You are here--->What do you have>Assess trees>Street trees
Street Trees
Trees along street are one of the most visible portions of the urban forest. For many communities, street trees make up the largest group of trees maintained by the urban forest program. However, even in cities with street tree programs, private property owners manage many of the trees along streets. These include front yard trees and trees in landscaped strips near commercial properties.
Understanding the composition, condition, and special management needs of street trees is important for most urban forest management plans. For some municipal urban forest programs, the urban forest management plan may be largely limited to street trees.
Due to their location, street trees provide specific benefits not provided by other trees. Benefits include traffic calming and extending the life of roadway pavement. Streets shaded by trees contribute to "sense of place", which can also contribute to increased community pride and property values.
Street trees are often located in very constrained locations. Pavement and utility lines may limit growing space. Other management issues that may be important for street trees include:
- Trees are commonly subject to damage by vehicles and street construction activities.
- Conflicts with utilities, hardscape (especially sidewalks, curbs, and gutters) and other built infrastructure are common.
- Branch, trunk, and root failures commonly have a high potential to cause property damage and/or injury.
- Tree canopies typically need to be maintained for street and sidewalk clearance and to minimize risk of branch failures.
- Falling leaves, seeds, and fruits may create hazards on sidewalks and contribute to storm drain clogging.
- Street trees may generate high numbers of service requests and complaints
Because of these issues, species selection is often a primary consideration. The species used may be specified in a master planting plan or on an approved species list. The palette of potential street tree species may be limited, which can sometimes lead to low species diversity. Low species diversity can pose a risk to the urban forest if one or more common species develop serious problems. The street tree assessment should look at both species diversity and the overall performance of various species in use.
Data from a well-maintained street tree inventory can help you determine how well various species are performing over time. Review the history of service calls, failures, tree replacements, sidewalk repairs and other issues. Problems may be more common with certain species, particular types of sites, or some species/site combinations. If you do not have inventory data, you can conduct sample surveys to provide this information. The Urban forest management tools page provides additional information and references related to assessing street tree populations.
Example
Much of the 2002 Urban Forest Management Plan for the City of Davis, CA, deals with street trees. The "State of the community forest" section (Section II.C.1) describes the number of street and park trees. It discusses species composition of street trees. The plan notes problems associated with some species, including sidewalk damage. The plan discusses the age class distribution of street trees and implications for management. Tree condition (by class - good, fair, poor, dead or dying) and shading of pavement are also discussed.
The plan includes a section on "Citywide Planting and Management Needs" (Section II.C.2). This section describes management needs of the street tree population. It includes data on planting and pruning needs by tree stem diameter class. Designated pruning classes included:
- needs pruning but not immediately (i.e. crown cleaning, thinning, reduction, raising, restoration);
- needs immediate pruning to alleviate dangerous structural defect;
- needs pruning for safety clearance (e.g. lines of sight or street sign/light obstruction);
- needs pruning due to inadequate growing space.
The plan also quantified the number of safety removals needed. The plan divides the city into management zones (i.e. Downtown Core Area, Central Davis, West Davis, etc.) and summarized maintenance needs in each zone.
The plan includes a section titled "Benefits and Costs Associated with Management of the Community Forest" (Section II.C.4). This section summarizes the financial costs and benefits associated the street tree population, drawing data and analyses from a report by Maco and McPherson (2003). This section presents the case for increased spending on tree maintenance based on the cost/benefit analysis.
Planning questions
- What types of tree and site data should be assessed / analyzed?
- Are necessary data available in an inventory or are surveys needed?
- What are the most meaningful ways to stratify tree data: by species, size class/age, condition class, maintenance needs, planting situation?
- It is practical or useful to divide street trees into geographic management zones? If management zones have been in use, how well do they work?
- How do we identify/quantify empty planting spaces?
- Is the long term sustainability of street tree canopy at risk due to a lack of age and/or species diversity?
- What is the frequency and severity of conflicts between street trees and other elements of infrastructure (e.g. curbs, sidewalks, overhead lines)?
Work plans
The tool below can be used to designate the information about street trees that you wish to consider for the urban forest management plan.
For each category listed below:
- indicate in column 1 which characteristics will be assessed and which portions of the street tree population will be included (trees maintained by your organization, trees maintained by others - e.g., public agencies or districts, commercial owners, residential owners)
- indicate the methods that will be used to collect the data, who will be responsible for collecting data, and their timeline for supplying the data
- indicate who will the be responsible for summarizing or analyzing the data and their timeline for providing the analysis for the plan
Street trees |
||||||
| Data collection | Data analysis | |||||
Tree ownership: |
Characteristic |
Methods |
By whom? |
Target date |
By whom? |
Target date |
Total number/density |
|
|||||
Species present and percent each species is of total trees |
||||||
Age/size by species |
||||||
Tree condition by species |
||||||
Age/species diversity by street or zone |
||||||
Maintenance needs |
||||||
Number of trees planted per year |
||||||
Number of trees pruned per year |
||||||
Number of trees removed each year |
||||||
Number of empty planting spaces |
||||||
Sidewalk damage by site/species |
||||||
Tree problems - failure prone species |
||||||
Tree problems - high maintenance species |
||||||
Tree problems - short life species/sites |
||||||
Other- specify |
||||||
Outline
| Add content related to street trees: |