| Location: | Canada (British Columbia, Alberta); United States (Colorado, Montana, New Mexico, Nevada, Utah, Wyoming, Oregon, California, Idaho, Washington) |
| Description: | This alliance includes only those stands of Populus tremuloides that are truly wetlands and riparian in their setting. Most stands of this alliance are found in riparian zones. Some may be near lakes where the ground is flooded or saturated for a short time in the spring. The moderate to closed tree canopy is dominated by Populus tremuloides; sometimes other tress are codominant, such as Populus angustifolia, Abies concolor, Pinus ponderosa, and Picea pungens. More open stands have a prominent shrub layer containing species such as Alnus incana, Cornus sericea, and Salix spp. This alliance is found in the Rocky Mountains of Alberta, Montana, Idaho, Wyoming, Colorado, Utah, eastern Oregon and Washington, and Great Basin mountain ranges of Nevada, possibly extending into the Sierra Nevada of California. In addition it occurs on high plateaus and canyons of New Mexico. |