Forests breathe life into your city maps, transforming generic landscapes outside the walls into locations that could a secret tomb or shelter a group of bandits. You never know what secrets might be lurking beneath the boughs! Pine trees can tell you something about the environment of the location. Perhaps it's an area with low-quality soil where only the hardiest trees can grow, or maybe it's an alpine location in the mountains. Either way, using different species of trees is a great way to subtly convey something about a location, which makes for a more immersive story for your players or readers.