Francine Tremblay - Profile on Academia.edu (original) (raw)
Papers by Francine Tremblay
Data from: Influence of habitat availability and fire disturbance on the northern range boundary of eastern white cedar (Thuja occidentalis L.)
Aim Non-climatic constraints on species northern range boundaries are often overlooked in attempt... more Aim Non-climatic constraints on species northern range boundaries are often overlooked in attempts to predict climate-induced range shifts. Here, we examined the effects of habitat availability and fire disturbance on the distribution of eastern white cedar (Thuja occidentalis L.) at the northern boundary of its range. Location North-western Quebec, Canada (46-51° N and 74-79° W) Methods We used forest inventory data (n=4,987) to characterize white-cedar habitat based on edaphic and topographic conditions at sampled sites along a 600-km latitudinal gradient. Non-metric multidimensional scaling was used to assess habitat similarity of sites in the south, where white-cedar stands are abundant, and sites in the north, where white-cedar stands are rare. We constructed ensemble white cedar distribution models based on habitat variables in the south and compared ensemble forecast projections of white cedar in the north with observed occurrences to determine if habitat availability was lim...
Aspen_SSR_Data_Latutrie_et _al
Canadian Journal of Botany, 2003
To determine overall genetic variability in aspen (Populus tremuloides Michx.) along the clay bel... more To determine overall genetic variability in aspen (Populus tremuloides Michx.) along the clay belt of northwestern Quebec, four populations were sampled at the transition zone between mixed-wood and conifer-dominated forests using a hierarchical strategy. Our objectives were (i) to estimate gene diversity among and within populations using microsatellite markers and (ii) to examine whether clonal structuring in aspen could be detected. For each population, three stands at least 1 km apart were sampled. Within each stand, five putative clones were sampled with a distance of 50 m between each clone. To examine potential genetic diversity within clones, for three of the putative clones sampled per stand, the three trees closest to this individual (potential ramets) were also sampled. All samples were analysed at four microsatellite loci. Measures of genetic variation all indicated that most of the variation occurred within rather than among the populations. R st , based on a stepwise mutation model, was 0.0409, slightly higher than F st , which was based on infinite allele model (0.0323). Within each stand, DNA fingerprint of five putative clones allowed the differentiation of genetically distinct individuals within these putative clones, and from 1.62 to 2.2 times more genetically distinct individuals were identified than by morphological identification. In the present study there was no correlation between the mean distance of the potential ramet to the central trunk (potential ramets were often within 2-3 m of the central trunk) and the possibility of the central trunk and ramet sharing the same genotype. The number of unique genotypes for the three putative clones sampled per stand varied from 11 genotypes per 15 samples to 14 per 15 samples. Consequently, it was not possible to identify clones by either distance from a given central trunk or morphological characteristics. Thus, after stand disturbance, suckers from different genotypes are likely to be closely mixed.
Disentangling the effect of topography and microtopography on near-ground growing-season frosts at the boreal-temperate forest ecotone (Québec, Canada)
New Forests, 2021
Frontiers in Plant Science, 2020
adapting the temperature-driven hypotheses of ecophysiological models predicting leafout to inclu... more adapting the temperature-driven hypotheses of ecophysiological models predicting leafout to include spring frost probability.
BMC Evolutionary Biology, 2019
BackgroundGenetic processes shape the modern-day distribution of genetic variation within and bet... more BackgroundGenetic processes shape the modern-day distribution of genetic variation within and between populations and can provide important insights into the underlying mechanisms of evolution. The resulting genetic variation is often unequally partitioned within species’ distribution range and especially large differences can manifest at the range limit, where population fragmentation and isolation play a crucial role in species survival. Despite several molecular studies investigating the genetic diversity and differentiation of European Alpine mountain forests, the climatic and demographic constrains which influence the genetic processes are often unknown. Here, we apply non-coding microsatellite markers to evaluate the sporadic peripheral and continuous populations of cembra pine (Pinus cembraL.), a long-lived conifer species that inhabits the subalpine treeline ecotone in the western Alps to investigate how the genetic processes contribute to the modern-day spatial distribution...
