A simple estimate of the carbon budget for burned and unburned Pinus densiflora forests at Samcheok-si, South Korea

Abstract

To clarify the effects of forest fire on the carbon budget of a forest ecosystem, this study compared the seasonal variation of soil respiration, net primary production and net ecosystem production (NEP) over the year in unburned and burned Pinus densiflora forest areas. The annual net carbon storage (i.e., NPP) was <TEX>$5.75t\;C\;ha^{-1}$</TEX> in the unburned site and <TEX>$2.14t\;C\;ha^{-1}$</TEX> in the burned site in 2012. The temperature sensitivity of soil respiration (i.e., <TEX>$Q_{10}$</TEX> value) was higher in the unburned site than in the burned site. The annual soil respiration rate was estimated by the exponential regression equation with the soil temperatures continuously measured at the soil depth of 10 cm. The estimated annual soil respiration and heterotrophic respiration (HR) rates were 8.66 and <TEX>$4.50t\;C\;ha^{-1}yr^{-1}$</TEX> in the unburned site and 4.08 and <TEX>$2.12t\;C\;ha^{-1}yr^{-1}$</TEX> in the burned site, respectively. The estimated annual NEP in the unburned and burned forest areas was found to be 1.25 and <TEX>$0.02t\;C\;ha^{-1}yr^{-1}$</TEX>, respectively. Our results indicate that the differences of carbon budget and cycling between both study sites are considerably correlated with the losses of living plant biomass, insufficient nutrients and low organic materials in the forest soil due to severe damages caused by the forest fire. The burned Pinus densiflora forest area requires at least 50 years to attain the natural conditions of the forest ecosystem prior to the forest fire.