Nutritional And Environmental Factors Affection Sap Flow And Yield In Nova Scotian Maple Trees

Abstract

Maple is an important industry to the Canadian economy accounting for $615 million in exports in 2023. The sugar maple (Acer saccharum L.) is a native tree species, especially in Eastern Canada and United States, and is the preferred tree species for tapping due to the higher sugar content of its sap. Of the maple producing regions, Nova Scotia has some of the lowest recorded tap yields. The purpose of this study was to determine factors that were most likely to affect sap flow and yield in Nova Scotian sugarbushes. One hundred trees over ten sites located in primary maple producing regions of mainland Nova Scotia were observed over a two-year period. Data was collected on weather, soil characteristics, tree physiology, nutrient content, associated vegetation, and site characteristics, and compared to sap flow and yield. Although, numerous factors showed correlations with sap yield, the strongest relationships consistent over the two years, were between the zinc content of soil, leaf, and core tissues, soil moisture, amount of snow on the ground, associated vegetation, longitude of the site, and sap pH of the first run. Associated vegetation provided a positive correlation with yield, where concentrations of zinc and iron had a negative relationship. The further west the site was in NS and having snow on the ground from December to March was indicative of higher yields. High soil moisture in August and September had a negative relationship with yields, as did the pH of the sap in the first run of the season. Although the relationships were statistically significant in this study, they were weak. Additional years of study, with a focus on the factors that showed the strongest correlations would be needed to further understand the true reason for the lower sap yield and to determine if a management practice could be developed to combat this issue.