Trees and urban forests matter because they impact the environment we live in by moderating temperature extremes, reducing wind speed, reducing water erosion, filtering pollutants from air, water and soil, providing visual and sound screens, help manage storm water and flooding, and increasing property values. Urban forests help mitigate the urban heat island effect, particularly important in the summer months by reducing the number of unhealthful ozone days. The presences of trees also helps slow down drivers and reduces the severity of car collisions.