English

Timber harvest can influence the rate of transfer of organic matter from the terrestrial catchment to streams, which may have both direct and indirect effects on in-stream nutrient pools and dynamics. In the interest of developing sustainable forestry practices, the continued study of the effects of forestry on nutrient dynamics in aquatic systems is paramount, particularly in sensitive nutrient-poor oligotrophic systems. The goal of this study was to investigate the impacts of harvest-related woody debris on stream nutrient status in streams located in the Canadian Shield region of south-central Ontario. Surveys showed greater large (> 10 cm) and small (< 10 cm) woody debris dry masses and associated nutrient pools in streams located in recently (2013) selectively harvested catchments, when compared with catchments not harvested for at least 20 years. Experimental releases of flagging tape underlined the importance of woody debris as a mechanism of coarse particulate organic matter (CPOM) retention. Sediment surveys showed a significant exponential decline in both OM content and nutrients associated with coarse sediment with distance upstream from debris dams. Laboratory leaching experiments suggest that fresh woody debris may be an important short-term source of water-soluble nutrients, particularly phosphorus and potassium. This study suggests that woody debris from timber harvest is both a direct and indirect source of nutrients, as trapped wood and leaves that accumulate behind debris dams can augment stream nutrient export over long time periods.

Author Keywords: nutrient leaching, nutrient pools, organic matter retention, selection harvest, southern Ontario, woody debris

Population aging has become a worldwide concern since the nineteenth century. The decrease in birth rate and the increase in life expectancy will make China's population age rapidly. If the growth rate of the number of workers is less than that of the number of retirees, in the long run, there will be fewer workers per retiree. This will apply great pressure to China's public pension system in the next several decades. This is a global problem known as the "pension crisis". In this thesis, a long-term vision for China's urban pension system is presented. Based on the mathematical models and the projections for demographic variables, economic variables and pension scheme variables, we test how the changes in key variables affect the balances of the pension fund in the next 27 years. This thesis applies methods of deterministic and stochastic modeling as well as sensitivity analysis to the problem. Using sensitivity analysis, we find that the pension fund balance is highly sensitive to the changes in retirement age compared with other key variables. Monte Carlo simulations are also used to find the possible distributions of the pension fund balance by the end of the projection period. Finally, according to my analysis, several changes in retirement age are recommended in order to maintain the sustainability of China's urban basic pension scheme.

Author Keywords: China, demographic changes, Monte Carlo simulation, pension fund, sensitivity tests, sustainability

This thesis is an attempt to provide a critical history of the Communist Party of Canada (CPC) during the Popular Front era, roughly November 1935 to September 1939. This study contains a detailed examination of the various stages of the Popular Front in Canada (the united front, the height of the Popular Front, and the Democratic front), with special attention paid to the CPC's activities in: the youth movement, the labour movement, the unemployed movement, the peace movement, and the anti-fascist movement. From this I conclude that the implementation of the Popular Front, the transformation of the CPC from a revolutionary party to a bourgeois party, was not a smooth process, but instead was punctuated and resisted by elements within the CPC in what can be considered a process of class struggle internal to the CPC itself.

Author Keywords: Canada, communism, Great Depression, labour, Popular Front, socialism

Decreasing lake calcium (Ca) concentration, in lakes located in base poor

catchments of the Muskoka River Watershed (MRW) in south-central Ontario, is a well- established acid-rain driven legacy effect threatening the health and integrity of aquatic ecosystems that can be compounded by additional Ca removals through forest harvesting. The objectives of this thesis were to assess patterns and temporal trends in key water chemistry parameters for a set of lakes in forested catchments in the MRW in south- central Ontario, to predict the pre-industrial steady state lake Ca concentration and the potential impact of harvesting on lake Ca levels in lakes located in managed MRW Crown forests, and to assess potential effects of various mitigation strategies in Ca depleted managed forests. Mean lake Ca (mg L-1) in 104 lakes across the MRW have decreased by 30% since the 1980's with the rate of decrease slowing over time. Mean Lake SO4 (mg L-1), and Mg (mg L-1) concentration also decreased significantly with time (37% and 29%, respectively) again with a declining rate of decrease, while mean lake pH and DOC increased significantly between the 1980's and the 1990's (16% and 12%, respectively) but exhibited no significant pattern after that. Principal components and GIS spatial analyses of 75 lakes with data from 2011 or 2012 water seasons suggested that smaller lakes, at higher elevation in smaller catchments with higher runoff and minimally impacted by the influence of roads and agriculture are associated with lower Ca concentrations and thus are the lakes at risk of amplified Ca depletion from forest harvesting. Spatial analyses of harvested catchments indicated that, under the proposed 10 year land forest management cut volumes, 38% of 364 lakes in the MRW will fall below the critical 1 mg L-1 Ca threshold compared with 8% in the absence of future harvesting. With respect to potential mitigation measures, soil pH and foliar Ca were indicated by meta-analysis to be more responsive to lime addition studies while soil base saturation and tree growth appeared more responsive to wood-ash addition. Future research should address the spatial extent of lakes at risk and identify when critical levels will be reached under harvesting regimes. Further investigation into the use of Ca-addition as a tool for managing the cumulative effects of past, present and future stressors is recommended.

