Thinning Target TPA From a Target SDI
The residual-stand number the prescription needs: TPA_target = (SDI_max x target%) / (QMD/10)^1.605, the trees to cut from the current TPA, and the residual basal area. A ponderosa stand (SDI_max 450) thinned to the 35% competition floor at a 10 in QMD keeps 157 trees per acre - a 300-TPA stand marks 143 for cutting at about 86 ft2/acre residual. The inverse of reineke-sdi; thinning from below raises the QMD, so the residual lands conservatively below the target. A management aid, not a prescription.
Formula and source
SDI_target = SDI_max x target% / 100; TPA_target = SDI_target / (QMD/10)^1.605; cut = max(0, TPA_current - TPA_target); BA_target = TPA_target x 0.005454 x QMD^2.
Reineke Stand Density Index inverted to a stocking target (Reineke 1933; USDA FS stocking-guide practice), by name.
Audience
This tile is built for trades and the adjacent professions in the Agriculture and Forestry group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.