Common (Translated Scientific) Name: Western Larch / Bride''s Bonnet Forest

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: 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; Larix occidentalis 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.

This mesic seral association is characterized by Larix occidentalis dominating the upper canopy, though other tree species occur with lesser cover, including both other species considered almost exclusively seral Pinus contorta and Pinus monticola and those capable of functioning as both seral and climax species, including those from warmer environments, Pinus ponderosa (very limited representation), Pseudotsuga menziesii, Thuja plicata, and Tsuga heterophylla and those of colder environments, Abies lasiocarpa, Abies grandis, and Picea engelmannii. The shrub layer may be highly diverse with tall shrubs (e.g., Acer glabrum, Taxus brevifolia, Amelanchier alnifolia), short shrubs (Symphoricarpos albus, Paxistima myrsinites, Rubus parviflorus, Spiraea betulifolia), and dwarf-shrubs (e.g., Chimaphila umbellata, Linnaea borealis, Mahonia repens) abundantly represented. The graminoid component is inconspicuous with no one species exhibiting high constancy, though Bromus vulgaris, Bromus ciliatus, and Calamagrostis rubescens are more consistently present and with greater cover than other graminoids. The cover of the diagnostic forbs Clintonia uniflora and Tiarella trifoliata is greatest when this type occurs in the zones potentially dominated by Thuja plicata and Tsuga heterophylla, up to 30% canopy cover (can even be a dominant forb), whereas in the colder environments characterized by Abies lasiocarpa, Abies grandis, and Picea engelmannii 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 Aralia nudicaulis, Adenocaulon bicolor, Coptis occidentalis, Cornus canadensis, Galium triflorum, Goodyera oblongifolia, Maianthemum stellatum, Osmorhiza berteroi, Orthilia secunda, Thalictrum occidentale, Trillium ovatum, Viola glabella (or Viola canadensis), and Viola orbiculata.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This association defines an extremely broad environmental range due to the relatively recent approach stipulated by the USNVC of defining as unique associations that would formerly have been subsumed within a number of different climax or potential vegetation types; in the case of this association it is a successional stage in environments as mild and wet (defining a Pacific maritime climatic influence) as those supporting Thuja plicata or Tsuga heterophylla / Clintonia uniflora associations (and permutations) to those of the lower subalpine zone characterized by Abies lasiocarpa, Abies grandis, Tsuga mertensiana, and even Picea engelmannii / Clintonia uniflora forest associations. That this association in fact occurs in the states and USFS sections listed derives from this writer''s interpretation of constancy/cover tables of various authors/publications; where Larix occidentalis is listed as a major seral species, the inference has been made that stands quite likely occur on the landscape where this species strongly dominates the upper canopy (often observed by this author throughout northern Idaho and western Montana). It should also be noted that this type is probably less common in zones where Thuja plicata and Tsuga heterophylla are the climax dominants because, following disturbance in these zones, the climax trees are quick to reclaim the site, i.e., they comprise a significant cover of the earliest forested successional stages. The crosswalking for this type is incomplete, and it may well eventually be documented west of the Cascade Crest in Oregon and Washington.

Similar NVC Types: No Data Available

note: No Data Available