A WETLAND DELINEATION OF THE CHAUTAUQUA ROAD SITE

Plant Biology 445 Wetland Ecology

Walker, C. H., Honu, Y. A. K., and Gann, V.

Presented on September 22, 2001

Southern Illinois University

Carbondale, IL

The 3 criteria as outlined by the Federal Manual were met. These criteria are 1) hydrophytic vegetation, 2) hydric soils, and 3) wetland hydrology. Herbaceous vegetation ranged from 78.2-100% at the three plots sampled along the transect. All trees at all 3 plots were wetland species. The soil at all 3 plots were determined to be hydric soils. Drift lines, surface scouring and oxidized rhizospheres were also observed. The Chautauqua Road Site was determined to be a wetland, but the outer boundaries were not determined.

The Federal Manual for Identifying and Delineating Jurisdictional Wetlands (Federal Interagency Committee for Wetland Delineation 1989) uses a three-criterion approach for delineating wetlands. These three criteria are (1) hydrophytic vegetation, (2) hydric soils, and (3) wetland hydrology. All three of these criteria must be met before an area can be classified as a wetland (Mendelssohn 1995). Plant species composition, soil tests, and personal observations were utilized with the Federal Manual for making our determinations.

The dominance ratio and the prevalence index are the two procedures utilized in determining whether vegetation is hydrophytic or not (Wakeley & Lichvar 1997). The results obtained from using these 2 procedures do not always agree. Wakeley & Lichvar 1997 found disagreement between the 2 methods on 16% of actual field plots in 8 states. The dominant ratio method was used in this study.

The objective of our study was to 1) to determine whether the Chautauqua Road Site is a wetland or not and 2) to delineate the upper boundary of the wetland.

The soil is classified as Belknap soil type. The soil depth ranges from 30.5-61.0cm deep. The Chautauqua Road delineation site is often flooded (Gibson et al 1997). The site is a bottomland of the sycamore -box alder vegetation type.

We laid 1m quadrat and identified all plant species in the quadrat. We estimated the % cover of all the species according to the modified Daubenmire scale (Abrams and Hubert 1987, Table 1).

We used a shovel to dig the soil down in the soil about 20 cm and took soil samples. 1) We compared the soil color with the Munsell (Kollmorgen Corporation 2000) soil color chart, 2) We tested for the presence of lime (CaCo₃) by using Hydrogen peroxide (H₂O₂), 3) We tested for the presence of Manganese concretions by using Hydrochloric acid (HCl), and 4) looked for oxidized rhizospheres (root channels).

Parthenocissus quinquefolia was the dominant species at our sample point and within the quadrat accounted for almost 75% of the relative cover (Table 2). Sanicula canadensis made up the bulk of the remaining relative cover. Both of these species are facultative wetland species (Table 2).

Boehmeria cylindrica accounted for 43% of the relative cover and it is classified as an obligate wetland species. Asimina triloba and Partenocissus quinquefolia, making up another 43% of the relative cover, are both facultative species (Table 3).

Asimina triloba accounted for 90.4 % of the relative % wetland cover and is classified as a facultative species. Lindera benzoin made up another 7.2 % of the cover and it is classified as facultative wetland species (Table 4).

Quercus imbricaria and Acer rubrum were the 2 tree species found in the north, south, east and west quadrants (Table 5). The average distance between these trees and the quadrat was 6.21 m (Table 5). The average ground area per tree was 38.60 sq m. Therefore, the average density was 0.026 trees per meter or 259 trees per hectare.

Acer negundo was present on 3 sides of the quadrat; it is classified as a facultative wetland species (Table 6). Data was not collected for quadrat distance and d.b.h. of the tree species.

Acer negundo was present on 2 sides of the quadrat; it is classified as a facultative wetland species (Table 6). The other 2 tree species were Ulmus americana and Platanus occidentalis. These are also classified as facultative wetland species. Data was not collected for quadrat distance and d.b.h. of the tree species.

Conspicuous oxidized rhizospheres (root channels) were present in the soil samples taken from within the 1 meter quadrat.

Drift lines and surface scouring were observed in the area, but no oxidized rhizospheres were present.

Oxidized rhizospheres were also present in the soil samples taken from within the 1 meter quadrat. Surface scouring and drift lines were observed in the area.

The herbaceous layer was composed of 78.22% of wetland species at Plot 1, composed primarily of Parthenocissus quinquefolia (Table 2). The 4 trees found at the 4 cardinal directions from the quadrat were also classified as wetland species (Table 5).

Wetland species made up 92.6% of the vegetation found at Plot 2. Boehmeria cylindrica, an obligate wetland species, made up 43% of this total (Table 3). The 4 trees found at the 4 cardinal directions from the quadrat were also classified as wetland species (Table 6).

Wetland species made up 100 % of the total at Plot 3 (Table 4). The 4 trees found at the 4 cardinal directions from the quadrat were also classified as wetland species (Table 7).

Herbaceous vegetation ranged from 78.2-100% at the three sites. All the trees at all 3 sites were wetland species. Section 3.6, number 2, of the Federal Manual for Identifying and Delineating Wetlands states that if 50% or more of the dominants are OBL, FACW, or FAC (including FACW+, FACW-, FAC+, and FAC-) then hydrophytic vegetation is present.

2) Hydric Soil

Soil color is the most diagnostic indicator of hydric soils in wetlands (Federal Interagency Committee for Wetland Delineation -FICWD 1989). Chroma 2 or less is an indicator for hydric soils (FICWD 1989). Black, various shades of gray, and the darker shades of brown and red are low chroma colors (FICWD 1989). The soil color observed at plot 1 was chroma 2 (gley 2). This equals the value needed for classification as a hydric soil. The soil type at plots 2 and 3 was chroma 3. All three plots were of the Belknap soil type. This soil is subject to frequent flooding from January to June with a high water table that is 30.5-61.0cm deep.

Orange or reddish brown colors along living root channels are the result of soil saturation for a long period during the growing season (FICWD 1989). We visually found conspicuous rust colored areas along root channel (oxidized root channels) in the soil sample taken from 20 cm below the surface. Root plaques and oxidized root channels indicate that anaerobic conditions were present during the growing season by virtue of their association with living roots. Therefore, the presence of root plaques and oxidized root channels is a good indicator of wetland hydrologic conditions (Mendelssohn 1995). Oxidized root channels were observed at plots 1 and 3, indicating wetland hydrologic conditions.

3) Wetland Hydrology

The water table was not observed to be within 0.5 feet of the surface as required by the Federal Manual. The soil may be inundated by water at our sampling point earlier in the year. According to Gibson et al (1999) the study site is subject to seasonal flooding.

The presence of rust-colored areas along root channels (redox conditions) would indicate that anaerobic conditions (flooded) were present during the growing season.

The 3 criteria as outlined by the Federal Manual were met. In conclusion the Chautauqua Road Site was determined to be a wetland, but the outer boundaries were not determined. Further studies at the Chautauqua Road Site should try to determine the outer boundaries of this wetland. A plot should be set up south of Plot 1 to try to delineate the outer boundary of this wetland site.

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