All developments, enlargements and site alterations on Tier I sites shall comply with the tree planting requirements set forth in this Section, whether or not existing trees are removed as a result of such development, enlargement or site alteration. However, the requirements set forth herein shall not apply to any enlargement of an existing building, provided that such enlargement does not increase the lot coverage of said building.

On-site trees, pre-existing or newly planted, shall be provided on the zoning lot at the rate of one tree for each 1,000 square feet of lot area, or portion thereof, or shall equal a total of 51 percent of all tree credits for trees originally on site, whichever is greater.

For any existing tree of at least six-inch caliper that is preserved, credit for one tree shall be given for the first six inches of caliper and, for each additional four inches of caliper, credit for an additional tree shall be given.

Single-trunk trees, newly planted to meet this requirement, shall be of at least three-inch caliper at the time of planting. Multiple-trunk trees and low-branching coniferous evergreens shall be at least 10 feet in height at the time of planting. On-site trees shall be of a species selected from Appendix B (Selection List for On-site Trees).