One year of continuous measurements of soil CH4 and CO2 fluxes in a Japanese cypress forest: Temporal and spatial variations associated with Asian monsoon rainfall. Issue 4 (14th April 2015)

• Record Type: Journal Article
• Authors: Sakabe, Ayaka; Kosugi, Yoshiko; Takahashi, Kenshi; Itoh, Masayuki; Kanazawa, Akito; Makita, Naoki; Ataka, Mioko
• Is Part Of: Journal of geophysical research. Volume 120:Issue 4(2015:Jun.)
• Page Start: 585
• Page End: 599
• Publication Date: 2015-04-14
• Subjects: Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2014JG002851
• Languages: English
• ISSNs: 2169-8953

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>We examined the effects of Asian monsoon rainfall on CH<sub>4</sub> absorption of water‐unsaturated forest soil. We conducted a 1 year continuous measurement of soil CH<sub>4</sub> and CO<sub>2</sub> fluxes with automated chamber systems in three plots with different soil characteristics and water content to investigate how temporal variations in CH<sub>4</sub> fluxes vary with the soil environment. CH<sub>4</sub> absorption was reduced by the "Baiu" summer rainfall event and peaked during the subsequent hot, dry period. Although CH<sub>4</sub> absorption and CO<sub>2</sub> emission typically increased as soil temperature increased, the temperature dependence of CH<sub>4</sub> varied more than that of CO<sub>2</sub>, possibly due to the changing balance of activities between methanotrophs and methanogens occurring over a wide temperature range, which was strongly affected by soil water content. In short time intervals (30 min), the responses of CH<sub>4</sub> and CO<sub>2</sub> fluxes to rainfall were different for each plot. In a dry soil plot with a thick humus layer, both fluxes decreased abruptly at the peak of rainfall intensity. After rainfall, CO<sub>2</sub> emission increased quickly, while CH<sub>4</sub> absorption increased gradually. Release of accumulated CO<sub>2</sub> underground and restriction and recovery of CH<sub>4</sub> and CO<sub>2</sub> exchange between soil and air determined flux responses to rainfall. In a wet soil plot and a dry soil plot with a thinner humus layer, abrupt decreases in CH<sub>4</sub> fluxes were not observed. Consequently, the Asian monsoon rainfall strongly influenced temporal variations in CH<sub>4</sub> fluxes, and the differences in flux responses to environmental factors among plots caused large variability in annual budgets of CH<sub>4</sub> fluxes.</p> </abstract>