The boreal forest covers 11% of the earth’s land surface and contains 37 percent of the planet’s terrestrial carbon, which is more than the combined total of both the tropical and the temperate forests [1]. This estimate translates to 703 Pg of carbon with the vast majority contained within the organic soils and peat layers [2-4]. The western-north American boreal forest is a fire ecosystem [2, 5-7] where fires typically occur every 50 to 200 years [8, 9], allowing vast quantities of carbon to re-enter the atmosphere. Understanding and estimating past fire history and the related changes in carbon budget [3, 4, 7, 10] in this biome is of significant importance for climate researchers as they attempt to model for future changes in the planet’s climate [2, 4, 11-14]. Many techniques are available to remotely sense wildfires - using optical, thermal and passive microwave remote sensors - during and immediately after an event - although resolution and availability of images due to cloud cover can make these techniques operationally challenging. Radar remote sensing can provide a complement to these optical and passive microwave techniques, since radar is not affected by cloud cover and solar illumination levels. The Advanced Land Observatory Satellite (ALOS) operates a phased array L band synthetic aperture radar (PALSAR) and Canada’s Radarsat-2 contains a C-Band (SAR) instrument. These radar satellites can be used to detect information about the boreal forest environment including the effects of wildfire. Polarimetric radar is an emerging technology whose full potential is still being actively explored and discovered. More specifically, this research is ground-breaking since very little work has been performed investigating the relationship between polarimetric radar data and historical boreal wildfire events. This area of investigation is a complex marriage of forestry, geospatial information and radar engineering that requires an extensive array of data sets to facilitate analysis. This research has demonstrated that both PALSAR L-Band and Canada’s Radarsat-2 C-Band full polarimetric radars can be used to detect and classify wildfire scars within individual images. The boreal forest is a dynamic ecosystem where both the level of burn severity and the subsequent regeneration of the forest is affected by many factors that can vary widely across small distances. This work contributes to the understanding of the relationships between remotely sensed quad-pol radar signals and both the boreal ecosystem and how wildfire interacts in this environment. / Graduate / 0478 / 0538 / 0984 / ghobart@nrcan.gc.ca

Unprecedented rates of climate change have increased forest stress and mortality worldwide. Previous research in the boreal forest has largely documented negative growth responses to climate in forest species and habitats characteristic of drier conditions, emphasizing the sensitivity of drier or warmer landscape positions to climate warming. Tree growth responses to recent climate warming may signal changes in the susceptibility of forest communities to compositional change and consequently impact a wide range of ecosystem processes and services. In this study, I explored relationships between climate and radial growth of black spruce, a dominant tree species typical of cool and moist habitats in the boreal forests of North America. I assessed how growth-climate responses varied with stand characteristics and landscape position across four different regions in Alaska and Yukon Territory and found widespread negative correlations between growth and temperature. Decreased tree growth in association with increasing temperatures is generally accepted as a signal of temperature induced drought stress. However, variations in tree growth alone do not reveal the physiological mechanisms behind recent changes in tree growth. Thus, I used stable carbon isotopes to test if the changes in growth were due to physiological drought stress. My results highlight the prominence of drought stress in the boreal forest, even for trees located in cool and moist landscape positions. As mature trees might be able to survive in stressful environmental conditions that do not permit successful post-fire recruitment and survival of seedling, drought stress could affect the resilience of the boreal forest ecosystem to disturbance from fire. I assessed drought stress in pre-fire trees and used post-fire forest compositional changes as a proxy for ecosystem resilience. My results suggest that forest stands with the lowest resilience to disturbance are those that experienced the compounding effects of climate induced drought stress and high fire severity. These sites were generally located at warmer and drier landscape positions, suggesting they are less resilient to disturbance than sites in cool and moist locations. I conclude that as temperatures continue to warm, the loss of boreal forest resilience to disturbance from fire will vary in association with environmental heterogeneity across the landscape.

Aboriginal communities in Canada are increasingly involved in land use planning initiatives to promote community-led economic renewal and advance self-determination. As analyzed by political ecologists elsewhere, international and national civil society organizations are also increasingly important actors in environmental governance in Canada. However, nascent conflicts due to the role of civil society organizations in influencing planning policy development, and its effects on Aboriginal–state relationships, have not yet been explored. Through community-based fieldwork with Pikangikum First Nation, interviews with Provincial Ministries and conservation organizations, and in-depth document analysis, this thesis analyzes the roots of contentious politics for land use planning in the Far North Region of Ontario. Specifically, it analyzes 1) the evolution of land use planning policy development between 1975 and 2010 in the region; 2) the role and strategies of civil society organizations in influencing planning policy development, and 3) the impacts that different planning approaches have for enabling Aboriginal decision-making authority in their territories. Results show that during four different planning processes held between 1975 and 2010, Aboriginal communities and organizations in the Far North actively resisted state-led land use planning and resource allocation, and developed partnerships with the Ontario Government to enable community-led planning in their traditional territories. Since 2008, Aboriginal organizations have condemned new comprehensive legislation for opening the Far North Region to development and setting a restrictive conservation target, without clarifying substantive issues of jurisdictional authority, sharing of resources, and consultation protocols. These changes were the result of international and national civil society organizations's actions to strategically mobilize public and political support. The planning approaches that emerged from different planning policies were found to directly influence how Aboriginal–state relations are developed; who sits at the decision-making table; how resources are distributed; and how knowledge systems are balanced. Without careful attention to how power is distributed across levels of governance and where accountability lies, multi-level governance—and the bridging role that is promoted for civil society organizations—may lead to patterns of scale dominance, and become a way to justify continued control by the state, corporations, and international civil society organizations on Aboriginal territories.

