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<br />South Platte River, Chatfield Downstream Channel Improvement Project- Vegetation Management Plan <br /> <br />Plant Associations <br />Field surveys using the U.S. National Vegetation Classification Standard clarified by <br />Colorado Natural Heritage Program was used in this analysis (Carsey et al. 2003). Riverine <br />Wetlands occur in the project area, which are typically known to occur along low-elevation <br />floodplains of mid- to high order streams, which have a perennial flow. These systems are <br />mainly supported by over bank flows and are important for flood control, maintaining water <br />quality, stabilizing streambanks, and providing habitat for fish and wildlife. <br /> <br />Several types of wetland and riparian plant associations can be found in the project area and <br />they are all classified as Deciduous Dominated Forests and Woodlands. These associations <br />are most commonly found below 7000 ft in elevation and are dominated by shrublands, <br />grasslands, and deciduous woodlands. In general, the project site is a riparian plant <br />community. The river banks are characterized by cottonwood and willow. Native upper <br />floodplains are characterized by cottonwood with snowberry understory. Upper floodplains <br />have been seeded with smooth brome or have been heavily grazed with adjacent smooth <br />brome pastures and have a few large cottonwoods. A mixture of the following plant <br />associations are found within the project area and descriptions of each plant association are <br />provided in Table 1. <br /> <br />1) Plains Cottonwood-PeachleafWillow/Sandbar Willow Woodland <br />(Populus deltoids-Salix amygdaloideslSalix exigua) <br />2) Plains Cottonwood/Western Snowberry Woodland <br />(Populus deltoids-Symphoriacarpos occidentalis) <br />3) Plains Cottonwood/Smooth Brome Woodland <br />(Populus deltoids-Bromus inermis) <br /> <br />Table 1: U.S. National Vegetation Classification for the Chatfield Downstream Channel <br />Improvement Project Site (Carsey et al. 2003) <br /> <br />Plant Plant Association Ecological Average % Cover <br />Association Description Processes Primary Vegetation <br />Plains Cottonwood - Mix of sapling/pole-sized Early to mid-seral stage. Willow 33% Populus deltoids <br />Peachleaf Willow/ cottonwood and willow. dominated moist-soil and 29% Salix exigua <br />Sandbar Willow Dense tree canopy with little cottonwood in drier soil; 17% Equisetum arvense <br />Woodland herbaceous cover. Found overtime cottonwoods mature 17% Salix amygdaloides <br /> on low stream banks and and dominate. <br /> frequently flooded islands. <br />Plains Cottonwood / Widely-spaced, mature Late seral stage. Large, widely- 51 % Populus deltoides <br />Western Snowberry plains cottonwood and spaced trees. Located on highest 26% Symphoricarpos <br />Woodland western snowberry surface of floodplain. occidentalis <br /> understory. Elevated ridges 15% Elymus lanceolatus <br /> and flat areas of floodplain. 15% Spartina pectinata <br />Plains Cottonwood / Few large plains Smooth brome undergrowth 47% Bromus inermis <br />Smooth Brome cottonwood, little to no product of direct seeding or 44% Populus deltoides <br />Woodland shrub understory, invasion from livestock pasture. 43% Anemone <br /> monotypic growth of non- Native grasses out-competed; Canadensis <br /> native smooth brome. Upper heavy grazing pressure. No 27% Poa pratensis <br /> terrace of floodplain cottonwood regeneration. <br /> <br />Page 9 <br />Final Report - April 30, 2008 <br />