tolerant hardwood forests occupy a broad geographic range in ontario and they are important for their ecological and economical values. although sugar maple (acer saccharum marsh.), american beech (fagus grandifolia ehrh.), and red oak (quercus rubra l.) are among the most common species in these forests, our knowledge about their ecological factors is limited. also, local foresters have to use models developed in other regions to predict the quality and productivity of sites associated with those hardwood species. in this study, 61 plots of sugar maple, american beech, and red oak were established in algonquin park, haliburton forest, and north bay area. at each plot 3-9 undamaged dominant study trees with no indication of previous disturbance were felled for stem analysis and producing site index. at each plot, three soil pits were dug and soil samples from h, a, and b horizons were collected. physical characteristics including texture, coarse fragment content, thickness of horizons, and depth of rooting system and chemical characteristics including ph and both concentration and pool of c, n, p, ca, mg, na, and k were measured. in the second chapter, the measured variables were compared/contrasted among the study species. in almost all cases, significant differences were found between beech and red oak, while sugar maple was associated with either of them. beech and sugar maple occurred on deeper soil with higher ph, p, mg, and ca in a horizon and silt content, ph, ca, and p in b horizon. also red oak and sugar maple were found on soils with higher c:n ratio and p in h horizon and lower n and na in h and a horizon and na in b horizon. in the third chapter, the soil variables were used to produce appropriate models to indirectly estimate site index of three study species in the region. the samples for sugar maple were stratified into three regions and the best models had of 0.51, 0.50, and 0.94 for algonquin park, haliburton forest, and north bay area respectively. also, the regression models for red oak and beech had r^ of 0.73 and 0.72 respectively. in the fourth chapter, the nutrient concentrations were compared/contrasted within site quality classes of study species in order to find possible trends which could be used in quantifying soil nutrient regime (snr). american beech was found to be a better site species indicator since more nutrients had linear trend within its site quality classes. moreover, p concentration was found a better element for quantification of soil nutrient regime. soil moisture regime (smr), on the other hand, showed no linear relationships with site quality classes of any of those three species.