Little research has been conducted on the sensitivity of earlywood vessel in ring-porous tree species in response to flooding. The impact of flooding and climate on vessel characteristics in black ash (Fraxinus nigra Marsh.) was studied in the boreal region of Lake Duparquet, northwestern Quebec. In addition to standard tree-ring measurements, numbers and cross-sectional area of earlywood vessels were examined and measured using an image analyzing program. Interestingly, among all Spearman rank correlations between chronologies and hydrologic/climatic variables, the strongest associations were found between earlywood vessel chronologies from floodplain trees and spring river discharge data. High water discharge in the spring was negatively correlated to earlywood vessel area and inversely correlated to number of vessels. The mean earlywood vessel area chronology developed from floodplain trees was found to be the best proxy for high magnitude flood events and it has potential to be used for flood reconstructions.

To understand the temporal dynamics of a forest, long-term direct observations are required. My study examined the long-term persistence of trembling aspen (Populus tremuloides Michx) and white spruce (Picea glauca (Moench) Voss) in the boreal mixed-wood forests of Riding Mountain National Park. A set of 266, disturbance-free, permanent sample plots were established in 1947 (stand age = 120 years) and followed through time for 55 years. My results indicate that although the density and basal areas of aspen do decline over the 55-year period, a successful regeneration and establishment occurs around 140 years. The long-term persistence of aspen is a result of clonal reproduction following the canopy breakup beginning around 130 years or earlier. This implies that the long-term persistence of both aspen and spruce occur and the expected succession to softwood dominance does not occur.

Aboriginal communities in Canada are increasingly involved in land use planning initiatives to promote community-led economic renewal and advance self-determination. As analyzed by political ecologists elsewhere, international and national civil society organizations are also increasingly important actors in environmental governance in Canada. However, nascent conflicts due to the role of civil society organizations in influencing planning policy development, and its effects on Aboriginal–state relationships, have not yet been explored. Through community-based fieldwork with Pikangikum First Nation, interviews with Provincial Ministries and conservation organizations, and in-depth document analysis, this thesis analyzes the roots of contentious politics for land use planning in the Far North Region of Ontario. Specifically, it analyzes 1) the evolution of land use planning policy development between 1975 and 2010 in the region; 2) the role and strategies of civil society organizations in influencing planning policy development, and 3) the impacts that different planning approaches have for enabling Aboriginal decision-making authority in their territories. Results show that during four different planning processes held between 1975 and 2010, Aboriginal communities and organizations in the Far North actively resisted state-led land use planning and resource allocation, and developed partnerships with the Ontario Government to enable community-led planning in their traditional territories. Since 2008, Aboriginal organizations have condemned new comprehensive legislation for opening the Far North Region to development and setting a restrictive conservation target, without clarifying substantive issues of jurisdictional authority, sharing of resources, and consultation protocols. These changes were the result of international and national civil society organizations's actions to strategically mobilize public and political support. The planning approaches that emerged from different planning policies were found to directly influence how Aboriginal–state relations are developed; who sits at the decision-making table; how resources are distributed; and how knowledge systems are balanced. Without careful attention to how power is distributed across levels of governance and where accountability lies, multi-level governance—and the bridging role that is promoted for civil society organizations—may lead to patterns of scale dominance, and become a way to justify continued control by the state, corporations, and international civil society organizations on Aboriginal territories.

