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Open Space Trees
Trees in natural open space areas may make up a large or small portion of your urban forest. These open space trees are often remnants of the native forest found along creeks or on hills. In some areas, some or all of these trees may be exotic species such as eucalyptus. Management goals and needs will depend on what types of species are present, their condition, and their location.
Tree management in open spaces is usually less intensive than in other parts of the urban forest. In some areas, open space trees may be largely unmanaged. However, these stands can and will change over time. Active management may be needed to:
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help maintain native stands that have low levels of natural regeneration
- suppress exotic species that may crowd out native trees in riparian areas
- replace flammable exotic species with lower risk trees such as native oaks.
Unless the stand is very small, a complete tree inventory of open space trees may not be practical or necessary. You will normally collect data on open space trees at the stand or forest level. Canopy cover can be assessed using aerial images. Use sample surveys to collect Information about species, size classes, condition, regeneration and other factors of interest.
Example
The City of Rocklin, CA, had established planning policies to help preserve oak woodlands as the city developed. As a result, the city acquired a number of large open space areas with oak woodlands. For the Rocklin urban forest management plan, the health and sustainability of these oak woodlands were evaluated.
The surveys assessed woodland characteristics, species composition, stand density and canopy cover, tree condition, regeneration, and invasive species. Evaluators set up permanent plots that were marked using GPS coordinates and tagged trees. To monitor stand changes over time, these plots can be relocated and reassessed. The plan addressed several management issues identified in the survey.
The City of Portland, OR, urban forest management plan recognized natural areas and open spaces as important segments of their urban forest.
Urban Land Environments. As noted earlier, street trees are only one part of the urban forest. Five basic categories called Urban Land Environments (ULEs) make up Portland’s urban forest. They are Residential; Commercial/Industrial/Institutional; Natural Areas and Stream Corridors; Transportation Corridors and Rights-of-Way; and Developed Parks and Open Spaces. The urban forest in each of these areas has similar characteristics and management needs. Chapter Four addresses these ULEs in detail.
City of Portland urban forest management plan
This plan but did not include data on open space trees, Instead, the plan included a SWOT [Strengths/Weaknesses/Opportunities/Threats] analysis of open space lands and identified the following issues:
ISSUES
- The need for people to have access to publicly owned natural areas often conflicts with the need to protect natural areas from human disturbance.
- Differences of opinion exist about the desired future condition and appropriate management of natural areas, e.g. thinning of trees in dense stands.
- Some identified City regulations and goals are in conflict with each other, e.g. increasing tree canopy competes with clearing for scenic view protection. Title 33 environmental zone regulations do not always recognize other Bureau of Planning regulations and goals.
- Best management practices (BMP’s) for street trees and individual English ivy smothering native plants public trees differ from BMP’s for trees in natural areas. Regulations that were developed for street trees and specimen trees in parks and other public areas are applied to trees in publicly-owned environmental zones.83 The result is duplication of permits and occasional conflicts in code requirements.
- Changing or modifying established active uses in order to restore or protect the resource is sometimes difficult.
City of Portland urban forest management plan
The plan identifies goals, objectives, and performance measures for open space lands that focused on the health of the entire ecosystem rather than on individual trees. Baseline data on conditions in these open space stands will be needed to see if progress is being made toward the plan's goals.
Planning questions
- What is the overall health of forests/woodlands in our open space areas?
- What changes have occurred in these stands?
- What changes are likely to occur over time under current management practices?
- How do current and projected uses of the open space and surrounding properties affect the management of the forests/woodlands?
- Are there information gaps related to management of open space stands?
Work plan
For each category listed below:
Save to work plan
- indicate with a check in column 1 those that apply to your situation and will be addressed in the UF management plan
- 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
Outline
Save to outline-goes to Tree Resource Assessment-Open space trees
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