Importance of landscape features and fire refuges on genetic diversity of Thuya occidentalis L., in boreal fire dominated landscapes
Conservation Genetics, 2018
The unburned forest remnants of boreal mixed-woods, also known as fire residuals, are essential i... more The unburned forest remnants of boreal mixed-woods, also known as fire residuals, are essential in providing habitats for disturbance-sensitive species and function as the main source of recolonization of disturbed sites. Forest remnants have been identified as historical or potential reservoirs of genetic diversity in several tree species in fire-prone landscapes. In this study, we investigate the genetic diversity of eastern white cedar (EWC, Thuya occidentalis L.), in forest sites that were affected by different fire regimes. The study area is located in northwestern Quebec, in the Lake Duparquet Research and Teaching Forest (79°10′W–48°30′N). We used 18 polymorphic microsatellite loci to investigate the genetic diversity of eastern white cedar, in forest sites where the fire regime history has been reconstructed to examine the importance of the temporal and spatial continuity of the forest on the genetic diversity of EWC. Three types of landscapes, including; islands within a large lake, fragmented fire refuges (forest patches) and non-fragmented mainland forests were studied. Our results revealed a source-sink dynamic associated with a high level of gene flow. Two of the mainland sites served as the main source of migrants. The level of gene flow in island sites was sufficiently high to counteract the effect of isolation. The fire refuges showed the lowest allelic richness, the highest population differentiation and the fewest number of private alleles. The mean fire-free intervals are much longer in fire-refuges causing environmental isolation through time and higher genetic differentiation. The conservation of large mainland sites should be given careful attention because they maintained high genetic diversity and function as the main source of gene flow. Fire refuges have an intrinsic conservation value in landscapes that are affected by spatially heterogeneous fires because they are important for population persistence through disturbances.
Journal of Biogeography, 2019
Global change biology, Jan 24, 2018
Contrary to the generally advanced spring leaf unfolding under global warming, the effects of the... more Contrary to the generally advanced spring leaf unfolding under global warming, the effects of the climate warming on autumn leaf senescence are highly variable with advanced, delayed, and unchanged patterns being all reported. Using one million records of leaf phenology from four dominant temperate species in Europe, we investigated the temperature sensitivities of spring leaf unfolding and autumn leaf senescence (S , advanced or delayed days per degree Celsius). The S of spring phenology in all of the four examined species showed an increase and decrease during 1951-1980 and 1981-2013, respectively. The decrease of the S during 1981-2013 appears to be caused by reduced accumulation of chilling units. As with spring phenology, the S of leaf senescence of early successional and exotic species started to decline since 1980. In contrast, for late successional species, the S of autumn senescence showed an increase for the entire study period from 1951 to 2013. The impacts of rising temp...
Biomass from young hardwood stands on marginal lands: Allometric equations and sampling methods
Biomass and Bioenergy, 2017
Abstract We developed allometric equations for small-diameter woody species growing on mixed fore... more Abstract We developed allometric equations for small-diameter woody species growing on mixed forest marginal lands, which are potential sources of biomass for bioenergy. Eleven species of trees and shrubs were sampled from a site located in eastern Canada. Equations derived in this study generally performed better than equations from the literature. Also, fixed-area plots (FAP) and line-intersect sampling (LIS) methods using both random or systematic selection of sampling units were compared to determine which method required the lowest number of measurements to estimate stand biomass for the same precision. The fixed-area plots method was successfully used to estimate relatively accurately oven-dry biomass per hectare. Results indicated that potentially harvestable woody biomass (oven dry basis) varied between 33-41 and 12–13 t ha −1 for the most and least productive marginal sites respectively. On the most productive site, LIS estimates (between 20 and 42 t ha −1 ) were usually lower than those obtained using different FAP sampling methods (i.e. systematic or random, small (50 m 2 ) or large (100 m 2 ) plots), but similar on the more open sites (between 10 and 14 t ha −1 ). Small FAP resulted in a plot without measurements in one case. Moreover, estimates based on small FAP were generally higher, even if not significantly different from larger plot estimates. We therefore suggest using FAP with 100 m 2 plots to estimate small-diameter woody biomass on marginal lands with dense vegetation, while LIS, even if promising for open stands, needs further evaluation before recommendation.
Frontiers in Ecology and Evolution, 2016
Tree species responses to climate change will be greatly influenced by their evolutionary potenti... more Tree species responses to climate change will be greatly influenced by their evolutionary potential and their phenotypic plasticity. Investigating tree-rings responses to climate and population genetics at the regional scale is crucial in assessing the tree behavior to climate change. This study combined in situ dendroclimatology and population genetics over a latitudinal gradient and compared the variations between the two at the intra-and inter-population levels. This approach was applied on the northern marginal populations of Thuja occidentalis (eastern white-cedar) in the Canadian boreal forest. We aimed first to assess the radial growth variability (response functional trait) within populations across the gradient and to compare it with the genetic diversity (microsatellites). Second, we investigated the variability in the growth response to climate at the regional scale through the radial growth-climate relationships, and tested its correlation with environmental variables and population genetic structure. Model selection based on the Akaike Information Criteria revealed that the growth synchronicity between pairs of trees of a population covariates with both the genetic diversity of this population and the amount of precipitation (inverse correlations), although these variables only explained a small fraction of the observed variance. At the regional scale, variance partitioning and partial redundancy analysis indicate that the growth response to climate was greatly modulated by stand environmental variables, suggesting predominant plastic variations in growth-response to climate. Combining in situ dendroclimatology and population genetics is a promising way to investigate species' response capacity to climate change in natural stands. We stress the need to control for local climate and site conditions effects on dendroclimatic response to climate to avoid misleading conclusions regarding the associations with genetic variables.
