The impact of climate change on southern Ontario’s maple syrup industry

Background/Question/Methods

The maple syrup industry is an important economic driver for many rural communities in northeastern United States and southeastern Canada. Given that maple syrup quality and yield is dependent on the timing and duration of the tapping season, there is growing concern over the industry’s vulnerability to climate change. Large changes in syrup quality and yield associated with warming spring temperatures, reduced winter snow cover, changes to precipitation patterns, and shifts in freeze-thaw cycles are increasingly being reported. What remains unknown is how these climatic changes are interacting with stand-level physiographic factors to impact maple tree health and syrup production. The purpose of our study is to determine the relative importance of climatic and physiographic factors on: (a) maple tree health, (b) sap sugar content, and (c) total sap yield. Seven commercial sugarbush stands were sampled in southern Ontario, Canada. Climactic, physiographic, and stand composition data were obtained for each site. The relative importance of climatic, physiographic, and stand composition factors on maple tree health, sap sugar content, and total yield will be determined using Principal Components Analysis (PCA) and information theoretic (IT) model selection using Akaike's information criterion (AIC) techniques.

Results/Conclusions

Preliminary results indicate that total precipitation during winter, maximum summer temperature, and sugarbush stand density strongly influence maple tree health (nb., components 1 and 2 accounted for 88.0 % of the total variation). Deep snow cover prevents soils from freezing, and thus, reduces damage to maple tree rooting systems. Moreover, snow cover impacts foliar Ca: Al ratios and increases foliar starch concentration. Higher density stands appeared less healthy given the more intense competition for canopy position and soil nutrients such as nitrogen (N) and phosphorus (P). Impacts of climatic and physiographic factors on sap sugar content and total yield will be discussed during our presentation (nb., to be determined after the spring 2022 tapping season).