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Theses From MAD Labbers |
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Master of Science Dendroclimatology and Dendroecology of the Dominant Coniferous Speces in Eastern Labrador, Canada By Dean Dumaresq |
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Honors Thesis Tree Age and Growth at Barrens Forest Edges in Cape Breton Highlands National Park By Sarah Coley |
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Master of Science Sedimentary Diatoms as Indicators of Water Quality and Ecosystem Change in Lakes of Riding Mountain National Park of Canada By Carrie White |
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Master of Science Dendroclimatology of Picea glauca at tree line in northern Labrador, Canada By Christopher Kennedy |
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Honours Thesis Comparison of maximum density analysis and ring width measurements: applications in dendroclimatology By Carrie White |
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Master of Science Thesis Climatic stress events and radial growth forecasting of Acer Saccharum across New Brunswick and central Nova Scotia, Canada By Benjamin E. Phillips |
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Honours Thesis Latitudinal gradient analysis of local site factors influencing in three boreal tree species By Felicia Pickard |
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Master of Science Thesis Dendroclimatology, dendroecology and climate change in western Labrador, Canada By Peter H. Nishimura |
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Honours Thesis Mapping the Sydney Steel Plant pollution: an application in dendroanalysis By Hannah C. MacDonald |
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Doctor of Philosophy On the spatio-temporal radial growth response of four alpine treeline species to climate across central Labrador, Canada By Mariana Trindade |
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Doctor of Philosophy Dendroclimatic response of high-elevation conifers, Vancouver Island, British Columbia By Colin P. Laroque |
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Master of Science Thesis The dendrochronology and dendroclimatology of yellow-cedar on Vancouver Island, British Columbia By Colin P. Laroque |
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Abstracts for Theses |
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by Dean Dumaresq Eastern Labrador is a region in Canada relatively unexplored both ecologically and climatologically. In light of recent extensive dendroclimatic and dendroecological studies conducted in the northern and western regions of Labrador, eastern Labrador represents the last area in a contiguous sampling grid across this large forested area. This thesis fills this gap by employing similar sampling and analytical methods to other studies in adjacent regions in order to form strong analytical tools that are applicable both on a
local and regional scale.
This thesis employs a systematic sampling grid consisting of three north-south transects and four east-west transects. Two tree-ring chronologies were developed from the dominant species present at each node. In total eight chronologies of black spruce (Picea mariana (Mill) B.S.P.), nine chronologies of balsam fir (Abies balsamea (L.) Mill), two chronologies of white spruce (Picea glauca (Moench) Voss) and one chronology of eastern larch (Larix laricina (Du Roi) K. Koch)
were developed. This thesis is centered on two manuscripts. The first is focused on the radial growth-climate relationship of the dominant tree species in eastern Labrador. This study identifies four distinct zones of growth response; the ‘maritime zone’, a continuance of a zone already identified in western Labrador; the ‘subarctic zone’ a continuance of a zone identified in northern Labrador; the ‘hyper-maritime zone’ a previously unidentified zone in southern Labrador; and the ‘upland maritime zone’ also a potential zone previously unidentified zone along the southeastern coast of Labrador. --- |
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Tree Age and Growth at Barrens Forst Edges in Cape Breton Highlands National Park by Sarah Coley Forest encroachment is occurring in non-forested habitats across North America. Barrens are unique non-forested habitats that contain a variety of plant species including rare species. Forest encroachment would lead to a loss of the unique barrens habitat. This study examines the age structure and growth rate of spruce dominated forests adjacent to barrens in Cape Breton Highlands National Park using dendrochronology. If the age of the forest decreases from interior to edge, we assumed that the forest is expanding into the barrens over time. Growth rate was measured to determine if trees at the edge compared to the interior forest were growing faster due to increased access to resources. Difference in growth rate between 1991-2000 and 2001-2010 was calculated to determine if growth was increasing or decreasing over time. Four transects were set up perpendicular to the forest edge with 20m by 5m plots set up every 20m for 80m, starting at the forest edge. Three reference plots of the same size were set up at least 100m away from the forest edge. Within each plot, trees >5cm diameter at breast height were cored. These cores were then examined using a Velmex stage system to estimate age, and to determine growth rate over the past 10 and 20 years. Analysis suggests that some forest areas may be encroaching, while others are stable. This difference may be due to differing microclimates in the area. Growth rate is not correlated with distance from edge, possibly due to increased shelter in the interior forest. Overall, growth is decreasing in this area for reasons that are unclear. --- |
