Characteristics of soil respiration in Pinus densiflora stand undergoing secondary succession by fire-induced forest disturbance

Abstract

The purpose of this study is to compare soil <TEX>$CO_2$</TEX> efflux between burned and unburned sites dominated by Pinus densiflora forest in the Samcheok area where a big forest fire broke out along the east coast in 2000 and to measure soil <TEX>$CO_2$</TEX> efflux and environmental factors between March 2011 and February 2012. Soil <TEX>$CO_2$</TEX> efflux was measured with LI-6400 once a month; the soil temperature at 10 cm depth, air temperature, and soil moisture contents were measured in continuum. Soil <TEX>$CO_2$</TEX> efflux showed the maximum value in August 2011 as 417.8 mg <TEX>$CO_2m^{-2}h^{-1}$</TEX> (at burned site) and 1175.1 mg <TEX>$CO_2m^{-2}h^{-1}$</TEX> (at unburned site), while it showed the minimum value as 41.4 mg <TEX>$CO_2m^{-2}h^{-1}$</TEX> (at burned site) in December 2011 and 42.7 mg <TEX>$CO_2m^{-2}h^{-1}$</TEX> (at unburned site) in February 2012. The result showed the high correlation between soil <TEX>$CO_2$</TEX> efflux and the seasonal changes in temperature. More specifically, soil temperature showed higher correlation with soil <TEX>$CO_2$</TEX> efflux in the burned site (<TEX>$R^2$</TEX> = 0.932, P < 0.001) and the unburned site (<TEX>$R^2$</TEX> = 0.942, P < 0.001) than the air temperature in the burned site (<TEX>$R^2$</TEX> = 0.668, P < 0.01) and the unburned site (<TEX>$R^2$</TEX> = 0.729, P < 0.001). <TEX>$Q_{10}$</TEX> values showed higher sensitivity in the unburned site (4.572) than in the burned site (2.408). The total soil <TEX>$CO_2$</TEX> efflux was obtained with the exponential function between soil <TEX>$CO_2$</TEX> efflux and soil temperature during the research period, and it showed 2.5 times higher in the unburned site (35.59 t <TEX>$CO_2ha^{-2}yr^{-1}$</TEX>, 1 t = <TEX>$10^3$</TEX> kg) than in the burned site (14.69 t <TEX>$CO_2ha^{-2}yr^{-1}$</TEX>).