BMC evolutionary biology, Oct 26, 2016
In North America, the last ice age is the most recent event with severe consequences on boreal sp... more In North America, the last ice age is the most recent event with severe consequences on boreal species' ranges. Phylogeographic patterns of range expansion in trembling aspen (Populus tremuloides) suggested that Beringia is likely to be a refugium and the "ice-free corridor" in Alberta may represent a region where small populations persisted during the last glacial maximum (LGM). The purpose of this study was to ascertain whether the origins of trembling aspen in western North America are reflected in the patterns of neutral genetic diversity and population structure. A total of 28 sites were sampled covering the northwestern part of aspen's distribution, from Saskatchewan to Alaska. Twelve microsatellite markers were used to describe patterns of genetic diversity. The genetic structure of trembling aspen populations was assessed by using multivariate analyses, Mantel correlograms, neighbor-joining trees and Bayesian analysis. Microsatellite markers revealed little...
Ecology and Evolution, 2016
Balsam poplar seeds are short-lived and require moist seedbeds soon after they are released to ge... more Balsam poplar seeds are short-lived and require moist seedbeds soon after they are released to germinate. In addition to sexual reproduction, balsam poplar stands can regenerate clonally by root suckering. The origin of stands will in turn affect their genetic structure and root system architecture, which are poorly understood for upland forest stands. Three stands were hydraulically excavated in Quebec (moist) and Alberta (dry) to determine the origin of trees and to characterize root systems with respect to presence of parental roots and root grafts connections. Clones were identified using single-nucleotide polymorphism (SNPs), and all stems, roots and root grafts were aged using dendrochronology techniques. All 82 excavated trees were of sucker origin, and four of the six stands contained a single clone. Parental root connections were found between 22% and 25% of excavated trees, and 53% and 48% of trees were linked with a root graft between the same or different clones, in Alberta and Quebec, respectively. Mean distance between trees connected by parental root was significantly lower than the distance between unconnected trees (0.47 ± 0.25 m vs. 3.14 ± 0.15 m and 1.55 ± 0.27 m vs. 4.25 ± 0.13 m) in Alberta and in Quebec, respectively. The excavations also revealed many dead stumps with live roots, maintained through root connections with live trees. This research highlights that balsam poplar growing in upland stands is a clonal species that can maintain relatively high genotypic diversity, with frequent root connections between trees at maturity. Maintaining an extensive root system through root connections increases the chances of a clone surviving when the above ground tree is dead and may also enhance the resilience of balsam poplar stands after disturbance.
Dissimilar patterns of Christ. populations in Bulgaria revealed by chloroplast microsatellites and terpenes analysis
Biochem Syst Ecol, 2005
Root connections affect radial growth of balsam poplar trees
Trees, 2016
Key messageConnected root systems reduced the negative impact of August temperatures and insect o... more Key messageConnected root systems reduced the negative impact of August temperatures and insect outbreak on growth.AbstractRoot connections between trees can be an ecological advantage of clonal plant species in environments with unevenly distributed resources. We investigated the effects of root connectivity in stands of balsam poplar in Quebec (Canada). We evaluated differences in growth response between groups of trees with and without root connections through climate-growth analyses, comparison of the growth dynamics, and analysis of growth response to a severe forest tent caterpillar (FTC) outbreak. Current May temperature had a positive influence on radial growth of both connected and non-connected trees. Growth of non-connected trees was negatively affected by August temperatures (r = −0.3) while connected trees did not reveal a significant relationship for that month. A mixed effect ANOVA showed a significant difference (F1, 25 = 5.59, p = 0.02) in growth responses to FTC outbreak between connected and non-connected trees. Connected trees grew on average 16 % better than unconnected trees during the outbreak, with bootstrapped 95 % confidence range from 2.28 to 31.36 %. The study suggests a sharing of resources through root connections, affecting radial growth of connected balsam poplar trees under both average and extreme environmental conditions.
