Understanding the first order controls over resource cycling and limitation in ecosystems is critical for predicting ecosystem response to disturbances. Topography and vegetation self-organizing mechanisms are first order controls over resource fluxes across the landscape. Topography controls downslope flow of resources (i.e water and nutrients). Through spatial feedbacks, vegetation is able to actively modify its environment and maximize resource flows towards it. To date, the impacts of these controls on ecosystem dynamics have mostly been investigated separately. As such, there is a knowledge gap in the understanding of how these first order controls together dictate the dynamics of the ecosystem. This dissertation aims to gain a better understanding of how self-organizing mechanisms and topography operate together to affect wetland ecosystem dynamics. A spatially explicit, wetland vegetation patterning model that includes for both vegetation self-organizing control and topographic control is developed (Nutrient Depletion Model, NDM). The model describes a scale dependent feedback between vegetation, transpiration and nutrient accumulation that drives the formation of vegetation patterns. The model is applied to investigate the effects of topography and self-organizing mechanisms on form and orientation of vegetation patterns and vegetation growth dynamics of wetland ecosystems. Results show that the two first order controls synergistically impact the formation of the various patterns as observed in wetland ecosystems. Results also show the following: (1) Self-organizing mechanisms result in a more efficient retention of resources, which result in higher biomass in the model that include for both self-organizing mechanism and topographic control (SO+TC) than in the model that that includes only for topographic control (TC). (2) However, when resources or topographic gradients increase or annual rainfall decrease, the vegetation growth dynamics of the TC+SO and TC models converge. The NDM is applied to arctic Alaska to investigate how do the two first order controls impact present and future C-N dynamics of an arctic ecosystem. Simulation results show no significant difference in the dynamics between the SO+TC model and the TC model. The climate change simulation results suggest that changes in daily variability of temperature and precipitation can impact ecosystem dynamics as much as the changes in mean temperature and precipitation. Results from this dissertation provide a more complete picture on the relative roles of the two first order controls over ecosystem nutrient cycling and vegetative growth dynamics. Finally, in this thesis, in order to simulate small-scale feedbacks over large spatial domains, the NDM is implemented in a GPU computing language, which accelerates computational simulation by at least two orders of magnitude. These tools for grid-based simulations can provide a platform for using GPUs in other areas of scientific investigation.

Human actions have led to the destruction or degradation of natural habitats in virtually all parts of the Earth. Ecosystem restoration is one method to mitigate the effects of habitat loss. But restoration ecology is a young discipline and there is much left to be learned about how to effectively restore ecosystem functioning. This dissertation examines how soil amendments and planted herbaceous species diversity affect the restoration of ecosystem functions in wetlands, while also testing basic ecological questions that help us understand ecosystem function. Using data from the greenhouse and from the biodiversity and ecosystem function field experiment in Duke Forest, in Durham, NC, I examine how plant trait diversity, average plant traits, and environmental conditions influence nitrogen (N) removal from restored wetlands. Field data collected from a restored wetland in Charlotte, NC, enables me to examine how soil organic amendments influence the development of soil properties, processes, and plant communities. Finally, combining field data from both sites, I compare how soil properties influence denitrification potential in both restored wetlands. One unanswered question in the research relating biodiversity and ecosystem function is whether species diversity or species traits are more important drivers of ecosystem function. The first portion of my dissertation poses several hypotheses about how plant traits, plant trait diversity (calculated as a multivariate measure of plant trait diversity), and environmental conditions are likely to influence two ecosystem functions, biomass N and denitrification potential (DEA), and then examines these hypotheses in a restored wetland in the Piedmont of N.C. Using multiple linear regression, I demonstrate that functional diversity (FD), of traits important for plant growth had no effect on biomass N, but two plant traits, leaf area distribution ratio (LADR) and water use efficiency (WUE), had strong negative effects. Soil inorganic N also had a positive effect. For DEA, FD of traits related to denitrification also did not have a significant effect, but there was evidence of a weak positive effect. Two plant traits had positive effects on DEA, aboveground biomass and aboveground biomass C:N ratio; two traits, belowground biomass C:N ratio and root porosity, had negative effects. Soil inorganic N and soil