Syeda, Batool

Nutrient losses from forest soils caused by decades of acid deposition and intensive tree harvesting have affected tree growth and forest health in North America and Europe. Non-industrial wood ash (NIWA), a substance rich in macronutrients, may be a potential remediation strategy to return lost nutrients to forest. However, the chemical composition of NIWA and its effects on soil and tree growth are poorly understood. This thesis evaluated the chemical variability of non-industrial wood ash, and its short-term effects on soil properties, sugar maple (Acer saccharum) foliar chemistry, tree growth, and understory vegetation community composition at three sugar bushes in Muskoka, Ontario. The chemical analysis of NIWA samples obtained from the residents of Muskoka, showed that NIWA contains high levels of macro nutrients such as calcium, magnesium, and potassium and contains relatively low concentrations of trace metals. Ash mixtures amalgamated in the field were relatively homogenous in their chemical composition and metal concentrations were generally below Ontario NASM regulation guidelines for land application. Concentrations of copper and zinc exceeded CM1 guidelines, however, were always below restricted metals land application limits (CM2). Ten months after NIWA application to three sugar bush sites, soil pH and exchangeable base cations increased significantly in the litter and FH horizons at all treatment plots compared with control plots. Few treatment effects were recorded for the surface (0 – 10 cm) mineral horizon, with only potassium increasing in mineral soil at all three study sites. Elevated concentrations of most metals and metalloids (aluminum (Al), boron (B), cadmium (Cd), copper (Cu), Iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), zinc (Zn)) were recorded in soil at all treatment plots, however these effects were generally restricted to the litter horizon. Diagnosis and recommendation integrated system analysis (DRIS) conducted on the sugar maple foliage indicated that potassium was the most limiting nutrient at all three study sites, and significant increases were recorded in foliar potassium concentrations ten months after ash application in sapling and mature trees at all treatment plots. Increases in foliar calcium and magnesium concentrations were small and variable amongst the study sites. No significant treatment effects of NIWA application were observed on sugar maple tree growth two years after ash application, while changes in understory composition were generally limited, but these also varied among sites.

Author Keywords: Acer saccharum, Base cations, Calcium decline, Forest soil amendment, non-industrial wood ash, Trace metals