Vegetation

Regional Vegetation

Closed spruce and hardwood forests dominate much of the lowlands, especially along major drainages and on moderate to well-drained lower slopes. The active floodplain immediately adjacent to the Unalakleet River and its major tributaries consist of closed boreal forest, closed alder-willow, or open gravel bars that appear to be frequently disturbed by flooding and support scattered willows and forbes. Extensive, poorly-drained lowland areas beyond the active floodplain support sedge tussock tundra and wet sedge meadow tundra. Lower subalpine slopes are covered with open spruce woodland, open and closed tall alder-willow shrub, and open tall shrub birch-willow shrub vegetation. The tall shrub and woodland vegetation usually had a conspicuously rich fruticose lichen-dominated understory. Young, healthy white spruce were consistently found upwards into the alpine zone at sites visited, suggesting that tree and shrub line is moving up in elevation throughout the region.

Alpine and upper subalpine slopes and ridges above 1500 feet elevation (460 msm) support dryas dwarf scrub where the substrate is relatively stable. Dryas-lichen-dwarf shrub tundra is found on the driest sites, whereas dryas-sedge-dwarf shrub tundra and dryas-dwarf shrub tundra are common on more moist sites. On ridge tops and semi-stable slopes, this vegetation is often broken up into patches by frost boil and downslope processes. Steep, unstable slopes support scattered alpine herbs, often in poorly developed stripes, and smaller, scattered patches of dryas dwarf shrub. Snowmelt meadows and gullies support dryas tundra rich in forbs, as well as both dry and mesic graminoid herbaceous meadows. Most vegetation classes are rich in fruticose lichens and several stabilized, alpine, block slopes are entirely covered with a well-developed mat of fruticose and foliose lichens. The abundance of lichens in all the major vegetation types throughout the region significantly influences the appearance of the regional vegetation and contributes to its being critical winter habitat for caribou and reindeer.

Vegetation types focused on during this survey included those found in the alpine, especially on unstable screes and in snowmelt zones, on unstable and/or lush subalpine slopes and ridges, and along the larger, active floodplains of the major rivers.