Effects of fire and management activities on carbon sequestration in longleaf pine stands in south-central Alabama, USA

A study is underway to examine carbon sequestration in longleaf pine stands and its relationship to seasons of burn (spring, summer, winter, and no-burn) and supplemental hardwood control treatments (one-time chemical, periodic mechanical, and untreated check).  The study is being conducted on the Escambia Experimental Forest located in south-central Alabama, USA.  This project has been superimposed on a study established in 1973 to examine the effects of different seasons of burn and hardwood control treatments on longleaf pine growth.  Understory vegetation and litter samples were collected in September 2003 to determine biomass and percent carbon. Understory vegetations were sorted out into four components: grasses, herbaceous, vines, and woody.   Soils were sampled in May 2006 at three depths, 0-10, 10-20 and 20+ cm, to determine percent carbon.  Analysis of variance was run to test for differences in percent carbon in the understory vegetation and soil.  Tukey’s studentized rage test and Dunnett’s t-test were used to make pair-wise comparison of soil carbon percent in different seasons of burn.  The no burn treatment had the highest percentage of carbon stored in the understory vegetation, with the winter burn having the highest among the burn treatments.  The interaction between the seasons of burn and supplemental hardwood treatments was not statistically significant.  Soil carbon was significantly different among the summer burn and no burn treatments only.  The no burn treatment had the highest soil percent carbon and the spring burn had the highest among the burn treatments.