Effects of Historic Addition of Charcoal on Soil Respiration in Catoctin Mountain Park, MD.

The addition of charcoal has an effect on long term storage of carbon in soils due to the slow decomposition of pyrogenic carbon. This study seeks to understand how the historic addition of charcoal at hearth sites has affected the soil respiration rate. The hearths analyzed in this study were used to make charcoal during the period from 1776 to 1873.  Four hearth sites were selected for investigation to determine the effect of charcoal production on soil respiration.  Sites were identified by landscape position (mountainflank or mountainbase) and aspect (northeast or southeast).  Three respiration measurements were collected from each hearth site and from a corresponding control area in the same landscape position.  The CO₂ released through soil respiration was collected for 30 minutes and measured using Draeger tubes.  Soil respiration at the sites will continue to be measured on a monthly basis throughout growing season. From the first set of measurements taken in May, a significant difference was found between hearth and control respiration rates (P = 0.001).  The arithmetic mean was 1.1 g CO₂-C/m²/d for the control areas and 0.8 g CO₂-C/m²/d for the hearths.  Additionally, a significant difference was found based on the landscape position and aspect (P=0.018), with mountainbase northeast (1.3 g CO₂-C/m²/d) and mountainflank southeast (1.2 g CO₂-C/m²/d) having the highest averages.  There was no significant interaction found between the effects of landscape position and charcoal production on soil respiration (P=0.658). Initial results indicate control sites to have higher respiration as compared to hearth sites across all landscape positions.  This relation of charcoal to soil respiration will be further investigated throughout the growing season.