Here are some clues to look for. Four-sided needles that are very sharp. Needles grow in bunches, wrapped together at the base. Take a walk outside and see if you can detect some of the ways trees serve the natural world. You can't really see , but you might guess at one way that trees are important, and that is their ability to hold the soil together with their far-reaching roots.
Animals live in other parts of trees, too.
Look for holes in trunks that squirrels and birds have made. On dead limbs, life the bark and look for squiggly tunnels and pinholes made by various insects. Of course, trees furnish food for many animals. Not only are nuts and fruits eaten, but also twigs, bark, and leaves. The leaves serve other functions as well.