Name:
Abies lasiocarpa - Picea engelmannii / Clintonia uniflora - Xerophyllum tenax Forest
Reference:
Western Ecology Working Group of...
Description:
This association has been described only for the northern Rocky Mountains. It occupies most of what was considered the dry and cold portion of the former Abies lasiocarpa / Clintonia uniflora association. It is found predominantly on well-drained sites with south- or west-facing exposures and all degrees of slope steepness; it is seldom found on toeslope positions or steam terraces. Within a given landscape (Glacier-Waterton International Peace Park) it exhibited a wide elevational range, from 4400 to 5900 feet; this upper elevation is extreme and beyond the elevational limits of Clintonia uniflora, but within the distributional limits of Tiarella trifoliata. Parent materials are dominated by granitics, quartzites, mica schists, and partially metamorphosed sedimentary types, such as argillite. In northern Idaho and western Montana ash caps of varying thickness are common. In local landscapes it grades to Abies grandis / Xerophyllum tenax - Clintonia uniflora or Thuja plicata / Clintonia uniflora at lower elevations, and above, or on drier sites, to Abies lasiocarpa / Xerophyllum tenax (which may be dominated by seral tree species). The tree canopy is dominated by a variable combination of Abies lasiocarpa and Picea engelmannii; cover of the upper canopy generally ranges from 60 to 80%. Seral tree species (Pinus contorta, Pseudotsuga menziesii, Larix occidentalis) are relatively more successful in post-disturbance colonization than they are in other Clintonia uniflora-characterized sites (stands dominated by seral tree species comprise a separate set of associations). This response essentially reflects the warmer, more open sites that following disturbance do not so readily regenerate to shrub dominance. The undergrowth is dominated by a low- to mid-shrub, discontinuous layer of Vaccinium membranaceum; other high-constancy shrubs, which seldom exceed 15% cover, include Lonicera utahensis, Spiraea betulifolia, Rubus parviflorus, Paxistima myrsinites, Acer glabrum, and Amelanchier alnifolia. The graminoid component often comprises less than 1% cover, and there are none that appear with even moderate constancy. The forb layer is generally dominated by Xerophyllum tenax, whose cover ranges from barely greater than 1% to 60 or 70% in more open stands. The other diagnostic forbs, Clintonia uniflora and Tiarella trifoliata, seldom exceed 5% cover. Other forbs of high constancy and occasional layer dominance include Thalictrum occidentale, Orthilia secunda, Viola orbiculata, Arnica latifolia (or Arnica cordifolia), Goodyera oblongifolia and Osmorhiza berteroi (= Osmorhiza chilensis).
Accession Code:
VB.CC.28260.ABIESLASIOCARPA
Plot-observations of this Community Concept:
0
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