Yukon - Charley Rivers National Preserve - Trees

Taiga, or boreal forest, reaches it"s north limit at about latitude 67° 30" N, which is just north of Yukon-Charley. This extensive forest thins into scattered stands of spruce mixed with hardwoods that follow the river valleys into the mountains to an elevation of about 2,100 feet. This spruce-hardwood forest takes two forms.

White spruce usually in association with scattered birch or aspen is commonly found on moderate south-facing slopes. Heaths, such as bearberry, crowberry, Labrador tea, blueberry and cranberry are common as are willows. Lichens and mosses cover the forest floor along with a variety of herbs. Some large, pure stands of white spruce occur along rivers such as the Kandik, Nation and Charley.

On the north-facing slopes and on poorly drained lowlands, black spruce is predominant. These trees, which grow very slowly, are usually stunted and often scattered. The understory in these areas is spongy moss and low brush. As the tree line is approached, the forest thins out until spruce are scattered among the shrub thicket community. In one type of shrub thicket, dwarf and resin birch, willows and alder may be extremely dense or open and interspersed with reindeer lichens, low heath-type shrubs or patches of alpine tundra. Alder is usually found on moister sites and birch on drier sites. Such shrub thickets typically occur up to 3000 feet in elevation.

A second type of shrub thicket association occurs along the alluvial plain and gravel bars of braided or meandering streams. Willows and alders predominate and are associated with dwarf fireweed, horsetails, prickly rose and other herbs and shrubs. These thickets develop rapidly in floodplains that are newly exposed after breakup and spring flooding.