Maximum size–density relationship for constraining individual tree mortality functions

A maximum size–density relationship between quadratic mean diameter and stand density was developed based on the self-thinning concept. Several functions were compared first by fitting the average size–density relationship and two equally good functions were selected based on both fitting and prediction statistics. They were then refitted with a defined loss function to derive the maximum size–density relationship. One final function was chosen for constraining existing individual tree mortality functions developed for major species in boreal mixedwood forests. It was found that site quality did not affect this maximum size–density relationship. The results also showed that separation of this relationship by species was not possible.