17.28.065 - Trees.
A. Designation of Tree Types.
1. Designation of Protected Trees. A protected tree is any existing tree with at least a six-inch diameter at breast height (DBH); or any existing tree two inches in DBH or larger located in the public right-of-way. To qualify as a protected tree, the tree shall not be listed on the most recent edition of the Tennessee Invasive Exotic Plant List and shall be in fair or better condition with no major insect or pathological problems.
2. Designation of a Heritage Tree.
a. A heritage tree is any tree that meets the one or more of the following criteria:
i. Any tree with a DBH that meets or exceeds the following sizes:
TREE TYPE | DBH | EXAMPLES but not limited to:
Deciduous Canopy | 24" | Oak, Maple, Poplar, Planetree, Ginko
Evergreen Tall | 10" | Am Holly, So. Magnolia, Pine, Spruce, Cedar
Deciduous Understory | 8" | Redbud, Dogwood, Flowering Cherry, Jap. Magnolia, Jap. Maple
Evergreen Low | 8" | Dwf. Magnolia, Hemlock, Hybrid Holly, Cherry Laurel (tree form)
ii. Any tree registered in the metro historic or specimen tree program; or
iii. Any tree listed on the Tennessee Champion Tree list or the Tennessee Landmark and Historic Tree Registry as maintained by the Tennessee Division of Forestry.
b. In addition to the criteria listed above, to qualify as a heritage tree the tree shall meet all of the following:
i. Shall not be listed on the most recent edition of the Tennessee Invasive Exotic Plant List;
ii. Must have a life expectancy of greater than fifteen years;
iii. Must have a structurally sound trunk without extensive decay;
iv. Must have no more than one major and several minor dead limbs; and
v. Must have no major insect or pathological problems.
3. Designation of Historic and Specimen Trees. Historic and Specimen Trees program is a volunteer program in which trees shall be designated by the Metropolitan Beautification and Environment Commission based on advice from the Metropolitan Tree Advisory Committee and consent of the property owner. No historic or specimen tree shall be removed without a finding by the Metropolitan Beautification and Environment Commission that the tree is a hazard or a determination that it is not economically or practically feasible to develop the parcel without removing the tree. All trees in the Historic and Specimen Trees program shall also be designated as Heritage trees as defined in Section 17.28.065 Trees.
B. Tree Preservation.
1. It is the intent of this section to minimize the removal of trees and to ensure that property owners and developers take reasonable measures to design and locate the proposed improvements so that the number of trees to be removed is minimized. In particular, the design shall attempt to preserve protected, heritage, and specimen and historic trees, which meet the criteria set forth in Section 17.28.065.A, designation of tree types. For purposes of this chapter, the term 'retained tree' means a tree that is selected to be saved or preserved for purposes of being counted toward the required tree density for the property and which is not listed on the most recent edition of the Tennessee Invasive Exotic Plant List and which is in fair or better condition, with no major insect or pathological problems.
2. Any tree with a diameter at breast height (DBH) of twenty-four inches or more, or that qualifies as a heritage tree under Section 17.28.065.A of this title, shall be survey located and depicted on the final site plan.
C. Replacement of Trees.
1. Trees removed pursuant to Section 17.40.470, tree removal permit procedures, shall be replaced at the expense of the property owner or developer to meet the required tree density standard.
2. Any retained tree that is removed without a tree removal permit shall be replaced on an inch for inch basis as specified Section 17.28.065.D.
3. Tree Density.
a. Each property, other than those residential properties provided for below. of this section, shall attain a tree density factor of at least twenty-two units per acre using retained or replacement trees, or a combination of both.
b. Residential properties shall attain the following tree density factors:
i. Property within a single and/or two-family residential subdivision for which the preliminary site plan is filed with the planning commission after the date of enactment of this subsection shall attain a tree density factor of at least fourteen units per acre using retained or replacement trees, or a combination of both, excluding the area of the building lots. Proof of compliance with this requirement shall be provided prior to the release of any applicable public infrastructure bonds.
ii. Requirements for individual single and two-family residential lots.
(1) Individual single and two-family lots, other than those lots zoned AG or AR2a, shall include at least one two-inch caliper tree for each thirty feet of lot frontage (or portion thereof), excluding alley frontage. Such trees must be chosen from the Urban Forestry Recommended and Prohibited Tree and Shrub List, and shall be of a form and quality set out in the American Standard for Nursery Stock (ANSI Z60.1, latest edition).
(2) Individual single and two-family lots on a cul-de-sac shall attain a tree density factor of at least two two-inch caliper trees for each thirty feet of lot frontage (or portion thereof). Such trees must be chosen from the Urban Forestry Recommended and Prohibited Tree and Shrub List, and shall be of a form and quality set out in the American Standard for Nursery Stock (ANSI Z60.1, latest edition).
