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

摘要

a- Quantifying stand density is a critical task, but is challenging in complex mixed-species forests. a- We used specific gravity within a tree-area approach to provide a parsimonious density model. a- The model is related to the additive version of Reineke's stand density index. a- Quantile regression and selection maintain consistency with accepted silvicultural guidelines. a- Maximum stand density may be lower in the northeastern U.S. than in the south or west. Quantifying stand density is important for accurate prediction of net biomass and carbon accumulation, for estimating growth and mortality risks of trees, stands, and regions, and for the management of forests for multiple goods and services. Building on previous work relating maximum stand density to wood specific gravity, we develop a stand density equation for the mixed species forests of the northeastern United States using data from the US Forest Service, Forest Inventory and Analysis program. We used quantile regression, in concert with a quantile selection and evaluation procedure, to ensure conformity between our density measure and previously developed guidance for well-studied stand types. The resulting strictly additive relative density measure appears to provide reasonable prediction of maximum density even for plantations of exotic conifers in the region. The results suggest that maximum stand densities after accounting for wood specific gravity may be lower in northeastern North America than in the south or west.