Name:
Thuja plicata - Tsuga heterophylla Central Rocky Mountain Forest Group
Reference:
NatureServe Biotics 2019
Description:
This forest group occurs in the Northern Rockies west of the Continental Divide within the maritime-influenced climatic zone of the northern Rocky Mountains of western Montana, west into northeastern Washington and southern British Columbia. These are forests dominated by <i>Tsuga heterophylla</i> and <i>Thuja plicata</i> in most cases, found in areas influenced by incursions of mild, wet, Pacific maritime air masses. Much of the annual precipitation occurs as rain, 25-50% falls as snow. Snowpacks are often melted by rain during warm winter storms. Occurrences generally are found on all slopes and aspects but grow best on sites with high soil moisture, such as toeslopes and bottomlands. At the periphery of its distribution, this group is confined to moist canyons and cooler, moister aspects. Generally these are moist, non-flooded or upland sites that are not saturated yearlong. Along with <i>Tsuga heterophylla</i> and <i>Thuja plicata, Pseudotsuga menziesii</i> commonly shares the canopy, and <i>Pinus monticola, Pinus contorta, Abies grandis, Taxus brevifolia</i>, and <i>Larix occidentalis</i> are major associates. <i>Cornus nuttallii</i> may be present in some situations. <i>Picea engelmannii, Abies lasiocarpa</i>, and <i>Pinus ponderosa</i> may be present but only on the coldest or warmest and driest sites. <i>Linnaea borealis, Mahonia nervosa, Paxistima myrsinites, Acer glabrum, Spiraea betulifolia, Symphoricarpos hesperius, Cornus canadensis, Rubus parviflorus, Menziesia ferruginea</i>, and <i>Vaccinium membranaceum</i> are common shrub species. The composition of the herbaceous layer reflects local climate and degree of canopy closure; it is typically highly diverse in all but closed-canopy conditions. Important forbs and ferns include <i>Actaea rubra, Achlys triphylla, Anemone piperi, Aralia nudicaulis, Asarum caudatum, Clintonia uniflora, Coptis occidentalis, Thalictrum occidentale, Tiarella trifoliata, Trientalis borealis, Trillium ovatum, Viola glabella, Gymnocarpium dryopteris, Polystichum munitum</i>, and <i>Adiantum pedatum</i>. Typically, stand-replacement, fire-return intervals are 150-500 years, with moderate-severity fire intervals of 50-100 years. Species in East Cascade forests (G212) that are absent to rare in the Northern Rockies are <i>Picea sitchensis, Abies amabilis, Acer macrophyllum, Acer circinatum, Gaultheria shallon, Rhododendron macrophyllum, Mahonia nervosa, Rubus spectabilis, Vaccinium alaskaense, Vaccinium parvifolium, Blechnum spicant, Achlys triphylla, Oxalis oregana, Anemone deltoidea, Anemone oregana, Rubus lasiococcus</i>, and <i>Streptopus streptopoides</i>.
Accession Code:
urn:lsid:vegbank.org:commConcept:40012-{96E33950-1E6E-43BB-B5BA-FD36EA325D7E}
Plot-observations of this Community Concept:
0
|
