Common (Translated Scientific) Name: (Rio Grande Cottonwood, Plains Cottonwood) / Narrowleaf Willow Riparian Woodland

Colloquial Name: No Data Available

Hierarchy Level:  Association

Type Concept: This is a lowland riparian association known from the Rio Grande, Pecos and Canadian river drainages of central and eastern New Mexico and probably elsewhere in northern New Mexico. It also occurs in the Great Plains of Colorado, North Dakota, Nebraska, Oklahoma, South Dakota, and Texas, and in the Colorado Plateau of Utah and Colorado. This association occurs in wide river corridors that have low-gradient and primarily sandy/gravelly beds (becoming cobbly with increasing gradients). Elevations range from 1380-1980 m (4525-6500 feet). The type is most often found proximal to perennial rivers on low sidebars and streambanks near stream bankfull levels (discharge ratios close to 1). Occasionally, it can be found within the active channel or nearby. Because of its low position, the type is flooded frequently (average recurrence interval is 5 years). Most soils are young and undeveloped Entisols, and soils within the active channel are classified as riverwash. Soils tend to be well-drained sands with mixtures of cobbles and gravels throughout the profile. Most soils tend to be moist or wet within 1 m, at least during seasonal high water. In some soils, moisture indicators are found at greater depths. This association is dominated by relatively young stands of Populus deltoides that form open to moderately open overstories (25-50 % cover) with thickets of Salix exigua in the understory. Baccharis salicina is often well-represented to abundant and may codominate. Herbaceous cover is abundant, particularly among graminoids, and numerous (23) native wetland indicators can be present, such as Schoenoplectus pungens, Scirpus microcarpus, Eleocharis palustris, Juncus arcticus ssp. littoralis, Juncus longistylis, Juncus tenuis, Glyceria striata, Carex aquatilis, Carex oreocharis, Carex scoparia, Carex stipata, Equisetum arvense, and Equisetum laevigatum. Overall herbaceous diversity is high (90 species) and still predominantly native in composition (66 species or 73%).

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Initially developing on exposed depositional sandbars, this mid-successional community type depends on periodic flooding for maintenance and growth, even when well-established. As sediments and debris become trapped among the woody stems, the bar becomes more stable. In this community type, the cottonwoods overtop the shrubby willows. Because the willows are limited to lower riverside bars or cutoff channels, the community type eventually changes as the trees develop into mature forests on higher terraces without the willow understory. Historically, when cottonwoods eventually died from old age or were removed in high-energy flood events, they were replaced by new, young trees. For this cycle to occur under regulated conditions, flows should mimic the natural flood regime as closely as possible.

Hink and Ohmart (1984) describe a cottonwood/coyote willow mapping unit with four structural sub-types for the middle Rio Grande. Dick-Peddie (1993) refers to a Populus fremontii / Salix exigua / Mesic Grass - Forb vegetation type as part of a Floodplains-Plains Riparian group that is probably inclusive of this type. This association is similar to ~Populus deltoides - (Salix amygdaloides) / Salix (exigua, interior) Floodplain Woodland (CEGL000659)$$ reported from the Great Plains states.

Similar NVC Types: No Data Available

note: No Data Available