Western white pine (Pinus monticola) is found in high elevation subalpine woodlands on serpentine substrates in the eastern mountains of the Shasta-Trinity National Forest. The Mt. Eddy Research Natural Area has an excellent example of this plant community type. On Mt. Eddy, the western white pine subalpine woodland occurs on high elevation ridges and steep south-facing slopes at elevations of 7,200 to 7,600 feet. The surface of the ground is composed of peridotite rock and bare mineral soil in varying degrees of serpentinization.

This subalpine woodland is dominated by scattered, open western white pines. The canopy closure approximates 20 percent. White fir (Abies concolor) and red fir (Abies magnifica) are both regularly present, but not abundant, within this subalpine woodland, especially at the lower range of the overall elevation. Scattered whitebark pine (Pinus albicaulis) and foxtail pine (Pinus balfouriana ssp. balfouriana) also occur regularly but not abundantly throughout the lower reaches of this woodland type; at the upper elevational limits of this subalpine woodland, whitebark pine and foxtail pine are co-dominant species. The western white pine may reach heights of 80 feet, whereas the foxtail pine and whitebark pine are much shorter (30 to 40 feet). All three pines have an idiosyncratic growth pattern of flagged tops and branches sticking out at odd angles, reflecting their lifelong exposure to harsh conditions of high winds and heavy snowfall.

The understory of this subalpine woodland is composed of a scattering of low shrubs and herbs within a mosaic of extensive, rocky, bare ground. The canopy cover is 10 to 15 percent although on more xeric and higher south-facing slopes it is much higher, 50 to 60 percent. Pinemat manzanita (Arctostaphylos nevadensis) and huckleberry oak (Quercus vaccinifolia) are co-dominant species in the shrub layer. Occasionally, other shrubs such as littleleaf creambush (Holodiscus microphyllus) may be encountered. Ground cover is sparse. The imposing angelica (Angelica arguta), looking like a leathery-leaved, giant wild carrot, is the most prominent plant in the herb layer, followed by Drummond’s anemone (Anemone drummondii), nakedstem hawksbeard (Crepis pleurocarpa), spreading phlox (Phlox diffusa), brittle sandwort (Minuartia nuttallii) and squirreltail (Elymus elymoides). The strange Siskiyou milkvetch (Astragalus whitneyi var. siskiyouensis) is found among the rocks. Two ferns are regularly seen in this harsh environment: Lemmon’s sword fern (Polystichum lemmonii) and lace lipfern (Cheilanthes gracillima).

Very rare plants found within this western white pine subalpine woodland include Siskiyou fireweed (Epilobium siskiyouense) and Trinity buckwheat (Eriogonum alpinum).

Western white pine subalpine woodland on Mt. Eddy. Photo by Julie Kierstead Nelson.

Curlleaf mountain-mahogany (Cercocarpus ledifolius) below the summit of Mount Eddy. Photo by Julie Kierstead Nelson.

Middle Deadfall Lake on Mount Eddy. Photo by Julie Kierstead Nelson.