I compared understorey communities under Alnus viridis ssp. crispa (Ait.) Pursh (green alder) and Corylus cornuta Marsh. (beaked hazel) in two boreal jack pine forests. There was no difference in inorganic soil nitrogen, but alder plots had lower species richness at Star Lake and higher evenness in the Sandilands. I incubated chopsticks and litterbags containing natural litter assemblages underneath A. crispa and C. cornuta in the field, and litterbags containing artificial litter mixes in a dark growth chamber. There was no significant difference between treatments for litterbags or chopsticks in the field, nor between mixes with or without alder in the growth chamber.

No description available.

A dock is a structure that is built on the shore of a body of water, to provide access to the lake. Traditionally built using timber, dock structures use a number of materials to minimize costs and maximize usable space alongshore for mooring boats, swimming, sunbathing and fishing. Constructed in three distinct types on Lake of the Woods, crib docks, pile docks, and floating docks currently function as a hindrance to ecological function on the lake shore. The Lake of the Woods watershed region is a boreal water body straddling three distinct landscape characters; aspen parkland, industrial agriculture, and the Canadian Shield. Lake of the Woods traverses three political borders in an intricate system of islands, bays, and straights, as water flows into the lake body from the south. Meandering North, and ultimately exiting into Hudson’s bay, fresh water in this lake supplies drinking water to 3 major cities and towns; Fort Francis, Kenora, and the City of Winnipeg. There is a significant human impact on this sensitive environment and it is an ongoing task to maintain a healthy economic-ecological balance. Water level manipulation, pulp and paper manufacturing, hydroelectric potential, and recreation all hold controlling stakes in the performance of intricate lake system, while the value of drinking water quality is one that is often taken for granted. To ensure a drinking water source into the future, it is important to actively manage the human impact on the Lake of the Woods watershed system. Development on shorelands adjacent to the water of Lake of the Woods region is considered a luxury, and many property owners consider water access by constructing a dock to be a paramount requirement for enjoyment of the lake. The study of this freshwater lake ecosystem in this project provides evidence to support a more intensive consideration for the health of the shallow water zone. This project intends to create a new dock prototype to minimize and reverse ecological destruction on the shoreline of Lake of the Woods. / May 2017

This thesis describes the natural variation and influence of aspen harvesting on stream chemical concentration and flow-weighted export from catchments typical of the Western Boreal Plain, Alberta, Canada. The catchment stream discharge and stream chemical concentrations presented are taken from a subset of a five-year paired catchment (2005-2010) HEAD2 NSERC-CRD study. Nutrients, major anions, major cations and two minor ions were monitored from second-order streams draining a 18.3 sq km reference catchment (R1) and compared to a 9.9 sq km experimental catchment (H1) for two years of pre-harvesting (2005-2006) and two years of sequential harvesting (2007-2008). Preliminary analyses showed that non-harvest high flows had a total average instantaneous export greater than 10 times that of low flows. In addition, summer storms and beaver dam breakages had stream export equivalent to or greater than spring melt. Intensive upland aspen harvesting showed no significant differences in major cation and anion export post-harvest with the exception of increased sulfate. / Ecology

In this thesis, I describe three experimental studies that investigate the hotly debated role of competition in structuring communities in unproductive habitats. The studies were done in a boreal forest understory plant community in the southwestern Yukon. The first study was a traditional neighbour removal experiment. Ten of the most common species were transplanted as seedlings into transects with and without neighbours in a factorial design with two levels of water addition and two levels of fertilizer addition. The presence of neighbours increased survival and biomass of 6 species indicating a facilitative effect of neighbouring plants. The second study used the Community Density Series (CDS) methodology. The first of these was a 10-speciesexperimental community established from seed and grown in sandboxes at 6 densities with 2 watering levels and 2 fertilizer levels in a factorial design. At the community level, density dependence was observed at all life stages, but was not consistently competitive or facilitative - both emergence and final per plant shoot mass were density dependent, while survival to the end of the season was inversely density dependent. The effect of water was positive at seed emergence whereas fertilizer negatively affected survival. Species specific responses were also dependent on life stage. The final study was a 4-year CDS in the field using 9 common understory species at 6 densities and 3 fertilizer levels. Density negatively affected the community every year except for the first with competition being important at all densities above x1/8th the average community density. Constant final yield was reached in plots above the naturalx1 density for the last two years of the study. Responses to density were species-specific and 7 species declined with increasing density. No facilitative effects were observed. These studies demonstrate that density dependence is important in structuring this unproductive boreal understory habitat. The CDS approach allows us to quantify both the intensity and importance of plant competition at the community and species levels and to determine whether the importance of these biotic interactions depend on abiotic factors. The results clearly show that species-specific responses to biotic interactions are not necessarily the same as community level responses and if we are to understand community structure, it is necessary to use appropriate methodologies.

