2010-12-17_REVISION - C1981019 (160)

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of this wetland, flood flows and/or subirrigation no longer saturate the surface with sufficient periodicity to preclude invasion by upland taxa. The majority of study area wetlands tend to exhibit similar properties with very dark soil matrix colors, bright mottles, typical saturation to the surface or near surface, and dominance by sedges and wetland grasses and forbs. Areas transitional to upland are typically governed by elevation, slope, and soil textures that preclude ponding or subirrigation of soils in the upper 12 inches of the soil profile. The most notable characteristic governing the location of (or simply correlated to) the wetland / upland boundaries, especially along the transitional margins of these fluvial areas, is the often not so subtle changes in elevation, topography, or soil porosity (usually 12 or less inches of elevation) which has resulted from historic fluvial erosion and deposition processes along the stream banks. These wetlands are characterized by a series of related vegetation communities variably dominated by a variety of taxa and include: Canada thistle (Cirsium arvense), water sedge (Carex aquati/is), bentgrass (Agrostis a/ba), cattail (Typha iatifoiia), Baltic rush (Juncus baiticus), cutleaf coneflower (Rudbeckia iaciniata), Canada goldenrod (Soiidago canadensis), Kentucky bluegrass (Poa pratensis), boxelder (Acer negundo), Nebraska sedge (Carex nebracensis), coyote willow (Saiix exigua), reed canarygrass (Phaiaris arundinacea), and hardstem bulrush (Schoenopiectus iacustris). Soils in the slightly higher topographic positions (transitional uplands) exhibit matrix chromas ranging from 2 to 3 and were never saturated and never exhibited mottling. Underlying materials along stream courses were typically a much brighter chroma value due to their nature as alluvial deposits (sands and small gravels). As elevation subtly decreases to the transitional wetlands of lower topographic positions, soils were more moist and exhibited slightly darker matrix chromas and bright mottles ranging from few to very abundant. At the lowest levels within the best wetland areas, soils are saturated to the surface or exhibit ponding, exhibit distinct mottles and a tendency toward gley colors at deeper profile depths. Typically wetland transition zones are comparatively narrow where obvious topographic differences occur. However, on occasion transition zones are quite broad forming a continuum where topographic changes are quite subtle as exemplified within the larger wetland units, especially Wetland # 4 (lower E. Fork of Jubb Cr.) that is in transition to upland. Soils in these transition zones have dark chroma colors but are not mottled or gleyed on the upland side within the upper 12 inches of the profile, which may reflect the somewhat excessively drained gravelly, loamy sand, or sandy loam nature of the subsurface soil textures often observed. Water tables associated with these upland transitional zones were observed to be seasonal and below 12-18 inches. On the wetland side, soils matrix chromas are slightly darker, 0 OmAR =IEIKASSO M, INC. Page 40 2005 Collom Vegetation Survey