Tree Diversity Standards and Inventory Expiration
While the subdivision ordinance was amended in 2019 to reflect the 2040 Comprehensive Plan's tree diversity standards, the portion of the ordinance that governs general landscaping standards was not amended to incorporate these standards.
The city's subdivision ordinance requires that a tree survey be submitted as part of the subdivision process, but does not require that the survey be current.
Goal six of the city’s 2040 Comprehensive Plan’s Natural Resources Section is to “maintain a healthy and diverse urban forest”. One of the four policies enumerated to support this goal is “Continue to maintain a diversity of species in all public tree planting projects. At a minimum, use the 30-20-10 rule to select trees for projects.” The 30-20-10 rule is the principle that no more than 30 percent of trees should come from any one family, no more than 20 percent of trees should come from any one genus, and no more than 10 percent of trees should come from any one species. This minimum level of diversity helps to limit the amount of damage that a single disease, pest, or event can do to the city’s urban forest. While the city’s subdivision ordinance was amended to incorporate this standard in 2019, the city’s general landscaping standards were not amended to include a tree diversity requirement. Staff proposes amending the City Code to extend this standard to the general landscaping requirements in order to ensure that site plans and other projects align with 2040 Comprehensive Plan’s goals and policies.
The city’s subdivision ordinance requires that applicants submit a tree survey in order to allow staff to evaluate the development’s impact on the natural environment and ensure compliance with the city’s tree preservation and canopy coverage requirements; however, unlike other environmental studies required by the city, there is no requirement that the tree survey be current. In some cases tree studies done many years prior to the subdivision application are submitted to meet this requirement. Since natural features like trees and forests change over time, this can lead to situations where the conditions represented by the submitted survey no longer reflect the conditions on the site. In order to ensure that the city has accurate information from which to determine a project’s compliance with the city’s tree preservation requirements, staff recommends amending the City Code to require that the submitted tree survey be no more than two years old.
The following section of the Chanhassen City Code is subject to changes:
- Sec. 18-61 – This section outlines the subdivision ordinance’s landscaping and tree preservation requirements, including the 30-20-10 rule and tree survey requirement.
- Sec. 20-1183 – This section lists the landscaping requirements that are applied to site plan reviews.
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