Effect of an artificially induced drought on leaf peroxidase activity, mineral nutrition and growth of sugar maple

The effect of an artificially induced drought was investigated in an 80-year-old sugar maple (Acer saccharum Marsh.) stand in southern Quebec. We hypothesized that leaf peroxidase activity would increase, and that leaf nutrient deficiencies typical of declining trees (K, Mg) would develop during the year following the imposition of the drought. An impermeable tarpaulin was placed on the ground at the base of the trees during the summer of 1991. Foliage and soils were sampled periodically during the summers of 1991 and 1992. The treated trees showed decreased leaf water potential and increased peroxidase activity over most of the 1991 growing season. Diameter growth was significantly reduced in 1992. Soil NO₃^- and K⁺ were elevated while Mn²⁺ was reduced under the tarpaulin treatment at various times during the 1991 growing season. Soil NO₃^-, NH₄⁺, K⁺ and Mg²⁺ were elevated in the treated plots at various times during the 1992 growing season even though there was a lack of effect on foliar nutrient concentrations over the same period. Drought conditions may have reduced water and nutrient uptake without significantly affecting leaf nutrient status.