Physiognomy and Structure: No Data Available

Floristics: The woodland association is characterized by an open tree canopy of Pinus albicaulis that is typically multi-stemmed (and stunted) on exposed, high-elevation sites, sometimes with occasional Pinus flexilis trees. On less exposed sites, the upper canopy may include scattered Pinus contorta, or Abies lasiocarpa may be present with Abies lasiocarpa or Pseudotsuga menziesii present in the subcanopy and understory. Occasional shrubs, such as Symphoricarpos spp., Dasiphora fruticosa ssp. floribunda, or Spiraea splendens (= Spiraea densiflora), may be present, but the understory is characterized by a relatively sparse to moderately dense (15-60% cover) herbaceous layer that is typically dominated by Carex geyeri. Other common graminoids include Achnatherum occidentale (= Stipa occidentalis), Carex rossii, Elymus glaucus, Festuca idahoensis, Poa nervosa, and Trisetum spicatum. Associated forbs, such as Achillea millefolium, Antennaria spp., Arnica cordifolia, Campanula rotundifolia, Erigeron spp., Geum triflorum, Lupinus argenteus, Pedicularis racemosa, Solidago multiradiata, Valeriana dioica, or Xerophyllum tenax, are often present with relatively low cover.

Dynamics:  Pinus albicaulis is a slow-growing, long-lived conifer that is common at higher elevations in the upper subalpine zone. It typically occurs in a mosaic of tree islands and meadows where it often colonizes sites and creates habitat for less hardy tree species. Birds and small mammals often eat and cache the large, wingless pine seeds and are responsible for the dispersal of this species. Most important is the Clark''s nutcracker, which can transport the seeds long distances and cache them on exposed windswept and burned-over sites. This results in the regeneration of pines in clumps from forgotten caches (Eyre 1980, Steele et al. 1983, Burns and Honkala 1990a, Schmidt and McDonald 1990).

Pests include the mountain pine beetle, Dendroctonus ponderosae, which has killed many mature trees in the past, during epidemics when populations of the beetle build up in lower elevation Pinus contorta stands, then move up into the Pinus albicaulis (Steele et al. 1983, Burns and Honkala 1990a, Schmidt and McDonald 1990). The exotic pathogen, white pine blister rust, Cronartium ribicola, is attacking and killing Pinus albicaulis trees in many parts of the interior northwestern U.S. It is especially destructive in more mesic habitats that favor infection of its alternate host, Ribes spp. Pinus albicaulis is very susceptible to this disease, and the only real hope is propagating individuals that have high genetic resistance to blister rust (Burns and Honkala 1990a, Schmidt and McDonald 1990, Steele et al. 1983).