Most cities are dominated by asphalt and concrete, which blocks the natural movement of rain water. Wetlands, riparian buffers, and roadsides are being lost or degraded in urban areas due to human development. Cities can be designed to benefit humans and nature by using techniques from green infrastructure and restoration ecology to improve urban sustainability. Parking lot M on McMaster University's west campus, constructed in 1968 on a former floodplain, directs the highly saline parking lot runoff into the adjacent Ancaster Creek. Natural groundwater sources along the surrounding hillslopes are directed into pipes under the parking lot and into the creek. A one-hectare riparian buffer restoration at lot M was used to assess the viability of depaving asphalt and establishing native plants through a vegetation study. Total native plant biomass was found to be similar to non-native plant biomass and was affected by road-salt salinity from the parking lot. Species richness per quadrat was higher for non-native plants, and greater for both non-native and native plants where less salt was present. Key hydrological fluxes were examined at the parking lot that could contribute to a proposed 0.6 hectare constructed wetland on the parking lot, known as “McMarsh.” Potential wetland water storage is in surplus year round, with an average storage of 265 mm/month. Successful restorations require maintenance following the establishment of native species. Management and maintenance of the restoration can help decrease non-native species. Engaging with the community through outreach and education on restoration projects is important for a successful restoration and increasing urban sustainability in cities. / Thesis / Master of Science (MSc) / Most cities are dominated by asphalt and concrete, which blocks the natural movement of rain water. Wetlands, riparian buffers, and roadsides are being lost or degraded in urban areas due to human development. Cities can be designed to benefit humans and nature by using techniques from green infrastructure and restoration ecology to improve urban sustainability. Parking lot M on McMaster University's west campus, constructed in 1968 on a former floodplain, directs the highly saline parking lot runoff into the adjacent Ancaster Creek. Natural groundwater sources along the surrounding hillslopes are directed into pipes under the parking lot and into the creek. A one-hectare riparian buffer restoration at lot M was used to assess the viability of depaving asphalt and establishing native plants through a vegetation study. Total native plant biomass was found to be similar to non-native plant biomass and was affected by road-salt salinity from the parking lot. Species richness per quadrat was higher for non-native plants, and greater for both non-native and native plants where less salt was present. Key hydrological fluxes were examined at the parking lot that could contribute to a proposed 0.6 hectare constructed wetland on the parking lot, known as “McMarsh.” Potential wetland water storage is in surplus year round, with an average storage of 265 mm/month. Successful restorations require maintenance following the establishment of native species. Management and maintenance of the restoration can help decrease non-native species. Engaging with the community through outreach and education on restoration projects is important for a successful restoration and increasing urban sustainability in cities.

Why evaluations of the ecological outcomes of stream and river restoration have largely reported inconclusive or negative results has been the subject of much debate over the last decade or more. Understanding the reasons behind the lack of positive results is important for bettering future restoration efforts and setting realistic expectations for restoration outcomes. This thesis explores possible explanations for why researchers have failed to find clear and predictable biotic responses to stream restoration: recovery time has been too short, that restoration of habitat complexity is not clearly linked to instream biodiversity, that one monitored organism group is not representative of the entire community, that restoration effort was not intense enough to restore the potential habitat complexity of a system, and that reach-scale restoration done in the presence of catchment-scale degradation obscures restoration results. The overarching goal of this thesis is to study the holistic effect of reach-scale restoration of historic reach-scale simplification, due to timber floating in northern Swedish streams, thus avoiding the added pressure of catchment-scale degradation typically found at most restoration sites (e.g., non-point-source pollution and impervious cover). Using this model system, I was able to show that it took 25 years for riparian plant species richness at restored sites to increase above that of channelized sites. Furthermore, it was clear that restoration of these streams caused a large and rapid change in N-processing in the riparian zone and this alteration persists for at least 25 years. Additionally, multiple metrics of geomorphic complexity were needed to explain some of the more subtle responses of organism groups. Macroinvertebrates, diatoms, and macrophytes did not respond concordantly and cannot serve as surrogates or indicators for each other. I found that older best practice methods of restoration rarely restored the large-scale features needed to bring the sites up to their potential complexity because these elements were destroyed or removed from the system. Advanced restoration techniques used in more recent restorations added big boulders and instream wood and increased complexity to a level that elicited a biological response. By combining surveys of multiple metrics of structure, diversity of multiple organism groups, and process in this thesis I was able to get a holistic view of the effects of restoration of streams after timber floating. We now know that it takes at least 25 years for riparian plants and N-cycling to recover, we understand that multiple metrics of geomorphic complexity should be measured to be able to explain biotic responses, and that restored complexity should better match the potential complexity of the site in order to elicit a biological response. Finally, we know that multiple organism groups need to be assessed when evaluating the response of biodiversity to restoration.

