Final answer:
Southern Ontario is a key region for Canada's exports, including agricultural products, manufactured goods, and lumber, with the latter being a focus due to Canada's lower opportunity cost in its production. Close economic ties with the United States also significantly influence the types of products exported.
Step-by-step explanation:
The key exports from southern Ontario that contribute to Canada's economy include various agricultural products, manufactured goods, and natural resources such as lumber. Southern Ontario, with its fertile farmland near the Great Lakes and the St. Lawrence River, is a major producer of dairy and agricultural goods which serve not only the local urban centers but are also part of Canada's exports. In addition, the Canadian economy's foundations have always been its abundant natural resources, with lumber being a commodity for which Canada has a relative lower opportunity cost, making it a significant export product.
Moreover, with over 80 percent of Canadian exports going to the United States, the strong manufacturing sector in southern Ontario is closely tied to cross-border trade, enhancing the region's contribution to Canadian exports. The rise of the service sector and the shift towards a knowledge-based economy have also played roles, with industries such as biotechnology and information technology becoming increasingly important, though these are typically located in urban areas to partner effectively with research institutions.