A community receives many benefits from the urban forest; however, there are also costs associated with having a healthy urban forest. Estimates for tree costs in the U.S. range from $12.87 to $65 per tree (McPherson et al. 2005). Working towards the common goal of managing the urban forest to maximize the benefits and minimize the costs helps communities grow and develop while maintaining a healthy environment for current and future generations. A healthy urban forest requires a community investment. The cost of urban trees varies widely and depends upon such site factors as location, species, and maintenance needs. Each of these factors needs to be considered when deciding to plant, maintain, or remove a tree in an urban area, whether it be an individual tree or a large-scale planting. With careful planning and coordination, these expenses can be minimized. Some of the costs involved in urban forestry are:
Management Costs McPherson's (1994a) cost-benefit research in Chicago indicates that a tree needs to live 9 - 18 years before the benefits outweigh the costs to the community. This serves as an incentive to use sound establishment and maintenance techniques that will extend the life of a tree. Several things can be done to help maximize the benefits and minimize the costs of the urban forest. These are the most important:
Planting The cost of planting depends on the species, size, site location, site preparation, and labor. Planting costs include purchasing the trees, their transport, site preparation, installation, and initial care. McPherson (1994a) found that planting and establishing a tree often represents a large percentage of total cost. Usually, the larger the tree, the higher the planting cost. Many problems and future costs can be avoided by tree selection, site preparation, and planting techniques.
Pruning All open-grown, urban trees will require periodic pruning, but the frequency depends on the species, age of the tree, and the location. Young trees need frequent pruning to develop a strong branching structure. The amount of pruning needed is also related to the site location. Trees located near overhead utility lines or sidewalks need more frequent attention. Choosing a species that is compatible with the site will help reduce pruning frequency and related costs.
Irrigation In most locations, irrigation is needed to supplement rainwater during the establishment period of newly planted trees. The cost of installing the irrigation system and supplying water are part of the maintenance cost. Irrigation can keep the tree from being stressed during droughts. However, the soil moisture needs careful monitoring to prevent over-watering, which can also cause stress. Generally, species native to the area do not need irrigating after establishment if the soils an underlying hydrology have not been altered. Selecting a drought-tolerant species can help reduce irrigation costs.
Insect and Disease Control There are times when trees need to be treated for insects and disease. Costs of insect and disease control can be reduced by selecting a species that is resistant to insects and disease, planting a variety of species, matching species to the site, and proper planting techniques.
Tree Removal Trees need to be removed in urban areas for many reasons. Hazardous trees, which are trees that have potential to fail and hit a target, can cause injuries or death and damage personal property. A tree may also need to be removed if it is interfering with water and sewage pipes or utility lines. However, it may be cheaper to relocate utility lines than remove the trees. Many trees need to be removed because of storm damage. Usually, the larger the tree, the more it costs to remove. Matching the growth habits of a tree to site conditions will increase its vitality and life span and avoid its untimely removal.
Tree Residue from Pruning and Removal When trees are pruned or removed, the residue must be recycled or disposed of. Sending the residue to the landfill is a costly option for some communities, and in many cases is no longer allowable. Many communities, homeowners, and utility companies now recycle tree residue into mulch, firewood, compost, and bioenergy instead of sending it to the landfill. These alternatives may reduce costs and even generate revenue.
Fire Protection As cities and communities continue to grow, homes are often being built in wooded areas adjacent to urban centers. These wildland urban interfaces create the potential for wildfires with the possibility of loss of life and property. Fire management involves fire prevention, fire suppression, and prescribed burning (using fire as a management tool), all of which cost money. Local ordinances can help ensure acceptable protection from naturally caused fires. The hazards of wildfires can be diminished by reducing dense vegetation and trees within 30 feet around homes and businesses and by creating greenspace (Harris et al. 2003).
Program Administration Managing the urban forest requires planning and a trained workforce to carry out those plans. Communities must pay the costs of the people and materials used in these programs.
Infrastructure Repair Tree growth can damage the infrastructure of a community, such as utilities, sidewalks, curbs, and sewer and water pipes. Sometimes repairs can cost less than removing and replacing the trees. Proper site and tree selection can prevent or minimize future infrastructure conflicts.
Liability and Litigation There can be legal costs when trees are damaged or when trees cause damage. Property owners may sue when trees are harmed by construction on adjoining property, or when trees die after underground utilities lines are installed. The damage caused by falling trees or limbs, such as during storms or from hazard trees, can also result in legal action. Sidewalks damaged by tree roots can cause trip-and-fall accidents, a common source of liability claims. Trees are sometimes stolen, especially unique specimens or rare species. Careful planning can preclude many of the costs related to the damage of trees during development and construction projects while placement considerations can also minimize future problems or likelihood of theft of valuable plantings. Selecting an appropriate species for the location and assuring proper maintenance can decrease the injuries to people and damage to property caused by trees.
More information on ways to decrease liability associated with trees.
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Citations:Harris, R.W. 1992. Arboriculture: integrated management of landscape trees, shrubs, and vines. Englewood Cliffs, NJ: Prentice Hall. 674 p. McPherson, E.G. 1994a. Benefits and costs of tree planting and care in Chicago. In: McPherson, E.G.; Nowak, D.J.; Rowntree, R.A. [compilers]. Chicago's urban forest ecosystem: results of the Chicago Urban Forest Climate Project. Gen. Tech. Rep. NE McPherson, E.G., Simpson, J.R., Peper, P.J., Maco, S.E. and Xiao, Q. 2005. Municipal Forest Benefits and Costs in Five Cities. Journal of Forestry. December (2005): 411-416.