Chapter 1.7
Urban Forestry and Vegetation

• ALL
• Remove Code Barriers
• Create Incentives
• Fill Regulatory Gaps

Tree Canopy Cover

INTRODUCTION

A local government’s tree canopy is the jurisdiction’s area that is shaded by trees. Typically, as land is developed, the tree canopy is reduced because trees are removed to clear space for development. One study estimates that urban areas across the United States lost 36 million trees per year from 2009 to 2014.[1] Tree canopies provide numerous public and private benefits, including reduced air pollution, reduced heating and cooling demands, increased property values, improved physical and mental health, and reduced storm water runoff.[2]

This ordinance facilitates the growth of local tree canopy cover by requiring minimal tree canopy coverage per site or development, reforestation standards, and/or landscaping credits to developers that voluntarily plant more trees than required. Local governments have a variety of options when it comes to drafting these ordinances. They may set canopy minimums by percentage or area, may make the minimums applicable to residential, commercial, and/or industrial uses, and may set different minimums for different lot or development sizes. In addition, local governments may take a carrot and/or stick approach in which they require minimum standards and create incentives for those projects that exceed the minimums.

EFFECTS

Municipalities have much to gain by increasing the tree canopy. Carbon dioxide is one of the most prevalent and damaging greenhouse gasses (GHGs) that contributes to global warming.[3] Trees are a carbon dioxide “sink,” meaning they naturally absorb carbon dioxide and release oxygen, intercepting that carbon dioxide before it enters the atmosphere.[4] Trees also provide shade that, when planted correctly, can help reduce the energy needed to cool a building during the summer and can help reduce the heat island effect.[5] Likewise, trees can deflect harsh winds, saving energy on heating buildings in the winter.[6] By reducing energy needs, energy providers burn less fossil fuel and thus reduce GHG emissions.[7]

One study found that the presence of trees on a property increased the value by approximately seven thousand dollars.[8] This increased value is then used to increase local revenues through higher property tax assessments. Another study found that streets covered by shade from trees reduced the maintenance costs of the street by over 50% and increased street longevity by an estimated ten years.[9] Other studies have found that increased presence of trees benefits both mental and physical health.[10] For example, living near more trees reduces the risk of childhood asthma.[11] Finally, expanding tree canopy coverage provides more habitats for wildlife.[12] Thus, providing incentives to developers to bolster tree canopy is a valuable strategy for increasing all aspects of sustainability.

Developers also have much to gain by taking advantage of incentives for planting more trees. Some local governments grant increased density bonuses for developers that exceed the minimum required tree coverage.[13] This allows developers to create more profit producing units while simultaneously increasing the property’s value.[14] Other municipalities decrease the minimum lot size requirement for developers that dedicate a tract exclusively to trees.[15] This allows developers to construct additional lots while providing greater tree canopy cover.

EXAMPLES

Charlotte, NC

To increase the citywide tree canopy cover to 50% by the year 2050, Charlotte requires a tree protection plan to accompany any application for grading, building, change of use, and zoning.[16] The plan must contain a root protection plan for any tree over two inches in diameter.[17] Charlotte also uses “tree save areas,” which are areas in which an existing tree canopy exists that can be measured in square feet.[18] For residential developments, a minimum of 10% of the lot must be dedicated to a tree save area. For commercial developments, 15% of the lot must be dedicated to a tree save area. No building can be erected within ten feet of the edge of any tree save area. Developers are prevented from disturbing tree save areas unless the city grants a permit to do so.[19] Even if a permit is granted, the city may require the developer to “mitigate” the loss.[20]

If a developer fails to plant the required number of trees, a $50 fine per tree is assessed. Each day constitutes a new violation until the required planting occurs, up to a maximum fine of $1,000.[21] Further, if a developer causes damage that results in the total loss of a tree, s/he will be liable for the market value of that tree, up to a maximum of $20,000.

In a carrot and stick type approach, Charlotte also creates a number of incentives for developers who contribute more than they are required to the tree canopy. To encourage preservation of existing trees, a developer can seek an exemption from additional planting requirements if the developer preserves existing “heritage” trees. Heritage trees are trees listed on the North Carolina Big Trees list.[22] Residential properties with an area saving existing trees receive setback reductions.[23] Developers who dedicate a tree save area to a common open space can receive density bonuses if the titleholder covenants to maintain the area as a common, open space.[24] Additionally, some developments may qualify for lot width reductions if more than 25 percent of the lot consists of tree save areas.[25]

To view the provision, see Charlotte, N.C., Code of Ordinances §§ 21-91 to 21-126 (2010).

Baltimore, MD

After determining that its existing tree canopy provided only twenty seven percent coverage, Baltimore implemented a forest conservation plan aimed at expanding its tree canopy coverage to forty percent by 2030.[26] To that end, the city requires that every development over 40,000 square feet provide a forest preservation plan along with the associated building permit application.[27] The plan must contain a map of the land and identify the location and species of trees contained thereon, a three-year maintenance plan, an afforestation or reforestation plan, and other technical requirements.[28]

Baltimore also establishes an afforestation requirement, which requires developers to plant trees where there was previously no tree cover.[29] For lower density uses like agriculture and medium density residential developments, at least twenty percent of the land must be afforested.[30] For higher density developments like planned unit developments and high-density residential developments, only fifteen percent of the land must be afforested.[31] Developers are also required to retain existing trees that are associated with a historical site, or that are in a sensitive area such as a critical wildlife habitat or a wetland.[32]

To enforce these provisions, the city may assess a monetary penalty of $1.20 per square foot of area that is out of compliance.[33] That money is then put into the Baltimore County Forest Conservation Fund and may be spent on projects related to forest preservation.[34] Alternatively, the city may seek an injunction, preventing the developer from continuing construction until the violation ceases.[35]

To view the provision see Baltimore, Md., Code of Ordinances §§ 33-6-101 to 33-6-122 (2004).

ADDITIONAL EXAMPLES

Ventura Cty., CA, Code of Ordinances § 8178-7.6.1 (2016) (requiring developers to plant 10 protected trees for each protected tree removed during development).

Erie, Colo., Unified Development Code §10.6.2 (C) (9) (2017) (granting developers of commercial and multifamily residential properties a reduction in required parking spaces for the preservation of trees beyond what is required by law).

Lake Forest Park, Wash., Municipal Code §§ 16.14.070 (2017) (establishing canopy coverage goals for different types of properties which are used in determining whether a tree removal permit will be granted).

Fort Worth, Tex., Code of Ordinances, App. A: Zoning Regulations § 6.302 (2009) (raising the city’s canopy cover to 30% by requiring minimal levels of canopy cover on developments, but reducing the requirements if trees are planted elsewhere).