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Climate Change Impacts:
Forests and Terrestrial Wildlife
Much of Ontario is still dominated by forests of spruce, and fir, and its forests are a key natural resource. The forest products industry in Ontario employs more than 90,000 people and generates more than $15 billion annually.

Climate change will affect Ontario's forests in multiple ways. Changes in temperature, soil moisture, fire conditions, carbon dioxide concentrations, atmospheric nitrogen, and ground-level ozone all will impact forests. Factors other than climate are also important drivers of change in forestry and forest ecosystems, and climate change may exacerbate existing stresses. Currently, it is not known how theses multiple changes will interact to alter the growth and distribution of Ontario's forests. Among the potential impacts of climate change with implications for forests and wildlife in Ontario are:

• A Shift in Forest Composition
  Warmer temperatures will likely cause boreal forests to shrink and other forest species will likely move northward. The ability of forest trees species to shift northward will depend not only on their own traits—such as seed dispersal methods—but also on physical barriers and geographic variations in soil, and human land-use decisions.
  
  
• A Reduction in Long-Term Forest Health
  Increased atmospheric carbon dioxide and nitrogen will likely spur forest growth in the short term. However, several other factors attributed to climate change, including higher concentrations of ground-level ozone, more frequent droughts and forest fires, and greater risks from insect pests, may counteract these gains. Damage to forests from these factors will likely outweigh the initial benefit of increased atmospheric carbon dioxide and nitrogen.
  
  
• A Loss of Bird Diversity
  Certain bird species may benefit from a warmer climate, while others could suffer the impacts of increased competition and ecosystem changes. Resident birds such as northern cardinals, and chickadees might be able to begin breeding earlier and raise more offspring. Greater resident bird populations, however, could increase competition for food and resources available for migratory songbirds and make it difficult for them to survive.
  
  
• A Change in Local Mammal Populations
  Climate warming may benefit some resident mammals while negatively affecting others. Nuisance mammals, such as raccoons, skunks, and the already prolific white-tailed deer, stands to benefit from milder winters. Moose, currently near their southern geographic limit, could be negatively affected by warming and increasing numbers of deer-carried parasites.
  
  
• An Increase in the Range of Forest Pests
  Insects have major effects on forest health as they influence primary production, community composition, nutrient cycling, and successional processes. The northern limit of some devastating forest pests, such as the gypsy moth, is currently determined by cold winter temperatures. These insects will almost certainly become more widely established throughout the region in a warmer climate.