organic matter also had positive effects on DEA. Results from a Principal Components Analysis (PCA) clustering plant species in trait-space, suggest that <em>Carex</em>, <em>Scirpus</em>, and <em>Juncus</em> species tend to be associated with traits that maximize biomass N, while there is no specific region of trait space or set of species that correspond to high DEA. Instead, there are multiple plant trait combinations that can lead to high DEA. These results suggest that, even though plant diversity (as measured by FD) does not significantly influence biomass N or denitrification, plant trait diversity is important to maintaining multiple ecosystem functions simultaneously. Restored wetlands tend to have lower levels of soil organic matter than natural reference wetlands. Low soil organic matter can limit nutrient cycling as well as plant survival and growth in restored wetlands. In the second portion of my dissertation, I examine how soil compost amendments influence the development of soil properties and processes as well as plant communities at a restored wetland in Charlotte, NC. Using two-way analyses of variance, multiple comparisons of means, and regression, I determine that available N and phosphorus (P) increase with increasing soil organic matter in both the low and high marsh. Total microbial biomass (MB) and microbial activity (measured by denitrification potential (DEA)) also significantly increase with increasing organic matter in both marsh communities, as does soil moisture. Neither total plant biomass (in the low marsh), nor plant species richness (in the high or low marsh) demonstrate any consistent patterns with soil organic matter level in the first three years post-restoration. These results suggest that compost amendments can positively influence some soil properties (i.e. soil available N, P, microbial biomass, and soil moisture) and some ecosystem functions including nutrient cycling (such as denitrification potential), but may have limited early impacts on plant communities. In restoration ecology there is a general assumption that restoring ecosystem structure will also restore ecosystem function. To test this fundamental assumption, I examine whether two restored wetlands demonstrate similar general relationships between soils variables (i.e. do the two systems have similar soil ecosystem structure), and whether the importance of each soil relationship is the same at both systems (i.e. do the two systems demonstrate the same soil function). I use structural equation modeling to both pose hypotheses about how systems function and to test them using field data. I determine that the same model structure of soil relationships is supported by data from these two distinct, yet typical urban restored wetland ecosystems (that is, the two systems have similar soil structure). At both systems higher soil organic matter is the most important predictor of higher DEA; however, most of the other relationships between soils variables are different at each system (that is, the two systems are not functioning in the same way). These results suggest that some fundamental relationships between soil properties and microbial functioning persist even when restored wetlands have very different land-use histories, plant communities, and soil conditions. However, restoring similar soil ecosystem structure does not necessarily lead to the restoration of similar soil function. Ultimately, I hope this research advances our understanding of how ecosystems function and improves future wetland restoration efforts. / Dissertation

The issues of wetland protection has been looked at attentively in Taiwan. However, the action of protecting wetlands can not replace the wetlands lost in speedy developments, which causes the wetland ecosystem in natural environment of Taiwan vanished stage by stage. The idea of ¡§created wetland¡¨ refers to the conversion of a persistent upland or shallow-water area into a wetland by human activity to help to compensate the natural wetlands lost due to destruction by human beings. Such kind of wetland is used to restore wetlands or to let it become a parkland. Created wetlands are different from ¡§constructed wetland¡¨ emphasize the function of wastewater treatment. In the past, park in urban area was usually designed for human use which caused other organisms can not abundantly, and thus the ecosystem in municipal areas became poor. Hence, there is a new concept that we combine the created wetland and park together in order to improve the biodiversity of the ecosystem in urban area. The Zhou-zai wetland park is located beside the Lotus pond in Zuo-ying of Kaohsiung City. This created wetland was initially wanted to attract Pheasant-tailed Jacana come Kaohsiung through the ecosystem. The park was not only designed for human activities but also for other creatures. We tried to use ¡§ecological engineering methods¡¨ to build this artificial habitat. We hope it can promote the biodiversity in urban city by this wetland ecosystem. In this study, we use Zhou-zai wetland park as a case study, and probed into the principles of planning and management in urban created wetland park. It was hoped that the result of this research can provide some consults about constructing created wetland parks in the feature in Taiwan, so that the strategies of wetland protection can then become positive.

