Reading 36 — Read an Academic Passage

Urban trees provide benefits that extend beyond appearance. Their leaves shade streets and buildings, which can reduce surface temperatures during hot weather. Trees also release water vapor through transpiration, a process that can cool surrounding air. In addition, leaves may capture some airborne particles. These effects vary by tree species, local climate, and planting design. A dense canopy can provide substantial shade, but trees also need enough soil, water, and space to remain healthy. For this reason, city planners increasingly treat urban forestry as infrastructure that requires long-term maintenance rather than as decoration alone.

Question: What is the passage mainly about?