High Elevation Pine Woodland - Code: Ne1G

These sparse woodlands are found near timberline on dry, rocky ridges and slopes in the mountains of the w. Nearctic and are populated by only the hardiest of trees. The trees are short in stature, rarely exceeding 35 ft. (11m) in height, and in persistent and intense winds are often reduced to the stunted form known as krummholz. In the zone where these woodlands are found, winters are long, and temperatures regularly go as low as⎻10°F (⎻23°C). In the hot, dry summer, daytime temperatures reach 90°F (32°C), though nighttime temperatures can still dip below freezing. Precipitation is generally scarce, with average rainfall ranging from 10 in. (250mm) in Great Basin Bristlecone Pine woodland in Nevada to 35 in. (900mm) in Foxtail Pine woodland in California. This habitat is a stark and emblematic feature of the high-mountain West, and spending time here usually requires a hike through some stunning mountain scenery. While the vegetation presents no obstacles, the steep slopes and loose, rocky soil can make exploration difficult. 
Nearctic High-elevation pine woodlands are open stands composed of five species in the white (five-needled) pine group that are often referred to as the “high five”: Great Basin Bristlecone Pine (Pinus longaeva), Rocky Mountain Bristlecone Pine (Pinus aristata), Foxtail Pine (Pinus balfouriana), Whitebark Pine (Pinus albicaulis), and Limber Pine (Pinus flexilis). With increasing elevation, tree size diminishes and distance between trees increases. Often these trees can only grow where they are sheltered from the wind by rocks or snow. Slow growth occurs at the base of the tree which is often large and dense. The upper parts of these trees often appear dead and gnarled and frequently are devoid of bark. These woodlands are generally monotypic, as each species has a disjunct range, though Limber Pine is occasionally mixed with the more restricted species. In parts of the n. Rocky Mountains and Cascades, Alpine Larch (Larix lyallii) will also form open monotypic stands at the edge of timberline. However, these larch woodlands lack the large-seeded cones of the high five and also lack most of the animals found in Nearctic High-elevation Pine Woodland.
There is no notable mid-story, and the groundcover is mostly bare rock, with only 5–25% vegetative ground cover on average. The sparse ground cover comprises small woody shrubs such as manzanitas (Arctostaphylos spp.), mountain mahoganies (Cercocarpus spp.), junipers (Juniperus spp.), gooseberries and currants (Ribes spp.), and bitterbrush (Purshia spp.). Herbaceous ground cover is diverse, due to the wide elevational and geographic ranges covered by this habitat, but usually includes a few grasses, especially fescues. The high five are all considered keystone and foundational species that heavily influence the structure, diversity, and stability of high-montane communities and are major sources of food for alpine animals. 
Some of these pines are impressively ancient—all high five species have specimens known to be over 1,000 years old. Foxtail and Rocky Mountain Bristlecone can reach over 3,000 years of age and an individual Great Basin Bristlecone Pine, at a staggering ~4,900 years old, is considered the oldest single organism on the planet. High Elevation Pine Woodlands are extremely susceptible to fire with even low intensity fires causing widespread tree death. The wood of these trees is incredibly dense and resinous which is an effective defense against most insects but ignites quite easily.