Structure of L. populations in Bulgaria revealed by chloroplast microsatellites and terpenes analysis: Provenance tests
Biochem Syst Ecol, 2005
Evolutionary Applications, 2016
Selection cutting is a treatment that emulates tree-by-tree replacement for forests with uneven-a... more Selection cutting is a treatment that emulates tree-by-tree replacement for forests with uneven-age structures. It creates small openings in large areas and often generates a more homogenous forest structure (fewer large leaving trees and defective trees) that differs from old-growth forest. In this study, we evaluated whether this type of harvesting has an impact on genetic diversity of sugar maple (Acer saccharum Marshall). Genetic diversity among seedlings, saplings, and mature trees was compared between selection cut and old-growth forest stands in Qu ebec, Canada. We found higher observed heterozygosity and a lower inbreeding coefficient in mature trees than in younger regeneration cohorts of both forest types. We detected a recent bottleneck in all stands undergoing selection cutting. Other genetic indices of diversity (allelic richness, observed and expected heterozygosity, and rare alleles) were similar between forest types. We concluded that the effect of selection cutting on the genetic diversity of sugar maple was recent and no evidence of genetic erosion was detectable in Qu ebec stands after one harvest. However, the cumulative effect of recurring applications of selection cutting in bottlenecked stands could lead to fixation of deleterious alleles, and this highlights the need for adopting better forest management practices.
Plasticity of bud phenology and photosynthetic capacity in hybrid poplar plantations along a latitudinal gradient in northeastern Canada
Environmental and Experimental Botany, 2016
Abstract Intensively managed plantations are being established in a wide range of environmental c... more Abstract Intensively managed plantations are being established in a wide range of environmental conditions to satisfy the high demand for wood products and reduce the exploitation pressure on natural forests. In this study, we investigated the plasticity of four hybrid poplar (Populus spp.) clones established in 2005 along a latitudinal gradient in northwestern Quebec, Canada. The effect of latitudinal gradient on maximum rates of electron transfer (Jmax) and carboxylation (Vcmax), dark respiration (Rd), spring and fall bud phenology, net photosynthesis (Pn), specific leaf area (SLA), per mass nitrogen leaf concentration (Nm) were assessed in order to evaluate if clonal plasticity would result in increased overall productivity. Growth season duration between the southernmost to the northernmost sites ranged 21–32 days, and was positively correlated to stem volume and negatively correlated to bud burst and bud set duration. Growth increment (stem volume) along the latitudinal gradient ranged 100–184% between the least and most productive clone. Clone 747215 had the most stable but the slowest growth. Leaf net photosynthesis decreased or did not change northwards except for the most productive clone for which it increased slightly likely due to a significant decrease in SLA. Maximum rates of carboxylation and photosynthesis electron transfer (Vcmax and Jmax) decreased northwards for three of the four clones, suggesting that photosynthesis of trees did not acclimate to lower temperatures from south to north. Plasticity of photosynthetic variables, measured with trait plasticity index was usually greater than that of SLA and Nm.
Tree physiology, Jul 3, 2016
Clonal integration between ramets can be an ecological advantage of clonal plant species in envir... more Clonal integration between ramets can be an ecological advantage of clonal plant species in environments where resources are patchily distributed. We investigated physiological integration among Populus balsamifera L. ramets under drought stress in order to demonstrate water sharing between connected ramets. Pairs of connected ramets were grown in separate pots in the greenhouse where half of ramets had the parental root connection severed and half were left intact. Drought stress was applied to one ramet, and growth, specific leaf area (SLA), net photosynthesis, stomatal conductance, leaf water potential and carbon isotopic composition (δ(13)C) were measured after an 8-week growing period. Droughted ramets connected to watered ramets were able to maintain high gas exchange activity and water potential, similar to watered ramets. Leaf water potential and SLA results showed that the root connection was more beneficial for proximal compared with distal ramets. The parental root connec...
Phyton, 2003
Analysis of chromosome morphology in natural populations of Pinus nigra ARN. (European Black Pine... more Analysis of chromosome morphology in natural populations of Pinus nigra ARN. (European Black Pine) in Bulgaria showed a karyotype diversity of 30% among populations. Seventy-nine Black Pine trees from 9 natural provenances were examined. Based on average values for all 12 chromosomes pairs (short arm S, long arm L, total length T, arm ratio and index class) for each provenance, a total of 9 different karyotypes were discovered, depending on the average values of the lengths of short arm and long arm of the chromosomes. Inter-population variability of the karyotype was summarized with Principal Component Analysis/ Factor Analysis. These analyses showed that European Black Pine in Bulgaria can be divided into three basic groups: (1) "Western Black Pine Formation"; (2) "Marginal Black Pine Formation" and (3) "Central Rhodopean Mountain Black Pine Formation". This pattern of inter-population differentiation suggest that after the warming of the climate, migration of European Black Pine to higher altitudes and recolonization of sites also with other tree species would have occured at different speeds with varying success. This has
Data from: Influence of habitat availability and fire disturbance on the northern range boundary of eastern white cedar (Thuja occidentalis L.)
