We measured the soil surface CO2 efflux (R
S) from January 2005 to December 2006 in two neighboring stands in Gwangneung Forest, central Korea: evergreen coniferous forest
(Abies holophylla, stand A) and broad-leaved deciduous forest (Quercus-dominated, stand Q). Regarding seasonal variation, R
S rate was low during the winter and early spring months in each stand and peaked in late July [1170 (stand A) and 1130 (stand
Q) in 2005, and 1000 (stand A) and 740 (stand Q) mg CO2 m−2 h−1 in 2006]. R
S rate was higher in stand A than in stand Q during most of the growing season. The pattern of summer rainfall differed between
2005 and 2006. R
S rate for both stands was suppressed significantly by the droughts in June 2005 and September 2006. After the heavy rainfall
of July 2006, R
S rate was lower than in July 2005 in both stands, but this decrement was much greater in stand Q than in stand A. In midsummer
(August) 2006, under higher soil temperature (ST) and lower soil water content (SWC) conditions than in August 2005, R
S rate of stand A was lower than that in August 2005, whereas stand Q showed no marked change. The exponential relationship
between ST and R
S accounted for approximately 91–97% of the R
S variability in each stand and in each year. In stand A, the application of a second-order polynomial function indicated a
significant correlation between SWC and R
S when the soil was warm (ST > 15°C). Our results suggest that the seasonality of R
S is strongly affected by the pattern of summer rainfall even in an Asia monsoon climate regime. In addition, the vegetation
type (i.e., evergreen coniferous forest vs. broad-leaved deciduous forest) plays a significant role in response of R
S to various environmental fluctuations such as drought, heavy rainfall, and hot-dry condition.
Keywords Drought - Soil CO2 efflux - Soil temperature - Soil water content - Precipitation