Fig. 2. Variation (a) of maximum and minimum daily air temperatures 2 m above the ground, (b) at the substrate surface and (c) in the rhizosphere, as well as the fluctuations in (d) relative humidity during the second growing season of air-slit containerized white spruce seedlings at Pampev Inc., a private forest nursery located in Saint-Louis-de-Blandford, QC, Canada (46° 25' N, 72° 00' W).