Cumulative effects, often minor individually but collectively significant, are continually being grappled with by researchers, policy makers and practitioners. Despite this the Canadian approach to cumulative effects assessment is thought by many to be ineffective. In this thesis I investigate the literature that surrounds cumulative effects and uncovered three distinct themes that occur chronologically: genesis, project-based approach and integration. During the genesis phase cumulative effects nomenclature, ideas and frameworks was created. The main theme of this era was to asses these effects at a large scale and to have a strong understanding of a systems ecology prior to the assessment. This approach was found to be too complex and so a more narrow project-based approach was implemented and still remains today. This approach is heavily criticized and as such researchers are now trying to find an approach that integrates these two divergent themes into a regional level assessment. I have found there to be several frameworks but an absence of effective regional methodologies. There is a need for regional metrics if this approach is to ever be institutionally supported. Food web structure can be evaluated at multiple scales and has been shown to be responsive to environmental variation; thus, it has potential for application as a metric for cumulative effects. Here, using stable isotope analysis, I field test integrative measures of food web structure (food chain length, habitat coupling, trophic omnivory) at sites of varying degrees of anthropogenic stressors in Georgian Bay, Ontario to evaluate the use of food webs as a metric for cumulative effects assessment. I found that food web structure varied significantly among sites. Sites with high levels of stress displayed structural characteristics reflective of human activities such as shorter food chain lengths, increased trophic omnivory, and reduced habitat coupling relative to the non-stressed sites. These results indicate that food web structure as an ecosystem level metric may provide insight into anthropogenic activities, and may be applied routinely as a metric for doing Cumulative Effects Assessment. / University of Guelph, Saugeen Ojibway Nation, Georgian Bay Forever

The behavior of wood shear walls has been the focus of researchers and engineers for many years due to their availability in the North American construction landscape. A review of the established literature showed that most of the research have focused on the shear wall behavior as a whole with no investigation specifically targeting the individual components of its deflection. Also, little to no attention has been given to the investigation of the cumulative effects especially when the out-of-plane diaphragm stiffness is considered. The current study aims at investigating the effects of construction details variation on the behavior of the shear walls and evaluating whether the current deflection equation, as per wood design standard (CSA 2014) can adequately predict the overall wall stiffness. A total of 27 full-scale single-storey walls, with different construction details and aspect ratios, were tested under either static or monotonic (as both are the same) loading. The parameters that were varied in the testing were the stud size and spacing, nail diameter and spacing, sheathing panel type and thickness and hold-down anchoring system/type. For the two-storey walls, two different loading cases were considered, namely where the load was applied at the top or bottom storey only. The results showed that the strength and stiffness correlated almost directly to the inverse of the wall aspect ratio. There was no clear trend when considering the effect of the walls’ aspect ratios on ductility. Unexpectedly, walls with aspect ratios not permitted according to the wood design standard (4:1 and 6:1) followed similar strength and stiffness trends and had sufficient ductility ratios as those with smaller aspect ratios. This observation explains in part some of the discrepancies found between engineering calculations and behavior of actual building with light frame wood shear walls. Significant discrepancies were found when comparing the various deflection constituent with those estimated using the design expression. Adding more end studs and changing the size of the studs had no significant effect on the overall wall capacity and little effect on its stiffness. Reducing the stud spacing had, as expected, no effect on the wall capacity; however, the results showed that the bending stiffness was affected by the overall number of studs in the wall and not solely by the end studs. Shear walls sheathed with plywood panels exhibits slightly higher peak load and initial stiffness than those with OSB, which was mainly attributed to the greater panel thickness, and possibly density, of the plywood. Both sheathing types provided similar levels of ductility, as expected. Thicker sheathing increased the capacity and stiffness of the wall with no significant change observed in ductility ratio. The wall strength was significantly affected by the nail diameter and nail spacing, but no difference was observed when the nail edge/end distance was increased. The results also showed that discrete hold-down system behaved in a non-linear manner with a significantly greater initial stiffness than that assumed in design. The study also showed that having continuous hold-down connections has a positive effect on the capacity, stiffness and ductility of the wall when compared with discrete hold-downs. Having no hold-down adversely affects the wall capacity and stiffness, but did not affect the ductility of the wall. For the two-storey walls, the deflection estimated based on the cumulative effect assumption showed slight differences when compared with that observed in the experimental study. It was observed that the majority of the cumulative effect stems from the rigid body rotation due to deformation in the hold-down devices. A Computer shear wall model (through SAP2000) was developed using linear “frame” and “membrane” elements for the framing and sheathing members, respectively, whereas the sheathing to framing nails and hold-down were modeled using nonlinear springs. It was found that the model was capable of predicting the peak load, ultimate deflection and yield loads with reasonable accuracy, but overestimated the initial stiffness and ductility of the walls. In general, when the force-displacement curves were compared it was evident that the model was capable of predicting the wall behaviour with reasonable accuracy. When investigating the cumulative effects using the model, the results clearly showed that the assumption of cumulative effects due to rigid body rotation is valid for stacked shearwalls with no consideration for the floor diaphragm. The effect of the diaphragm on the behavior of the shear walls, in particular its out-of-plane rigidity was simulated by modeling the floors as beam. The out of plane stiffness of the shear walls was investigated for idealized (infinitely stiff or flexible) as well as “realistic”. The results showed reductions in the shearwall deflection in the magnitude of approximately 80% considering the out of plane rigidity of the diaphragm. It was also concluded that considering conservative estimates of out of plane stiffness might lead to a very significant reduction in deflection and that assuming the floor diaphragm to be infinitely rigid out of plan seems reasonable. For diaphragms supported on multiple panels further reduction in the deflection was observed. More work, particularly at the experimental level, is needed to verify the finding obtained in the numerical investigation related to the effect of out of plane diaphragm stiffness.

