Temperature response curve of (A) the maximum carboxylation capacity of rubisco (Vcmax), (B) the maximum electron transport rate (Jmax) and (C) mesophyll conductance to CO2 (gm) of two geographically distant white spruce seed sources measured in the Watford plantation site in 2016 (fourth growing season) (n = 3). South SS, southern seed source (SO1-1); North SS, northern seed source (SO1-5).