Name:
Larix occidentalis / Clintonia uniflora Forest
Reference:
Western Ecology Working Group of...
Description:
Broadly distributed throughout the northern Rocky Mountains and adjacent terrain, this large-patch to matrix seral community occupies relatively moist (mesic) and warm to cool sites having free air drainage and lacking frost pocket conditions. Elevations range in the north from760 to 1585 m (4500-5200 feet) (extreme outliers at 1710 m (5600 feet)), whereas to the south it ranges from 1060 to 1710 m (3500-5600 feet). It occurs on slopes of all degrees of steepness and aspect orientation, though it is more likely to occur from toeslope through midslope positions (predominantly collecting positions). At the dry extreme of its distribution it is more strongly associated with protected positions such as concave slopes, moist depressions on gentle slopes or plateaus, stringers along perennial stream bottoms, toeslopes and northeastern aspects. Though sites are mesic, verging on hygric, they are inferred to be only briefly or seasonally influenced, if at all, by a high water table; <i>Larix occidentalis</i> occurrence is strongly associated with well-drained positions. A wide variety of parent materials are represented, including those as disparate as granite and limestone, including all manner of glacial-fluvial material. In northern Idaho and northwestern Montana it is routinely found on ash caps, ranging from 3 to 60 cm in depth. The soil textures are predominantly loams and silt loams (reflecting in part the volcanic ash); soils typically have less than 15% coarse fragment content and are well-drained.<br><br>This mesic seral association is characterized by <i>Larix occidentalis</i> dominating the upper canopy, though other tree species occur with lesser cover, including both other species considered almost exclusively seral <i>Pinus contorta</i> and <i>Pinus monticola</i> and those capable of functioning as both seral and climax species, including those from warmer environments, <i>Pinus ponderosa</i> (very limited representation), <i>Pseudotsuga menziesii, Thuja plicata</i>, and <i>Tsuga heterophylla</i> and those of colder environments, <i>Abies lasiocarpa, Abies grandis</i>, and <i>Picea engelmannii</i>. The shrub layer may be highly diverse with tall shrubs (e.g., <i>Acer glabrum, Taxus brevifolia, Amelanchier alnifolia</i>), short shrubs (<i>Symphoricarpos albus, Paxistima myrsinites, Rubus parviflorus, Spiraea betulifolia</i>), and dwarf-shrubs (e.g., <i>Chimaphila umbellata, Linnaea borealis, Mahonia repens</i>) abundantly represented. The graminoid component is inconspicuous with no one species exhibiting high constancy, though <i>Bromus vulgaris, Bromus ciliatus</i>, and <i>Calamagrostis rubescens</i> are more consistently present and with greater cover than other graminoids. The cover of the diagnostic forbs <i>Clintonia uniflora</i> and <i>Tiarella trifoliata</i> is greatest when this type occurs in the zones potentially dominated by <i>Thuja plicata</i> and <i>Tsuga heterophylla</i>, up to 30% canopy cover (can even be a dominant forb), whereas in the colder environments characterized by <i>Abies lasiocarpa, Abies grandis</i>, and <i>Picea engelmannii</i> potential dominance cover of these diagnostics and all forbs is generally less. Other forbs of high constancy, at least in some portion of this association's considerable range, are <i>Aralia nudicaulis, Adenocaulon bicolor, Coptis occidentalis, Cornus canadensis, Galium triflorum, Goodyera oblongifolia, Maianthemum stellatum, Osmorhiza berteroi (= Osmorhiza chilensis), Orthilia secunda (= Pyrola secunda), Thalictrum occidentale, Trillium ovatum, Viola glabella</i> (or <i>Viola canadensis</i>), and <i>Viola orbiculata</i>.
Accession Code:
VB.CC.32157.CEGL005880
Plot-observations of this Community Concept:
0
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