Aim Non-climatic constraints on species northern range boundaries are often overlooked in attempt... more Aim Non-climatic constraints on species northern range boundaries are often overlooked in attempts to predict climate-induced range shifts. Here, we examined the effects of habitat availability and fire disturbance on the distribution of eastern white cedar (Thuja occidentalis L.) at the northern boundary of its range. Location North-western Quebec, Canada (46-51° N and 74-79° W) Methods We used forest inventory data (n=4,987) to characterize white-cedar habitat based on edaphic and topographic conditions at sampled sites along a 600-km latitudinal gradient. Non-metric multidimensional scaling was used to assess habitat similarity of sites in the south, where white-cedar stands are abundant, and sites in the north, where white-cedar stands are rare. We constructed ensemble white cedar distribution models based on habitat variables in the south and compared ensemble forecast projections of white cedar in the north with observed occurrences to determine if habitat availability was lim...
Aspen_SSR_Data_Latutrie_et _al
Canadian Journal of Botany, 2003
To determine overall genetic variability in aspen (Populus tremuloides Michx.) along the clay bel... more To determine overall genetic variability in aspen (Populus tremuloides Michx.) along the clay belt of northwestern Quebec, four populations were sampled at the transition zone between mixed-wood and conifer-dominated forests using a hierarchical strategy. Our objectives were (i) to estimate gene diversity among and within populations using microsatellite markers and (ii) to examine whether clonal structuring in aspen could be detected. For each population, three stands at least 1 km apart were sampled. Within each stand, five putative clones were sampled with a distance of 50 m between each clone. To examine potential genetic diversity within clones, for three of the putative clones sampled per stand, the three trees closest to this individual (potential ramets) were also sampled. All samples were analysed at four microsatellite loci. Measures of genetic variation all indicated that most of the variation occurred within rather than among the populations. R st , based on a stepwise mutation model, was 0.0409, slightly higher than F st , which was based on infinite allele model (0.0323). Within each stand, DNA fingerprint of five putative clones allowed the differentiation of genetically distinct individuals within these putative clones, and from 1.62 to 2.2 times more genetically distinct individuals were identified than by morphological identification. In the present study there was no correlation between the mean distance of the potential ramet to the central trunk (potential ramets were often within 2-3 m of the central trunk) and the possibility of the central trunk and ramet sharing the same genotype. The number of unique genotypes for the three putative clones sampled per stand varied from 11 genotypes per 15 samples to 14 per 15 samples. Consequently, it was not possible to identify clones by either distance from a given central trunk or morphological characteristics. Thus, after stand disturbance, suckers from different genotypes are likely to be closely mixed.
Disentangling the effect of topography and microtopography on near-ground growing-season frosts at the boreal-temperate forest ecotone (Québec, Canada)
New Forests, 2021
Frontiers in Plant Science, 2020
adapting the temperature-driven hypotheses of ecophysiological models predicting leafout to inclu... more adapting the temperature-driven hypotheses of ecophysiological models predicting leafout to include spring frost probability.
BMC Evolutionary Biology, 2019
BackgroundGenetic processes shape the modern-day distribution of genetic variation within and bet... more BackgroundGenetic processes shape the modern-day distribution of genetic variation within and between populations and can provide important insights into the underlying mechanisms of evolution. The resulting genetic variation is often unequally partitioned within species’ distribution range and especially large differences can manifest at the range limit, where population fragmentation and isolation play a crucial role in species survival. Despite several molecular studies investigating the genetic diversity and differentiation of European Alpine mountain forests, the climatic and demographic constrains which influence the genetic processes are often unknown. Here, we apply non-coding microsatellite markers to evaluate the sporadic peripheral and continuous populations of cembra pine (Pinus cembraL.), a long-lived conifer species that inhabits the subalpine treeline ecotone in the western Alps to investigate how the genetic processes contribute to the modern-day spatial distribution...
