Ecology

The Independence Pass corridor is notable for passing through three major life zones—the montane, subalpine, and alpine, each of which has specific characteristics determined by elevation. In addition, the Roaring Fork River and its tributaries support riparian ecosystems along their banks. From the harsh, windblown tundra at the summit of the Pass, to the lush oxbow meadows of the North Star Nature Preserve and Twin Lakes area, the Pass corridor presents a wide variety of flora and fauna which are characteristic of high valleys in the Rocky Mountains.

Montane

The montane zone extends from the lush meadows just east of Aspen to the Lincoln Creek drainage at around 10,000 feet, and on the east side of the Pass from Twin Lakes to the South Fork Lake Creek turnoff. This zone is made up of relatively cool, moist upland slopes where large evergreens constitute the climax vegetative type. Douglas fir, Ponderosa pine, Colorado blue spruce, and aspen are typical tree types, and alder, narrowleaf cottonwood, and willow line the riparian corridors. Columbine, meadow rue, aster, and Indian paintbrush are typical wildflower types. Understory shrubs include kinnikinnick, mountain ash, thimbleberry, chokecherry, serviceberry, and wild raspberry.

North Star Nature Preserve, which was acquired by Pitkin County in the late 70s, is the largest flat area in the montane zone. At this location, an ancient lateral moraine marked the end of the glaciers that filled the Pass corridor during the last ice age. The moraine dammed the Roaring Fork River as the glacier retreated, creating an ancient lake. The lake, in turn, collected silt, plant debris, and fine soils, which created the deep, peaty subsoil here. This area was a vast willow wetland before it was cleared for farming and ranching in the late 19th century. The total area now protected by public ownership in this location is over 150 acres between the east end of Aspen and Difficult Campground.

The old oxbow lakes on North Star and elsewhere at the lower end of the Pass corridor support a host of plants and animals ranging from microscopic plankton to herons and moose. The Tagert Lake property, a private inholding near the Winter Gate on Highway 82, marks the uppermost end of these willow and sedge-dominated wetlands.

Subalpine

The subalpine zone extends from Lincoln Creek to the Linkins Lake Trailhead 1.5 miles below the summit of the Pass on the west, and to the hairpin turn near the summit on the east. The Lincoln Creek, Roaring Fork, and Lake Creek valleys are marked by the glaciers that shaped them 10,000 years ago. Glacial debris, scoured rock faces, and deeply incised river canyons are typical features. Short growing seasons, extreme temperature fluctuations, and deep snow cover dictate that plants and animals in this zone are hardy, well adapted, and slow growing.

Englemann spruce, Subalpine fir, Lodgepole pine, and aspen at the lower end are typical in this zone, and common wildflowers include Parry's primrose, marsh marigold, fireweed, and many species of orchid. Beaver colonies are found in areas where the river can be dammed, and elk and mule deer use this area for summer grazing. Year-round animal inhabitants include marmots, pine marten, coyote, black bear, lynx, and various small rodents.

Alpine

The alpine zone begins approximately 500 feet below the summit of Independence Pass (at 12,100’). This zone is characterized by extreme temperature fluctuations, high winds, and a very short growing season. Vegetation and wildlife use is limited by the short growing season and harsh conditions. Typical plants include moss campion, alpine forget-me-nots, sky pilot, mosses and lichen, willows, and a variety of hardy grasses and wildflowers. Wildlife living in the alpine zone year around includes ptarmigan, pika, marmot, mountain goat, and pocket gopher.