In the boreal forests of northeastern Alberta and northwestern Saskatchewan, one of the most abundant and reliable sources of lithic material was the Quarry of the Ancestors. This Quarry is located 50 km northwest of Ft. McMurray, AB and is the primary source of Beaver River Sandstone; a lithic raw material that dominates the archaeological stone tool and debitage assemblages in this region. Other lithic materials, such as quartzite, chert, and quartz, were accessible in gravel and glacial tills and in lakeshore and river beds scattered across northern Alberta and Saskatchewan. The analysis of stone tools from 31 archaeological sites spanning 260 km from the Quarry into the Descharme River system, in northwestern Saskatchewan, suggests that as pre-contact people moved across the landscape and away from the Quarry, they maintained and recycled their tools and used whatever other lithic resources were available. In contexts where there were issues with the availability, quality and abundance of lithic raw materials, the mobility of pre-contact hunter-gatherers may have been strongly influenced by the distribution of these lithic sources. However, the availability of food resources may have also been a strong influence over mobility patterns in circumstances where these lithic raw material issues were less marked. Northern Dene groups of this region are known to have travelled hundreds of kilometers seasonally following barren-ground caribou whose wintering grounds extended well into northwestern Saskatchewan. Through the distribution of lithic raw material and the analysis of lithic tool technology, I explore the role these two important resources had in shaping the overall organization of pre-contact hunter-gatherer mobility strategies employed in these two regions.

Boreal peatlands are important ecosystems to the global carbon cycle. Although they cover only 3% of the earth's land surface area, boreal peatlands store roughly one third of the world's soil carbon. Peatlands also comprise a large natural source of methane emitted to the atmosphere. Some methane in peatlands is oxidized before escaping to the atmosphere by aerobic methane oxidizing bacteria. With changing climate conditions, the fate of the stored carbon and emitted methane from these systems is uncertain. One important step toward better understanding the effects of climate change on carbon cycling in peatlands is to ascertain the microorganisms actively involved in carbon cycling. To investigate the active aerobic methane oxidizing bacteria in a boreal peat bog, a combination of microcosm experiments, DNA-stable isotope probing, and next generation sequencing technologies were employed. Studies were conducted on samples from the S1 peat bog in the Marcell Experimental Forest (MEF). Potential rates of methane oxidation were determined to be in the range of 13.85 to 17.26 μmol CH₄ g dwt⁻¹ d⁻¹. After incubating with ¹³C-CH₄, DNA was extracted from these samples, separated into heavy and light fractions with cesium chloride gradient formation by ultracentrifugation and needle fractionation, and fractions were fingerprinted with automated ribosomal intergenic spacer analysis (ARISA) and further interrogated with qPCR. Based on ARISA, distinct banding patterns were observed in heavy fractions in comparison to the light fractions indicating an incorporation of ¹³C into the DNA of active methane oxidizers. This was further supported by a relative enrichment in the functional gene pmoA, which encodes a subunit of the particulate methane monooxygenase, in heavy fractions from samples incubated for fourteen days. Within heavy fractions for samples incubated for 8 and 14 days, the relative abundance of methanotrophs increased to 37% and 25%, respectively, from an in situ abundance of approximately 4%. Phylogenetic analysis revealed that the methanotrophic community was composed of both Alpha and Gammaproteobacterial methanotrophs of the genera Methylocystis, Methylomonas, and Methylovulum. Both Methylocystis and Methylomonas have been detected in peatlands before, however, none of the phylotypes in this study were closely related to any known cultivated members of these groups. These data are the first to implicate Methylovulum as an active methane oxidizer in peatlands, though this organism has been detected in another cold aquatic ecosystem with consistent methane emissions. The Methylovulum sequences from this study, like Methylocystis and Methylomonas, were not closely related to the only cultivated member of this genus. While Methylocystis was dominant in ¹³C-enriched fractions with a relative abundance of 30% of the microbial community after an eight-day incubation, Methylomonas became dominant with a relative abundance of approximately 16% after fourteen days of incubation. The relative abundance of Methylovulum was maintained at 2% in ¹³C- enriched fractions after eight and fourteen days.

While traditional management of the boreal forests results in even-aged forests with low landscape scale variability, recent work has suggested that much of the eastern boreal forest of North America is subject to long natural fire return-intervals. This has led to the development of new management strategies to maintain a mosaic of even and multi-aged stands. In this context I investigated the relationships between diameter-distributions, stand age, forest structure and bird communities. Results showed weak associations of the bird community with cohort classes, but that diameter-distributions can work to succinctly describe some of the variation in stand structure and bird communities. I also explored the utility of LiDAR to measure important structural features for bird communities. Results showed that LiDAR can outperform traditional measures of stand structure at explaining bird communities at differing scales.

The maintenance of downed woody debris supplies is increasingly being recognized as an integral part of forest management. In order to better manage this resource, it is important to assess its role in supporting biodiversity. In this thesis, I investigate the responses of carabid communities to variation in woody debris availability in an experimental manipulation of woody debris volume in closed canopy forests and following a biomass harvest in a clearcut. Within closed-canopy forests, total carabid abundance and the abundances of eight species increased significantly with increasing volumes of various types of woody debris, particularly large diameter, late-decay conifer wood. Similarly, a strong affinity with woody debris was observed in the clearcut. These findings suggest that reductions in woody debris will have negative consequences for carabids and indicate the need to ensure a diverse and abundant supply of woody debris during stand development.