Table 2. Mean ambient plant surface temperatures (± SD) and the degrees above ambient achieved by the warming treatment from June 1st to September 30th (the portion of the growing season when the majority of photosynthesis occurs, and all our measurements were conducted). Means are shown for 24h periods, as well as for the period of the day when most photosynthetic activity occurs (08:00-16:00 hours) for the days when gas exchange measurements were conducted and overall means for the entire period between June 1st and September 30th across all years. All averages are pooled across years (2009 – 2019) and both sites (Cloquet Forestry Center – in Cloquet, MN and Hubachek Wilderness Research Center – Ely, MN), but separately for both canopies.