General information

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

MLRA notes

Major Land Resource Area (MLRA): 232X–Yukon Flats Lowlands

The Yukon Flats Lowlands MLRA is an expansive basin characterized by numerous levels of flood plains and terraces that are separated by minimal breaks in elevation. This MLRA is in Interior Alaska and is adjacent to the middle reaches of the Yukon River. Numerous tributaries of the Yukon River are within the Yukon Flats Lowlands MLRA. The largest are Beaver Creek, Birch Creek, Black River, Chandalar River, Christian River, Dall River, Hadweenzic River, Hodzana River, Porcupine River, and Sheenjek River. The MLRA has two distinct regions—lowlands and marginal uplands. The lowlands have minimal local relief and are approximately 9,000 square miles in size (Williams 1962). Landforms associated with the lowlands are flood plains and stream terraces. The marginal uplands consist of rolling and dissected plains that are a transitional area between the lowlands and adjacent mountain systems. The marginal uplands are approximately 4,700 square miles in size (Williams 1962).
 
This MLRA is bounded by the Yukon-Tanana Plateau to the south, Hodzana Highlands to the west, Porcupine Plateau to the east, and southern foothills of the Brooks Range to the north (Williams 1962). These surrounding hills and mountains partially isolate the Yukon Flats Lowlands MLRA from weather systems affecting other MLRAs of Interior Alaska. As a result, temperatures are generally warmer in summer and colder in winter than is characteristic in other areas at comparable latitude. There is a moisture and temperature gradient in which the lowlands region tends to be drier and colder and the surrounding marginal uplands region tends to be moister and warmer (PRISM Climate Group 2006).

The Yukon Flats Lowlands MLRA is mostly undeveloped lands that are sparsely populated and not accessible by a road system. A number of villages, including Beaver, Birch Creek, Chalkyitsik, Circle, Fort Yukon, Stevens Village, and Venetie, are adjacent to the Yukon River or one of its major tributaries. The largest village is Fort Yukon, which according to the 2010 U.S. Census has 583 residents that are dominantly Gwich’in Alaska Natives.

LRU notes

Alaska has no officially recognized LRU. However, there appear to be two distinct LRU in the Yukon Flats Lowlands MLRA. These LRU are thought to have differing climatic regimes, landforms, and soil types (STATSGO and Jorgensen and Meidinger 2015). The two LRU were previously discussed in the MLRA notes section above and are termed the lowlands LRU and the marginal uplands LRU.

This ecological site is associated with the marginal uplands LRU.

Classification relationships

Yukon Flats Lowlands MLRA.

Ecological site concept

This ecological site is associated with erosive escarpments in the marginal uplands region of the Yukon Flats Lowlands MLRA. During field work, these escarpments had limited sampling. Flight and satellite reconnaissance results in readily recognizable escarpments in the marginal uplands region of the Yukon Flats Lowlands MLRA (fig. 3). Escarpments are considered very steep (50 to 100 percent slope), excessively drained, and appear to be erosive. Based on this reconnaissance and limited data collected from the Yukon Flats Lowlands and Interior Alaska Highlands MLRA, escarpments are believed to support multiple plant communities. These steep and dry slopes are likely prone to fire and this disturbance may result in significant slope erosion and multiple plant communities.

Reference state plant communities are believed to be closed deciduous forest and open low scrub (Viereck et al. 1992). Species that are thought to commonly occur in the reference state are quaking aspen (Populus tremuloides), prickly rose (Rosa acicularis), prairie sagewort (Artemisia frigida), common juniper (Juniperus communis), kinnikinnick (Arctostaphylos uva-ursi), purple reedgrass (Calamagrostis purpurascens), slender wheatgrass (Elymus trachycaulus), and American pasqueflower (Pulsatilla pates), northern bedstraw (Galium boreal), Rocky Mountain goldenrod (Solidago multiradiata), and three toothed saxifrage (Saxifraga tricuspidata).

Associated sites

Similar sites

Table 1. Dominant plant species

Legacy ID

F232XY211AK