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 Colin Laroque Room 305, Avard-Dixon | |||||
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• Degrees
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Sunwapta Lake research site | |||||
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| Degrees | |||||
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| Affiliations | |||||
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Funding Agencies NSERC UFA | |||||
| Teaching Evaluations | |||||
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GENS 1401 - The Physical Environment - GENS 2411 - Geomorphology - GENS 2421 - Weather and Climate - GENS 3401 - Research Methods in Environmental Science
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Research Interests | |||||
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My research interests focus on past and future climates in Canada, especially on how they relate to dynamic ecosystem and geomorpholgical processes. My specialization is dendrochronology (tree-ring analysis) and I use dendrochronological techniques to gain an understanding about past climates, past glacier activity and extent, past ecosystem dynamics, and even past human activities through dendroarchaeological and dendrochemical investigations. I began my research career in 1991 studying glacial activity in the Kananaskis Front Ranges region of southwestern Alberta, and have continued my field studies in every year since. I have studied in many alpine regions including the Insular Mountain range of Vancouver Island, the Coastal Mountains of British Columbia, and in many areas of the Monashee, Selkirk, Purcell, and Main Ranges of the Canadian Rocky Mountains in British Columbia and Alberta. From 1995 to
2003 I was closely associated with the University of Victoria Tree-Ring
Laboratory (UVTRL) in the
Department of Geography at the University of Victoria. I have completed my
two postgraduate degrees through the UVTRL, and have been involved in a
number of other projects under the auspices of the lab. In the fall of 2003 I moved to Mount Allison University, where I have set up the first dendrochronology laboratory in Atlantic Canada. The Mount Allison Dendrochronology Lab (MAD Lab) was formed in January of 2004 and has concentrated its research efforts in the 4 Atlantic Canadian provinces. The future looks very positive as we have already initiated dendroclimatological, dendroarchaeological, dendrogeomorphological and dendroecological investigations. I urge you to visit the MAD Lab website to see what we are curently up to. I am also the webmaster for the CanDendro group. Please feel free to check out the website to see links to dendrochronological sites in Canada,the Canadian bibliographic database, or simplyto find links to dendrochronologists in Canada. | |||||
| Refereed Publications | |||||
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| Conference Presentations | |||||
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| Abstracts for Publications | |||||
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The relationship between monthly climate predictors and radial growth of Engelmann spruce (Picea engelmanni Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt) were explored using both a standard dendroclimatological approach and a multiple adaptive regressions splines (MARS) framework. Consistent with previous research, the radial growth of fir and spruce was related to temperature variables over the time period of the instrumental record. We identify important temporal instability in the statistical relationships between climate variables and the radial growth of both subalpine fir and Engelmann spruce. Using a 30-year running window, only four of the climate variables related to the radial growth of either spruce or fir did not show a switch in the sign of the correlation. A multiple adaptive regressions spline method was then used to gain insight into thresholds that may relate to radial growth/climate instabilities. Using MARS, we were able to identify knots and non-monotonic relationships between radial growth and climate predictors that may be indicators of ecological thresholds. This combination of dendroclimatic methods provides valuable insight into the complex nonlinear responses that both subalpine fir and Engelmann spruce have been growing under in the past centuries. | |||||
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Trindade, M., Bell, T., Laroque, C.P., Jacobs, J.D., and Hermanutz, L., 2011. Dendroclimatic response of a coastal alpine treeline: a multispecies perspective from Labrador. Canadian Journal of Forest Research, 41: 469-478. Coastal alpine forests are highly vulnerable to oceanic climate trends, yet these diverse environmental interac- tions remain poorly understood. We used a multispecies perspective to try to better assess the radial growth response of al- pine treeline species within the Northeast Atlantic region of North America to climate variables using bootstrapped correlation analysis. The four species present, 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 (Du Roi) K. Koch) were sampled in an effort to capture tree–climate sensitivity that is representative of this entire alpine treeline. The climate–growth rela- tionships of spruce trees were comparable with those reported in other Labrador studies, but spring drought sensitivity as reported for coastal northern white spruce trees was not observed. Rather, high levels of precipitation suggest that drought did not limit the radial growth of any of the four species. The relatively small number of statistically significant correla- tions between monthly climate variables and fir and larch trees suggests that factors other than climate limit their radial growth. The multispecies approach better highlighted the range of species-specific relationships between alpine treeline forests and maritime climates (monthly temperature and precipitation) found at the treeline ecotone. | |||||
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Trisalyn A. Nelson, Laroque, C.P., and Dan J.