Importance of landscape features and fire refuges on genetic diversity of Thuya occidentalis L., in boreal fire dominated landscapes
Conservation Genetics, 2018
The unburned forest remnants of boreal mixed-woods, also known as fire residuals, are essential i... more The unburned forest remnants of boreal mixed-woods, also known as fire residuals, are essential in providing habitats for disturbance-sensitive species and function as the main source of recolonization of disturbed sites. Forest remnants have been identified as historical or potential reservoirs of genetic diversity in several tree species in fire-prone landscapes. In this study, we investigate the genetic diversity of eastern white cedar (EWC, Thuya occidentalis L.), in forest sites that were affected by different fire regimes. The study area is located in northwestern Quebec, in the Lake Duparquet Research and Teaching Forest (79°10′W–48°30′N). We used 18 polymorphic microsatellite loci to investigate the genetic diversity of eastern white cedar, in forest sites where the fire regime history has been reconstructed to examine the importance of the temporal and spatial continuity of the forest on the genetic diversity of EWC. Three types of landscapes, including; islands within a large lake, fragmented fire refuges (forest patches) and non-fragmented mainland forests were studied. Our results revealed a source-sink dynamic associated with a high level of gene flow. Two of the mainland sites served as the main source of migrants. The level of gene flow in island sites was sufficiently high to counteract the effect of isolation. The fire refuges showed the lowest allelic richness, the highest population differentiation and the fewest number of private alleles. The mean fire-free intervals are much longer in fire-refuges causing environmental isolation through time and higher genetic differentiation. The conservation of large mainland sites should be given careful attention because they maintained high genetic diversity and function as the main source of gene flow. Fire refuges have an intrinsic conservation value in landscapes that are affected by spatially heterogeneous fires because they are important for population persistence through disturbances.
Journal of Biogeography, 2019
Global change biology, Jan 24, 2018
Contrary to the generally advanced spring leaf unfolding under global warming, the effects of the... more Contrary to the generally advanced spring leaf unfolding under global warming, the effects of the climate warming on autumn leaf senescence are highly variable with advanced, delayed, and unchanged patterns being all reported. Using one million records of leaf phenology from four dominant temperate species in Europe, we investigated the temperature sensitivities of spring leaf unfolding and autumn leaf senescence (S , advanced or delayed days per degree Celsius). The S of spring phenology in all of the four examined species showed an increase and decrease during 1951-1980 and 1981-2013, respectively. The decrease of the S during 1981-2013 appears to be caused by reduced accumulation of chilling units. As with spring phenology, the S of leaf senescence of early successional and exotic species started to decline since 1980. In contrast, for late successional species, the S of autumn senescence showed an increase for the entire study period from 1951 to 2013. The impacts of rising temp...
Biomass from young hardwood stands on marginal lands: Allometric equations and sampling methods
Biomass and Bioenergy, 2017
Abstract We developed allometric equations for small-diameter woody species growing on mixed fore... more Abstract We developed allometric equations for small-diameter woody species growing on mixed forest marginal lands, which are potential sources of biomass for bioenergy. Eleven species of trees and shrubs were sampled from a site located in eastern Canada. Equations derived in this study generally performed better than equations from the literature. Also, fixed-area plots (FAP) and line-intersect sampling (LIS) methods using both random or systematic selection of sampling units were compared to determine which method required the lowest number of measurements to estimate stand biomass for the same precision. The fixed-area plots method was successfully used to estimate relatively accurately oven-dry biomass per hectare. Results indicated that potentially harvestable woody biomass (oven dry basis) varied between 33-41 and 12–13 t ha −1 for the most and least productive marginal sites respectively. On the most productive site, LIS estimates (between 20 and 42 t ha −1 ) were usually lower than those obtained using different FAP sampling methods (i.e. systematic or random, small (50 m 2 ) or large (100 m 2 ) plots), but similar on the more open sites (between 10 and 14 t ha −1 ). Small FAP resulted in a plot without measurements in one case. Moreover, estimates based on small FAP were generally higher, even if not significantly different from larger plot estimates. We therefore suggest using FAP with 100 m 2 plots to estimate small-diameter woody biomass on marginal lands with dense vegetation, while LIS, even if promising for open stands, needs further evaluation before recommendation.
Frontiers in Ecology and Evolution, 2016
Tree species responses to climate change will be greatly influenced by their evolutionary potenti... more Tree species responses to climate change will be greatly influenced by their evolutionary potential and their phenotypic plasticity. Investigating tree-rings responses to climate and population genetics at the regional scale is crucial in assessing the tree behavior to climate change. This study combined in situ dendroclimatology and population genetics over a latitudinal gradient and compared the variations between the two at the intra-and inter-population levels. This approach was applied on the northern marginal populations of Thuja occidentalis (eastern white-cedar) in the Canadian boreal forest. We aimed first to assess the radial growth variability (response functional trait) within populations across the gradient and to compare it with the genetic diversity (microsatellites). Second, we investigated the variability in the growth response to climate at the regional scale through the radial growth-climate relationships, and tested its correlation with environmental variables and population genetic structure. Model selection based on the Akaike Information Criteria revealed that the growth synchronicity between pairs of trees of a population covariates with both the genetic diversity of this population and the amount of precipitation (inverse correlations), although these variables only explained a small fraction of the observed variance. At the regional scale, variance partitioning and partial redundancy analysis indicate that the growth response to climate was greatly modulated by stand environmental variables, suggesting predominant plastic variations in growth-response to climate. Combining in situ dendroclimatology and population genetics is a promising way to investigate species' response capacity to climate change in natural stands. We stress the need to control for local climate and site conditions effects on dendroclimatic response to climate to avoid misleading conclusions regarding the associations with genetic variables.