(3) If the width of an individual single or two-family lot is less than twenty-five percent of the average lot depth, the lot shall attain a tree density factor of at least seven units per acre using retained or replacement trees, or both.
(4) Proof of compliance with this subsection shall be provided prior to the issuance of a certificate of occupancy.
iii. Alternative tree density requirements for single and two-family residential lots. In lieu of the requirements of subsection 2.a.ii of this section, a home builder may petition the urban forester for credit for retaining existing trees on the building lot, provided that the overall tree density, including both replacement and retained trees, is not less than seven units per acre. Retained trees used to satisfy this requirement shall be protected according to Section 17.28.065.A. Proof of compliance with this requirement shall be provided prior to the issuance of a certificate of occupancy.
c. Compliance with this subsection 3., tree density, shall be calculated using gross acreage of the property but shall not include the following:
i. The portion of the land area currently or proposed to be covered by buildings;
ii. The fenced area of any athletic field;
iii. The area of a lake or pond which is covered by water year round; and
iv. Open areas of golf facilities.
v. Natural areas preserved in open space pursuant to Section 17.12.090 Conservation Development.
d. Retained and replacement trees shall contribute toward the tree density.
e. Tree density schedules shall be calculated according to the following schedules.
Retained Tree Schedule
UNITS represents basal area
DBH refers to diameter at breast height
DBH | UNITS | DBH | UNITS | DBH | UNITS | DBH | UNITS
6 | 1.8 | 20 | 6.0 | 34 | 11.9 | 48 | 28.8
8 | 2.4 | 22 | 6.6 | 36 | 12.6 | 50 | 30.0
10 | 3.0 | 24 | 8.4 | 38 | 13.3 | 52 | 31.2
12 | 3.6 | 26 | 9.1 | 40 | 20.0 | 54 | 35.1
14 | 4.2 | 28 | 9.8 | 42 | 23.1 | 56 | 36.4
16 | 4.8 | 30 | 10.5 | 44 | 26.1 | 58 | 37.7
18 | 5.4 | 32 | 11.2 | 46 | 27.6 | 60 | 42.0
Heritage Tree Schedule
UNITS represents basal area
DBH refers to diameter at breast height
DBH | UNITS | DBH | UNITS | DBH | UNITS
8 | 3.2 | 14 | 5.6 | 20 | 8.0
10 | 4.0 | 16 | 6.4 | 22 | 8.8
12 | 4.8 | 18 | 7.2 | 24* | 9.6
*Greater than 24" equals DBH × 0.5 per inch.
Replacement Tree Schedule
UNITS represents basal area
CAL refers to caliper size (a tree's diameter measured six inches from the top of the root ball)
Canopy Trees
CAL | UNITS | CAL | UNITS | CAL | UNITS | CAL | UNITS
2 | 0.5 | 5 | 0.9 | 8 | 1.3 | 11 | 1.9
3 | 0.6 | 6 | 1.0 | 9 | 1.5 | 12 | 2.1
4 | 0.7 | 7 | 1.2 | 10 | 1.7 | 14 | 2.3
Understory and Columnar Trees
CAL | UNITS | CAL | UNITS | CAL | UNITS | CAL | UNITS
2 | 0.25 | 5 | 0.5 | 8 | 0.7 | 11 | 1.0
3 | 0.3 | 6 | 0.5 | 9 | 0.8 | 12 | 1.1
4 | 0.4 | 7 | 0.6 | 10 | 0.9 | 14 | 1.2
4. Existing prohibited trees may be counted for full credit of the tree density requirement if in the opinion of the urban forester, they are healthy existing trees.
5. Single-trunk replacement trees shall be (i) a minimum width of two-inch calipers; (ii) a minimum height of six feet; and (iii) shall consist of recommended species listed in the Urban Forestry Recommended and Prohibited Tree and Shrub List.
6. A retained tree moved from one location to another on the site may be given credit upon approval of the urban forester.
7. Except for sites located within the Downtown Code (DTC) zoning district, credit toward the required tree density may be given for the installation of street trees that meet the following criteria:
a. Street trees shall be chosen from the Urban Forestry Recommended and Prohibited Tree and Shrub List and shall be a minimum of two-inch caliper and a minimum of six feet in overall height. Canopy trees shall be installed except where conflicts with overhead utility lines exist; in those instances, understory trees may be substituted.
b. Street trees installed for tree density credit shall be depicted on the landscape plan.
c. The proposed location of street trees and planting area dimensions and standards shall be subject to review and approval by the urban forester and metro public works.
d. The owner of the property frontage along which the street trees are installed shall maintain street trees installed per this title to International Society of Arboriculture standards.
