Alexandre Florent Nolin, Xiao Jing Guo, Yves Bergeron, Martin-Philippe Girardin, Jacques Tardif, France Conciatori. A 247-year tree-ring reconstruction of spring temperature
and relation to spring flooding in eastern boreal Canada. 2022. Int. J. Climatol. 42(12):6479-6498
DOI : 10.1002/joc.7608
Few records of spring paleoclimate are available for boreal Canada, as biological proxies recording the beginning of the warm season are uncommon. Given the spring warming observed during the last decades, and its impact on snowmelt and hydrological processes, searching for spring climate proxies is receiving increasing attention. Tree-ring anatomical features and intra-annual widths were used to reconstruct the regional March to May mean air temperature from 1770 to 2016 in eastern boreal Canada. Nested principal component regressions calibrated on 116 years of gridded temperature data were developed from one Fraxinus nigra and 10 Pinus banksiana sites. The reconstruction indicated three distinct phases in spring temperature variability since 1770. Ample phases of multi-decadal warm and cold springs persisted until the end of the Little Ice Age (1850–1870 CE) and were gradually replaced since the 1940s by decadal to interannual variability associated with an increase in the frequency and magnitude of warm springs. Significant correlations with other paleotemperature records, gridded snow cover extent and runoff support that historical high flooding were associated with late, cold springs with heavy snow cover. Most of the high magnitude spring floods reconstructed for the nearby Harricana River also coincided with the lowest reconstructed spring temperature per decade. However, the last 40 years of observed and reconstructed mean spring temperature showed a reduction in the number of extreme cold springs contrasting with the last few decades of extreme flooding in the eastern Canadian boreal region. This result indicates that warmer late spring mean temperatures on average may contribute, among other factors, to advance the spring break-up and to likely shift the contribution of snow to rain in spring flooding processes.
Alexandre Florent Nolin, Yves Bergeron, Jacques Tardif, France Conciatori. Flood-Rings Production Modulated by River Regulation in Eastern Boreal Canada. 2021. Frontiers in Plant Science 12:2422
DOI : 10.3389/fpls.2021.757280
In northeastern boreal Canada, the long-term perspective on spring flooding is hampered by the absence of long gage records. Changes in the tree-ring anatomy of periodically flooded trees have allowed the reconstruction of historical floods in unregulated hydrological systems. In regulated rivers, the study of flood rings could recover past flood history, assuming that the effects of hydrological regulation on their production can be understood. This study analyzes the effect of regulation on the flood-ring occurrence (visual intensity and relative frequency) and on ring widths in Fraxinus nigra trees growing at five sites distributed along the Driftwood River floodplain. Driftwood River was regulated by a dam in 1917 that was replaced at the same location in 1953. Ring width revealed little, to no evidence, of the impact of river regulation, in contrast to the flood rings. Prior to 1917, high relative frequencies of well-defined flood rings were recorded during known flood years, as indicated by significant correlations with reconstructed spring discharge of the nearby Harricana River. After the construction and the replacement of the dam, relative frequencies of flood rings and their intensities gradually decreased. Flood-ring relative frequencies after 1917, and particularly after 1953, were mostly composed of weakly defined (less distinct) flood rings with some corresponding to known flood years and others likely reflecting dam management. The strength of the correlations with the instrumental Harricana River discharge also gradually decrease starting after 1917. Compared with upper floodplain trees, shoreline trees at each site recorded flood rings less frequently following the construction of the first but especially of the second dam, indicating that water level regulation limited flooding in the floodplains. Compared with the downstream site to the dam, the upstream ones recorded significantly more flood rings in the postdam period, reemphasizing the importance of considering the position of the site along with the river continuum and site conditions in relation to flood exposure. The results demonstrated that sampling trees in multiple riparian stands and along with various hydrological contexts at a far distance of the dams could help disentangle the flooding signal from the dam management signal.
