Southern Ontario
Southern Ontario has a very different climate from the rest of the country. It is the only area of Canada that has Carolinian forest. Many trees, plants, and wildlife in Southern Ontario are not found anywhere else in Canada. Some rare trees to Canada in this region include the tulip tree, pawpaw fruit tree and the cucumber tree. The Carolinian forests of Southern Ontario have in large part been destroyed by development sprawl. Very few original growth areas remain.
Boreal forest of Canada
The particular mixture of tree species depends upon factors including soil moisture, soil depth, and organic content. Upland forests can be closely mixed with forested peatlands. The resulting conifer forests are produced by and dependent upon recurring disturbance from storms, fires, floods and insect outbreaks. Owing to the accumulated peat in the soil, and the predominance of coniferous trees, lightning-caused fire has always been a natural part of this forest. It is one of many ecosystems that depend upon such recurring natural disturbance. For example, fire dependent species like lodgepole and jack pine have resin sealed cones. In a fire, the resin melts and the cones to open, allowing seeds to scatter so that a new pine forest begins (see also fire ecology). It has been estimated that prior to European settlement, this renewal process occurred on average every 75 to 100 years, creating even-aged stands of forest. Fire continues to cause natural forest disturbance, but fire suppression and clear-cutting has interrupted these natural cycles, leading to significant changes in species composition.