Initial effects of artificial warming and drought on soil respiration of Pinus koraiensis seedlings.

This study examined the effects of atmospheric warming and drought on soil respiration rate (R_S) in an open-field experiment with Pinus koraiensis seedlings for two years. In May 2016, a nursery was established with 12 plots (1.5 m × 1.0 m) in Korea University, and 90 2-year-old P. koraiensis seedlings were planted in each plot. There were three replicates for each treatment (control (C), drought (D), warming (W), and warming plus drought (W*D)). The air temperature of the W and W*D plots was set to be 3°C higher than the C and D plots using infrared lamps. Drought was induced by covering 30% of the plot area with transparent panels. R_S was measured between 10:00 and 12:00 monthly from June 2016 to May 2018 using the portable CO₂ sensors and closed PVC chambers (n=3). Warming significantly enhanced R_S by an average of 32% and 18% in the W and W*D, respectively, while drought had no effect on R_S. R_S was significantly different among the months; R_S of all treatments were highest in summer and lowest in winter during the study period. These results of R_S corresponded to changes in soil temperature, which are similar to those of previous studies. Compared to the C and D plots, R_S in the W and W*D plots was higher, but they were less sensitive to soil temperature changes; as a result of linear regression analysis between R_S and soil temperature, was 1.77 and 1.48 in temperature control and warming plots, respectively. Estimating the responses of plant-root biomass and soil microbial activities to warming, which are key factors of soil respiration, is required to determine the soil CO₂ flux.

This study supported by Ministry of Environment (2014001310008) and Korea Forest Service (2017044B10-1819-BB01).