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Community Field Guide

Scientific Name:
Carex scirpoidea - Geum rossii Herbaceous Vegetation

Common Name:
Spike sedge - Ross' avens Herbaceous Vegetation

Community Description

This community has been described for only southwestern Montana in the Tobacco Root, East Pioneer and Madison ranges. Stands may be restricted to non-calcareous substrates, having been reported from granitic, intrusive volcanics, and gneiss parent materials (all non-calcareous) in mountain ranges that have an abundance of exposed calcareous substrates. This association spans nearly the full range of alpine elevations in this portion of Montana, from 9300-10,340 feet. Sampled sites are about evenly divided between low-gradient slopes and steeper slopes, with all aspects represented. The most characteristic environmental parameter is some degree of enhanced effective moisture (relative to dry turf associations) through increased snowpack or delayed snowmelt. This vegetation occurs as small to large patches, often scattered among boulders that act as eddy current creating snow fences, serving to increase snowpack in their immediate vicinities. Fibrous-rooted graminoids dominate and create an alpine turf community, not much exceeding 1 dm in height, with the exception of flowering stalks. Graminoids average about 40% canopy cover. Though named for Carex scirpoidea, which has a high constancy and average canopy cover (24%) and is considered diagnostic, other Carex spp. (Carex phaeocephala, Carex albonigra, Carex atrosquama) are diagnostic as well (note none of the above-named Carices are employed as naming-species elsewhere in the National Vegetation Classification System). Other high-constancy graminoids include Luzula spicata, Poa alpina, Poa secunda, and Trisetum spicatum, with the moister sites having scattered Deschampsia caespitosa (under 5% cover). Exhibiting 100% constancy and 37% average canopy cover Geum rossii is a conspicuous dominant; other high-constancy forbs include Minuartia obtusiloba, Potentilla diversifolia, Phlox pulvinata, Polygonum bistortoides, Erigeron simplex, Lloydia serotina, and Lupinus argenteus. This association most frequently grades to drier turf or cushion plant communities, usually Carex elynoides Herbaceous Vegetation (CEGL001852) or Carex rupestris - Potentilla ovina Herbaceous Vegetation (CEGL001862) of more exposed positions and DRY SLOPE and MOIST SLOPE community types on steeper, more unstable slopes.

We regard Carex scirpoidea / Geum rossii as a geographic/ substrate variant of Carex scirpoidea / Potentilla diversifolia. It was a common plant association in the Beaverhead Mountain sections, relatively moist mountain ranges dominated by granitic or metamorphosed intrusive volcanics, and the East Pioneer and Tobacco Root Ranges. It was also found in the Madison Range, exclusively on gneiss. It spanned nearly the full range of alpine elevations available in these ranges, from 9,300 to 10,320 feet. Sample sites were about evenly divided between low-gradient slopes and steeper slopes. All aspects were represented. Most characteristic was some degree of enhanced effective moisture through increased snowpack or delayed snowmelt. Often Carex scirpoidea / Geum rossii turf occurred as patches scattered among boulders which act as snow fences creating eddy currents and increasing snowpack. Carex scirpoidea / Geum rossii graded to drier turf types, usually Carex elynoides, of more exposed positions and to dry slope or moist slope community types of steeper, unstable slopes.

Graminoid canopy cover averaged only 37%, of which 24% was Carex scirpoidea. Carex phaeocephala, Carex atrata and Carex albonigra were also dominant in at least one stand. Common turf graminoids, Carex rupestris, Carex elynoides and Festuca ovina, had moderate coverages or high constancy but are much less important than in the Carex scirpoidea / Potentilla diversifolia community type. Other graminoids with high constancy were Luzula spicata, Poa alpina, Poa secunda and Trisetum spicatum. The moister sites supported Deschampsia caespitosa (=Deschampsia cespitosa), but its cover did not exceed 5%. Carex scirpoidea / Geum rossii forb coverage averaged 51%, very similar to that of Carex scirpoidea / Potentilla diversifolia. With the exception of Geum rossii, which was 100% constant and averaged 37% canopy cover in this type, the two Carex scirpoidea dominated turf types had many forb species of high constancy or coverage in common e.g., Minuartia obtusiloba, Potentilla diversifolia, Phlox pulvinata, Polygonum bistortoides, Erigeron simplex, Lloydia serotina and Lupinus argenteus. Nonetheless, these two mesic turf types had fewer herbs in common (55) than were found in only one of the two types (63).

Global Rank: G4 State Rank: S4

Global Rank Comments:
This association has been revised from G3 to G4 based on the fact that there are 14 well documented occurrences and that an abundance of potential, uninventoried habitat exists in southwestern and south-central Montana (including the Madison, Gallatin, Absaroka and Beartooth Ranges), and within the Rocky Mountain Front in Montana, as well as within east-central Idaho. There are no immediate threats to this association, only the potential consequences of livestock overgrazing and somewhat remote possibility of mining and recreational impact (via compaction from off-road vehicle use). It should also be noted that neither the flora or environmental parameters associated with this type are regionally unique and that this type may well exist elsewhere in the western U.S. This type has not been adequately crosswalked with potentially similar types (accepting that more than one diagnostic Carex spp. defines this type) that exist in Utah, Colorado, New Mexico and the North Cascades of Washington.

Community References


97/10 / S. V. Cooper et al.

Baker 1983a, Bamberg and Major 1968, Bourgeron and Engelking 1994, Cooper and Lesica 1992, Cooper et al. 1997, Douglas and Bliss 1977, Driscoll et al. 1984, Komarkova 1976, Lewis 1970

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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
406 444-5354