8. Subdivision developments, other than single and two-family residential subdivisions required to meet the tree density requirements of subsection 2. of this section, shall be exempt from the tree replacement provisions of this title during the phases of construction to install streets, utilities and drainage structures required to be installed or bonded prior to recording of a final plat, so long as: (1) the tree survey includes the area to be disturbed by the construction of streets, utilities and required drainage facilities; and (2) the removal of protected and heritage trees, as set forth in subsection 17.28.065, is confined to the area of disturbance determined by the planning commission to be the minimum area necessary to install the infrastructure required by the subdivision regulations; and (3) so long as no protected and heritage trees, as set forth in subsection 17.28.065, are to be removed outside of the agreed upon disturbed area. Development of individual parcels within the subdivision must comply with the tree replacement provisions unless exempted by other provisions of this title.
9. Existing developments not otherwise exempted shall comply with the tree replacement provisions of this title when undergoing expansions as follows:
a. No additional compliance is required if there is no enlargement of the lot, or in the improved portion of the existing lot, and either:
i. The value of any one expansion is less than twenty-five percent, or the value of multiple expansions during any five-year period is less than fifty percent, of the value of all improvements on the lot prior to expansion; or
ii. The total building square footage of any one expansion is less than twenty-five percent, or the total building square footage of multiple expansions during any five-year period is less than fifty percent of the total building square feet of all improvements on the lot prior to expansion.
b. When the previously improved portion of a lot is enlarged, or additional area is incorporated into the lot, only the additional area or expanded area of improvement is required to be brought into compliance with the tree replacement requirements, if either:
i. The value of any one expansion is less than twenty-five percent, or the value of multiple expansions during any five-year period is less than fifty percent of the value of all improvements on the lot prior to expansion; or
ii. The total building square footage of any one expansion is less than twenty-five percent, or the total building square footage of multiple expansions during any five-year period is less than fifty percent of the total building square footage of all improvements on the lot prior to expansion.
c. Total compliance is required if exemption cannot be claimed under other provisions of this section.
10. Any replacement tree planted for credit shall be replaced by a tree of equal or greater diameter than originally planted if the tree dies. Under no circumstances shall any replacement tree, planted for credit, be removed by the owner or developer without the prior permission of the urban forester. All trees and shrubs required by this code shall be inspected within three years of initial planting. Notwithstanding the foregoing provision of this subsection to the contrary, there is no requirement that a replacement tree planted for credit be replaced if the tree dies as a result of a natural disaster or other act of God. For purposes of this section, 'natural disaster' shall not include drought.
11. Where construction work will be completed under a phased schedule, site work and tree removal for the entire tract may be completed at one time and replacement or addition of trees can be deferred for a maximum of five years, so long as each phase is in compliance with the tree density requirements upon completion of that phase, and so long as the entire site is in compliance with the tree density requirements within five years, or upon completion of the entire project, whichever occurs first.
12. Notwithstanding any provisions of this title to the contrary, the board of zoning appeals may hear and decide appeals from any order, requirement, decision or determination made by the urban forester in carrying out the enforcement of this chapter.
D. Protection of Trees During Development Activities.
1. General. To assure the health and survival of retained trees, the following kinds of tree injuries shall be prohibited during all development activities:
a. Mechanical injuries to roots, trunk and branches;
b. Injuries by chemical poisoning or soil flooding;
c. Injuries by grade changes;
d. Injuries by excavations, trenching, or soil compaction; and
e. Injuries by paving or other soil covering or material storage.
2. Tree Protection Zone. A tree protection zone shall be established around each retained tree, tree preservation area, and natural area, as required, as shown in Figure 17.28.065.D. The tree protection zone shall be comprised of two distinct areas.
a. The structural root zone (SRZ) is to be determined by measuring one-half foot per each inch of tree diameter at breast height. If the SRZ is less than six feet, then the SRZ shall be a minimum of six feet.
1. No area within the SRZ shall be disturbed or modified.
b. The critical root zone (CRZ) shall be directly adjacent to the SRZ and is to be determined by measuring one foot per each inch of tree diameter at breast height. If the CRZ is less than ten feet, the protection zone shall be a minimum of ten feet.
1. The configuration of the CRZ may be adjusted up to twenty percent upon approval of planning or codes staff, as applicable. This may include pre-existing site conditions such as structures, foundations, or utilities. It may also include tree characteristics such as species and tolerance to stress and construction activities.
[image omitted; see the official code]
[2. Reserved.]
3. Development Prohibited within the Tree Protection Zone. All development activities shall be prohibited within the tree protection zone provided for any protected trees, including any construction of buildings, structures, paving surfaces, and storm-water retention/detention ponds. All temporary construction activities shall also be prohibited within tree protection areas, including all digging, concrete washing, storage of construction material, and parking of construction vehicles.