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Sedimentay Diatoms as Indicators of Water Quality and Ecosystem Change in Lakes of Riding Mountain National Park of Canada by Carrie White The relationship between diatoms and water quality variables was examined in Riding Mountain National Park, Manitoba. In addition, fossil diatom assemblages in Clear Lake and Lake Katherine were assessed in relation to lake trophic status. Through the use of multivariate statistical methods, including Canonical Correspondence Analysis ordination, total phosphorus was determined to be the most significant environmental variable accounting for the greatest proportion of variation among modern diatom communities. Weighted Averaging and Partial Least Squares models were developed as transfer functions to be applied to fossil diatom assemblages, facilitating inferences of historical and pre-historical total phosphorus and lake trophic state. Short core diatom assemblages provided information regarding the most recent changes in lake trophic state, including those driven by human influence, whereas long core assemblages revealed pre-historical conditions indicative of the natural lake state. Paleolimnological assessments of Clear Lake and Lake Katherine revealed a natural borderline oligo-mesotrophic state. Marked changes in the diatom communities coincide with human settlement of the area and, more recently, expanded activities, cottage and golf course development, and sewage system failure. In the most recent decades, changes meant to reduce total phosphorus input have been implemented but the diatom communities have not returned to their pre-settlement composition. ---
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Dendroclimatology of Picea glauca at tree line in northern Labrador, Canada By Christopher Kennedy This thesis applies standard dendroclimatological techniques to compare the radial growth response of the dominant species persisting across treeline in northern Labrador, Canada. White spruce ( Picea glauca (Moench) Voss) tree ring width chronologies were constructed fromten sites spanning treeline in northern Labrador from the Labrador Sea to the Québec border. The effects of climate on radial tree growth were examined at various spatial and temporal scales. This is the first study to conduct a regional dendroclimatological analysis of Labrador’s treeline with respect to delineating the extent of maritime and continental climatic influences on radial growth. Pearson product moment correlations and response function analyses were used to identify two distinct tree bioclimate zones acting on treeline in northern Labrador. The arcticmaritime zone consists of the northern extension of treeline along Labrador’s coast and is primarily characterized by a strong positive correlation to June and July temperatures of the current growing season. Also defined is the subarctic maritime zone encompassing the area immediately below the arctic maritime zone. Trees here also demonstrate a strong positive sensitivity to June and July temperatures, as well as a negative association to current spring temperatures and a positive correlation to previous fall temperatures. These findings indicate that a bioclimatic shifting of the climate-radial growth relationship of white spruce occurs at roughly 56°75’N along treeline in northern Labrador. Furthermore, as white spruce trees at their northern range limit are expected to be susceptible to future changes in climate, radial growth models using only climate variables are produced and future forecasts (2009 - 2100) are also developed. Models were constructed using a stepwise regression analysis, employing monthly compiled variables for all ten sites. Model outputs were cross-referenced and important climate variables to white spruce radial growth were verified and landscape patterns of climatic responses were noted. Radial-growth forecast model outputs illustrate a generally decreasing radial growth rate at extreme northern locales, and moderate radial growth increases for more southern sites by 2100 AD. The radial growth forecasts produced here suggest that southern and intermediate latitude treeline sites may expand inland, while no expansion is expected at extreme northern locales along the coast. ---
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Comparison of Maximum Density Analysis and Ring Width Measurements: Applications in Dendroclimatology by Carrie White X-ray densitometry and maximum density analysis are techniques that have been extensively used for dendroclimatic reconstruction, though their application to treeline sites in northeastern Canada have been limited. In order to evaluate the potential of maximum density analysis for paleoclimatic reconstruction in setting, we sampled two locations along latitudinal treeline in Labrador using both a 5.1mm increment borer for standard total-ring width analysis, and 12mm increment borer for maximum density analysis. Total-ring width and maximum density chronologies were developed for white spruce ( Picea glauca ) at both locations. Sampleswere analyzed using standard dendroclimatological methods to determine their relationship to various climate variables and elucidate the influence of climate on their annual growth increments. Maximum density has been previously identified as a parameter of radial tree growth that is closely related to temperatures during the growing season. Through correlation and response function analysis it was determined that the radial growth of trees located at the more coastal northern site had a significant relationship between May temperature with the maximum density chronology, whereas no relationship was found with the total ring width chronology. The same scenario was found for the inland treeline site, where a relationship between maximum density and summer temperature was illustrated with the maximum density chronology, but no relationship found for the ring-width chronology. We determined that several maximum density growth parameters allow for superior climate-growth insights, including improved autocorrelation and mean sensitivity relationships. Identification of these radial growth relationships allowed for the reconstruction of a proxy climate data extending beyond the instrumental record for both sites. These results highlight the potential of using X-ray densitometry instead of simple ring-width analysis to construct proxy climate records. ---
