2017 ASHS Annual Conference

Keywords: Maple, sap, yield, flow, foliar nutrients, soil nutrients, canopy, core tissue, brix levels

Abstract

The maple industry in Canada is not only economically important, but culturally important as well. Canada produces 85% of the world’s maple syrup supply, amounting to approximately 12.2 million gallons in 2016. Quebec is Canada’s top producing province responsible for more than 90% of Canadian production. Ontario, New Brunswick and Nova Scotia produce most of the remaining maple product with NS contributing about 1% of the Canadian maple product. NS has a growing industry proven by increasing from 19,000 gallons in 2015 to 48,000 gallons in 2016. However, while the number of taps are increasing province wide, the average yield per tap has declined. This study examined tree physiological health and the impact of various environmental factors in comparison to sap yield and flow. Ten sites in the key production areas of NS were used to represent the provinces maple industry over two years. Measurements of site characteristics, canopy, leaf and core nutrition, trunk circumference, soil moisture content and potential, soil nutrients, vegetative competition and weather parameters were taken each month beginning June 2015. Maple sap was collected in the spring of 2016 and 2017. The sap was evaluated for yield, nutrients, and brix levels at the beginning and end of each tapping season. Over the two years of the study, there was no significant change in soil organic matter or trunk circumference. Soils were drier and canopies denser in 2015 compared to 2016. In year one there was a correlation between sap flow and yield at most sites, where trees with larger trunk diameters had higher average flow. Zinc concentrations proved significant in soil, leaf and core tissues when correlated with sap flow/yield though direction of correlations depended on sample type and time of analysis. Higher soil moisture content in August and March correlated positively with sap yield (r² 0.15, p<0.05), while higher LAI readings in July correlated with lower sap yields in the 2016 tapping season (r² 0.16, p<0.05). There were no significant relationships between site slope, elevation or latitude, however longitude was positively correlated with sap yield (r² 0.12, p<0.05). Leaf canopy densities in July displayed a negative correlation with sap brix levels, where denser canopies resulted in lower brix level. Overall, sap yield and flow is a complex process affected by various factors associated with tree health.