Temperature effects on ethylene and methane production from temperate forest soils

Abstract

Change in temperature affects the activity of soil microorganisms. However, there is limited knowledge about temperature effects on ethylene (C2H4) and methane (CH4) production from forest soils. Topsoil samples (0–5 cm) collected from different temperate forest stands (e.g., Pinus sylvestris L., Cryptomeria japonica, and Quercus serrata) were used to compare C2H4 and CH4 production from soils at temperature from 5 to 35°C under oxic and anoxic conditions. The rates of C2H4 and CH4 production from soils under oxic conditions were measured by using inhibition of acetylene (C2H2) and carbon monoxide (CO). The consumption of C2H2 by soils at an initial concentration of c. 250 Pa C2H2 was negligible at 5 and 15°C, but it was significantly increased at 25 and 35°C. The presence of 2 kPa CO in the headspace gases tended to decrease the consumption of C2H2 by soils at high temperature. The Q10 values for the soil C2H2 consumption ranged from 2.3 to 3.8, and there were no significant differences in Q10 values between these topsoil samples. The rate of CH4 production from each sample under oxic conditions was larger than the soil C2H4 production at 5–35°C, particularly at low temperature, and presented a smaller Q10 value. Ethylene production from soil after 1 week of anoxic incubation at 5–35 °C was larger than the soil CH4 production, and presented a larger Q10 value. However, CH4 production from Quercus serrata forest soil and its response to temperature increased significantly with incubation time. Long-term anoxic conditions of in situ upland forest soils are normally not prevalent, so it can be reasonably concluded that there is a larger C2H4 production rather than CH4 production under temperate forest stands due to heavy rainfall in summer.