Jacques Tardif, Susanne Kames, Alexandre Florent Nolin, Yves Bergeron. Earlywood Vessels in Black Ash (Fraxinus nigra Marsh.) Trees Show Contrasting Sensitivity to Hydroclimate Variables According to Flood Exposure. 2021. Frontiers in Plant Science 12:2192
DOI : 10.3389/fpls.2021.754596
In recent years, the utility of earlywood vessels anatomical characteristics in identifying and reconstructing hydrological conditions has been fully recognized. In riparian ring-porous species, flood rings have been used to identify discrete flood events, and chronologies developed from cross-sectional lumen areas of earlywood vessels have been used to successfully reconstruct seasonal discharge. In contrast, the utility of the earlywood vessel chronologies in non-riparian habitats has been less compelling. No studies have contrasted within species their earlywood vessel anatomical characteristics, specifically from trees that are inversely exposed to flooding. In this study, earlywood vessel and ring-width chronologies were compared between flooded and non-flooded control Fraxinus nigra trees. The association between chronologies and hydroclimate variables was also assessed. Fraxinus nigra trees from both settings shared similar mean tree-ring width but floodplain trees did produce, on average, thicker earlywood. Vessel chronologies from the floodplain trees generally recorded higher mean sensitivity (standard deviation) and lower autocorrelation than corresponding control chronologies indicating higher year-to-year variations. Principal components analysis (PCA) revealed that control and floodplain chronologies shared little variance indicating habitat-specific signals. At the habitat level, the PCA indicated that vessel characteristics were strongly associated with tree-ring width descriptors in control trees whereas, in floodplain trees, they were decoupled from the width. The most striking difference found between flood exposures related to the chronologies' associations with hydroclimatic variables. Floodplain vessel chronologies were strongly associated with climate variables modulating spring-flood conditions as well as with spring discharge whereas control ones showed weaker and few consistent correlations. Our results illustrated how spring flood conditions modulate earlywood vessel plasticity. In floodplain F. nigra trees, the use of earlywood vessel characteristics could potentially be extended to assess and/or mitigate anthropogenic modifications of hydrological regimes. In absence of major recurring environmental stressors like spring flooding, our results support the idea that the production of continuous earlywood vessel chronologies may be of limited utility in dendroclimatology.
Jacques Tardif, Heather Dickson, Alexandre Florent Nolin, Yves Bergeron, France Conciatori. Are periodic (intra-annual) tangential bands of vessels in diffuse-porous tree species the equivalent of flood rings in ring-porous species? Reproducibility and cause. 2021. Dendrochronologia 70:125889
DOI : 10.1016/j.dendro.2021.125889
Tree rings from ring-porous species have often been used as flood proxy. Many ring-porous species produce characteristic flood rings in response to stem submersion during vessel formation. Flood rings have earlywood vessels that are more numerous and/or of smaller cross-sectional area than “normal” rings. This study aimed at determining if diffuse-porous balsam poplar and trembling aspen, like ring-porous black ash, produce anatomically distinct annual tree rings in response to flooding. More specifically, we asked (i) if periodic tangential bands of vessels (hereafter PTBV) could be as easily identified/quantified as flood rings and (ii) if PTBV could be associated with spring flooding. Sampling of black ash, balsam poplar and trembling aspen trees took place along a flood exposure gradient in the floodplain of Lake Duparquet in northwestern Québec. Two observers recorded flood rings and PTBV. Consistency between observers was greatest when identifying flood rings. In both diffuse-porous species, PTBV occurred less abundantly than flood rings in black ash. They also occurred less often in balsam poplar than in trembling aspen. Years in which PTBV were initiated early in the growing season were associated with years in which flood rings occurred. Like flood rings, early occurring PTBV were more abundant in springs characterized by high mean river discharge, extensive snow cover, cold temperatures and heavy precipitation. Early-occurring PTBV dominated in flooded sites and late-occurring ones dominated in the control site. However, PTBV of the late-types were also observed in both flood exposures indicating that spring flood may not be the only factor modulating their formation. While flood rings seem to be associated with a change in the transport of growth regulators resulting from stem submergence and excess water, PTBV may be reflective of rhythmic alterations in the transport of growth regulators resulting from either water excess or deficit. Despite promising findings, many questions remain before PTBV in riparian diffuse-porous species can be widely used as a flood proxy. Why do species and individual trees differ in their ability to record them? What is the full range of environmental conditions triggering PTBV’s formation especially in unflooded sites and in the late growing season?