The effects of small-scale shoreline residential development on littoral fish abundance and species richness was examined at three different scales of observation (within 122, 244, and 488 meters) in Lake Simcoe (Ontario, Canada). A mixed model regression was used to test for effects of development after accounting for seasonal and spatial variation in environmental variables known to affect distribution and abundance of fish. Fish were aggregated near single development structures, such as permanent docks, and repelled from other single structures, such as bank stabilisation. Shoreline developed with multiple features, such as docks combined with break walls, tended to be positively correlated with fish abundance but negatively correlated with species richness. Features such as docks and break walls combined with boathouses were generally associated with a decrease in both abundance and richness. Cluster analysis detected no consistent pattern of association between specific fish assemblages and residential development across the three scales of observation. Increased density and diversity of shoreline residential development tended to be associated with reduced fish abundance and species richness. The specific development features associated with these patterns change with the scale of observation, indicating that fish responded to proximally and distantly located habitat alterations.

This dissertation describes a proposed methodology for Cumulative Effects Assessment (CEA) with the purpose of improving the process by making it both more substantive and quantitative. The general principles of the approach include the following: use of effect-based analyses where selected Valued Component (VC) sensitivities are identified first and then effect pathways are determined building bottom-up linkages from VC sensitivities to potential stressors or combinations of stressors to effect drivers and forces behind the drivers. Models were developed based on statistical or historic trend analysis or literature review that predicted the responses of the VCs to changes in effect drivers. Further, scenarios of divergent futures were created that involved different developments of each effect driver or force, and finally the models were applied to each scenario to project the state of the studied VCs. A practical implementation was conducted to demonstrate the use of the proposed methods on future population trends of two anadromous salmon species from the Cowichan River, British Columbia, Chinook and Coho. The assessment was conducted for both early freshwater and marine phases of their life. For the freshwater phase, the assessment focused on two main factors affecting salmon survival, streamflow and stream temperature and established two main drivers affecting these stressors, land use and climate change, and two main forces behind these drivers, Local and Global human development driven change, respectively. Effects of stream temperature and streamflow on salmon freshwater survival were simulated using two models; one was based on Chinook freshwater survival correlations with stream temperature and was developed only for Chinook, and the other was based on literature-derived temperature and streamflow thresholds and was developed for both species. Connections between the stressors (stream temperature and streamflow) and drivers (land use and climate change) were established through a hydrologic model and stream temperature regression model. For the marine environment, models were created using Pearson correlation and stepwise regression analysis examining links between survival of Cowichan River Chinook and Strait of Georgia hatchery-raised and wild Coho and various environmental variables of the nearshore zone of Strait of Georgia and Juan de Fuca Strait. The models were applied to project future salmon survival under four future scenarios for 2050 that were created by combining two opposite scenarios of land use in the watershed, forest conservation and development, and two climate change scenarios, extreme and moderate. Scenario projections showed a decrease in overall (combined early freshwater marine) survival by 2050 for all three studied salmon populations. None of them are likely to survive in scenarios with extreme climate change, while scenarios with moderate climate change showed positive survival rates although lower than present-day baseline levels. Analysis also showed that land use management within the Cowichan River watershed can also affect freshwater survival of both Chinook and Coho and marine survival of Chinook through influence of river discharge on nearshore processes. However, our land-use management scenarios have considerably weaker effect than climate change on salmon survival. Therefore, we conclude that land use management alone is not sufficient to offset effects of climate change on salmon survival. / Graduate

