THE EFFECTS OF CLIMATE-CHANGE ON LANDSCAPE DIVERSITY - AN EXAMPLE IN ONTARIO FORESTS

The predicted increase in climate warming will have profound impacts o n forest ecosystems and landscapes in Canada because of increased temp erature, and altered disturbance regimes. Climate change is predicted to be variable within Canada, and to cause considerable weather variab ility among years, Under a 2 x CO2 scenario, fire weather index (FWI) is predicted to rise over much of Ontario by 1.5 to 2 times, FWI may a ctually fall slightly, compared to current values, in central eastern Ontario (Abitibi), but for central-south Ontario it is expected to ris e sharply by as much as 5 times current values, We predict that the co mbination of temperature rise and greater than average fire occurrence will result in a shrinkage of area covered by boreal forest towards t he north and east; that some form of Great Lakes forest type will occu py most of central Ontario following the 5 C isotherm north; that pyro philic species will become most common, especially jack pine and aspen ; that patch sizes Will initially decrease then expand resulting in co nsiderable homogenization of forest landscapes; that there will be lit tle 'old-growth' forest; and that landscape disequilibrium will be enh anced. If climate change occurs as rapidly as is predicted, then some species particularly those with heavy seeds may not be able to respond to the rapid changes and local extinctions are expected. Anthropogeni cally-altered species compositions in current forests, coupled with fi re suppression over the past 50 years, may lead to forest landscapes t hat are different then were seen in the Holocene period, as described by paleoecological reconstructions. In particular, forests dominated b y white pine in the south and black spruce in the middle north may not be common. Wildlife species that respond at the landscape level, i.e. , those with body sizes >1 kg, will be most affected by changes in lan dscape structure. in particular we expect moose and caribou population s to decline significantly, while white-tailed deer will likely become abundant across Ontario and Quebec.