Common (Translated Scientific) Name: Narrowleaf Cottonwood / Narrowleaf Willow Riparian Woodland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: The type is widespread in mountainous regions of the San Juan, Pecos, and Rio Grande river basins in northern and central New Mexico and widely distributed throughout the Rocky Mountain region and Intermountain West. It is found in wide to narrow valleys at mid to upper elevations from 1670 to 2360 m (5480-7750 feet). It occurs on streamside alluvial bars that border perennial rivers and intermittent streams of low to moderate gradients (0.7-2.8%). In Colorado, this riparian woodland occupies point bars, gravel bars, benches and low areas that are flooded annually. It is a very common plant community of young seedling and sapling Populus angustifolia intermixed with Salix exigua. Sites are typically flooded every five years, sometime more often, and most are within the 25-year floodplain. Stream channel materials are usually coarse and composed of cobbles or gravel. Soils are young and weakly developed Entisols with wet (aquic) conditions within the top 50 cm or at least within rooting depth. They are well-drained sands and sandy loams mixed with gravels and cobbles. This type is characterized by middle-aged stands of Populus angustifolia in an open upper canopy, with a shrubby understory dominated by Salix exigua. Populus angustifolia saplings (derived from root sprouts) are common beneath the canopy. Other shrubs such as Salix irrorata may be well-represented but clearly subordinate to Salix exigua. The herbaceous layer is very diverse, with 98 species recorded for the type, 23 of which are native wetland indicators.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Several other Salix species may be present, and the canopy may have other species of Populus as well.

The community is widely distributed on younger depositional bars of moderate-sized streams with unregulated flows and few diversions. Since the stands are well-adapted to flooding, they are well-suited for streambank stabilization. Typically found in wider valleys where ranches and livestock are common, the coarse-textured soils are not susceptible to compaction. However, the streamside location of these stands makes them prone to heavy usage by livestock. Without careful management, woody components such as saplings and shrubs decrease. Under continuous pressure from grazing, these stands have limited self-sustainability and are eventually replaced by non-cottonwood-dominated stands prone to streambank erosion. Managers should maintain a buffer strip of cottonwoods along streambanks to avoid erosion. When grazing pressure is lessened, regrowth of cottonwoods is rapid, riparian shrubs return, and streambanks become more stable. In addition, species diversity and wildlife habitat increase. Populus angustifolia and Salix exigua are obligate riparian species which require flooding for reproduction, growth, and maintenance. Depending on the depth of the water table, these stands will respond positively to fire disturbance with rapid regrowth. Both species are highly palatable to beaver and livestock, and potential usage is high.

Medina (1986) described a Populus acuminata / Salix exigua community type in southwestern New Mexico that is very similar to this one. This type has been well-documented in Colorado (Ramaley 1942, Woodbury et al. 1961, Hess 1981, Baker 1984a, Hess and Alexander 1986, Johnston 1987, Kittel and Lederer 1993, Kittel et al. 1994, 1996) and in Nevada (Manning and Padgett 1995).

Similar NVC Types: No Data Available

note: No Data Available