Temperature effects on ethylene and methane production from temperate forest soils

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 Q ₁₀ 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 Q ₁₀ 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. Supported jointly by National Natural Science Foundation of China (Grant Nos. 20777071 and 20477044), Hundred Talents Project from the Chinese Academy of Sciences, and the Japan Society for the Promotion of Sciences