Name:
Larix occidentalis / Vaccinium caespitosum / Clintonia uniflora Forest
Reference:
Western Ecology Working Group of...
Description:
This mesic, small- to large-patch forested community is a minor type found from northwestern Montana (west of the Continental Divide) westward across northern Idaho to northeastern Washington as far west as the Okanogan Plateau; it southern extent is central Idaho's Seven Devils and southern Batholith regions. In both northeastern Washington and western Montana, it is found at elevations predominantly between 915 to 1220 m (3000-4000 feet) with extremes from 680 to 1400 m (2230-4590 feet); at its southern extent it is found between 1400 and 1675 m (4600-5500 feet). This association typically is found on lower elevation benchlands and gentle lower slopes of low gradient, areas that would be expected to be frosty or where cold-air ponding occurs with a relatively high frequency. Daytime temperatures are warm, which results in a strong diurnal contrast that is apparently limiting to tree species that potentially are climax dominants. Sites are confined to well-drained glacial till and outwash deposits or similarly derived relatively coarse-textured sediments (mostly fine sandy loams to loams in texture) that frequently have an appreciable gravel content. Soil reactions vary from acidic to very acidic.<br /><br />The upper canopy is relatively open (ranging from 40 to 70% canopy cover with extremes to 20%) and dominated by <i>Larix occidentalis</i> with minor contributions of <i>Pinus contorta</i> and <i>Pseudotsuga menziesii</i>. <i>Pseudotsuga</i> characteristically has the greatest understory cover, followed by <i>Abies lasiocarpa, Picea engelmannii</i>, or <i>Picea engelmannii x glauca</i> hybrids. With the exception of <i>Amelanchier alnifolia</i>, tall shrubs are not represented, and while a diversity of short shrubs (<i>Shepherdia canadensis, Spiraea betulifolia, Lonicera utahensis, Paxistima myrsinites, Vaccinium membranaceum</i>) are consistently present, their aggregate cover does not often exceed 20%. Besides containing two of the three undergrowth indicator species, <i>Vaccinium caespitosum</i> and <i>Arctostaphylos uva-ursi</i>, the dwarf-shrub layer in combination with consistently high <i>Calamagrostis rubescens</i> cover (in excess of 30%) gives modal stands their prevailing aspect of nearly continuous cover; other dwarf-shrubs of moderate to high constancy and highly variable cover include <i>Linnaea borealis, Mahonia repens</i> or <i>Mahonia aquifolium</i> (depending on locality), <i>Chimaphila umbellata, Vaccinium scoparium</i>, and <i>Vaccinium myrtillus</i>. Of two forbs, <i>Clintonia uniflora</i> and <i>Cornus canadensis</i>, indicative of this association's relatively mesic status (as compared to say <i>Larix occidentalis / Vaccinium caespitosum</i>) only <i>Clintonia</i> is also 100% constant and used as an indicator. Forbs are usually a negligible component with only <i>Arnica cordifolia, Fragaria</i> spp., <i>Orthilia secunda (= Pyrola secunda), Lupinus sericeus</i> or <i>Lupinus argenteus</i> (depending on locality), <i>Hieracium albiflorum</i>, and <i>Maianthemum racemosum</i> exhibiting moderate to high constancy and a combined cover seldom exceeding 10%.
Accession Code:
VB.CC.31133.CEGL005883
Plot-observations of this Community Concept:
0
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