In cool, high-latitude subpolar regions, forests are dominated by hardy conifers like pines, spruces, and larches. These taiga (boreal) forests have prolonged winters and between 250 and 500 mm (10 and 20 inches) of rainfall annually.
In more temperate high-latitude climates, mixed forests of both conifers and broad-leaved deciduous trees predominate. Broad-leaved deciduous forests develop in middle-latitude climates, where there is an average temperature above 10 °C (50 °F) for at least six months every year and annual precipitation is above 400 mm (16 inches). A growing period of 100 to 200 days allows deciduous forests to be dominated by oaks, elms, birches, maples, beeches, and aspens.
In the humid climates of the equatorial belt, tropical rainforests develop. There heavy rainfall supports evergreens that have broad leaves instead of needle leaves, as in cooler forests. In the lower latitudes of the Southern Hemisphere, the temperate deciduous forest reappears.
Britannica, 2015