A crown story: how tree size and structure drive maple syrup yields

Maple syrup production is strongly influenced by spring weather conditions, particularly the frequency and intensity of freeze–thaw cycles. However, marked individual differences in sap and sugar yields persist among trees growing under similar stand conditions, indicating additional tree-level sources of variation. This study aimed to explain inter-individual variability in maple yields in commercial high-vacuum syrup production using structural, morphological, and growth characteristics. We used terrestrial light detection and ranging to derive variables describing crown, stem, and whole-tree size, biomass, and structure in 38 mature sugar maples. We related these variables to individual yields, including sap volume, sugar content, and syrup production. Our models explained substantial inter-individual variability: 52 % in sap sugar content, 44 % in sap volume, and 47 % in syrup production. Laterally expanded crowns were associated with higher sap sugar content, as were lower growth rates in the outermost 25 mm of wood. Sap volume was highest in large, heavily branched trees with crowns extending vertically along the stem. Crown area was the strongest predictor of syrup yield, with an estimated increase of 250 mL per 5.6 m². These findings highlight the importance of multidimensional crown development in maximizing individual yields in maple syrup production.