Open oak and pine forests dominated the central and southeastern United States until recently. Dense forests have replaced open forests and many tree species have increased in abundance. I used historical and current tree surveys to closely examine change in tree density and composition, including shade tolerance.
Results/Conclusions
Forests show densification compared to historical open forests. Most current forests are fully stocked with greater densities of smaller diameter trees. Historically abundant oak and pine species have decreased relative to a range of other species that have increased, notably red maple and eastern redcedar. Approximately 30 year trends show a slight increase of 2% to 4% in mean shade tolerance in three regions of eastern US. A slight increase in mean shade tolerance may not be ecologically meaningful, but the concept of mesophication conveys the major trend of transition from fire-tolerant oak and pine species to diversity of other species.