BMC evolutionary biology, Oct 26, 2016
In North America, the last ice age is the most recent event with severe consequences on boreal sp... more In North America, the last ice age is the most recent event with severe consequences on boreal species' ranges. Phylogeographic patterns of range expansion in trembling aspen (Populus tremuloides) suggested that Beringia is likely to be a refugium and the "ice-free corridor" in Alberta may represent a region where small populations persisted during the last glacial maximum (LGM). The purpose of this study was to ascertain whether the origins of trembling aspen in western North America are reflected in the patterns of neutral genetic diversity and population structure. A total of 28 sites were sampled covering the northwestern part of aspen's distribution, from Saskatchewan to Alaska. Twelve microsatellite markers were used to describe patterns of genetic diversity. The genetic structure of trembling aspen populations was assessed by using multivariate analyses, Mantel correlograms, neighbor-joining trees and Bayesian analysis. Microsatellite markers revealed little...
Ecology and Evolution, 2016
Balsam poplar seeds are short-lived and require moist seedbeds soon after they are released to ge... more Balsam poplar seeds are short-lived and require moist seedbeds soon after they are released to germinate. In addition to sexual reproduction, balsam poplar stands can regenerate clonally by root suckering. The origin of stands will in turn affect their genetic structure and root system architecture, which are poorly understood for upland forest stands. Three stands were hydraulically excavated in Quebec (moist) and Alberta (dry) to determine the origin of trees and to characterize root systems with respect to presence of parental roots and root grafts connections. Clones were identified using single-nucleotide polymorphism (SNPs), and all stems, roots and root grafts were aged using dendrochronology techniques. All 82 excavated trees were of sucker origin, and four of the six stands contained a single clone. Parental root connections were found between 22% and 25% of excavated trees, and 53% and 48% of trees were linked with a root graft between the same or different clones, in Alberta and Quebec, respectively. Mean distance between trees connected by parental root was significantly lower than the distance between unconnected trees (0.47 ± 0.25 m vs. 3.14 ± 0.15 m and 1.55 ± 0.27 m vs. 4.25 ± 0.13 m) in Alberta and in Quebec, respectively. The excavations also revealed many dead stumps with live roots, maintained through root connections with live trees. This research highlights that balsam poplar growing in upland stands is a clonal species that can maintain relatively high genotypic diversity, with frequent root connections between trees at maturity. Maintaining an extensive root system through root connections increases the chances of a clone surviving when the above ground tree is dead and may also enhance the resilience of balsam poplar stands after disturbance.
Dissimilar patterns of Christ. populations in Bulgaria revealed by chloroplast microsatellites and terpenes analysis
Biochem Syst Ecol, 2005
Root connections affect radial growth of balsam poplar trees
Trees, 2016
Key messageConnected root systems reduced the negative impact of August temperatures and insect o... more Key messageConnected root systems reduced the negative impact of August temperatures and insect outbreak on growth.AbstractRoot connections between trees can be an ecological advantage of clonal plant species in environments with unevenly distributed resources. We investigated the effects of root connectivity in stands of balsam poplar in Quebec (Canada). We evaluated differences in growth response between groups of trees with and without root connections through climate-growth analyses, comparison of the growth dynamics, and analysis of growth response to a severe forest tent caterpillar (FTC) outbreak. Current May temperature had a positive influence on radial growth of both connected and non-connected trees. Growth of non-connected trees was negatively affected by August temperatures (r = −0.3) while connected trees did not reveal a significant relationship for that month. A mixed effect ANOVA showed a significant difference (F1, 25 = 5.59, p = 0.02) in growth responses to FTC outbreak between connected and non-connected trees. Connected trees grew on average 16 % better than unconnected trees during the outbreak, with bootstrapped 95 % confidence range from 2.28 to 31.36 %. The study suggests a sharing of resources through root connections, affecting radial growth of connected balsam poplar trees under both average and extreme environmental conditions.
