• Murphy, Paul A.
  Forestry Sciences Laboratory, Monticello, AR, Southern Forest Experimentation Station, U.S. Department of Agriculture
  
• Farrar Jr., Robert M.
  Forestry Sciences Laboratory, Monticello, AR, Southern Forest Experimentation Station, U.S. Department of Agriculture
  

A mortality  rate function for numbers of trees utilizing dominant stand height as an independent variable was formulated as a differential equation. Because dominant stand height also changes with age, the description of mortality must also incorporate a stand height development function. This need was fulfilled by expanding to a  two-equation system by including a function for stand height development. Because the mortality rate function does not have a closed-form solution for the integral, a special fitting procedure was followed that is used in pharmacokinetic modeling. It consists of using numerical integration in conjunction with nonlinear regression. The equation and technique are illustrated using data from unthinned longleaf pine (Pinus palustris Mill.) plantations.