Wetland-based treatment systems are often implemented as a method to remove unwanted substances from contaminated groundwater. Wetlands are effective due to the high biological activity that naturally takes place in the rhizosphere and soil. In support of a demonstration surface wetland system at a site in Columbus, Georgia, laboratory-scale wetland systems were designed to study the effect of different carbon sources and their biodegradability, COD:N ratio and temperature on the rate and extent of nitrate reduction of nitrate-bearing groundwater. Nitrate reducing bacteria are ubiquitous in surface and subsurface wetlands but a major limiting factor for these systems is carbon availability. Two major carbon sources were investigated in both continuous-flow and batch systems: a natural source, hay and a commercial source, MicroC GTM, a concentrated carbohydrate mix. Between these two carbon sources, the nitrate removal rate was not significantly different as long as sufficient biodegradable carbon was provided. The effect of both hydraulic retention time (HRT) and COD:N ratio on nitrate removal were investigated in continuous-flow systems. The specific nitrate removal rate in open to the atmosphere batch reactors was estimated at 0.55 mg N/mg biomass VSS-day. The effluent nitrate concentration in a continuous-flow system maintained with an HRT of 5 days at room temperature (22 to 23°C) was less than 3 mg nitrate-N/L. The COD:N ratio was kept at 6:1 for the majority of the experiments (approximately twice the theoretical requirement) to ensure sufficient carbon loading. Lower COD:N ratios of 5, 4, 3, 2, 1, and 0.5 were also investigated in the continuous-flow system and the minimum required carbon loading to achieve an effluent nitrate concentration below 10 mg N/L for an influent groundwater nitrate concentration between 65 and 70 mg N/L was determined to be 5:1 COD:N. The effect of temperature on the nitrate removal rate was also investigated at 22, 15, 10 and 5°C. As expected, the rate of nitrate reduction decreased with the decrease in temperature, especially below 10°C. Overall, the surface wetland is a feasible solution to treating nitrate-bearing groundwater even at relatively low ambient temperature values, provided that sufficient, biodegradable carbon is present.

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There is a growing interest to restore Bay of Fundy salt marshes diked for agriculture. Marshes recovering for several decades from storm-breached dikes can serve as analogues for restored marshes. In this study I examine factors driving sub-surface hydrology and vegetation at recovering and reference Bay of Fundy salt marshes. In Fundy marshes, groundwater at channel edges is insensitive to tidal flooding (&lt;10 cm change in depth) and deep draw-downs (40-100 cm) occur. Sub-surface hydrology here differs from organogenic, microtidal marshes due to low saturated hydraulic conductivity, infrequent flooding of marsh interiors, and larger hydraulic gradients imposed at channel edges. By calculating marsh elevation at dike-breach and considering Spartina alterniflora's vertical range, it is apparent that salt marsh vegetation could establish when dikes breached. Multivariate analysis indicates that reference and restored/recovering sites should have similar sizes and tidal ranges. These criteria introduce problems as Fundy dikelands are more extensive than marshes not targeted for agriculture and tidal range increases exponentially up-Bay.

The wetlands on the Eastern Shores of Lake St Lucia are primarily groundwater fed and exhibit a variety of hydrological regimes that give rise to a high degree of habitat and species diversity. Hydrologically unstable systems experience ecophasal shifts that can disrupt an established steady state within the wetland ecosystem. Communities of both plants and animals can accordingly disintegrate into more or less isolated populations, open to re-invasion by preceding or "new" species when conditions change again. Given the ephemeral and episodic nature of much of the surface water on the Eastern Shores, ecological dynamics of this type are likely. Fish and aquatic invertebrates were sampled from a number of routine and other sites between May 2002 and April 2003. Measurements of various environmental and abiotic factors (including pH, ionic conductivity and dissolved oxygen levels) were taken with each sample in order to establish relationships between environmental changes and the assemblages of aquatic fauna occurring within the Eastern Shores wetlands. Conditions on the Eastern Shores during the study were somewhat anomalous, as the region experienced drought conditions during this period. The Eastern Shores wetlands support a diversity of aquatic fauna, including at least four species of freshwater fish listed as rare or threatened by the IUCN. The aquatic organisms existing within this dynamic system exhibited changes in abundance and distribution that reflected the spatial and temporal changes in their environment. The relationships between aquatic organisms and their environment were complex, with assemblages being affected by combinations of changing environmental and habitat variables as well as other factors such as the environmental stability of habitats and stochastic effects. Given the complex nature of these interactions, aquatic macrofauna on the Eastern Shores are likely to be best conserved through the preservation a heterogeneous mix of wetland habitats, maintaining the diversity of wetland structure and function on the Eastern Shores that can facilitate an element of lottery in the development and structure in biotic assemblages. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

The purpose of this research document is to inform the author about the manners in which built form can be reconfigured within landscapes. As such the focus is twofold: Firstly, the concept of landscape must be explored and defined and secondly, theoretical approaches to the reconfiguration of built form within the landscape must be determined. Through research it is found that landscape is not, as is popular belief, merely a natural phenomenon, but consists of a visual and imagined component. The visual component in turn, consists of the natural and the cultural landscape. An argument is made that the predominate contemporary paradigm should determine the manner in which the built form is designed. As such, the theme of complement (between built form and landscape) is derived as an interpretation of the current global awareness of environmental issues. The imagined landscape is found to relate to the cultural landscape in the sense of both being influenced by it and influencing it. From the contemporary, global mindset of environmental sensitivity, the concept of complement is derived. Complement refers to the idea of mutual symbiosis of two parties, i.e. both parties benefit from their relation. As such, the theory of synchronized geometry and progressive tradition is investigated in terms of the natural and cultural landscape respectively. The intention and potential application of the theories is tested by discussion in relation to certain precedents and cases of built form (such as the Mapungubwe Interpretation Centre) and landscape (the landscape of iSimangaliso Wetland Park). / Thesis (M.Arch.)-University of KwaZulu-Natal, Durban, 2012.