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Climatic Stress Events and Radial Growth Forecasting of Acer saccharum Across New Brunswick and Central Nova Scotia, Canada By Ben E. Phillips Sugar maple (Acer saccharum Marsh) trees near their northern range limit have beenaffected by stress episodes in the past impacting radial growth. This study examines the past occurrence and causes of short- and long-term radial growth suppression periods. Radial growth models using only climate variables are produced for sugar maple and future forecasts (2000 - 2100) are developed for New Brunswick and central Nova Scotia, Canada. Improvements over past radial growth forecasting methodologies are sought to create more reliable future model projections. Tree-ring samples were collected from ten sugar maple stands in close proximity to long-term climate stations covering an area of climatic variability. A non-standard methodology was undertaken with the composition of climatic variables for application to the forecasting models by using daily climate records in an attempt to more effectively explain past short-term climatic events. Models were constructed using a stepwise regression analysis, employing both daily and monthly compiled variables for all ten sites. The model outputs were then cross-referenced to verify the important climate variables to sugar maple radial growth, and the landscape patterns of climatic responses were noted. Late winter thaw/refreeze events were examined for synchrony with sugar maple radial growth reduction periods, and Coupled Global Ocean-Atmosphere Interactions were evaluated for influence on sugar maple climatic responses. Radial growth forecast model outputs illustrate a generally decreasing radial growth rate across all sites, and extreme radial growth reductions for more the more southern sites. Coupled Global Ocean-Atmosphere Interaction correlation results indicate a strong positive relationship between sugar maple radial growth and long-term positive phases of the Atlantic Multidecadal Oscillation index. Additionally, a strong negative relationship was discovered with positive multidecadal phases of the North Atlantic Oscillation winter index. When all stressor information is synthesized, it appears that a period of favourable growing conditions may prevail until approximately 2025. After this time frame, climatic stress should increase, potentially leading to uneven effects across the landscape. This will cause growth reductions, crown dieback and limited mortality in sugar maple across the study area. Consequences of this outcome would be an expected impact to the volume of sugar maple sap for use in the production of maple syrup products, the aesthetics of fall foliage, and the various ecological services that sugar maple trees provide to the Acadian Forest Region. ---
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Latitudinal Gradient Analysis of Local Site Factors Influencing Growth in Three Boreal Tree Species By Felicia Pickard Boreal tree species are affected by a range of factors including the climate and local site components ranging from nutrient availability to soil quality. It is important to understand what factors play a role in affecting tree growth in order to predict the effects a changing climate will have on tree species. Three common boreal tree species: Larix laricina, Picea mariana and Piceaglauca were sampled along latitudinal gradients in northern and western Labrador to betterunderstand how variations in local site factors like foliar nitrogen concentrations and rooting depth affect the radial growth of these species. It was hypothesized that there would be decreased levels of foliar nitrogen and lower growth at more northern sites, while radial growth at the southern sites would be more affected by the local site factors. Although no latitudinal trends were found in this study for any of the species, there was a functional group response observed in terms of the species relationships between foliar nitrogen concentrations and radial growth. Larixlaricina , a deciduous conifer displayed increased growth with increased levels of nitrogen whichis representative of the performance based growth strategy of this species. Picea mariana andPicea glauca are both evergreen conifers. These two species displayed conservative growthstrategies with no response and a very weak response, respectively, in terms of their growth rates with foliar nitrogen concentrations. Rooting depth and tree height were also found to be contributing factors in association with radial growth for Picea glauca. The lack of anylatitudinal growth responses in relation to the measured variables of this study makes it difficult to predict future growth trends in relation to global climate change, but it does provide an initial understanding of the different factors which could play a role in affecting growth. ---
