PARENT SESSION
Contributed Oral Session 153: Forest Soils and Nutrient Cycling
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 514 A, Level 5, Palais des congrès de Montréal

The effects of small-scale silviculture on soil CO₂ efflux and soil temperature in mixed oak forests of southeastern Ohio.

Black, Dawn^*,1, Brown, Kim¹, ¹ Ohio University, Athens, OH, United States of America

ABSTRACT- Thinning and prescribed burning are increasingly common forest management practices in oak forest ecosystems. However, the effects of thinning and burning on soil carbon dynamics are not well defined. Soil CO₂ efflux (Rs) is a major route for carbon loss from forests, as it is a function of autotrophic (root) and heterotrophic respiration. However, heterogeneity of soil properties and biotic communities at the landscape scale make it difficult to determine whether differences in Rs are due to silvicultural effects. To examine thinning and burning effects on Rs, while controlling for variation in soil properties, we utilized a randomized complete block design with two effects, slope position (upper or lower) and canopy cover (CC, full or 50%). Five replicates (total of 20 blocks) were implemented in mixed oak forests of southeastern Ohio. Each block consisted of five 2×2 m treatments: control, low intensity fire, high intensity fire, lime fertilization, and leaf litter removal. The fertilization treatment was intended to simulate the effects of ash deposition following fire, while litter removal simulated the effects of litter consumption by fire, without the heat. Rs, soil temperature, and soil moisture was measured from April to November 2004. Continuous monitoring of soil temperature (-2 cm) from May to December 2004 in the upper slope blocks revealed greater temperatures in the full CC high burn, 50% CC low burn, and 50% CC litter removal treatments. Repeated measures analysis of variance revealed significant effects of treatment and time on Rs. Both soil temperature and soil moisture were significantly affected by slope position, canopy cover, treatment, and time. Reduced Rs rates suggest that low intensity prescribed fires, routinely used in forest management in southeastern Ohio, are capable of reducing soil CO₂ efflux from soils, perhaps a result of suppressing soil biotic activity.×

Key words: forest thinning, prescribed fire, soil CO2 efflux, oak forests