[M-IS14] Biogeochemistry

[MIS14-09] Carbon buried underground by volcanic ash: Estimating the amount of buried carbon by Tarumae-c and Tarumae-d volcanic ash

*Satoru Hobara¹, Tatsumi Kase¹, Shizuku Okada¹, Tomoko Hatanaka¹, Tatsuro Nakaji², Takuji Sawamoto¹, Mihoko Moriizumi³, Shingo Matsumoto⁴, Khew Ee Hung¹, Nobuhiko Yoshimura¹ (1.Rakuno Gakuen University, 2.Hokkaido University, 3.Ryukoku University, 4.Shimane University)

Keywords:soil carbon, volcanic ash, Mt. Tarumae, buried soil

Volcanic ash often covers the land surface and transforms terrestrial ecosystems. In terrestrial ecosystems, organic matter buried underground by volcanic ash fall can be preserved for tens of thousands of years or more. In Japan, organic soils buried by volcanic ash are found in various areas, but little is known about how much organic matter is buried by a single volcanic deposit. In this study, we conducted a survey to estimate the amount of carbon buried underground by volcanic ash. Three study sites were set up in the Tomakomai Research Forest of Hokkaido University, located at the foot of Mt. Tarumae, and heavy machinery was used to excavate 6 m of soil from the surface to the deeper layers. At all study sites, four volcanic ash deposits (Ta-a, Ta-b, Ta-c, and Ta-d from the top) from Mt. Tarumae were observed, with Ta-c and Ta-d being particularly thickly deposited. Based on carbon analysis of these volcanic ash soils, it was estimated that the amount of carbon retained in the soil, including the buried soil, was about 10 times greater than that retained by plants above ground. We also estimated the carbon stocks of two volcanic ashes, Ta-c and Ta-d, in the entire terrestrial forest area where the ashes fell, using GIS.