The degradation of wetlands and loss of their associated ecosystem services is widely recognised in South Africa, however, at present there is no standard method of biologically assessing wetland health in this country. Internationally, particularly in the U.S.A and Australia, wetland bioassessment techniques using macroinvertebrates are well established. A number of these wetland bioassessment protocols have been derived from local river biomonitoring techniques, as there is a belief that river and wetland ecology and macroinvertebrate assemblages at family level are similar. However, some authors consider wetland macroinvertebrate assemblages and ecological processes to differ greatly from those found in rivers, and believe that such techniques are not transferable. South Africa has a well established macroinvertebrate biomonitoring protocol for rivers called SASS5 (South African Scoring System Version 5). This study is a preliminary investigation into the extent to which the SASS5 scoring system is applicable to the assessment of nutrient enriched wetland water quality. Macroinvertebrates are particularly suitable as biomonitoring tools: they respond to a variety of stressors, have life cycles that allow for integrated responses to episodic pollution, and are relatively easy to identify to family level. When selecting wetlands for the development of a biomonitoring protocol, wetlands should all be of the same; classification (Le. palustrine), geomorphological and climate setting, hydrological regime and dominant vegetation class. Sampling was restricted to sedge-dominated palustrine wetlands in the midlands of KwaZulu-Natal, with similar hydro-geomorphological settings. Due to wetlands and rivers having different biotopes (e.g. no riffles present in wetlands), the SASS5 sampling protocol could not be used, thus a pilot investigation was undertaken to derive a suitable sampling technique for \ collecting a representative and diagnostic sample of aquatic macroinvertebrates from a wetland. This technique was developed based on published methods. Both sweep net and activity trap sampling were conducted, and each evaluated for their effectiveness at macroinvertebrate collection. Sweep net sampling was tested over a range of sweep intensities (2-6 sweeps), and activity traps were placed at four different depths: at the water surface, just below the surface, 0.10.15m below surface and on the substrate. A total of 32 taxa identified to family level were identified in the samples. Taxon diversity and composition did not differ in the activity traps placed at the four depth locations. Taxon diversity did not differ significantly between different sweep intensities; however there was a significant difference in taxon composition between the different sweep intensities and between activity trap and sweep net samples (p<0.05). Sixty-eight percent of taxa appeared more frequently in sweep net sampling compared to activity trap sampling. Six taxa were found exclusively in sweep net samples, and two taxa were recorded exclusively in activity traps. There was no trend in either method collecting more or missing any unique trophic group. In conclusion, activity traps are not required to supplement sweep net data, and a technique using a sweep net with a sweep intensity of five would be suitable to collect a representative sample of wetland macroinvertebrates. Using the derived technique, four reference and three wetlands impacted by dairy effluent were sampled. Six macroinvertebrate samples were collected from each of the seven wetland, together with data for selected physico-chemical variables, macrohabitat condition, biotope suitability and organism detectability. For each sample, the macroinvertebrates were identified and assigned a predetermined SASS5 tolerance score between 1 and 15, with higher scores indicating increased sensitivity to poor water quality. 