Alexandre Florent Nolin, Yves Bergeron, Jacques Tardif, France Conciatori. Spatial coherency of the spring flood signal among major river basins of
eastern boreal Canada inferred from flood rings. 2021. Journal of hydrology 596:126084
DOI : 10.1016/j.jhydrol.2021.126084
In eastern boreal Canada, long-term perspective in water resources and hydroelectric dam management is currently limited by the lack of long-term hydrological records. The research for new paleohydrological proxies would help fill this hydrological data gap and provide regional hydroclimatic predictive trajectories in the context of climate change. The development of long annually resolved series of earlywood vessel cross-sectional area has recently demonstrated a high potential for reconstructing high and low discharges. This study analyzes a network of 10 sites scattered around Lake Duparquet. The region covers an area of about 20 000 km2 including four river basins characterized by natural and regulated rivers, and unflooded control sites. The objectives were to assess 1) the spatial coherency in flood-rings chronologies among sites and Lake Duparquet, and among hydrological regimes (natural, regulated and unflooded control) and 2) their degree of association with i) annually resolved chronologies of earlywood vessel cross-sectional area and number, ii) a reconstruction of the Harricana River spring discharge and iii) discharge data from eleven hydrometric stations distributed in the study area. It was hypothesized that flood rings would be consistent among natural rivers and absent from regulated rivers. Results showed high spatial coherency among natural rivers with flood rings recording the major floods of the last 250 years. Flood ring and earlywood vessel chronologies were strongly correlated to both reconstructed and instrumental discharge data. On regulated rivers, trees were younger than at the other sites and mainly spring floods that occurred prior to dam creation and the few extreme floods after dam creation were recorded by flood rings. One hypothesis is that older trees (before dam) most likely recorded the natural dynamic of the river, while younger trees (after dam) most likely recorded dam management maneuvers and spring flood exceeding dam capacity. Flood rings and earlywood vessel chronologies provided comparable and complementary hydrological evidence. Flood rings were easily identified visually allowing fast determination of major flood years whereas developing earlywood vessel chronologies, while being more tedious and time consuming, allowed capturing a larger spectrum of hydrological conditions
Alexandre Florent Nolin, Jacques Tardif, France Conciatori, Susanne Kames, D.M. Meko, Yves Bergeron. Multi-century tree-ring anatomical evidence reveals increasing frequency
and magnitude of spring discharge and floods in eastern boreal Canada. 2021. Global and Planetary Change 103444
DOI : 10.1016/j.gloplacha.2021.103444
In eastern boreal Canada, variability in river discharge is poorly understood at the multi-century scale due to short instrumental records. In recent decades, increased magnitude and frequency of spring floods have raised concerns about the potential effects of climate change on flood risk. Unlike tree-ring width, flood rings have a demonstrated dendrochronological utility for reconstructing high discharge in boreal environments. In this study, twelve chronologies of earlywood vessel cross-sectional area (a new hydrological proxy) and ring width were developed from riparian Fraxinus nigra trees periodically flooded in spring. These chronologies were used as predictors of Harricana River spring discharge, which was reconstructed for the period 1771–2016. The reconstruction captured 69% of the variance over a 102-year calibration period. The reconstruction indicates that the magnitude and frequency of spring high discharge has increased since the end of the Little Ice Age (1850–1870 CE) and since 1950. The change from a multi-decadal frequency in the late 19th century to a decadal and then interannual frequency in the late 20th century is associated with an increase in snow cover over much of central-eastern Canada. The association between the reconstructed spring discharge and spring atmospheric circulation indices NINO3.4, AMO, NAO may also have changed in these periods and further work is needed to assess the stability of these associations. The correlation between reconstructed and instrumental spring discharge at the regional scale, as well as the shared features in reconstructed discharge and other paleorecords from subarctic Québec suggest a common hydrological signal across the study area and for the early 20th to 21st centuries. The unprecedently low and high spring discharge in recent decades compared to the historical natural variability of the last 250 years also suggests that the increase in flood frequency and magnitude originates from climate change.
