PARENT SESSION
Contributed Oral Session 103: Forest Ecology : Carbon Stocks and Cycling
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 520 C, Level 5, Palais des congrès de Montréal
Post-disturbance trends in soil respiration following forestry management.
Concilio, Amy*,1, Ryu, Soung-Ryoul 1, Ma, Siyan2, Chen, Jiquan1, North, Malcolm3, 1 University of Toledo, Toledo, OH2 University of California- Berkeley, Berkeley, CA3 University of California- Davis, Davis, CA
ABSTRACT- Soil respiration is a major pathway for carbon cycling and it can, thereby, contribute much to our understanding of carbon flow through an ecosystem. Little is currently known about how disturbances affect the dynamics of soil respiration rate (SRR), although evidence suggests that both natural and anthropogenic disturbances may have significant and lasting effects on the soil environment. This study examines SRR reponse to prescribed burning and thinning treatments in a mixed-conifer, old-growth forest on the western side of the Sierra Nevada Mountains from one to three years after disturbance. Treatments were applied in 2001 using a full factorial design consisting of two levels of burning (no burn and prescribed burn) and three levels of thinning (no thin, CASPO or understory thin, and shelterwood or overstory thin). We sampled three replicates of SRR, soil moisture (MS), soil temperature (TS), and litter depth (LD) at each of three dominant patch types (closed canopy, open canopy, and Ceanothus shrub) within each treatment type (n=54). The same sampling points were measured from May to August in 2000 (pre-disturbance) and in 2002, 2003, and 2004 (post-disturbance). We found that SRR changed significantly with time since disturbance (p<0.0001), treatment type (p<0.0001) and patch type (p<0.0001). Burning produced no significant change in SRR (p<0.05) with or without thinning. Both levels of thinning increased SRR in closed canopy and Ceanothus patches (p<0.05), but the magnitude of response varied with time-since disturbance and patch type. There was no significant change in SRR with treatment in open canopy patches, aside from a slight decrease with shelterwood thinning. SRR response was more pronounced both two and three years post-disturbance than one year. Relationships of SRR with MS, TS, and LD varied by patch type and year, highlighting the complexity of interactions between SRR and the soil environment after forestry management. After three years, we found that the soil environment was still exhibiting post-disturbance responses and our study site should, therefore, continue to be monitored in the future to track changes in SRR with time-since disturbance.
Key words: soil respiration, patch type, prescribed burning, thinning