Characterizing base-cation immobilization in the stem of six hardwoods of eastern Canada

Rates of base-cation immobilization in the stem of basswood, beech, red oak, red maple, sugar maple and white ash were compared to identify the relative potential for impoverishing soils. Two natural stands in southern Quebec were studied. Allometric equations predicting stem nutrient content from stem diameter were developed. Between 20 and 25 trees per species were sampled for age and stem diameter at breast height, and the area covered by the projection of the tree crown on the ground. Rates of K, Ca and Mg immobilization were assessed by dividing stem nutrient content by age and crown projection. Stem K and Ca content for similar stem diameter classes were highest in white ash and sugar maple, respectively, whereas red oak was lowest in stem Mg content. Overall rates of base-cation immobilization were highest in mid-successional white ash (1.9 g m(-2) yr(-1)) and red oak (1.4 g m(-2) yr(-1)).