A comparison of pre-European settlement (1857) and current (1981-1995) forest composition in central Ontario

Presettlement forest composition along a 278 km long transect through centr al Ontario was recreated from Ontario land survey notes (1857) and compared with existing forest composition as derived from Forest Resource Inventori es (1981-1995). Trends through time were analyzed by means of detrended cor respondence analysis and univariate statistics (paired t tests and Wilcoxon matched-pair signed-ranks tests). Ordinations based on the first tree taxo n listed in a stand and on all tree taxa provided similar results. The east ern half of the transect was initially dominated by boreal conifers, wherea s the western half supported stands typical of Ontario's Great Lakes - St. Lawrence (GLSL) region. Significant reductions of yellow birch (Betula alle ghaniensis Britt.), balsam fir (Abies balsamea (L.) Mill.), and eastern whi te cedar (Thuja occidentalis L.) and significant increases of poplar (Popul us spp.) and white birch (Betula papyrifera Marsh.) were observed within th e boreal half. A significant reduction in eastern white cedar and an increa se poplar were observed in the western half. Changes in the boreal region s trongly support previous studies conducted over shorter time periods and ma y be attributed to clear-cut harvesting. The persistence of shade-tolerant hardwoods within the GLSL region can be attributed to the prevalence of sma ll-scale disturbances associated with partial-cut harvesting systems.