Wood ash application in sugar maple stands rapidly improves nutritional status and growth at various developmental stage. Forest Ecology and Management. 489 (2021) 119062

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Wood ash as soil amendment is increasingly being used globally to counter forest soil acidity, increase base cation availability, especially Ca, and correct foliar nutritional deficiencies/imbalances. Knowledge remains limited regarding the effects of wood ash in temperate hardwood forests dominated by sugar maple and supported by acidic soils with low availability of base cations. The main objective of this study was to determine short-term effects of wood ash application on the soil’s acid base-status and nutrient availability, foliar nutrition, and growth of seedlings and mature sugar maple trees. A first experiment was established in 15 stands across southeastern Quebec, which included an unamended control and a 20 Mg ha􀀀 1 treatment. A layer of naturally regenerated sugar maple seedlings was present in these stands. A second experiment was conducted on four other sites, which included an unamended control and three ash treatments (5 Mg ha􀀀 1, 10 Mg ha􀀀 1, 20 Mg ha􀀀 1); sugar maple seedlings were then planted at high density (50 × 50 cm). In Experiment 1, ash application resulted in increased pH and concentrations of P, Ca and Mg in the forest floor after 3 years. Only marginal treatment effect was detected in the upper mineral soil, where pH and Ca and Mg concentrations tended to be higher under the ash treatment. Nutritional diagnoses using the DRIS approach revealed that the different ash treatments were associated with a decrease in Ca deficiency and N excess in sugar maple (seedlings and mature trees). Using dendrochronological data from 288 trees, we measured a positive effect of the 20 Mg ha􀀀 1 ash treatment on the basal area increment (BAI) of mature sugar maple from the first year after application. Within 3 years following ash application, mean annual BAI of sugar maple in the ash treatment was 20% higher (+1.9 cm2 y􀀀 1) than that of the control. The ash treatments exerted no effect on sugar maple seedling growth. Varying wood ash doses had weak effects on seedling nutrition in Experiment 2. Our results indicate that ash application may exert positive short-term effects on the soil acid-base status, foliar nutrition, and diameter growth of mature sugar maple trees.