PARENT SESSION
OOS 5: Restoration Effects of Fire and Thinning Treatments on Mixed-Conifer Ecosystems.
Organized by: M North and J Innes
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room E 148.

Soil respiration response to experimental disturbance in mixed conifer and hardwood forests.

Concilio, Amy^*,1, Ma, Siyan¹, Li, Qinglin¹, LeMoine, James¹, Chen, Jiquan¹, North, Malcolm ², Moorhead, Daryl¹, Jenson, Randy³, ¹ University of Toledo, Toledo, OH² University of California, Davis, CA³ Missouri Department of Conservation, Ellington, MO

ABSTRACT- Soil respiration rate (SRR) was measured with a portable infrared gas analyzer from June to August of 2003 in two experimental forests. We compared the main drivers of respiration and the responses to disturbance in a Sierra Nevada mixed-conifer forest and a mature upland oak-hickory and oak-pine forest in the Missouri Ozarks. The mixed-conifer forest was treated with thinning and burning manipulations in 2001 and the hardwood forest was treated with thinning manipulations in 1996 and 1997. Microclimatic variables and litter depth were sampled at both sites throughout the season. We found that selective thinning produced a similar effect on both forests by elevating SRR, soil moisture, and soil temperature, although the magnitude of response was greater in the mixed-conifer forest. Mean SRR for the season was 3.66 and 3.86 mol m^-2 s^-1 at disturbed plots and 3.38 and 3.71 mol m^-2 s^-1 at control plots in the mixed conifer and hardwood forests, respectively. The main drivers of SRR were different between the two sites and by treatment types within the sites. At the mixed conifer site, SRR varied by disturbance (p=0.0662), patch type (p=<0.0001), soil temperature (p=0.0024) and litter depth (p=<0.0001); and at the hardwood site, SRR varied by disturbance (p=0.0242) and patch type (p=<0.0001).

Key words: disturbance, microclimate, soil respiration, management