The planning and implementation of actions to establish, protect, restore, and maintain trees and forests in cities and smaller communities. When it began in the 1960s, the field of urban forestry focused on individual trees along streets and adjacent to homes and buildings, and on groups of trees in specific spatial areas such as parks. Since then, it has evolved toward more holistic consideration of the structure, processes, and functions of urban ecosystems at a larger scale. Scientists have come to realize that trees and forests play a critical role in maintaining healthy urban ecosystems, providing ecological services such as filtering water and air pollution, reducing stormwater flows, sequestering carbon emissions, conserving energy, and reducing soil erosion, as well as providing human health benefits, recreation, esthetics, and fish and wildlife habitat. These ecological services can be translated into economic values worth billions of dollars by comparing them to the costs of achieving the same benefits with technology and human-made infrastructure. Urban trees, forests, and related vegetation are often referred to as green infrastructure in order to compare and contrast them with human-made or hard infrastructure, such as buildings and roads. See also Ecological communities; Ecological succession.
New satellite remote sensing and geographic information system tools are enabling communities to assess changes in their green infrastructure and to develop plans for restoring and maintaining urban trees and forests. City planners and policymakers use the same tools to address other urban infrastructure needs, such as transportation and housing, which allows them to integrate green infrastructure information into plans for other infrastructure development.
As urban forestry has expanded to include larger ecosystems, spatial boundaries between urban and rural areas have begun to blur. Their ecological, social, and economic links have come into view. Watershed connections have become a key consideration, while other social and economic links related to movements of people, businesses, goods, and services have also become clearer. Rural lands, both public and private, provide an array of ecological services to nearby cities, including drinking water, recreational opportunities, fish and wildlife habitat, and agricultural and forest products.
Urban forests are owned by a diverse array of public and private entities, including individual homeowners, private businesses, and federal, state, and local governments. Their management and use are closely tied to the homes, buildings, transportation systems, utilities, and other infrastructure in an urban area. A key challenge is coordinating the efforts of the large number of individuals, groups, and organizations involved in urban forestry, each with its own information, resources, and objectives. See also Land-use planning.
