Calamovilfa longifolia / Carex inops ssp. heliophila Plant Association 



(syn. Calamovilfa longifolia / Carex heliophila var. inops or Carex pennsylvanica) 



GALLON / CARINO; prairie sandreed / sun sedge 



MTNHP rank: G3/S3 



Environment: This plant association type usually occurs in small patches (fractions of an acre) with 

 abrupt ecotones to associated grassland, shrub and forest types, but is widespread in Carter County 

 on substrates derived primarily from sandstone. It constitutes an edaphic climax in sandy range sites, 

 i.e., with effectively coarse substrates and high infiltration rates. It may also occurs on shale, if the 

 product of mechanical decomposition is dominated by sand-sized (and larger) platy particles, a 

 condition observed elsewhere in Carter County and as far west as Phillips County. In southern Carter 

 County this type was sampled at two sites in alluvial washes draining eroded ridges. 



Vegetation: Respective cover by the two rhizomatous indictor species, Calamovilfa longifolia, a 

 grass, and Carex inops, a sedge, varies greatly between the two plots. At the site on sandstone, there 

 is high cover by both grass (ca. 70%) and sedge (ca. 40%). and there is near total ground cover by 

 litter. Except for the weedy exotic annual grass, Bromus japonicus (ca. 20% cover, in patches), other 

 graminoids and especially forbs and shrubs are few and found only in trace amounts. Species 

 richness (23) is the lowest of any type sampled with the exception of the saline- and alkali-stressed 

 types such as SARVER / ELYLAN. DeVelice et al. (1995) also found low forb cover and richness 

 (av. 1 species / site) for this association in northeastern Montana. The plot on shale substrate has 

 much lower total cover, and here Carex inops is dominant with about 40% cover; Calamovilfa 

 longifolia has only about 1 0% cover and Rosa arkansana is also well represented with about 1 0% 

 cover. Bimodal pattern of floristic composition of our plots on shale vs. sandstone is consistent with 

 stands of C ALON / CARINO on these respective substrates in northeastern Montana (DeVelice et 

 al.l995). We note that these species are not consistently found together on the respective substrates, 

 and further vegetation sampling may warrant a split in this unit as representing two discrete types. 



This type was surrounded by sagebrush (ARTTSW / ELYLAN) and grassland (ELYLAN) types 

 occupying less eroded positions; it was also observed in alluvial wash openings of oak woodlands 

 (QUEMAC / CARINO) on the toe-slopes of a bentonite ridge. In northern Carter County it was 

 sampled on BLM land near Mill Iron on resistant upland sandstone mesas, where it occurs in small 

 patches with abrupt edges, usually in water collecting positions, within matrix grasslands of 

 STICOM - CARFIL. It has not been determined what factors distinguish sites of this association 

 from contiguous types or types occurring on very similar landscape positions and coarse-textured 

 soils, e.g. STICOM - CARINO or STICOM - CARFIL; GALLON - CARINO may have a more 

 favorable water balance, associated with collecting positions. It differs from SCHSCO - CARINO 

 in not being associated with upper slope to slope shoulder positions subject to erosion (though it may 

 be in a sediment-receiving position). 



Soils: The coarse textured substrates (sandy loams) and leached nature of these sites is reflected in 

 relatively low values for pH and conductivity. Hanson and Hoffman (1988) found very similar 

 values for these soil variables in the same association across the Ashland District of the Custer 

 National Forest. The co-dominance of Calamovilfa longifolia and Rosa arkansana (with Eriogonum 



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