Jian Kang, Shaowei Jiang, Hanxue Liang, Shaokang Zhang, Jingye Li, Biyun Yu, Yves Bergeron, Sergio Rossi, Zhou Wang, Peng Zhou, Jian-Guo Huang, Jacques Tardif. Radial growth responses of two dominant conifers to climate in the Altai
Mountains, Central Asia. 2021. Agric. For. Meteorol. 298-299:108297
DOI : 10.1016/j.agrformet.2020.108297
The boreal forests of Central Asia play a vital role in biodiversity protection and regional economic development. It is important to study potential changes in the growth dynamics of boreal species in a context of global change. In this study, we developed a network of 34 tree-ring chronologies for two tree species, Siberian larch (Larix sibirica Ledeb.) and Siberian pine (Pinus sibirica Du Tour). The network extended across a large latitudinal gradient (45°N to 55°N). Principal component analysis (PCA) was used to detect spatial patterns in tree radial growth during a common period 1943–2004. Results indicated an obvious clustering pattern with chronologies being divided into a northeastern (NR) and a southwestern (SR) region. Bootstrapped correlation analyses of regional climate versus aggregated chronologies showed that tree radial growth in both regions was positively associated with summer temperature (June and July). Tree radial growth in the northeastern region was however positively associated with early spring precipitation and spring Palmer Drought Severity Index (PDSI) whereas, in the southwestern region, it was characterized by negative correlations with early summer precipitation and summer PDSI. The warm pool El Niño-Southern Oscillation (WP ENSO) and North Atlantic Oscillation (NAO) regulated tree radial growth through their influence on regional precipitation and temperature. Results suggest that tree radial growth in the region may decline with future projected climate change. This study provides a more comprehensive understanding to tree growth-climate associations across Central Asia.
Justin Waito, Yves Bergeron, France Conciatori, Adam Ali, Martin-Philippe Girardin, Jacques Tardif. Recent fire activity in the boreal eastern interior of North America
is below that of the past 2000 yr. 2018. Ecosphere 9(6):e02287
DOI : 10.1002/ecs2.2287
The North American boreal forest has been developing since the end of the last glaciation
approximately 10,000 yr ago. With climate warming and human occupation, it is anticipated that fire danger,
ignition, and activity will be increasing, compromising forests’ benefits for generations to come. In this
study, we show, however, that a century of rapid climate changes and human densification has had the
opposite effect in the boreal eastern interior of the North American continent, reducing biomass burning to
values below two millennia of historical levels. A multi-millennial fire history was reconstructed for eight
forested landscapes from the Lake of the Woods Ecoregion (LWE) located at the boreal–prairie ecotone.
Fire history was reconstructed using a combination of archival (period 1920–2010), tree-ring (stand initiations
and fire scars: period 1690–2010), and lake sediment charcoal (2500 BP to present) records. The archival
record revealed recent large fires (>200 ha) in 1948, 1980, and 1988. An additional 19 fires were
identified by the fire-scar record. Fire events in 1805, 1840, 1863, and the 1890s were identified in numerous
locations around multiple lakes suggesting that they were of large extents. In accordance with the tree-ring
record, the charcoal accumulation rate (CHAR) peak record generally identified the major fires but tended
to lag from the tree-ring records by several decades. Within LWE, the long-term charcoal record revealed
that CHAR was higher for each lake in the earlier portion of the record including the warm Medieval
Climate Anomaly (AD 900 to AD 1000), followed by a progressive decrease toward the cool Little Ice
Age period. This decline was abruptly interrupted in the mid- to late 19th century with large synchronized
fires, also reported over western and central North America, and resumed approximately four decades
later. Fire disturbance level is today below the historical range, despite the accentuated climate warming.
Aging of the forest landscape may create biodiversity loss notably in fire-adapted species while at the same
time setting the tone for major fires in upcoming decades if no action is taken for managing fuels.
Susanne Kames, Yves Bergeron, Jacques Tardif. Continuous Earlywood Vessels Chronologies in Floodplain Ring-Porous Species can Improve Dendrohydrological Reconstructions of Spring High Flows and Flood Levels. 2016. Journal of hydrology 534:377-389
DOI : 10.1016/j.jhydrol.2016.01.002
Plants respond to environmental stimuli through changes in growth and development. Characteristics of wood cells such as the cross-sectional area of vessel elements (hereafter referred to as vessels) may store information about environmental factors present at the time of vessel differentiation. The analysis of vessel characteristics therefore offers a different time resolution than annual ring width because vessels in tree rings differentiate within days to a few weeks. Little research has been conducted on the sensitivity of earlywood vessels in ring-porous species in response to flooding. The general objectives of this study were to determine the plasticity of earlywood vessel to high flows and spring flooding in floodplain black ash (Fraxinus nigra Marsh.) trees and to assess the utility of developing continuous earlywood vessel chronologies in dendrohydrological reconstruction. In contrast, most dendrohydrological studies until now have mainly used vessel anomalies (flood rings) as discrete variables to identify exceptional flood events. The study area is located in the boreal region of northwestern Québec. Vessel and ring-width chronologies were generated from F. nigra trees growing on the floodplain of Lake Duparquet. Spring discharge had among all hydro-climatic variables the strongest impact on vessel formation and this signal was coherent spatially and in the frequency domain. The mean vessel area chronology was significantly and negatively correlated to discharge and both the linearity and the strength of this association were unique. In floodplain F. nigra trees, spring flooding promoted the formation of more abundant but smaller earlywood vessels. Earlywood vessels chronologies were also significantly associated with other hydrological indicators like Lake Duparquet’s ice break-up date and both ice-scar frequency and height chronologies. These significant relationships stress the utility of developing continuous vessels chronologies for hydrological reconstructions prior to instrumental data. Continuous earlywood vessel chronologies may also be useful in determining the impact of altered hydrological regime in floodplain habitat regulated by spring floods. Future research should involve quantifying the impact of high flows and flooding on other cell constituents and also determining the plasticity and utility of continuous anatomical series in floodplain diffuse-porous species.
