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Abstract Detail



Ecological Section

Flowers, Knox [1], Davis, Micheal [1].

Soil CO2 Efflux in Burned and Unburned LongLeaf Pine Forest.

The longleaf pine savanna was a once vibrant ecosystem spanning across the majority of the southeastern United States. There is renewed interest to these savannas to increase the ecological health of southeastern ecosystems. These ecosystems are naturally maintained by fire, so fire is being utilized as a land management practice in this experiment. Measurements of soil respiration rates (CO2 efflux rates: μmol m¯²s¯¹) were taken at twelve field plots (6 burned, 6 unburned) established on a 160 acre longleaf pine preserve (LLPP) located in Lamar County, MS. These measurements were taken over synchronous diurnal cycles using two LICOR LI-8100 automated CO2 soil efflux systems with four long term chambers on soil collars randomly positioned within a fifteen meter radius. Efflux data (n=15,258) were collected during three sampling periods in 2012: a pre-burn, spring period (April and May); a post-burn, spring-summer period (May-August); and a post-burn, fall period (November). Using a mixed model ANOVA for statistical analyses (α=0.05), CO2 soil efflux were used to ascertain the effects of fire and season on ecosystem function. The unburned (ub) plots had nearly significant greater mean effluxes when compared to burned (b) plots (F(1,15242)= 4.33, p=0.06; mean efflux: 1.54 (ub) vs. 1.0 (b) μmol m¯²s¯¹ ). There was seasonal variability in overall mean effluxes (F(2,15242)= 3285.3, p<0.0001*) ; a Tukey’s HSD revealed that post-burn spring-summer had the highest mean efflux, followed by pre-burn spring, and lastly post-burn fall. The results of the ANOVA revealed an interaction between the burn treatment and season (F(2,15242)= 265.84, p<0.0001*), although the interaction was due to non-significant differences in pre-burn spring effluxes from burned and unburned plots. This was likely due to a two year gap between prescribed burns on the LLPP, which gave the burned plots time to recover from the effects of the fire. This study was primarily focused on looking at overall CO2 efflux rates, although long term goals focus on identifying the key factors seen in varying CO2 efflux rates, such as fine root turnover, litter microenvironment and microbial/micro-arthropod communities.

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1 - University of Southern Mississippi , Biological Sciences, 118 College Drive, Box #5018, Hattiesburg, MS , 39406, USA

Keywords:
Longleaf pine savanna
Prescribed burning
Soil CO2 Flux.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:45 PM
Number: PEC007
Abstract ID:552
Candidate for Awards:Ecological Section Best Graduate Student Poster


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