Urban forests are a significant national resource that promise to increase in extent
and importance in the years ahead.
Metropolitan areas (urban counties) represent the broadest extent of urbanization in the country, including 24.5 percent of the total area and roughly 80 percent of the total population in the 48 adjacent United States. With an average tree cover of 33.4 percent, metropolitan areas collectively support nearly one- quarter of the Nation’s total tree canopy cover—some 74.4 billion trees. Trees found in urban areas (cities, towns, and villages) also comprise a substantial portion of the Nation’s resource base. Covering 3.5 percent of the total area and containing more than 75 percent of the total population, urban areas support trees that account for 2.8 percent of the total tree canopy cover in this country—about 3.8 billion trees. The aver- age percentage of tree canopy cover for both metropolitan areas (33.4 percent) and urban areas (27.1 percent) is close to that for all land in the conterminous United States (32.8 percent), thereby demonstrating that urban areas and urban influence can coexist with a significant tree canopy.
The urban forest resource differs in extent across the United States. The Northeast is the most urbanized portion of the Nation; 9 of the 10 states with the highest proportion of urban land occur in this region. States with the highest proportion of their total tree cover in urban areas include New Jersey (22.3 percent), Massachusetts (14.4 percent), and Connecticut (14.0 percent) (table 1). States with the largest urban tree populations are generally in the South and Northeast and include Georgia (232.9 million urban trees), Alabama (205.8 million), and Ohio (191.1 million) (table 1). The surrounding natural environment has a significant impact on the urban forest resource and its man- agement. Cities that developed in forested areas average 34.4 percent tree cover; cities in grasslands, 17.8 percent; and cities in deserts, 9.3 percent.
Urban forest resources in the United States are large and expanding in extent and significance. They provide many valuable goods, services, and experiences to the nearly 80 percent of the population that live, work, and recreate in urban areas. In addition, urban forests have ecological and social links that extend the influence of urban forests and forestry beyond urban areas. Involvement by urban residents with urban forests and forestry often influences their perceptions and behaviors about forests and forestry in exurban areas.
Urban forests are highly diverse, connected, and ever changing ecosystems. They are complex environments linked with many other components of the urban system and occur where people, their activities, and their developments play significant roles in altering the physical and social environment. Management of these systems involves a wide range of disciplines, organizations, owners, users, and managers to sustain forest health and desired functions.(2000) by John F. Dwyer, David J. Nowak, Mary Heather Noblemanu, and Susan M. Sisinni for the US Forest Service.