Wetlands are significant contributors to global biodiversity, supporting disproportionately high numbers of species relative to their area. Riparian areas associated with wetlands provide many services that are both ecologically and economically important, such as groundwater recharge, sediment capture and shoreline stabilization, flood mitigation, nutrient processing, increased water quality, carbon sequestration, and essential habitat for wildlife. Agricultural activity has resulted in the drainage or modification of between 40-70% of wetland basins within the Prairie Pothole Region of the northern Great Plains. The impacts of human activity on the remaining wetlands are difficult to estimate and there is no one optimal indicator or assessment method that is applicable to all regions or situations. Locally developed riparian health assessments, designed to evaluate wetland function under different grazing regimes, are cost-effective with the potential for broader use in wetland environmental assessment, monitoring, and management or restoration activities. In this study I investigated the hypothesis that riparian health assessments can distinguish between wetlands in five categories of land use that represent different levels of anthropogenic modification: ungrazed cultivated cropland, ungrazed native grassland, grazed native grassland, ungrazed tame perennial forage, and grazed tame perennial forage. Noting that current riparian health assessment protocols lack a community composition component other than the presence and distribution of invasive and disturbance species, I also sampled plant species frequency at each of my study sites. I found that wetlands in cultivated croplands had significantly lower riparian health scores than wetlands in both tame and native grasslands. Among tame and native sites, grazing status was more important than upland cover type in determining wetland health, with grazed wetlands receiving significantly lower scores than their ungrazed counterparts. Despite their functional similarity to wetlands within native grasslands, species composition of wetlands within ungrazed tame perennial forage more closely resembled that of wetlands in cultivated uplands. Although grazing negatively affected riparian ground cover and soil stability, it significantly reduced both the overall cover and distribution of invasive plant species along wetland reaches. These results suggest that upland revegetation and restoration of function to degraded wetlands is not necessarily followed by re-establishment of original riparian species composition. If biodiversity is a desired outcome of wetland restoration efforts, additional measures must be taken to enable the establishment and persistence of preferred plant species.

