Kirkwood, MO Tree Protection: Heritage & Protected Trees (2026)

Section 24-2 of the Tree Code defines SIGNIFICANT TREE as any tree six inches in DBH (diameter at breast height, measured four and a half feet above ground) or greater, in fair or better condition, excluding invasive species and trees the City classifies as "undesirable." That definition matters because significant trees are the trigger point for mandatory protection under Section 24-4. Full site development, demolition, grading, or complete redevelopment always requires an approved tree protection plan and tree study under Section 24-4(b), prepared by a certified arborist.

For a smaller partial remodel or addition that impacts less than a third of the lot, Section 24-4(c)(3) still forces the issue if the work will include grading or construction activity within 10 feet of a significant tree or a City-owned street tree: tree protection measures have to be installed and maintained for the life of the project, even though a full tree study is not required in that scaled-down case. The tree study itself, when one is required, must appraise every significant tree on site and on neighboring lots within 10 feet of the property line, recording species, DBH, and a dollar appraisal using the Trunk Formula Technique from the "Guide for Plant Appraisal, 10th Edition." Damaging a protected significant tree during construction triggers replacement obligations under Section 24-4(f): the developer replants based on the tree's adjusted diameter or pays the City $250 per adjusted diameter inch into a fund reserved for tree maintenance and protection.