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Dendroclimatology, dendroecology and climate change in western Labrador, Canada By Peter H. Nishimura For the first time, a systematic radial growth analysis was undertaken to determine growth trends of conifers in western Labrador. Dominant and co-dominant species were sampled at 12 sites within a 3 x 4 grid of sites at the intersection of 52 °N, 53°N, 54°N and 55N latitude, and 62°W, 64°Wand 66 °W longitude. Master chronologies were developed for balsam fir (Abies balsamea), whitespruce ( Picea glauca), black spruce (Picea mariana), and eastern larch (Larix laricina), producing atotal of 24 chronologies. Samples were analyzed to determine the nature of growth-climate relationships in western Labrador, and response function analysis revealed positive growth response to summer temperature. Peak correlation values varied, however, from west to east, suggesting the presence of a gradient of continentality in the data and suggesting that western Labrador is subject to the converging influences of both continental and maritime climate. Radial growth was also examined for evidence of larch sawfly and spruce budworm outbreaks in the region. Growth reductions in eastern larch host series indicate previous larch sawfly activity as far back as the 18th century, and coincide with reconstructed sawfly outbreaks from adjacent studies. Investigation into past spruce budworm outbreaks are complicated by the absence of a true nonhost species. A new method was attempted whereby host series were compared to same-species regional running mean chronologies acting as nonhosts. Results of this analysis provide convincing evidence of spruce budworm outbreak that parallel outbreak documented in other eastern boreal studies. The revelation of western Labrador as a region of convergence climatic and disturbance influences provides a unique opportunity for bioclimatic study, particularly within the context of a changing climate. Climatically-influenced natural disturbances such as fire and insect outbreak are reviewed, with emphasis on Labrador and its gradient of continentality. Future climate change in Labrador, likely to be characterized by warmer summers and an eastward expansion of continental influences, may result in reduced growth-temperature correlations at the peak of the growing season. Additionally, increased summer precipitation will result in reduced fire frequency and subsequently greater influence of insect activity upon the landscape. Imminent climate change will precipitate unprecedented changes to Labrador’s forests. Further study is needed as we attempt to gain a more complete understanding of forest dynamics in this under-researched region. ---
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Mapping the Sydney Steel Plant Pollution: An Application in Dendroanalysis by Hannah C. MacDonald The Sydney Steel Plant operated for almost a century in the middle of the growing city of Sydney, Nova Scotia. Along with its steel, the plant (specifically the Coke Ovens) produced an array of pollutants including toxic metals. Although historically relevant, there is no consistent written record of this pollution throughout the steel plant’s history. The goal of this study is to produce a record of the Sydney Steel Plant pollution through both time and space. In order to establish a record, a natural bioindicator was needed. Within the Sydney area, a previous study determined that white birch ( Betula papyrifera) were able to incorporate varyingamounts of lead and zinc from the environment into their annual growth rings. In order to access this record, 18 white birch trees were sampled within a five kilometre radius of the Coke Ovens. Two cores were extracted per tree - one processed for dendrochronological analysis and the other processed into biannual segments for dendroanalytical analysis. The dendroanalysis consisted of using energy-dispersive x-ray fluorescence to detect the lead and zinc concentrations. In order to standardize the study area samples with base level concentrations of the metals, white birch samples from two pristine sites were also analyzed in the same manner. Lead and zinc concentration data were analyzed for spatial and temporal trends using a repeated-measures 2-way ANOVA, temporal change mapping and biannual pollution map animations. The results from this study illustrate a temporal trend of decreasing concentrations of both metals over time, especially after the Coke Ovens closure. The spatial trend indicates differential pollution distribution following the dominant wind direction. Although the results are approximate, the animations produced in this study are the most thorough pollution record for the Sydney Steel Plant. Overall, this study proved to be a successful application of dendroanalysis providing the highest annual resolution record using the energy-dispersive x-ray fluorescence technique to date. ---
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On spatio-temporal radioal growth response of four alpine treeline species to climate across central Labrador, Canada by Mariana Trindade This thesis applies standard dendrochronological techniques to contrast and compare between the radial growth responses of alpine treeline species across a climate gradient in central Labrador, Canada. Four species were examined: black spruce (Picea mariana (Mill.) B.S.P.), white spruce (Picea glauca (Moench) Voss), balsam fir (Abies balsamea (L.) Mill.) and eastern larch (Larix laricina (DuRoi) K. Koch). Eighteen tree ring width (TRW) chronologies were constructed at five alpine treeline sites across a 600 km long transect from the Labrador Sea to the Quebec border. The effects of climate and forest disturbance events on radial tree growth were examined at various spatial and temporal scales. This study is the first to conduct dendrochronological studies on black spruce, fir and larch in Labrador and to use samples from across central Labrador. The chronology statistics are in accordance with regional publications, with the exception of the larch chronologies, which have exceptionally high sensitivity values (MS > 0.3). These results suggest that the radial growth response of each one of the tree species sampled is uniquely adapted to monthly and/or seasonal temperature and precipitation values during the growing