Tree Rings in common garden Experiments (T-REX)

Girardin, M.P., Isabel, N., Guo, X.J., Lamothe, M., Duchesne, I., Lenz, P. 2021. Annual aboveground carbon uptake enhancements from assisted gene flow in boreal black spruce forests are not long-lasting. Nature Communications. https://doi.org/10.1038/s41467-021-21222-3
Assisted
gene flow between populations has been proposed as an adaptive forest
management strategy that could contribute to the sequestration of carbon. Here
we provide an assessment of the mitigation potential of assisted gene flow in
46 populations of the widespread boreal conifer Picea mariana, grown in two 42-year-old common garden experiments
and established in contrasting Canadian boreal regions. We use a dendroecological
approach taking into account phylogeographic structure to retrospectively
analyse population phenotypic variability in annual aboveground net primary
productivity (NPP). We compare population NPP phenotypes to detect signals of
adaptive variation and/or the presence of phenotypic clines across tree
lifespans, and assess genotype‐by‐environment interactions by evaluating
climate and NPP relationships. Our results show a positive effect of assisted
gene flow for a period of approximately 15 years following planting, after
which there was little to no effect. Although not long lasting, well-informed
assisted gene flow could accelerate the transition from carbon source to carbon
sink after disturbance.