Production and consumption of ethylene in temperate volcanic forest surface soils

Abstract

SummaryTo date our knowledge is limited with regard to the cycling of ethylene (C2H4) in temperate forest soils containing volcanic ash, and the effect of forest‐to‐orchard conversion on its cycling. We studied ethylene accumulation in such forest soils by oxic and anoxic incubations, along with the stimulatory effect of glucose addition on soil C2H4 accumulation. We also studied the effect of antibiotics and autoclaving on C2H4 production and consumption by volcanic forest soils, and the cycling of C2H4 and CH4 in surface soils after conversion of a Japanese cedar forest to an orchard. Ethylene production and consumption by forest surface soils results from a microbial process, and soil streptomycin‐sensitive bacteria make a minor contribution. Soil C2H4 accumulation was much larger during anoxic than during oxic incubation, which indicates that anoxic conditions can induce C2H4 accumulation in forest soils. Glucose addition as a carbon source can sharply increase C2H4 accumulation rates in the anoxic and oxic forest soils during the first week of incubation. However, there was no difference in total C2H4 accumulation in the amended and non‐treated soils after 35 days of anoxic incubation. Ethylene production of the 0–5 cm and 5–10 cm soils beneath forest and orchard showed the greatest rate after 2 weeks of anoxic incubation when soil CH4 production started to increase sharply, and later it was strongly suppressed. The forest‐to‐orchard conversion showed little influence on the CH4 production of surface soils during short‐term anoxic incubation, but significantly reduced soil C2H4 production. The conversion also significantly decreased the consumption of soil CH4 and C2H4, the former more than the latter. Soil properties such as total C, water‐soluble organic C and pH contribute to the consumption and production of C2H4 in the 0–5 cm and 5–10 cm soils, and there are the parallels between CH4 and C2H4 consumption in soils, which suggests the presence of similar microorganisms. Long‐term anoxic conditions of in situ surface upland soils are normally not prevalent, so it can be reasonably concluded that there is a larger C2H4 accumulation rather than CH4 accumulation in surface soils beneath forest and orchard after heavy rainfall, especially beneath forest.