Monday, August 6, 2007
Exhibit Halls 1 and 2, San Jose McEnery Convention Center
The causal agent of sudden oak death (SOD), Phytophthora
ramorum, is predicted to eventually invade forests in the
southern Appalachians. Dominant overstory, Quercus rubra, and
understory, Rhododendron maximum, could be eliminated by SOD.
We seek to quantify the effects of simulated SOD on vegetation and
seedling establishment; soil properties; and canopy structure, leaf
area, and light interception. In 2005, nine experimental plots
were established at the Coweeta Hydrologic Laboratory in western
North Carolina in stands containing at least 15% Q. rubra and
15% R. maximum. Plots were matched by similarity vegetation
and randomly assigned treatment: control, Q. rubra girdle, and
both Q. rubra girdle and R. maximum removal. Canopy
light interception was estimated using spherical densiometers.
Girdling of Q. rubra and removal of R. maximum occurred
in early 2006. Soil respiration, temperature, and moisture were
measured biweekly during the growing season in 2006 and 2007.
Vegetation subplots were censused in fall, spring, and summer. Litter
was collected seasonally. Preliminary analysis of soil respiration
for 2006 suggests a decrease in the full treatment relative to the
control and girdle only treatments, due to death of R. maximum.
Since girdled trees take longer to die, we expect a lag in the girdle
only treatment and lower soil respiration in 2007. In 2006, soil
temperature was higher in the full treatment plots because of lack of
shade. Data from this study will be used to develop a predictive
model of long-term forest responses and to inform management
decisions.
