St. Tammany Parish, LA Tree Protection: Heritage & Protected Trees (2026)

The parish's Unified Development Code defines Heritage Tree in section 100-5 as 'a hardwood tree which is 18-inch dbh or greater, which is assigned a Grade B or better which does not include pine trees,' tying the designation to trunk diameter, species and a documented health grade rather than to age or landmark status alone. Grading follows the same A-through-D scale used for live oaks and cypress under Exhibit 600-3-9, where a Grade B tree has a 50 to 77 percent live crown ratio with only minor structural defects an arborist can address.

2 builds a Major Subdivision Incentive around preserving them. Under that incentive table, preservation of heritage trees earns a 5 percent decrease in the minimum required lot width or area for every 108 caliper inches of heritage trees a developer preserves, provided the trees sit within a natural area or buffer area that has not been and will not be graded or filled for development. 3(G), any heritage tree that is to be retained or counted toward a Major Subdivision Incentive must be physically flagged with its species and caliper marked before a department of planning and development inspection, and its root zone must be protected with fencing set back at least 2 feet from the drip line, with the fencing kept in place until landscaping activities are complete.

Fill within a protected root zone is capped at one inch, and no grading or cutting is permitted there for any purpose, including drainage or utility work, absent a planning department inspection and approval.