season and, in some cases, to winter snowfall amounts. These climate sensitivities are also site-specific and indicative of a strong reliance on the proximity of the Labrador Sea. This study simultaneously compares the radial growth patterns of the four alpine treeline species in a region that, to date, has been largely understudied. As a result, this study has identified possible periods of outbreaks of spruce budworm (Choristoneura fumiferana (Clem.)) and larch sawfly (Pristiphora erichsonii Hartig), which are synchronous with outbreaks reported from eastern Quebec. The intensity and frequency of these insect outbreaks is also climate-dependent, and can be so severe as to mask the climate sensitivity in the larch trees. A palaeoclimatic reconstruction (1847-2004) using merged spruce chronologies at one of the sites, the Mealy Mountains, is in accordance with other published records but has weak significance values due to a high degree of variability in climate sensitivity throughout the instrumental record (1942-present). The high degree of variability in the climate sensitivity of spruce trees across central Labrador is partly due to the effect of spruce budworm outbreaks on the radial growth of trees, but other site-specific factors such as moisture effects must also be contributing to the variability. Further studies are needed to determine the cause of this episodic divergence in the relationship between radial tree growth and climate in central Labrador in order to comprehend more fully which environmental factors influence radial tree growth, and how this changes with time. ---
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Dendroclimatic Response of High-Elevation Conifers, Vancouver Island, British Columbia by Colin P. Laroque The aim of this research program was to examine the growth response of high-elevation conifers on Vancouver Island to past, present and future climates. Forty locations were sampled and 88 chronologies were used to describe radial-growth changes over time and space. Radial-growth trends have been similar across Vancouver Island for most of the past 500 years. Large-scale oceanic influences on climate were shown to be strong forcing mechanisms to radial growth. Master chronologies were constructed for each of the five tree species examined: mountain hemlock, Tsuga mertensiana (Bong.) Carr., yellow-cedar, Chamaecyparis nootkatensis (D. Don) Spach, western hemlock, Tsuga heterophylla (Raf.) Sarg., Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, and western red-cedar, Thuja plicata Donn. The responses of these species to climate were combined to develop multiple aggregate chronologies (MACs). The MACs are able to record a stronger relationship to climate than all but the best single-species chronologies, with relationships to seasonalized parameters improved to a greater degree than those of single-month variables. < /p > < p align = "left" > Using these MAC relationships, proxy information was derived for four climate parameters < p align = "left" > (April 1 snowpack,June-July temperature, July temperature, July precipitation). The explained variance of the models was higher in the two seasonal reconstructions (April 1 snowpack depth r2 = 41 %, June-July temperature r2 = 34 %) than for individual monthly reconstructions (July precipitation r2 = 15 %, July temperature r2 = 24 %). A wavelet analysis showed that each of the four models contains dominant modes of variability throughout time at approximately 16, 32, 65 and 130-150 year periods. Each mode of variability seems to be linked to ocean forcing mechanisms. < /P > Climate/radial-growth relationships were used to predict radial growth under various future climate scenarios. TREE (Tree-ring Radial Expansion Estimator) was developed to present an interactive, internet-based radial- growth model, which calculates the short-term radial-growth response for each tree species to user-defined climate change scenarios. Long-term radial-growth responses were produced using data from general circulation models to develop relationships that predict future radial growth of each tree species. These predictions highlight which species are susceptible to future shifts in climate and indicate which climate parameters may drive changes in radial growth. ---
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The Dendrochronology and Dendroclimatology of Yellow-cedar on Vancouver Island, British Columbia by Colin P. Laroque The purpose of this study was to investigate the dendrochronological and dendroclimatological potential of yellow- cedar in the Pacific Northwest of North America. A primary objective was to establish whether the growth response of yellow-cedar is sensitive to climate fluctuations. Once it was determined that yellow-cedar was inherently sensitive, further dendroclimatological investigations were attempted. Trees were sampled at five sites between latitudes 50° and 51° on Vancouver Island. A total of 380 increment cores were collected in the summer of 1994. The samples were subsequently visually cross-dated, prior to ring- width measurement. Site indices were created and the five sites revealed a strong visual and statistical similarity. A regional index was constructed that represents the oldest living chronology for tree growth in Canada. A response function analysis was initiated to determine the significant climatic parameters to ring growth. This analysis identified previous August temperature as the variable most likely to influence variation in ring width. This variable was used to estimate current August temperature and associated parameters. The chronologies were compared to other relevant research on Vancouver Island and a common climate signal was apparent.
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Maintained by Colin P.
Laroque March 13, 2014 |
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