Structure of L. populations in Bulgaria revealed by chloroplast microsatellites and terpenes analysis: Provenance tests
Biochem Syst Ecol, 2005
Evolutionary Applications, 2016
Selection cutting is a treatment that emulates tree-by-tree replacement for forests with uneven-a... more Selection cutting is a treatment that emulates tree-by-tree replacement for forests with uneven-age structures. It creates small openings in large areas and often generates a more homogenous forest structure (fewer large leaving trees and defective trees) that differs from old-growth forest. In this study, we evaluated whether this type of harvesting has an impact on genetic diversity of sugar maple (Acer saccharum Marshall). Genetic diversity among seedlings, saplings, and mature trees was compared between selection cut and old-growth forest stands in Qu ebec, Canada. We found higher observed heterozygosity and a lower inbreeding coefficient in mature trees than in younger regeneration cohorts of both forest types. We detected a recent bottleneck in all stands undergoing selection cutting. Other genetic indices of diversity (allelic richness, observed and expected heterozygosity, and rare alleles) were similar between forest types. We concluded that the effect of selection cutting on the genetic diversity of sugar maple was recent and no evidence of genetic erosion was detectable in Qu ebec stands after one harvest. However, the cumulative effect of recurring applications of selection cutting in bottlenecked stands could lead to fixation of deleterious alleles, and this highlights the need for adopting better forest management practices.
Plasticity of bud phenology and photosynthetic capacity in hybrid poplar plantations along a latitudinal gradient in northeastern Canada
Environmental and Experimental Botany, 2016
Abstract Intensively managed plantations are being established in a wide range of environmental c... more Abstract Intensively managed plantations are being established in a wide range of environmental conditions to satisfy the high demand for wood products and reduce the exploitation pressure on natural forests. In this study, we investigated the plasticity of four hybrid poplar (Populus spp.) clones established in 2005 along a latitudinal gradient in northwestern Quebec, Canada. The effect of latitudinal gradient on maximum rates of electron transfer (Jmax) and carboxylation (Vcmax), dark respiration (Rd), spring and fall bud phenology, net photosynthesis (Pn), specific leaf area (SLA), per mass nitrogen leaf concentration (Nm) were assessed in order to evaluate if clonal plasticity would result in increased overall productivity. Growth season duration between the southernmost to the northernmost sites ranged 21–32 days, and was positively correlated to stem volume and negatively correlated to bud burst and bud set duration. Growth increment (stem volume) along the latitudinal gradient ranged 100–184% between the least and most productive clone. Clone 747215 had the most stable but the slowest growth. Leaf net photosynthesis decreased or did not change northwards except for the most productive clone for which it increased slightly likely due to a significant decrease in SLA. Maximum rates of carboxylation and photosynthesis electron transfer (Vcmax and Jmax) decreased northwards for three of the four clones, suggesting that photosynthesis of trees did not acclimate to lower temperatures from south to north. Plasticity of photosynthetic variables, measured with trait plasticity index was usually greater than that of SLA and Nm.
Tree physiology, Jul 3, 2016
Clonal integration between ramets can be an ecological advantage of clonal plant species in envir... more Clonal integration between ramets can be an ecological advantage of clonal plant species in environments where resources are patchily distributed. We investigated physiological integration among Populus balsamifera L. ramets under drought stress in order to demonstrate water sharing between connected ramets. Pairs of connected ramets were grown in separate pots in the greenhouse where half of ramets had the parental root connection severed and half were left intact. Drought stress was applied to one ramet, and growth, specific leaf area (SLA), net photosynthesis, stomatal conductance, leaf water potential and carbon isotopic composition (δ(13)C) were measured after an 8-week growing period. Droughted ramets connected to watered ramets were able to maintain high gas exchange activity and water potential, similar to watered ramets. Leaf water potential and SLA results showed that the root connection was more beneficial for proximal compared with distal ramets. The parental root connec...
Phyton, 2003
Analysis of chromosome morphology in natural populations of Pinus nigra ARN. (European Black Pine... more Analysis of chromosome morphology in natural populations of Pinus nigra ARN. (European Black Pine) in Bulgaria showed a karyotype diversity of 30% among populations. Seventy-nine Black Pine trees from 9 natural provenances were examined. Based on average values for all 12 chromosomes pairs (short arm S, long arm L, total length T, arm ratio and index class) for each provenance, a total of 9 different karyotypes were discovered, depending on the average values of the lengths of short arm and long arm of the chromosomes. Inter-population variability of the karyotype was summarized with Principal Component Analysis/ Factor Analysis. These analyses showed that European Black Pine in Bulgaria can be divided into three basic groups: (1) "Western Black Pine Formation"; (2) "Marginal Black Pine Formation" and (3) "Central Rhodopean Mountain Black Pine Formation". This pattern of inter-population differentiation suggest that after the warming of the climate, migration of European Black Pine to higher altitudes and recolonization of sites also with other tree species would have occured at different speeds with varying success. This has