Author Keywords: calcium, harvesting, lakes, lime, Muskoka River Watershed, wood-ash

Although the concept of environmental sustainability has become increasingly popular, the literature offers little practical guidance to direct priorities or actions to support environmental sustainability in northern Indigenous communities. A case study in Hopedale, Nunatsiavut, and a systematic literature review was undertaken to understand: 1) what aspects of the local environment are of value to a northern Indigenous community; and 2) what does existing literature identify as key elements of a community-based approach to monitor valued aspects of the environment in a northern Indigenous context. Hopedale residents spoke to the importance of going off on the land and identified a number of categories of places in their local environment of importance to them, including: 1) valued areas for human-use, 2) areas to protect, 3) areas of environmental concern, and 4) areas to monitor. The systematic literature review highlighted trends on community-based monitoring (CBM) publications, and identified key 13 elements of CBM approaches that are pertinent to northern Indigenous communities. Insights from this study will inform environmental planning and management in the case community of Hopedale, as well as offer guidance to enhance current and future CBM activities in the North and elsewhere.

Author Keywords: community-based monitoring, environmental sustainability, Inuit, Labrador, participatory mapping, systematic literature review

Around the world, many populations of migratory shorebirds appear to be declining. Conservation strategies to reverse declining trends rely on, among other information, a firm understanding of breeding ground population dynamics. From 2010 to 2014, I studied a breeding population of Dunlin (Calidris alpina hudsonia) near Churchill, Manitoba using mark-recapture methods. I found that females were significantly larger than males. I subsequently developed an equation based on morphological features that successfully classified 87.1% of females and 92.6% of males, sexed using molecular techniques. Using program MARK, I quantified the annual apparent survival of adults (± SE) within the breeding population (0.82 ± 0.063 for males, 0.73 ± 0.12 for females). Transient adults made up a significant percentage of the female population (32%, P = 0.011), but non-significant in the male population (12%, P > 0.05). Re-sight rate was high for both sexes, and ranged from 0.86-0.90 per year. Sex, year, and nest initiation date were the factors that had the greatest influence on annual returns. There was no significant difference in mean inter-annual nest site distance between sexes (male: 82.01 ± 13.42 m, female: 208.38 ± 55.88 m, P > 0.05). The high survival estimates obtained in this study suggest that the breeding population is stable and may not be contributing to suspected population declines within the subspecies.

Author Keywords: demography, discriminant function analysis, mark-recapture, sexual size dimorphism, survival

This thesis critically analyses the connection between ideology and nature, and in particular, aims to reflect on the dominant discourses on the topic of ecological crisis. The ecological thought framework that I adhere to rests on a combination of Frankfurt School and Žižekian theories. This combination is not without serious tensions and deviations; however, central to this project are the ways in which their respective works extensively critique ideology, and propose subversive alternatives to and new meanings of how we can conceptualize nature without domination. Dominant ideas and critiques of nature and natural history emerged during the Enlightenment era, and as Adorno argues, fell victim to a "reduction ad hominem," or the claim that in order to free oneself, one must dominate, appropriate, and master nature. I claim that the extreme choices in environmental politics today - namely organic populism on one hand and increased technological intervention on the other - fail to account for the ways 'nature' is a socio-historical construct, and moreover, is situated within a false reality wherein the 'essence of existence' is reduced to technological mastery. What we encounter in this cautionary armoury of paradoxical approaches to nature, then, is the ideological currents of established belief systems. By exposing the illusions within the concept nature, such as the argumentative persuasion that there exists an inherent balance, the elementary cell of ideology reveals itself alongside revolutionary possibilities.

