A stand density index for complex mixed species forests in the northeastern United States

▶ Quantifying stand density is a critical task, but is challenging in complex mixed-species forests. ▶ We used specific gravity within a tree-area approach to provide a parsimonious density model. ▶ The model is related to the additive version of Reineke's stand density index. ▶ Quantile regression and selection maintain consistency with accepted silvicultural guidelines. ▶ Maximum stand density may be lower in the northeastern U.S. than in the south or west.