Environmental Correlates of Oak Decline and Red Maple Increase in the North Carolina Piedmont

ABSTRACT
We examine the decline of oaks (Quercus spp.) in eastern forests and the concomitant increase in red maple (Acer rubrum) abundance using data collected over 75 years near Durham, North Carolina. Oaks declined in abundance on all hardwood-dominated sites, while early-successional pine stands showed a slight increase in oak abundance. Red maple has increased in density 6-fold over the last 75 years in all stands. Diameter distribution data from mapped stands suggest that oak decline results from a lack of recruitment. An analysis of environmental characteristics influencing the rate of increase in red maple density shows that the rate is slowest on sites with wet, sandy, high pH soils. Oak decline occurs faster on sites with higher initial oak abundance, and appears unrelated to changes in red maple abundance. Overall, the rate of transition from oak to red maple dominance is influence by both local site and landscape characteristics.