A prática de Avaliação de Impacto (AI) mostra-se consolidada como elemento de suporte ao processo decisório ao redor do planeta. No entanto, apresenta uma série de limitações relacionadas à inclusão dos impactos sociais e efeitos cumulativos como objeto de análise, que se mostram mais intensas no contexto da implantação de grandes projetos de desenvolvimento. No Estado de São Paulo, a região do Litoral Norte se destaca pela perspectiva de intensificação dos processos de desenvolvimento econômico a partir da implantação de projetos ligados à exploração de óleo e gás e seus empreendimentos derivados. Ainda que as mudanças de caráter socioambiental venham sendo analisadas em estudos ambientais estratégicos e estudos de impactos ambientais de projetos, planos diretores municipais, dentre outros instrumentos, verifica-se uma lacuna em termos de seus aspectos cumulativos que, associada ao baixo grau de integração entre os instrumentos de planejamento aplicados na região, tem limitado a sua capacidade de influenciar as decisões tomadas. Nesse contexto, a presente pesquisa se utiliza de métodos de Avaliação de Impactos para a verificação de impactos sociais e seus efeitos cumulativos sobre o Litoral Norte paulista, considerando a implantação de projetos já em andamento e sua compatibilização com os cenários de desenvolvimento esperados para a região. De modo específico, foram aplicados os métodos da Rede de Impactos para identificação da relação de causalidade entre impactos sociais diretos e indiretos e verificação de sua cumulatividade, e da Sobreposição de Mapas para agregação de dados geográficos e visualização de sua distribuição espacial. A metodologia adotada favoreceu a identificação de impactos sociais indiretos, assim como a compreensão de sua cumulatividade sobre diferentes receptores e também sobre a área de estudo, mostrando-se útil para a inserção da dimensão social na AI voltada para grandes projetos de desenvolvimento. / Impact Assessment (IA) practice has different inadequacies, especially about identification and assessment of social impacts and cumulative effects. Hence, there is the demand of exploring methods for minding this gap, mainly in the context of impacts derived from large development projects in Brazil. The North Coast of São Paulo was used a case study, as the region was announced to receive different development projects related to oil and gas exploitation and logistic for exportation. There are many socioenvironmental changes predicted by different instruments such as Strategic Environmental Assessment (SEA), Environmental Impact Statements (EIS) of projects, Master Plans, among others. This research aimed to verify the contributions of the use of Impact Network and Map Overlaying to consider the social dimension in Impact Assessment. The Impact Network method allowed to address the causality of direct and indirect social impacts, linking them to different receptors for comprehending its cumulativeness. The Map Overlaying method added spatial data from different sources, allowing to identify current and expected social impacts and its spatial and temporal cumulativeness. The main results are: identification of indirect social impacts, comprehension of cumulative social impacts in different receptors and the identification of spatial cumulativeness now and considering the planning future scenario. These methods are currently poorly applied and were important to deal with social impacts and cumulative effects. In the end, it was concluded that the approach contributed to better consider the social dimension in Impact Assessment of large projects.

Ecosystems in the modern world face a vast array of disturbances, from globally shifting abiotic conditions, to increasingly variable extreme natural events, to high intensity discrete human-caused disturbances. Well-developed, applicable theoretical frameworks on how ecosystems can respond to and withstand these disturbances are needed for adequate management of valued ecological systems. To date, the most promising theoretical development for understanding ecological response to complex sets of disturbances is resilience. Ecological resilience acknowledges non-linear ecosystem behavior, incorporates the role of slowly changing environmental parameters in ecological dynamics, and offers one of the few potential methods to predict, and avoid, impending ecological collapse. However, as ecological resilience has evolved conceptually to include social, political, and economic fields, it has become increasingly difficult to clearly define in, and apply to, managed ecosystems. This dissertation pairs ecological resilience with other, well-established attributes of ecological response to disturbance, namely resistance, persistence, and recovery. By doing so, we can clearly define and quantify each attribute in a range of ecosystem types and over a variety of ecological scales. In Chapter 1, we use microcosm communities to test the relationship between one potential mechanism, landscape connectivity, and multiple attributes of ecological response to disturbance including resistance, resilience, and recovery. We find that each attribute responds uniquely to connectivity, and that generalizing the role of connectivity over all three may give an inaccurate prediction of how ecosystems may respond to individual disturbances. In Chapter 2, we experimentally investigate the presence of early warning indicators of approaching critical thresholds. Using water table drawdown treatments in bog, we test for critical slowing and increased autocorrelation as the bog approaches a transition to forest. We find that critical slowing is clear in composition and moss cover, but that autocorrelation is not apparent. The decoupling of critical slowing and increased autocorrelation could be due to a number of complex ecosystem dynamics, all of which are common in ecosystem management globally. Thus, early warning indicators likely need further development if they are to become applicable. In Chapter 3, we observationally study how conservation management actions may increase or decrease ecological resilience. In particular, we explore how invasive species management intensity correlates with changes in functional redundancy, response diversity, and spatial occurrence of regime shifts in Garry oak meadows. We find that more intense management correlates with less area lost to woody encroachment and increases in functional redundancy through time. However, the relationship was strongly mediated by individual landscape settings. Finally, in Chapter 4, we scale up to a provincial study, investigating persistence of ecosystems and large mammal species in the face of the continuous pressures of land use change. In the results from all four chapters, it is clear that individual attributes of ecological response to disturbance, i.e. resistance, persistence, resilience, or recovery, all play unique roles in ecosystem dynamics. Additionally, the metric chosen to quantify each attribute can play a pivotal role in how we interpret observed dynamics. The work in this dissertation highlights that we cannot understand or predict ecological response to disturbance without clear, measurable concepts. Around a single state of interest, resilience is only one among a suite of attributes that are important to understand. Its additional strength, of potentially predicting the occurrence of ecological thresholds, is still being developed as we explore methods of quantification and application in individual ecosystems. / Graduate

