Thursday, August 9, 2007

PS 67-158: Effects of fire and fire surrogate treatments on forest C and N storage

Jianjun Huang and Ralph E.J. Boerner. ohio state university

Understanding how fire and fire surrogate treatments impact C and N storage is critical to the evaluation of these management alternatives in the context of increasing atmospheric CO2 and deposition of anthropogenic N. In this study we evaluated the impacts of the FFS treatments on network-wide C and N stocks in soil, forest floor, coarse woody debris (CWD), vegetation and the entire forest ecosystem. C and N were mainly stored in soil and live trees. At the FFS Network scale, meta-analyses indicated that burning alone significantly decreased C and N storage in forest floor and live trees, but had no significant impacts on storage in soil, CWD, or the whole ecosystem. Mechanical thinning alone increased C and N storage in CWD but decreased C and N in live trees and the whole ecosystem. Burning+thinning decreased C and N storage in forest floor, live trees, and for the whole ecosystem.  Among the twelve individual FFS sites, burning alone significantly reduced C and N storage in 10 site-by-C and 9 site-by-N compartment combinations.  Mechanical treatment alone resulted in decreases in 10 and 9 site-by-C and site-by-N compartment combinations, respectively. The combination of mechanical treatment and fire resulted in significant decreases in C and N storage in 18 and 15 site-by-compartment combinations.  Mechanical treatment and mechanical+fire resulted in increases in CWD C and N in 1-2 sites. We will present the results of Bayesian analysis designed to separate the relative effects of treatments and inter-site variations on changes in C and N storage.