Francine Tremblay - Academia.edu (original) (raw)

Papers by Francine Tremblay

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...

Canadian Journal of Botany, 2003

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...

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 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

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

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.

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.

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...