A prática de Avaliação de Impacto (AI) mostra-se consolidada como elemento de suporte ao processo decisório ao redor do planeta. No entanto, apresenta uma série de limitações relacionadas à inclusão dos impactos sociais e efeitos cumulativos como objeto de análise, que se mostram mais intensas no contexto da implantação de grandes projetos de desenvolvimento. No Estado de São Paulo, a região do Litoral Norte se destaca pela perspectiva de intensificação dos processos de desenvolvimento econômico a partir da implantação de projetos ligados à exploração de óleo e gás e seus empreendimentos derivados. Ainda que as mudanças de caráter socioambiental venham sendo analisadas em estudos ambientais estratégicos e estudos de impactos ambientais de projetos, planos diretores municipais, dentre outros instrumentos, verifica-se uma lacuna em termos de seus aspectos cumulativos que, associada ao baixo grau de integração entre os instrumentos de planejamento aplicados na região, tem limitado a sua capacidade de influenciar as decisões tomadas. Nesse contexto, a presente pesquisa se utiliza de métodos de Avaliação de Impactos para a verificação de impactos sociais e seus efeitos cumulativos sobre o Litoral Norte paulista, considerando a implantação de projetos já em andamento e sua compatibilização com os cenários de desenvolvimento esperados para a região. De modo específico, foram aplicados os métodos da Rede de Impactos para identificação da relação de causalidade entre impactos sociais diretos e indiretos e verificação de sua cumulatividade, e da Sobreposição de Mapas para agregação de dados geográficos e visualização de sua distribuição espacial. A metodologia adotada favoreceu a identificação de impactos sociais indiretos, assim como a compreensão de sua cumulatividade sobre diferentes receptores e também sobre a área de estudo, mostrando-se útil para a inserção da dimensão social na AI voltada para grandes projetos de desenvolvimento. / Impact Assessment (IA) practice has different inadequacies, especially about identification and assessment of social impacts and cumulative effects. Hence, there is the demand of exploring methods for minding this gap, mainly in the context of impacts derived from large development projects in Brazil. The North Coast of São Paulo was used a case study, as the region was announced to receive different development projects related to oil and gas exploitation and logistic for exportation. There are many socioenvironmental changes predicted by different instruments such as Strategic Environmental Assessment (SEA), Environmental Impact Statements (EIS) of projects, Master Plans, among others. This research aimed to verify the contributions of the use of Impact Network and Map Overlaying to consider the social dimension in Impact Assessment. The Impact Network method allowed to address the causality of direct and indirect social impacts, linking them to different receptors for comprehending its cumulativeness. The Map Overlaying method added spatial data from different sources, allowing to identify current and expected social impacts and its spatial and temporal cumulativeness. The main results are: identification of indirect social impacts, comprehension of cumulative social impacts in different receptors and the identification of spatial cumulativeness now and considering the planning future scenario. These methods are currently poorly applied and were important to deal with social impacts and cumulative effects. In the end, it was concluded that the approach contributed to better consider the social dimension in Impact Assessment of large projects.

No description available.

Includes bibliographical references (leaves [268]-285) / xiv, 285, [85] leaves : ill. (some folded), maps (col., folded) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geographical and Environmental Studies, 2002