Tree Inventories and GIS in Urban Forestry

GIS is a tool that gives urban foresters and planners the ability to better manage and predict future growth of the urban forests. However, urban forests are very complex systems. Unlikelarge tracts of forest lands that are managed by one owner or organization with a set of goals, urban forests are broken up into many small tracts or plots with multiple owners and many different land uses. Urban land can be categorized into three different land uses; non-industrial or private, industrial or commercial, and public land. Due to the diversity in land uses, managing and maintaining urban trees is an extremely difficult task.

Urban forests are managed by a large number of individuals who have many different objectives and goals. Arborists, landscapers, horticulturists, planners, and wildlife biologists are among some of the professionals who are involved with managing urban forests. Homeowners, garden clubs, and other nature groups are also involved and interested in beautifying their community. In addition teachers are constantly looking for places where children can learn about the trees and forests, and the important biological role they play in our global system. The activities of all the different owners and multiple land uses influence the overall appearance and quality of the entire community. 

Having such a diverse group involved means there is a vast level of knowledge and understanding with regard to the trees and how all of their functions relate in the urban forest. It is up to urban foresters as well as other trained and educated professionals to provide the public with current and correct information regarding urban forestry. Educating the public regarding urban forestry issues and all of the associated benefits urban forests provide is essential to help improve the quality of life in the urban setting.

A large amount of money is spent each year on trees and landscaping in a community, from planting new trees to tree removals or take downs. All too often, new landscapes are over planted, meaning too many plants or the wrong plant species were selected for the area resulting in either the lack of growing space for the trees root system or the crown competes for space and interfere with overhead utility wires. It is very important to select the right tree species for the right site to meet the intended objective.

When selecting a tree for a particular area in the landscape several components need to be considered such as shade tolerance, the amount of sun or shade that plant requires, how large the tree will grow when it is mature, and selecting trees that are healthy and have good form. Other problems that are commonly found in the landscape are that trees are not planted correctly, often the roots balls are planted too deep or too shallow. Trees that are planted incorrectly can cause the tree to decline or die. The importance of young tree pruning is very beneficial to improve tree form at maturity. The minor costs of correctly pruning a young tree can improve tree form which in turn can save a lot of money later on. Providing tree care for young trees can reduce future hazardous problems and liability.

Tree inventories are generally not conducted for the private sector or on a plot by plot basis because most of these areas only have a few trees on each plot. Street and park trees are primarily the only trees being inventoried and managed in the urban setting, these trees are located on commercial and public lands. However, trees that are on private land make up a large percentage of the entire urban forests and many of these trees are not being managed. Street and park trees only make up a small percentage of all of the trees that are located in the urban landscape. An ecosystem management approach would include all of the trees that make up the urban forests. Inventorying all the trees in
the three land use categories would allow urban foresters to better predict the cost benefits and management needs that are required.  GIS applications such as CITYgreen have the capability of analyzing the entire urban forested areas. They have the potential to predict future maintenance costs and to project future growth and energy savings.

Urban foresters and planners have to start working closely together to effectively plan the urban system. Construction sites in the past have often been cleared of all existing trees, shrubs, and the organic matter. There has been efforts to keep some of the existing trees which unfortunately usually die due to numerous problems such as soil compaction, root disturbance, change in soil grade, and impervious surfaces which reduces or prohibits infiltration and water uptake by tree roots.

Urban planners and contractors need to work with urban foresters to determine which trees should be preserved on a given site and the best ways to minimize damaging these trees. In the planning stage planners have to make sure there is sufficient space to allow for trees to be planted if trees are included in a plan. For example; the area between sidewalks and roads needs to be wide enough to sustain the root system of a tree or planters in a parking lot should be large enough to ensure the tree will have enough nutrients and water to maintain tree vigor and health. Urban foresters and urban planners can work together using GIS to better manage this resource. Urban planners usually know very little about what conditions and space trees require, just as most urban foresters know very little about designing a city. However, the two disciplines working together can be very effective in producing a beautiful urban setting.

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