Chandler, Jennifer L. Appalachian State University, Boone, NC.

(Presented at The Future of Ginseng and Forest Botanicals Symposium, July 12-14, 2017, Morgantown, WV)

Abstract

An understory plant’s ability to exploit alterations to the light environment caused by canopy disturbance leads to changes in population dynamics.  The purpose of this work was to determine if population growth of American ginseng increases in response to additional light inputs caused by canopy disturbance, or alternatively, declines due to long-term selection under low light conditions. We parameterized stage-based matrix models to quantify the demographic response of ginseng to three natural forest canopy disturbances. Asymptotic growth rates, stochastic growth rates, and simulations of transient dynamics were used to quantify population-level responses.  Population growth rates at each disturbed site increased the transition period directly after canopy disturbance.  Stochastic models revealed that growth rates increased in simulations that included disturbance matrices relative to those that excluded disturbance.  Transient models indicated that population size was larger for each population when disturbances were modeled.  American ginseng is likely pre-adapted to take advantage of canopy gaps and light influx to a degree, and this pre-adaptation may be due to long-term selection under dynamic old-growth canopies. This study provides evidence to aid our understanding of the population-level response of understory herbs to disturbances whose frequency and intensity are predicted to increase as global climates shift.

Please see full published paper:

Chandler, Jennifer L. and James B. McGraw.  2017.  Demographic stimulation of the obligate understorey herb, Panax quinquefolius L., in response to natural forest canopy disturbances.  Journal of Ecology 105: 736–749. doi: 10.1111/1365-2745.12695