Effect of tapping for syrup production on sugar maple tree growth in the Quebec Appalachians

Some studies suggest that tapping sugar maple (Acer saccharumMarshall) trees can cause their growth to decline, particularly on poor and acidic soils. We tested this hypothesis in seven sugar bushes located in the Quebec Appalachians by comparing the growth of tapped trees with nearby untapped trees. The sites represented a range of soil fertility, from very good for sugar maple to strongly deficient in calcium. Trees were cored, and individual dendrochronology series were used to analyze trends in basal area growth, from a period of 10 years before, to 8-10 years after tapping began. Basal area growth of sugar maples did not appear to be influenced by tapping (p >= 0.134), except at one site (p < 0.001), where the growth of tapped trees decreased by 33% over 10 years. This decline could not be explained only by the poor soil fertility observed at the site. Although a tree biomass distribution budget indicated that maple syrup production represented only 4-6% of the carbon allocated annually to net primary production, the long-term relationship between maple syrup production and tree growth requires further study.