Smith, 2011. Detecting spatial connections within a
dendrochronological network on Vancouver Island, British Columbia.
Dendrochronologia 29:49-54. | |||||
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Mariana Trindade, Trevor Bell , Laroque, C.P., 2011.
Changing climatic sensitivities of two spruce species across a moisture
gradient in Northeastern Canada. Dendrochronologia, 29:25-30. | |||||
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Felicia Pickard, André Robichaud and Laroque,
C.P., 2011. Using dendrochronology to date the Val Comeau canoe,
New Brunswick and developing an eastern white pine chronology in the
Canadian Maritimes. Dendrochronologia, 29:3-8. | |||||
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Hannah C.
MacDonald, Laroque, C.P., David E.B. Fleming and Mihai R.
Gherase, 2011. Dendroanalysis of metal pollution from the Sydney
Steel Plant in Sydney, Nova Scotia. Dendrochronologia, 29:9-15. | |||||
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Nishimura, P.H., and Laroque, C.P., 2010.
Observed continentality in radial growth-climate relationships in a twelve
site network in western Labrador, Canada. Dendrochronologia, 29:17-23. Despite their suitability for dendroclimatological research, the boreal regions of central and western Labrador remain under-researched. In an attempt to evaluate the growth trends and climatic response of this region's trees, master chronologies have been developed for its four dominant conifer species. Balsam fir (Abies balsamea (L.) Mill.), white spruce (Picea glauca (Moench) Voss), black spruce (Picea mariana (Mill.) Britton, Sterns, Poggenb.) and eastern larch (Larix laricina (DuRoi) K. Koch) were sampled systematically within a 3E—4E grid of twelve sites at the intersection of 62EW, 64EW and 66EW longitude, and latitudes 52EN, 53EN, 54EN and 55EN. The two most dominant species at each site were sampled, yield- ing a total of twenty-four master chronologies, all of which reflected a highly significant common signal at each site. The chronologies were subjected to a response function analysis to determine the nature of the growth-climate relationships in the region. Summer temperature proved to be the predominant limiting factor with regard to radial growth at most sites. The onset of the optimum temperature regime, however, varies across the network of sites, revealing evidence of a gradient of continentality in the data. Growth-temperature correlations indicated a significant relationship with July temperature at most east- ern sites, while western sites tended to correlate with May, June and August temperatures. Central sites tended to correlate with June-July temperatures. We interpret these results as demonstrating the biocli- matic gradient of change between coastally proximal, maritime-influenced sites and inland, continentally influenced locales. This transition occurs approximately 330 km inland from the open Labrador Sea. | |||||
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Quann, S.L., Young, A.B., Laroque C.P., Falcon-Lang, H.J., and Gibling, M.R., 2010. Dendrochronological dating of coal mine workings at Joggins Fossil Cliffs, Nova Scotia, Canada. Atlantic Geology 46:185-194.
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Nishimura, P.H., and Laroque, C.P., 2010.
Tree-ring evidence of larch sawfly outbreaks in western Labrador, Canada.
Canadian Journal of
Forest Research, 40:1542-1549. As many insect outbreak reconstructions are typically based on targeted single-site sampling, researchers have often been limited in their ability to draw conclusions about regional trends as opposed to local trends in the data. The results of this paper demonstrate the value of a systematic sampling design when studying spatio-temporal processes that can vary greatly within large continuous areas of forest. Many single-site research programs have been conducted to reconstruct the history of larch sawfly (Pristiphora erichsonii Htg.) outbreaks in the eastern boreal region of North America. However, no such research has yet been conducted in the region of Labrador. In an attempt to illustrate the strength of a systematic gridded sampling protocol over a single-site study, we sampled a 12-site grid in western Labrador. Dominant and codominant species were sampled at each grid point, resulting in 24 master chronologies. Six eastern larch (Larix laricina (Du Roi) K. Koch) chronologies (host) and a regional black spruce (Picea mariana (Mill.) Britton, Sterns, Poggenb.) chronology (nonhost) were used to establish a host–nonhost analysis of past sawfly outbreaks on a regional scale. Both re- gional and localized larch sawfly outbreaks were identified, but in general, larch sawfly outbreaks in western Labrador appeared to be spatially synchronous and regional in scale.
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M. Trindade and Laroque, C.P., 2009.
Multidisciplinary applications of tree-ring analysis in Newfoundland and
Labrador. Ktaqamkuk (Irish Journal of Newfoundland and Labrador
Studies), 1: 126-143. | |||||
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Robichaud, A., and Laroque, C.P., 2008. Dendroarchaeology in southwestern Nova Scotia and the construction of a regional red spruce chronology. Tree-Ring Research, 64(1): 17-25.
