In recent years, the success of wetland mitigation projects and their ability to function as natural systems has been questioned. This study was conducted (i) to characterize and examine differences between mitigation and natural wetlands, (ii) to examine differences in soil morphology along a wetness gradient in mitigation and natural wetlands, and (iii) to observe changes in mitigation wetlands with time. Site characteristics, including soil properties, hydrology, and vegetation, were analyzed for three mitigation-reference wetland pairs located in the Virginia Coastal Plain. Hydrologic regimes of mitigation areas, when compared to reference areas, generally showed larger differentials between seasonal high and low watertables. Mitigation areas, dominated by herbaceous vegetation, tended to be lower in C and N levels and higher in soil pH, and much higher in bulk density than the mature forested reference wetland. Initially low levels of C and N did not increase significantly over the five-year study period. Soils in the mitigation area were more uniform and considerably less differentiated when compared to those of the reference area. Testing for Fe(II) with alpha-alpha, dipyridyl dye solution produced mixed results, obtaining both positive and negative reactions to saturated samples. Oxidized rhizospheres, associated with active root channels in surface horizons, formed in less than ten years under the current hydrologic conditions. These features were more abundant and more prominent in areas saturated at or above the surface for longer periods of time. Overall, site differences between mitigation and reference areas are mainly due to construction practices and a lack of organic matter accumulation. Better design methods should incorporate the addition of organic amendments, with attempts to minimize soil compaction. / Master of Science

Thesis (M.E.S.)--The Evergreen State College, 2006. / Title from title screen (viewed 3/11/2010). Includes bibliographical references (leaves 41-53).

Thesis (M.S.)--University of West Florida, 2007. / Title from title page of source document. Document formatted into pages; contains 114 pages. Includes bibliographical references.

Thesis (M.A.)--Ohio University, November, 2009. / Release of full electronic text on OhioLINK has been delayed until September 1, 2014. Title from PDF t.p. Includes bibliographical references.

Thesis (Ph. D.)--Florida State University, 2007. / Advisor: Keith Ihlanfeldt, Florida State University, College of Social Sciences, Dept. of Economics. Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 2, 2008) Includes bibliographical references.

Theses (M.S.)--Marshall University, 2004. / Title from document title page. Includes abstract. Includes vita. Document formatted into pages: contains ix, 146 pages. Bibliography: p. 118-121.

Past research indicates that created non-tidal wetlands in the mid-Atlantic region are considerably lower in soil organic matter than native forested hydric soils. However, optimal loading rates for created wetland soil reconstruction have not been rigorously established. Our objective was to determine appropriate organic amendment loading rates for a Coastal Plain mitigation wetland based on 1) soil properties reflective of hydric soil development, 2) the formation of redoximorphic features, and 3) the growth and vigor of hydrophytic vegetation. The study contained wet (CCW-Wet) and dry (CCW-Dry) experiments, each receiving 6 compost treatments (0 Mg/ha untilled and 0, 56, 112, 224, and 336 Mg/ha tilled). Over the 1.5-year monitoring period, redox potential decreased and redoximorphic feature formation increased with compost loadings up to 112 Mg/ha. Surface bulk density decreased with loadings up to 224 Mg/ha, while no treatment differences were noted in sub-surface bulk density. In the CCW-Dry experiment, soil moisture peaked in the 224 Mg/ha treatment, while soil moisture in CCW-Wet increased consistently across all loadings. Total biomass in CCW-Wet and Betula nigra L. growth in both experiments increased with loading rate. Total biomass in CCW-Dry and Quercus palustris Muench. growth in both experiments peaked at 112 Mg/ha, although differences were not significant. Collectively, these findings indicate that 112 Mg/ha of high quality organic amendment was optimal for inducing hydric soil conditions and positive hydrophytic vegetation response. Incorporating compost at rates exceeding 112 Mg/ha is challenging and leads to higher surface elevations and redox levels in the initial growing season. / Master of Science

Litter decomposition is a poorly understood function of constructed and natural forested wetlands. This study compared rates of litter mass loss, changes in litter morphology, and associated macroinvertebrate populations in constructed and natural non-tidal wetlands. Two sets of wetlands (constructed vs. natural) were studied in eastern Virginia; a 9 year-old riparian set near Fort Lee, (FL), and a 2 year-old wet flat set in Charles City County, (CC). Mixed deciduous forest litter collected from the FL natural wetland decayed more rapidly in the created wetlands than the adjacent forested wetlands. Mixed emergent marsh litter collected from the FL created wetland exhibited a similar relationship, although marsh litter decomposed slower than forest litter. Litter area and weight loss followed a similar pattern, although area loss lagged behind weight loss, consistent with an initial leaching phase of decomposition. Both the FL and CC created wetlands exhibited faster litter decomposition than their adjacent forested wetland, however, the FL created wetland had a lower weight:area ratio and higher detritivore abundance than the adjacent forested wetland, while the reverse was true for the CC wetland pair. These relationships suggest macroinvertebrates played an important role in decomposition in the FL created wetland, while other factors were more significant at CC. Faster decomposition in the created wetlands may be of concern for long-term soil organic matter accumulation, or conversely, may indicate quick recovery of the litter decomposition function. Overall, these findings point out the difficulties involved in using certain functional indicators to compare very young and mature systems. / Master of Science

A predicted loss of agricultural rice-wetlands and increasing urbanization and development threatens the remaining freshwater wetlands along the upper Texas coast. To avoid, minimize, and mitigate wetland loss, the U.S. Army Corps of Engineers (Corps) is directed to enforce Section 404 of the Clean Water Act (1975 amendment) by administering permits for development. Furthermore, a 1990 Memorandum of Agreement (MOA) between the Corps and the U.S. Environmental Protection Agency (EPA) proposed a national goal of no net wetland loss (NNL). My goals were to identify the frequency of occurrence of freshwater wetland loss due to dredge or fill, assess final plans to mitigate wetland loss, and verify the persistence of the created compensatory wetlands. I created a database of 96 individual, Section 404 permits issued from 1981 to 2001 in the counties of Chambers, Hardin, Jefferson, Liberty, Montgomery, Orange, and San Jacinto (Galveston District Office, U.S. Army Corps of Engineers). Descriptive statistics were calculated for permit characteristics in relation to issue date (pre- or post-NNL). Public comments received from national and state agencies were rank ordered against mitigation plan type to determine Spearman's Rank Order Correlation Coefficient. Visual identification (via site visits and 1996 aerial photos) was used to validate compensatory wetland persistence. Shoreline protection of private property and oil and gas drilling (64% of permit applicants and 59% of impacts) had the greatest effect on wetland loss in the region, particularly Chambers, Jefferson, and Montgomery counties. Overall, 79.3 ha of freshwater wetlands were gained; however, gain was overestimated due to large projects for habitat enhancement. Permits issued post-NNL were more likely to have formal mitigation plans (58% vs. 13% pre-NNL) and allowed no net wetland loss. Although agency comments recommending more formal mitigation plans increased after NNL, only a weak positive correlation was detected (Spearman's r less than or equal to 0.4). Six of seven created wetlands remained in existence through 2006 though they are freshwater ponds replacing more diverse aquatic systems. I recommend the development of a comprehensive method to track wetland loss, mitigation, and changes in watersheds over time.