4. Development Prohibited within the Natural Areas. All development activities shall be prohibited within any tree protection zone established for a natural area preserved in open space pursuant to Section 17.12.090 Conservation Development.
5. Fencing of Tree Protection Zone or Natural Area Open Space. Prior to the commencement of grading or construction, the developer shall enclose the entire tree protection zone or natural area open space within a fence as follows:
a. Chain link fencing at least four feet in height and secured using appropriate posts spaced not more than ten feet apart.
b. During construction, each tree protection zone shall be identified with temporary signs to clearly demarcate the extent of the zone. Signs shall be made of a recyclable material and installed on the tree protection fence, visible on all sides of the fenced-in area at a rate of at least one sign for every one hundred linear feet. The size of each sign must be a minimum of two feet by two feet and shall contain the following language in English and Spanish: "TREE PROTECTION ZONE: KEEP OUT. ZONA DE LA PROTECCION DEL ARBOL. NO SE PERMITE ENTRAR". The owner shall maintain the protective barrier during the entire construction process and shall make certain that it is observed by the contractor.
c. The location of tree fence shall be coordinated with any required silt fence. Tree fence shall be located toward the tree with the silt fence outside to prevent erosion inside a tree preservation area.
d. Tree fence shall be maintained until applicable staff has completed a final inspection and released the project. For the purposes of this section, "applicable staff" means the urban forester or staff designated by the urban forester.
6. Tree Protection Zone Encroachment.
a. Utility Excavation. Excavating or trenching shall not be permitted within the tree protection zone. Utilities shall be located away from the tree protection zone. If trees are damaged or destroyed during excavation or trenching, the damaged or destroyed trees shall be replaced in accordance with Section 17.28.065. Placing of utilities through the use of tunnelling may be permitted with approval from planning or codes staff, as applicable. Applicable staff may propose rules and regulations governing and/or limiting utilities in the tree protection zone.
b. Sodding and Groundcover. Placement of sod or other groundcovers and the preparation of the ground surface for such covers shall be permitted within the tree protection zone, so long as tree roots in the area are not damaged by the method of preparation.
c. Tree Care. Pruning of branches or roots or removal of dead limbs on a tree/s located within the tree protection zone shall be permitted. An ISA certified arborist shall be required to supervise all operations related towards tree care. All tree care activities shall be done without the use of heavy machinery or vehicles within the tree protection zone. Prior to tree care activities, planning or codes staff, as applicable, shall be informed in writing.
7. Inspections.
a. All retained trees, pursuant to a tree survey, shall be inspected by applicable staff one year following completion of the project to ensure that they are surviving in a healthy condition.
b. Retained trees which require replacement shall be determined by planning or codes staff, as applicable.
c. Any retained tree which is damaged during construction, or with damage occurring as a result of construction, shall be replaced as provided in Section 17.28.065. Trees planted to replace damaged or removed protected trees shall not be counted toward the site TDU.
d. The owner shall be notified in writing of staff's determinations.
8. Tree Protection Violations.
a. Civil penalties shall be assessed in the event of injury, damage, or removal of trees within the tree protection zone. Penalties shall be assessed at fifty dollars per violation, per day. Each tree, in which a violation occurred, shall be considered an individual violation. No notice of violation shall be required prior to the assessment of civil penalty pursuant to this subsection.
b. In the event disturbance occurs, all trees within the tree protection zone shall no longer be counted for TDU requirements unless an assessment has been provided by an ISA certified arborist and approved by applicable staff.
c. Any injury, damage, or removal of tree shall be determined as removal without a permit and shall be replanted in accordance with Section 17.28.065.
d. A site shall be considered in compliance with the submittal of a revised landscape plan and planting deadline approved by planning or codes staff, as applicable. In the event that replacement trees are not planted by the agreed-upon deadline, civil penalties previously assessed shall resume until final inspection of replacement trees.
E. Less Desirable Trees. The urban forester shall compile a list of plants which are considered less desirable in the area of the metropolitan government. Upon adoption following public hearing and comment by the metropolitan planning commission, such list shall have the force and effect of regulation. The metropolitan beautification and environment commission, upon advice of the tree advisory board, may add or delete trees from such list from time to time following public hearing. Once such list of less desirable plants is duly adopted, the plants included therein may not be used to satisfy the requirements of Section 17.28.065.C, except as specifically permitted therein. Use of such trees in excess of the requirements of sections listed above is not prohibited.
(Amdt. 1 to Ord. BL2024-687 § 2, 2025; Ord. BL2024-687 § 2, 2025; Ord. BL2022-1122 § 11, 2022)
