Optimum nutritional levels for most commercial hardwoods of eastern Canada are unknown. This thesis dealt with the development of a method to determine nutritional standards using within site variation in tree growth and foliar chemistry. To this end, sugar maple (n = 87) and red maple (n = 39) trees were sampled in summer 2001 at the Station de biologie des Laurentides. Leaves were sampled for nutrients (N, P, K, Ca, Mg and Mn) and tree stems were measured for determination of basal area growth (BAG). Similar measurements for trees sampled annually during 1995--2001 were also used to measure the effect of annual variation on nutritional standards. A boundary line approach was used to assess tree growth response to nutrition using nutrient concentrations and Compositional Nutrient Diagnosis (CND) scores as predicting variables. A Basal Area Growth Index (BAGI) was computed using the live crown ratio to correct for the effect of stand density on BAG. An iterative and unbiased protocol was also developed to eliminate outliers. Optimum, critical and optimal range levels were derived from quadratic models significant at P < 0.15.

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Red maple seedlings grown from fruits collected from matched wet and dry sites from three physiographic regions of Virginia were flooded to test whether red maple seedlings derived from wet sites are affected differently by flooding than are seedlings derived from dry sites. Thirteen weeks of soil inundation on seedling growth found no interactions between flooding and maternal hydrologic condition. However, flooding significantly decreased leaf, stem, and root dry matter accumulation as well as height growth, leaf area growth, root to shoot ratio, mean relative growth rate, net assimilation rate, and mean leaf area ratio. Thirteen days of rhizosphere inundation as well as six days of recovery on seedling gas exchange determined that flooding significantly decreased photosynthetic rate and leaf conductance. A larger decrease in photosynthetic rate than in leaf conductance resulted in decreased water use efficiency and leaf limitation. There were no interactions between flooding and maternal hydrologic condition. Fourteen days of flooding decreased root aerobic respiratory capacity and root ethylene evolution, and caused shoot water potential to be less negative. As in the previous studies, no interaction between flooding and maternal hydrologic condition existed. Although rhizosphere inundation negatively affected the growth and physiology of red maple seedlings, there does not appear to exist any genetic differentiation between wet site and dry site populations affording either of the populations enhanced flood tolerance. Rather, red maple appear to have the species wide phenotypic plasticity to survive flooded conditions. / Master of Science