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Riparian buffers are promoted for water quality improvement, habitat restoration, and stream bank stabilization. While considerable research has been conducted on the effects of riparian buffers on water quality and aquatic habitat, little is known about the influence of riparian vegetation on stream bank erosion. The overall goal of this research was to evaluate the effects of woody and herbaceous riparian buffers on stream bank erosion. This goal was addressed by measuring the erodibility and critical shear stress of rooted bank soils in situ using a submerged jet test device. Additionally, several soil, vegetation, and stream chemistry factors that could potentially impact the fluvial entrainment of soils were measured. A total of 25 field sites in the Blacksburg, Virginia area were tested. Each field site consisted of a 2nd-4th order stream with a relatively homogeneous vegetated riparian buffer over a 30 m reach. Riparian vegetation ranged from short turfgrass to mature riparian forest. Multiple linear regression analysis was conducted to determine those factors that most influence stream bank erodibility and the relative impact of riparian vegetation. Results of this research indicated woody riparian vegetation reduced the susceptibility of stream bank soils to erosion by fluvial entrainment. Riparian forests had a greater density of larger diameter roots, particularly at the bank toe where the hydraulic stresses are the greatest. These larger roots (diameters > 0.5 mm) provided more resistance to erosion than the very fine roots of herbaceous plants. Due to limitations in the root sampling methodology, these results are primarily applicable to steep banks with little herbaceous vegetation on the bank face, such as those found on the outside of meander bends. In addition to reinforcing the stream banks, riparian vegetation also affected soil moisture and altered the local microclimate. While summer soil desiccation was reduced under deciduous riparian forests, as compared to herbaceous vegetation, winter freeze-thaw cycling was greater. As a result, in silty soils that were susceptible to freeze-thaw cycling, the beneficial effects of root reinforcement by woody vegetation were offset by increased freeze-thaw cycling. Using the study results in an example application, it was shown that converting a predominately herbaceous riparian buffer to a forested buffer could reduce soil erodibility by as much as 39% in soils with low silt contents. Conversely, for a stream composed primarily of silt soils that are prone to freeze-thaw cycling, afforestation could lead to localized increases in soil erodibility of as much as 38%. It should be emphasized that the riparian forests in this study were deciduous; similar results would not be expected under coniferous forests that maintain a dense canopy throughout the year. Additionally, because dense herbaceous vegetation would likely not develop in the outside of meander bends where hydraulic shear stresses are greatest, the reductions in soil erodibility afforded by the herbaceous vegetation would be limited to areas of low shear stress, such as on gently sloping banks along the inside of meander bends. As the first testing of this type, this study provided quantitative information on the effects of vegetation on subaerial processes and stream bank erosion. It also represents the first measurements of the soil erosion parameters, soil erodibility and critical shear stress, for vegetated stream banks. These parameters are crucial for modeling the effects of riparian vegetation for stream restoration design and for water quality simulation modeling. / Ph. D.

Water quality in streams around the world continues to be degraded by a series of human activities that feed pollutants into the vulnerable stream ecosystem via surface and subsurface runoff. This continues to accelerate global biodiversity and habitat losses within the stream environments and across entire watersheds with net adverse effects on public health and the ability of communities and ecosystems to adapt or become resilient to the prevalent impacts of climate change. One commonly used approach for protecting stream water from pollution is the use of vegetated riparian buffer zones to mitigate pollutants in surface and subsurface runoff prior to runoff entry into the stream channel. The optimal success of this approach requires land and water resource managers to understand the mechanisms by which riparian buffer zones function and the full range of factors that influence the effectiveness of riparian buffer vegetation in abating stream water pollution. Despite this need, resource managers in different geographical locations around the world still struggle to understand the linkages between riparian vegetation and stream chemical quality. This literature review therefore sought to synthesize findings from various scientific articles on the ways in which the major attributes of riparian vegetation [type, age, width, restoration and shading effect] influence the effectiveness of riparian vegetation in protecting the chemical quality of water in streams. This was aimed at generating conclusions and perspectives that could improve academic knowledge and natural resource managers’ understanding of the intricate linkage between riparian vegetation and changes in water chemistry. The study finds that the factors of riparian vegetation type, age, width, restoration and shading effects require due consideration in the development of riparian buffer zone and stream water chemical quality management interventions. I find that these factors require a high degree of integration, triangulation and context-specificity to achieve the objectives of riparian management intervention. I further find that stream water quality decision-making processes need to combine riparian vegetation-based approaches with other measures for mitigating and containing the spillage of pollutants at the source. / <p>Presentation was conducted via Skype</p>

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