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Selig, N., Laroque, C.P., and Marsh, S., 2007. Dendroarchaeological investigations in the Maritimes: A case study of Dorchester House, New Brunswick. Material Culture Review, 66:42-49. This paper describes a method that allows social scientists to discern, with annual and even subannual precision, the construction dates of structures of historic value. The assignment of construction dates is seen as an instrumental starting point when historical investigators are researching individual buildings. By utilizing dendroarchaeological methods (tree-ring analysis), questions concerning when a structure was built, and who originally built or had the structure built, can be greatly illuminated. Dorchester House is one such example in New Brunswick. Description of the procedures to dendroarchaeologically date the structure are described and the initial date of construction (1821) and subsequent renovations (1859) are put in a better historical context once these dates are ascertained. The complex history of the area and the original lot is put into a much clearer timeline once the two dates are assigned to different sections of the house. The vast array of historical sources that relate to the property assessments and census records can be much more selectively filtered to describe with a higher probability the actual historical facts surrounding Dorchester House. The methods, although not new, could greatly assist research on the many other historical wooden structures in Atlantic Canada and elsewhere that have assumed and/or controversial dates of construction, and that are vulnerable to being lost through fire, demolition, or decomposition. This study highlights the underutilization of dendroarchaeological methods in Canada, and illustrates the utility it has to offer to many historical questions. | |||||
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Campbell, L.J.,, and Laroque, C.P.,, 2007. Decay progression and classification in two old-growth forests in Atlantic Canada. Forest Ecology and Management, 238: 293-301. This paper investigates the relationship between visually apparent stage of decay of coarse woody debris (CWD) and time since death of decaying balsam fir (Abies balsamea L.) and black spruce (Picea mariana [P. Mill]) in old-growth forests in western Newfoundland and in the Cape Breton Highlands (CBH) of Nova Scotia. These sites are two of the least disturbed old-growth forest locations remaining in Atlantic Canada. In Newfoundland, a total of 42 detrital samples were collected from downed logs and standing snags, of which 36 had their mortality dates determined. In the CBH, 50 detrital samples were collected, of which death dates for 44 samples were obtained. For both sites, samples represented all visually discernable classes of decay. In Newfoundland, these visual decay classes were separated by approximately 17 years for a minimum decay time of 85 years. In CBH, a faster rate of decomposition was apparent, with 12-year classes and a minimum decay time of logs of 60 years. Evidence points toward a climate-driven decay regime in both locations, with the longer time frame evident in Newfoundland thought to result from lower temperatures and fewer snow-free days than in CBH. | |||||
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Laroque, C.P., and Smith, D.J., 2005. Predicted short-term radial-growth changes of trees based on past climate on Vancouver Island, British Columbia. Dendrochronologia, 22: 163-168. Biologically-based deterministic multiple regression models are developed to investigate the consequences of future climates on the radial growth response of five high-elevation conifer species on Vancouver Island. Historical climate data and tree ring chronologies are used to establish robust relationships between climate and radial growth. Coupled General Circulation Modelled (CGCM) outputs are then used to provide monthly predictions of future climates from 2000 to 2100 AD. The established historical relationships are projected into the future using the CGCM data to predict radial growth. Results indicate that each species will react individually to predicted changes in climate, with no one dominant radial growth trend established. The most radical changes in the radial-growth behaviour occur within mountain hemlock (Tsuga mertensiana) trees that have adapted to survive in deep snowpack environments, a condition that future predictions highlight as the most susceptible to change. | |||||
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Bachrach, T., Jakobsen, K., Kinney, J., Nishimura, P., Reyes, A., Laroque, C.P., and Smith, D.J., 2004. Dendrogeomorphological assessment of movement at Hilda rock glacier, Banff National Park, Canadian Rocky Mountains. Geografiska Annaler A, 86A(1): 1-9. The results of this dendrogeomorphological study provide evidence of the active movement of Hilda rock glacier, a tongue-shaped rock glacier in the Columbia Icefield region of Banff National Park. Cross-sectional samples were cut from 44 detrital subalpine fir (Abies lasiocarpa (Hook.) Nutt.) and Engelmann spruce (Picea engelmannii Parry) boles killed and buried by debris spilling off the steep distal slope of the rock glacier. The samples were crossdated using locally and regionally developed tree-ring chronologies, and were shown to have been killed between 1576 and 1999. Our results show that Hilda rock glacier has advanced at an average rate of 1.62 cm/year since the late 1790s, with limited evidence of similar rates of activity extending back to the mid-1570s. This rock glacier activity is believed linked to persistent periglacial processes that appear to be independent of the climatic forcing mechanisms known to influence glacier mass balances over the same interval. | |||||
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Laroque, C.P.,
and Smith, D.J., 2003. Radial-growth forecasts for five
high-elevation conifer species on Vancouver Island, British Columbia.