Author Keywords: Crises, Critical Theory, Ideology, Nature, Slavoj Zizek, Theodor Adorno

Groundwater recharge was estimated and compared in two open grasslands, three mixed deciduous forest stands (100+ years in age), three young red pine plantations (27 ¨C 29 years in age) and two old red pine plantations (62 ¨C 63 years in age) on the Oak Ridges Moraine, southern Ontario, Canada. Recharge was estimated using a 1-d water balance with measured precipitation, throughfall, stemflow, snowpack water equivalent and soil water storage, and modelled evapotranspiration. Throughfall distribution beneath red pine canopies showed no consistent variation with distance from the tree boles. Old red pines were not major stemflow producers and although the young red pines showed a slight tendency to focus stemflow (focussing ratio > 1), the inclusion of focussed stemflow when calculating recharge at the stand scale made little difference. Conversely, sugar maple (the predominant species in the mixed deciduous stands) showed a strong tendency to focus throughfall proximal to tree boles and produce large quantities of stemflow, resulting in relatively high soil moisture contents and enhanced opportunities for recharge within ~ 0.5 m of tree boles. Inclusion of these focussed inputs resulted in a ~ 11 ¨C 18 % increase in stand scale recharge estimates. The interpretation of land cover control on recharge was complicated by variations in soil texture between sites. Soil texture and its influence on soil water storage capacity resulted in temporal variations in recharge, with sites exhibiting large storage capacities producing less recharge in the fall and greater recharge in the spring than sites with limited storage capacities. Recharge estimates for the entire study period or seasonal values for sites grouped on the basis of soil water storage capacities showed a general trend of increasing recharge in the order: old red pine ¡Ö young red pine ¡ú mixed deciduous forest ¡Ö open grasslands. The disparity between the red pine plantations and the other sites was driven in large part by greater modelled evapotranspiration in the red pine plantations. The similarity in recharge between mixed deciduous forests and open grasslands was the result of focused inputs and less soil evaporation and transpiration in the mixed deciduous forests compared to the open grasslands. The results of this study suggest planting red pine on grasslands on the Oak Ridges Moraine will initially decrease recharge and this decrease will continue as the red pines mature. However, as the red pine plantations are succeeded by mixed hardwood stands recharge will recover to that of the initial grasslands.

Author Keywords: Groundwater Recharge, Land Cover Type, Oak Ridges Moraine, Stemflow, Throughfall, Water Balance

Giardia lamblia is an intestinal parasite found globally in freshwater systems that is responsible for endemic outbreaks of infectious diarrhea. As a unicellular parasite that lacks mitochondria, a respiratory chain and lives in the anaerobic environment of its host's intestine, Giardia was assumed for decades to lack heme proteins. However, its genome encodes several putative heme proteins, including three with sequence similarity to the cytochrome b5 family, referred to as Giardia cytochromes b5 (gCYTb5). Recombinant expression of one of these genes (gCYTb5-I), results in a protein (17-kDa) that is isolated with noncovalently bound heme. Resonance Raman and UV-visible spectra of gCYTb5-I in oxidized and reduced states resemble those of microsomal cytochrome b5, while sequence alignment and homology modelling supports a structure in which a pair of invariant histidine residues act as axial ligands to the heme iron. The reduction potential of gCYTb5-I measured by cyclic voltammetry is -165 mV vs the standard hydrogen electrode and is relatively low compared to those of other family members. The amino- and carboxy-terminal sequences that flank the central heme-binding core of the gCYTb5 are highly charged and do not occur in other family members. An 11-kDa core gCYTb5-I variant lacking these flanking sequences was also able to bind heme; however, we observe very poor expression of this truncated protein as compared to the full-length protein.

Author Keywords: b-type cytochrome, cytochrome b5, electron transfer protein, Giardia intestinalis, heme/heam protein, spectroelectrochemistry

Chemical cues are used commonly by prey to identify predation risk in aquatic environments. Previous work has indicated that negatively-charged ions of m/z 501 are possibly a kairomone that induces anti-predator responses in tadpoles. This thesis found that this ion species: (i) is produced by injured tadpoles; (ii) exhibits increased spectral intensity with higher tadpole biomass; and (iii) is not produced by starved predators. These results refute the hypothesis that the ion is a kairomone, and rather support its role as an alarm cue released from tadpoles. High resolution mass spectrometry (HR-MS) revealed a unique elemental composition for [M-H]-, m/z 501.2886, of C26H45O7S-. Collision induced dissociation (CID) of ion m/z 501 formed product ions of m/z 97 and m/z 80, HSO4- and SO3-, respectively, indicating the presence of sulfate. Green frog (Lithobates clamitans) tadpoles exposed to m/z 501, and an industrial analogue, sodium dodecyl sulphate (NaC12H25O4S), exhibited similar anti-predator responses, thereby suggesting the potential role of organic sulfate as a tadpole behavioural alterant.

Author Keywords: Alarm cue, Amphibian, Chemical Ecology, Mass spectrometry, Predator-prey interactions