PARENT SESSION
Oral Session #5: Ecosystem processes: Decomposition and litter. Presiding: K. Lajtha.
Monday, August 6, 2001. 8:00 AM to 12:15 PM. Hall of Ideas E.

Experimental evaluation of woody debris decay dynamics in mixed-oak forests of the central Appalachians.

RUBINO, DARRIN¹, McCARTHY, BRIAN¹, ¹

ABSTRACT- Woody debris serves various ecological roles in forested ecosystems. However, few studies have experimentally addressed the variety of factors that influence decay dynamics. The objectives of this study were to evaluate decay rates and nitrogen and carbon dynamics of woody debris of ten tree species common to the central Appalachians. To investigate variability in decay dynamics in this topographically dissected region, wooden blocks were placed on ridges and valleys of northeast- and southwest-facing slopes to maximize variability in microsite temperature and moisture. Decay rate (12 mo exposure) varied significantly (P < 0.05) among species with the greatest mean (±SE) percent weight loss observed for Liriodendron tulipifera (28.96 ± 2.10%) and the least for Prunus serotina (5.19 ± 0.14%). Decay varied across topographic position with significantly greater decay on northeast-facing slopes (6 mo) and ridges (12 mo). Significant interactions among aspect, position, and species were also observed. After 6 mo of exposure, all ten species exhibited an increase in percent nitrogen (N%) and a decrease in percent carbon (C%). Decay at 6 mo was significantly positively correlated with N% (r = 0.38) and negatively with C% (r = -0.57). Additionally, C% and N% varied significantly among slope aspect and position for several species. Initial findings of this long-term study suggest that decay dynamics are spatially variable and that microsite and species identity play an important role in the decay process.

KEY WORDS: decomposition, wood, debris