in the landscape is associated with past fire regimes.
Global Rank: G2? State Rank: S2
Global Rank Comments:
This community is not under immediate threat, but in the long term it faces weed invasion and the consequences of overgrazing (in the extreme, the local extirpation of Festuca campestris). In Montana the overlap in distribution of the species for which the type is named is extremely restricted. In Washington both species have restricted distributions, making the type rare throughout its range. A couple of Montana occurrences are located within conservation easements but the protection afforded by the specifics of these easements is unknown. There are no known occurrences with any formal protection status; in Montana, all examples are on private or state lands and those of Washington are not on BLM holdings. This ownership pattern means a decreased potential for their protection in such management designations as ACEC or RNA, or via similar protection strategies. The limited number of occurrences, their generally small area and uncertainty over the long-term course of succession in this type (how to manage for its perpetuation) argues for applying a high rank. The possibility of its occurrence in Canada needs further inventory.
Community References
Identifier:
CEGL001537
Author:
S.V. Cooper
Citations:
Bourgeron and Engelking 1994, Driscoll et al. 1984, WANHP n.d.
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This information is from the:
Montana Natural Heritage Program
Montana State Library--Natural Resource Information System
1515 East Sixth Ave., Helena, MT 59620-1800
406 444-3989
mtnhp.org
mtnhp@mt.gov
