Intra- and inter-annual productivity of Betula glandulosa in Umiujaq, Nunavik (QC)
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The main objective of this project is to quantify the increased productivity of Betula glandulosa Michx in Umiujaq, Nunavik, northern Quebec and evaluate how climatic and edaphic conditions influence this change. The speed at which climate change is affecting the northern ecosystems remains poorly understood and data are needed to anticipate future ecological and physiological trajectories of the vegetation. We produced a tree-ring chronology from approximately 40 specimens of Betula glandulosa collected from two well-drained and two poorly-drained sites (mineral and organic soils). Tree rings were made into thin sections using a sliding microtome, stained and mounted on slides for analysis under the microscope. The samples were photographed using a camera mounted on a microscope. In addition to ring widths, multiple anatomical variables were measured from the thin sections such as the vessel sizes and the lumen area. These analyses enabled us to determine the interannual variability of shrub productivity within two different drainage conditions. H2O and CO2 gas exchanges were also monitored (3 years) using an eddy covariance flux tower (GPP, ER, NEP, NEE, EVT) within the vicinity. These data are coupled with local hydrometeorological variables in order to describe intra-annual variations in shrub productivity. Preliminary results show a strong positive correlation between the samples from the same environment, as well as between the environments, suggesting that the shrub productivity in Umiujaq (QC) responds to the same climate variables.