PARENT SESSION
Contributed Oral Session 130: Forest Infestations and Mortality
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 514 A, Level 5, Palais des congrès de Montréal
Current biomass and stand dynamics of a southern Appalachian spruce-fir forest.
Moore, Patrick*,1, Van Miegroet, Helga 1, Nicholas, Niki2, 1 Utah State University, Logan, UT2 Yosemite National Park, El Portal, CA
ABSTRACT- Southern Appalachian spruce-fir forests of the southeastern United States have undergone significant structural changes due to the invasion of the balsam woolly adelgid (BWA) starting in the 1970s, as well as the possible impacts of atmospheric deposition. In addition, rates of biomass accumulation and overstory stand dynamics have also been affected by windthrow of mature dead trees and ice storms. Though these forests have been predicted to recover to some degree from these disturbances, the level of recovery is uncertain and forests have yet to rebound in terms of stand maturity and biomass acquisition. Current forest conditions were assessed from a total forest inventory on 54 permanent plots located between 1525 and 1966 m, and representative of the high elevation southern Appalachian spruce-fir ecosystem. In each plot, overstory tree biomass, understory tree and shrub biomass as well as understory herbaceous biomass was determined. Temporal trends in biomass accumulation and stand dynamics were determined from comparisons with similar data sets collected in 1993 and 1998. Currently, aboveground live biomass of all woody and herbaceous plants is 322 Mg ha-1 across the entire study area. Between 1993 and 1998, overstory standing live biomass decreased at a rate of 1028 kg ha-1yr-1, mostly due to windthrow of large stems and further disturbance by falling fir snags. However, between 1998 and 2003, overstory standing live biomass increased again at a rate of 664 kg ha-1yr-1, mainly due to ingrowth and positive growth increment of spruce and fir. Yellow birch showed no evidence of release from these disturbances. These forests appear to be recovering; however, because the effect of BWA on future generations of Fraser fir is uncertain, long-term forecasts cannot be made. These forests demonstrate a high level of spatial heterogeneity at the watershed scale. Understanding the nature of this heterogeneity as well as the future behavior of the BWA is critical to predicting the future of this forest.
Key words: stand dynamics, spruce-fir, recovery