What is the adaptive potential of Black Spruce populations to climate stress?

Questions: What trait combinations will be under selection in warmer and drier climates? Are some black spruce populations adapt more easily, (plastically within generations and evolutionarily among generations) to selection gradient under these stresses?

Study system: 7 black spruce populations each measured in 3 common-garden sites established in 1974

Results: t.b.d.

What are the plastic and performance responses of tree seedlings under heat and water deficit?

Question: In Canada climate change is expected to lead to concurrent heat and drought stresses. (1) Can we disentangle the plastic trait response of these two stressors on tree species? (2) Will this plasticity allow some tree species to maintain their performance (growth) in the face of these stressors?

Study system: 2-yr-old seedlings from 5 common tree species were grown in the greenhouse in 6 environments reflecting a combination of heat & no heat and low, medium and high water deficit. leaf, stem and root traits were measured.

Preliminary results: The traits showing a plastic response to heat stress and to water deficit were almost entirely different. The two stresses did not compound each other to increase the loss of performance. The plasticity of few traits were associated with the maintenance of growth rate under stress.

Can traits predict plant species response to warming?

Work with Mark Vellend, Antoine Becker-Scarpitta, Cyrille Violle and Yuanzhi Li

Question: We (1) assess whether changes in species  abundances and elevation can be predicted by phenotypic traits, and; (2) examine how functional diversity has changed over time in response to a warming climate. 

Study System: The 37 most common understory species from Mont Mégantic’s temperate and boreal forests were studied (Qc, Canada). Leaf, whole-plant and root traits were measured in 9-12 individuals from each species and 48 plots sampled in 1974 were re-sampled in 2012 to measure community functional diversity, species mean elevation and mean abundance in both time periods.

Results: We find that root traits and leaf mass fraction predict species shift in abundance and elevation. We also find that the trait composition of high-elevation plots has shifted to resemble that of low-elevation plots, leading to homogenization

Pith eccentricity decreases the accuracy of basal area increment estimations but taking multiple cores can account for this error

Questions: (Q1) How much does basal area increment (BAI) estimation error results from pith and stem eccentricities, (Q2) How does the number of cores sampled affect estimation error due to eccentricity, and (Q3) Are some area calculation methods better than others at accounting for BAI estimation error arising from eccentricity?

Study System: 109 cross sections from 25 temperate angiosperm tree species were studied. The pith offset and stem eccentricity of each cross-section was quantified. The true BAI between two adjacent rings was calculated, as well as the estimated BAI from 1, 2-perpendicular, 2-opposite, 3 and 4 cores, using various area calculation methods.

Results: (Q1) When sampling only one core, eccentricity does increase BAI estimation error, with pith eccentricity explaining 21% of the variance in estimation error and stem eccentricity explaining 8%. (Q2) These effects can be reduced by taking more cores, as for both types of eccentricity, estimation error decreases with an increasing number of cores sampled. In fact, taking four cores completely accounts for eccentricity. Adding a second opposite core leads to the largest decreases in error. (Q3) Different estimation methods did not perform differently.

Loss of foliage on Black Spruce promotes abundance and richness of epiphytic bryophytes and lichens along branches

Questions: Do tree physiological traits drive the abundance and composition of epiphytic bryophytes and lichen communities?

Study System: We characterized 3 physiological and 5 morphological traits of 20 black spruce (Picea mariana) individuals from a boreal forest stand. On each tree, the abundance, richness and composition of the epiphytic communities of branches and stems was characterized.

Results: Older and larger trees had less foliage and were associated with an increase in both epiphytic coverage and richness on branches but a decrease in coverage on the trunk.

Does phenotypic integration In sunflowers change under salt stress?

Questions: Does the overall phenotypic integration and pairwise trait correlations of sunflowers increase under salinity stress?

Study System: Population of 288 sunflower inbred lines. 6 traits were measured: 2 size traits, 2 photosynthetic traits and 2 biomass allocation traits.

Results: Patterns of integration are largely similar between benign and stressful environments, with 2 trait-trait correlations disappearing and 1 appearing under stressful environments. The overall. The overall integration strength increased about ~10%.

Can traits predict tree performance?

Questions: We examine three key assumptions: (1) that traits are good predictors of plant performance, (2) that traits are better indicators of plant performance than species identity, and (3) that environmental filtering operates on traits.

Study System: 18-20 tree saplings from each of the 24 most common tree species on Mont Saint-Hilaire (Qc, Canada) for a total of 380 saplings. 21 traits and 20 environmental variables and basal area growth were measured on each sapling.

Results: Preliminary analyses find that (1) traits explains most of variance in RGR, (2) that adding species does not improve the models but instead that species affect RGR through traits, and (3) that the environment affects RGR largely through its interaction with traits.

Do genetic constraints underpin the intraspecific tradeoff between leaf lifespan and maximum photosynthetic rate?

Question: Here we test the hypothesis that a proximate mechanism responsible for the upper limit of the trade-off between Leaf Lifespan and maximum photosynthetic rate is reduced genetic variation within species.

Study system: We tested this hypothesis in Arabidopsis thaliana, an autogamous species that naturally exhibits little to no genetic diversity through meiosis. We compared 308 individuals from natural accessions (F0) and 2nd (F2) generations, which were created from manually crossing the F0 lines.

Results: t.b.d.

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This research was made possible by funding from:

• Programme de Coopération en recherche dans la francophonie canadienne

• Discovery Grants
• Early Career Launch Supplement
• Postodoctoral Fellowships

• John R. Evans Leaders Fund

• Bourses de recherche postdoctorale

• Sustainability Action Fund

• Small Infrastructure Funds