Forest Ecology and Management 183: 313-325. | |||||
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Laroque, C.P., Lewis, D.H., and Smith, D. J.,
2000/01. Treeline dynamics on southern Vancouver Island, British
Columbia. Western Geography, 10/11: 43-63. | |||||
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Kellner, A.E.,
Laroque, C.P., Smith, D.J., and Harestad, A.S., 2000. Chronological
dating of high-elevation dead and dying trees on Northern Vancouver
Island, British Columbia. Northwest Science, 74: 242-247. | |||||
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Carter, R.,
LeRoy, S., Nelson, T., Laroque, C.P., and Smith, D.J., 1999.
Dendroglaciological investigations at Hilda Creek rock glacier, Banff
National Park, Canadian Rocky Mountains. Géographie physique et
Quaternaire, 53: 365-371. | |||||
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Laroque, C.P.,
and Smith, D.J., 1999. Tree-ring analysis of yellow-cedar
(Chamaecyparis nootkatensis) on Vancouver Island, British Columbia.
Canadian Journal of Forest Research, 29: 115-123. | |||||
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Smith, D.J., and
Laroque, C.P., 1998. Mountain hemlock growth dynamics on Vancouver
Island. Northwest Science, 72 (Special Issue 2): 67-70. | |||||
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Smith, D.J., and
Laroque, C.P., 1998. High-elevation dendroclimatic records from
Vancouver Island. In: Decoding Canada’s Past: Climate Variations and
Biodiversity Change During the Last Millennium. MacIver, D.C. and Meyer,
R.E. (eds.). Atmospheric and Environment Services, Downsview, Ontario,
33-44. | |||||
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Smith, D.J., and
Laroque, C.P., 1996. Dendroglaciological dating of a Little Ice Age
glacial advance at Moving Glacier, Vancouver Island, British Columbia.
Géographie physique et Quaternaire, 50: 47-55. | |||||
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Denton, J.J.,
Laroque, C.P., Williams, A.E., and Wilson, P.J., 1995. Proglacial
sedimentation in the Loss Creek valley, southwestern Vancouver Island,
British Columbia. Western Geography, 5: 1-12. These results do not support past research indicating that a single post-Vashon maximum resurgence of the Juan de Fuca ice lobe formed a 460 m ice dam at the mouth of Loss Creek. It seems more likely that the region experienced multiple sequences of advance and retreat phases. Further research is necessary to fully decipher the complex glacial history of this area. | |||||
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Lawby, C.P.,
Smith, D.J, Laroque, C.P., and Brugman, M.M., 1995. Glaciological
studies at Rae Glacier, Canadian Rocky Mountains. Physical Geography, 15:
425-441. Rae Glacier has experienced a significant loss in size and mass during the historical period due to a lengthy interval of negative mass balance conditions. The glacier has decreased in surface area by over 50% and now contains less than 25% of the ice it did at the end of the last century. Surface ice velocity varied between 1.4-5.4 m in 1990 to 1991. Rates of ice ablation proved to be highly variable, with steeper areas showing up to 50% more ablation. Combined with data on the emergent flow component of the glacier, the ablation data suggest the glacier is presently unable to replenish the amount of ice annually being lost to ablation. The glacier has a lag time of between five to ten years which confirms it is sensitive to climatic fluctuations and responds to changes in mass balance within a very short time. This observation is supported by an estimated response time of 42 years. | |||||
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Abstracts for Theses
Laroque, C.P.,
2002. Dendroclimatic Response of High-Elevation Conifers, Vancouver
Island, British Columbia. Ph.D. Dissertation, University of Victoria,
Victoria, British Columbia, 213p. Using these MAC relationships, proxy information was derived for four climate parameters (April 1 snowpack depth, 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. 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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Laroque, C.P.,
1995. The Dendrochronology and Dendroclimatology of Yellow-cedar on
Vancouver Island, British Columbia. M.Sc. Thesis, University of Victoria,
Victoria, British Columbia, 104p. 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 the Faculty of Social
Sciences
November 13, 2012
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