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Yves Bergeron, Lihong Zhai, Frank Berninger, Jian-Guo Huang, Bernhard Denneler, Jacques Tardif. Impact of Future Climate on Radial Growth of Four Major Boreal Tree Species in the Eastern Canadian Boreal Forest. 2013. PlosOne
DOI : 10.1371/journal.pone.0056758
Immediate phenotypic variation and the lagged effect of evolutionary adaptation to climate change appear to be two key processes in tree responses to climate warming. This study examines these components in two types of growth models for predicting the 2010–2099 diameter growth change of four major boreal species Betula papyrifera, Pinus banksiana, Picea mariana, and Populus tremuloides along a broad latitudinal gradient in eastern Canada under future climate projections. Climate-growth response models for 34 stands over nine latitudes were calibrated and cross-validated. An adaptive response model (A-model), in which the climate-growth relationship varies over time, and a fixed response model (F-model), in which the relationship is constant over time, were constructed to predict future growth. For the former, we examined how future growth of stands in northern latitudes could be forecasted using growth-climate equations derived from stands currently growing in southern latitudes assuming that current climate in southern locations provide an analogue for future conditions in the north. For the latter, we tested if future growth of stands would be maximally predicted using the growth-climate equation obtained from the given local stand assuming a lagged response to climate due to genetic constraints. Both models predicted a large growth increase in northern stands due to more benign temperatures, whereas there was a minimal growth change in southern stands due to potentially warm-temperature induced drought-stress. The A-model demonstrates a changing environment whereas the F-model highlights a constant growth response to future warming. As time elapses we can predict a gradual transition between a response to climate associated with the current conditions (F-model) to a more adapted response to future climate (A-model). Our modeling approach provides a template to predict tree growth response to climate warming at mid-high latitudes of the Northern Hemisphere.
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Lou Delayance, Alexandre Florent Nolin, Yves Bergeron, Jacques Tardif. Susceptibilité des peuplements de frêne noir (fraxinus nigra) à la régulation du niveau des crues printanières sur le lac Duparquet 24e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-11-22)
Jacques Tardif Comparative analysis of the daily and monthly radial growth of seven boreal tree species in northwestern Québec International conference on dendrochronology for the third millenium. Mendoza, Argentina.
Martin-Philippe Girardin, Jacques Tardif, Micheal Flannigan, Yves Bergeron. Reconstructing atmospheric circulation history using tree rings: one more step toward understanding temporal changes in forest dynamics 3rd International Sustainable Forest Management Network Conference, Shaw Conference Centre, Edmonton, Alberta, Canada.
Jian-Guo Huang, Yves Bergeron, Jacques Tardif, Bernhard Denneler, Frank Berninger, Martin-Philippe Girardin. Response of four major boreal tree species to climate warming along a latitudinal gradient in western Quebec, Canada 1st American Dendro Conference, Vancouver, BC.
Martin-Philippe Girardin, Jacques Tardif, Micheal Flannigan, Yves Bergeron. Synoptic scale atmospheric circulation and summer drought variability of the past three centuries, Boreal Canada 90th Annual Meeting of the Ecological Society of America, Montreal, Quebec, Canada.
Jian-Guo Huang, Yves Bergeron, Bernhard Denneler, Jacques Tardif. Dendroclimatological analyses of trembling aspen (Populus tremuloides Michx.) along a latitudinal gradient in western Quebec, Canada 7th International Conference on Dendrochronology, Beijing, China.