Complex sentence: The American Chestnut Cooperators Foundation breeds surviving American chestnuts, which have shown some native resistance to blight, and the Canadian Chestnut Council is an organization attempting to reintroduce the trees in Canada, primarily in Ontario.
Split into simpler sentences: The American Chestnut Cooperators Foundation breeds surviving American chestnuts, which have shown some native resistance to blight. The Canadian Chestnut Council is an organization attempting to reintroduce the trees in Canada, primarily in Ontario.