Why can evergreen trees make food(photosynthesis) all year long and other trees can't make food all year long?

Question

Evergreen trees can make their own food all year long (using photosynthesis) but why can't other trees do the same as evergreens?

Answer 1

Non-evergreen trees (otherwise known as deciduous trees) drop their leaves during fall/winter, and leaves make the food for the tree.

The reason deciduous trees do this is because it takes energy to keep their leaves in tip-top shape, and in the winter the light is too dim to make much food. So they sort of hibernate to save up for when there is food energy (sunlight) again in the summer.

Answer 2

Evergreens in cold climates shut down photosynthesis in the winter, so they really aren't making food all year.  They have the advantage of not needing to regrow all of their leaves, but the disadvantage of needing their leaves to be protected from the elements and herbivory, which makes them less efficient at photosynthesis.