Urban forests of Tennessee, 2009

Abstract

Trees in cities can contribute significantly to human health and environmental quality. Unfortunately, little is known about the urban forest resource in the State of Tennessee and what it contributes locally and regionally in terms of ecology, economy, and social wellbeing. In an effort to better understand this resource and its values, the U.S. Department of Agriculture (USDA) Forest Service, Forest Inventory and Analysis, and community forestry programs, in partnership with USDA Forest Service research and the Tennessee Department of Agriculture, Division of Forestry, initiated a pilot study to sample trees within all urban areas across the State. Urban forest structure, functions, health, and values in Tennessee were analyzed using the i-Tree Eco (formerly Urban Forest Effects) model. Results reveal urban areas in Tennessee have an estimated 284 million trees in urban areas with canopies that cover 37.7 percent of the area. Most trees are found in forested areas (56 percent) with the most common species being Chinese privet, Virginia pine, and eastern redcedar. Yellowpoplar, chestnut oak, and white oak were the top three species in terms of basal area, while hackberry, yellow-poplar, and flowering dogwood were the top three in terms of leaf area. Tennessee’s urban forests currently store about 16.9 million tons of carbon valued at $350 million. In addition, these trees remove about 890,000 tons of carbon per year ($18.4 million per year) and about 27,100 tons of pollution per year ($203.9 million per year). Trees in urban Tennessee are estimated to reduce annual residential energy costs by $66 million per year. The structural, or compensatory, value is estimated at $79 billion. Overall, 9.4 percent of the sampled trees were within maintained areas. Land uses with the highest proportion of trees in maintained areas were agriculture, residential, and commercial/industrial. Overall, 1.8 percent of trees found were standing dead. Species with at least 100,000 trees in the population with the highest percent of its population in dead trees were sassafras (17.3 percent), black locust (14.7 percent), and black walnut (14.0 percent). Species with highest percent crown dieback were black walnut, sassafras, and shagbark hickory. Information in this report can be used to advance the understanding and management of urban forests to improve human health and environmental quality in Tennessee.