Mistik Askiwin Dendrochronology Laboratory

Theses From MAD Labbers


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Master of Science 

Dendroclimatology and Dendroecology of the

Dominant Coniferous Speces in

Eastern Labrador, Canada


Dean Dumaresq



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Honors Thesis 

Tree Age and Growth at Barrens Forest Edges in Cape Breton

Highlands National Park


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


Carrie White



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Master of Science

 Dendroclimatology of Picea glauca at tree line in

northern Labrador, Canada


Christopher Kennedy



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Honours Thesis

 Comparison of maximum density analysis and ring width

measurements: applications in dendroclimatology


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


Benjamin E. Phillips



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Honours Thesis

 Latitudinal gradient analysis of local site factors influencing

in three boreal tree species


Felicia Pickard



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Master of Science Thesis

 Dendroclimatology, dendroecology and climate change

 in western Labrador, Canada


Peter H. Nishimura



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Honours Thesis

 Mapping the Sydney Steel Plant pollution:

 an application in dendroanalysis


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


Mariana Trindade



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Doctor of Philosophy

 Dendroclimatic response of high-elevation conifers,

Vancouver Island, British Columbia


Colin P. Laroque



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Master of Science Thesis

 The dendrochronology and dendroclimatology of yellow-cedar

 on Vancouver Island, British Columbia


Colin P. Laroque

Abstracts for Theses

Dendroclimatology and Dendroecology of the Dominant Coniferous Tree Species in Eastern Labrador, Canada

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.


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.


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.



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 from

ten 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.



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. Samples

were analyzed using standard dendroclimatological methods to determine their relationship to

various climate variables and elucidate the influence of climate on their annual growth


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.



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 been

affected 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.



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 Picea

glauca were sampled along latitudinal gradients in northern and western Labrador to better

understand 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. Larix

laricina, a deciduous conifer displayed increased growth with increased levels of nitrogen which

is representative of the performance based growth strategy of this species. Picea mariana and

Picea glauca are both evergreen conifers. These two species displayed conservative growth

strategies 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 any

latitudinal 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.



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°W

and 66°W longitude. Master chronologies were developed for balsam fir (Abies balsamea), white

spruce (Picea glauca), black spruce (Picea mariana), and eastern larch (Larix laricina), producing a

total 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.



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 varying

amounts 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.



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.



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.



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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2014 Mistik Askiwin Dendrochronology Lab

Maintained by Colin P. Laroque
March 13, 2014