Ecology of California - Forested Mountains

Forested Mountains

The cooler and wetter mountains of northern California are covered by forest ecoregions. Both the WWF and the EPA divide the mountains into three ecoregions: the Sierra Nevada, the Klamath Mountains, and the Eastern Cascades Slopes and Foothills (occurring on the Modoc Plateau).

The Sierra Nevada are home to half of the vascular plant species of California, with 400 species that are endemic to the region. Like many mountain ranges, the plant communities of the Sierra group into biotic zones by altitude, because of the increasingly harsh climate as the altitude increases. These biotic zones include montane forest dominated by conifers such as Jeffrey pine and Lodgepole pine, subalpine forest dominated by whitebark pine, up to alpine tundra which cannot support trees. The Sierra are also notable for giant sequoia trees: the most massive on earth.

The Klamath and Siskiyou Mountains are a notable biodiversity hotspot, containing one of the four most biodiverse temperate forests in the world. The diversity is caused by the ecoregion being adjacent to a number of other ecoregions, diverse soil, and having refugia caused by isolation in the last ice age. Some endemic species in the Klamath mountains are limited to only one mountain or valley.

The Eastern Cascades slopes of the Modoc Plateau are characterized by a mosaic of open ponderosa pine forest, grasslands, and shrublands. Although high, these slopes and mountains are in the rain shadow of the Cascade Range, and hence are drier and more open.