11 A total of 39 taxa, identified to family level, were collected during sampling. SASS5 scores ranged from 15-82. Five of the wetlands had mean SASS5 scores of between 46 and 59. Five of the wetlands had an intra-wetland SASS5 score range greater than 30. ASPT values ranged from 3.3 to 5.5, and few high scoring (~8) taxa were collected. There was no significant difference in SASS5 scores between samples collected above, at and downstream of an effluent discharge point within the same impacted wetland. SASS5 scores for reference wetlands were also not significantly higher than those recorded for impacted wetlands. Comparison of ranked SASS5 scores and environmental data did suggest a relationship between the variables, but was not significant. Based on the SASS5 score water quality guidelines, all sampled wetlands were considered to have impacted water quality; however, this was not supported by the macrohabitat and physico-chemical results. Possible reasons for the low SASS5 scores include: the lack of 'stones in/out current' biotopes in wetlands, lower levels of dissolved oxygen present compared to rivers, and the limited detectability of organisms due to large amounts of substrate in the samples. A wetland adaptation of SASS5 would require the reassignment of modified scores to certain taxa based on their distribution in wetlands of varying water quality. The SASS5 score level of 100 and the ASPT value of 6 (as specified in the SASS5 score water quality guidelines) were found to be inappropriate for wetlands. It is suggested that, either the range of taxa tolerance scores be increased (1 to >15), or the score level of 100 be lowered. The ASPT value should also be reduced. Although SASS5 appears unsuitable for assessing wetlands, variations in taxon composition between sampled wetlands, identified through CA analysis, suggests that macroinvertebrates are responsive to changes in wetland condition, and thus have potential as indicators of wetland water quality. Nine taxa responsive to the presence of nitrogen have been identified as being potentially good indicators. iii Further research should focus on the testing of SASS5 throughout the year, in a range of wetland types, and in wetlands moderately to severely impacted by pollutants other than dairy effluent. It is recommended that a habitat or biotope index be developed and used in conjunction with any future wetland macroinvertebrate bioassessment protocols. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

This study examines the status and distribution of rail populations in northern Indiana. Because rails are secretive and difficult to study, there have been few attempts in Indiana to determine the impact of wetland loss on the populations of rails and other marsh-nesting birds. There can be little doubt, however, that the loss of Indiana wetlands during historic times has caused a dramatic decline in rail populations.Using tape-recorded calls to elicit vocalizations, the status and distribution of five species of rails were studied in a 25,900 km2 area in northern Indiana in 1993 and 1994. A total of 107 surveys were conducted at 46 natural wetlands and 42 restored wetlands. The species surveyed were Sora (Porzana carolina), Virginia Rail (Rallus limicola), King Rail (Rallus elegans), Yellow Rail (Coturnicops noveboracensis), and Black Rail (Laterallus jamaicensis). Playbacks were also used to detect American Bittern (Botaurus lentiginosus), Least Bittern (Ixobrychus exilis), Marsh Wren (Cistothorus palustris) and Sedge Wren (Cistothorus platensis). Data were also collected on all other species of marsh-nesting birds detected during this study.Rails exhibited a patchy distribution. A total of 25 Soras, 33 Virginia Rails, and 1 King Rail was detected in natural wetlands in 1993. In 1994, 75 Soras, 46 Virginia Rails, and 1 King Rail was detected in the natural wetlands. A total of 30 Soras and 9 Virginia Rails was found in the restored wetlands studied in 1993 and 1994. No Yellow or Black Rails were found. Ten Least Bitterns, 31 Marsh Wrens, and 6 Sedge Wrens were detected in natural wetlands, but these species were not observed in restored wetlands.The occurrence of rails in natural wetlands was positively correlated with wetland size, presence of shrub vegetation in the watershed, amount of emergent vegetation, proximity of other wetlands, and extent of cattail cover. Negative correlations were found for human disturbance, amount of open water, and watershed characteristics. The strongest negative correlationswere found for human disturbances in or around the wetland.In restored wetlands, a significant difference was found between the occurrence of Sora and Virginia Rails with Soras occurring more frequently than Virginia Rails. A near significant difference in rail occurrence between natural and restored wetlands was also found, with rails occurring more frequently in natural wetlands, suggesting that natural wetlands surveyed may be a more suitable habitat for rails than the restored wetlands surveyed.Restored wetlands surveyed in this study failed to attract American Bitterns, Least Bitterns, Marsh Wrens or Sedge Wrens. American Bitterns were reported in natural wetlands during this study, but they were not observed. / Department of Biology