The boreal forest forms a band that stretches across the continents of the northern hemisphere. Wildfire disturbances have helped transform this forest into stands of varying ages with varying soil drainage. It is well known that the boreal forest contributes greatly to the global water cycle, but less is known as to how variable these water fluxes are throughout the forest mosaic. Throughout the growing seasons of 2006 and 2007, meteorological measurements were taken during the growing season from three different aged black spruce stands near Thompson, MB. The stands that were burned in 1930 and 1964 each included upland and lowland sites with independent measurements. The stand burned in 1850 had measurements taken only from an upland site. Evapotranspiration (ET) was calculated from the residual energy after net radiation (Rn), sensible heat flux (H) and ground heat flux were measured. We sought to investigate whether ET varied with stand age and topographic location. Results indicate that there is a significant increase in Rn, H, and ET as forests age. ET levels range from being 4% to 19% lower for younger stands. It is assumed that the depth of the organic layer at older sites allows for mosses to more effectively wick up available moisture through capillary rise, and have higher transpiration levels. The larger tree density at the 1964 sites compared to the 1930 sites may account for a portion of the observed increase in ET for these ages. Differences in drainage between the 1930 and 1850 sites may also account for a portion of the increase in ET observed between these two ages. Wetland sites had H and ET that were significantly less than for the upland sites. ET rates were 11 to 20% higher at the upland sites than the wetland sites; part of this difference is thought to be due to the presence of larger trees, with an increased capacity to transpire water at upland sites. As the number of forest fires has been predicted to increase substantially in the future, the prospect of the boreal forest average stand age being younger would affect the boreal’s water and energy budgets. Our data helps to describe water and energy budgets for forest stands with different drainage capabilities, for stands between the ages of 45 and 160 years. This knowledge will be used to help predict the degree and speed of climate change that will be experienced in the boreal forest. / October 2008

Area burned in boreal forests is increasing due to climate change effects and regional increases in fuels due to a history of successful fire suppression. An increase in area burned threatens valuable resources and infrastructure in timber resources areas and communities. The ecological integrity of protected areas may also be threatened if fires increase in frequency and size beyond what would have occurred prior to effective fire suppression and the effects of climate change. Fuel management is one strategy being tested by fire management agencies and researchers to address these concerns. However the pattern of fuel management that best regulates area burned has yet to be determined. This thesis investigates random fragmentation of highly flammable fuels in the boreal forests of North-western Ontario. A case study of Quetico Provincial Park is used. Using the fire growth simulation model, Prometheus, I tested whether, under extreme fire behaviour conditions, fuel isolation (FI) and fuel conversion (FC) were effective at reducing average area burned in the park. Through the simulation of over 21,000 large fires, I determined that FI and FC are effective in significantly reducing area burned for this case study. Based on these findings, random FI and FC should be studied further on a regional basis and as a prescriptive, proactive method of reducing area burned in boreal forests.

Area burned in boreal forests is increasing due to climate change effects and regional increases in fuels due to a history of successful fire suppression. An increase in area burned threatens valuable resources and infrastructure in timber resources areas and communities. The ecological integrity of protected areas may also be threatened if fires increase in frequency and size beyond what would have occurred prior to effective fire suppression and the effects of climate change. Fuel management is one strategy being tested by fire management agencies and researchers to address these concerns. However the pattern of fuel management that best regulates area burned has yet to be determined. This thesis investigates random fragmentation of highly flammable fuels in the boreal forests of North-western Ontario. A case study of Quetico Provincial Park is used. Using the fire growth simulation model, Prometheus, I tested whether, under extreme fire behaviour conditions, fuel isolation (FI) and fuel conversion (FC) were effective at reducing average area burned in the park. Through the simulation of over 21,000 large fires, I determined that FI and FC are effective in significantly reducing area burned for this case study. Based on these findings, random FI and FC should be studied further on a regional basis and as a prescriptive, proactive method of reducing area burned in boreal forests.

In this thesis, I describe three experimental studies that investigate the hotly debated role of competition in structuring communities in unproductive habitats. The studies were done in a boreal forest understory plant community in the southwestern Yukon. The first study was a traditional neighbour removal experiment. Ten of the most common species were transplanted as seedlings into transects with and without neighbours in a factorial design with two levels of water addition and two levels of fertilizer addition. The presence of neighbours increased survival and biomass of 6 species indicating a facilitative effect of neighbouring plants. The second study used the Community Density Series (CDS) methodology. The first of these was a 10-speciesexperimental community established from seed and grown in sandboxes at 6 densities with 2 watering levels and 2 fertilizer levels in a factorial design. At the community level, density dependence was observed at all life stages, but was not consistently competitive or facilitative - both emergence and final per plant shoot mass were density dependent, while survival to the end of the season was inversely density dependent. The effect of water was positive at seed emergence whereas fertilizer negatively affected survival. Species specific responses were also dependent on life stage. The final study was a 4-year CDS in the field using 9 common understory species at 6 densities and 3 fertilizer levels. Density negatively affected the community every year except for the first with competition being important at all densities above x1/8th the average community density. Constant final yield was reached in plots above the naturalx1 density for the last two years of the study. Responses to density were species-specific and 7 species declined with increasing density. No facilitative effects were observed. These studies demonstrate that density dependence is important in structuring this unproductive boreal understory habitat. The CDS approach allows us to quantify both the intensity and importance of plant competition at the community and species levels and to determine whether the importance of these biotic interactions depend on abiotic factors. The results clearly show that species-specific responses to biotic interactions are not necessarily the same as community level responses and if we are to understand community structure, it is necessary to use appropriate methodologies.

No description available.