Japanese Forest Soils Consume Twice the Methane of Those in the US and Europe

Forested land in Japan can absorb almost twice the atmospheric methane as forested land in Europe and the U.S.A., and emits less than half the nitrogen oxide (N2O) measured in terms of unit surface area, the Forestry and Forest Products Research Instituted (FFPRI) of Japan announced on December 20, 2007 in a brief study report. The study was part of efforts by the Ministry of Agriculture, Forestry and Fisheries to combat global warming, and was conducted through a joint observation network involving local forest and forestry research institutes and universities. Methane consumption and N2O emissions were measured and analyzed at 26 sites with typical Japanese forest soils.

Forest soils in general are known to absorb atmospheric methane and emit N2O. The whole picture of methane uptake and N2O emissions by Japanese forest soils, however, has not been fully understood due to a lack of data. In this study, the annual mean rates of methane uptake and N2O emissions per hectare were estimated for all studied sites, obtaining 6.9kg and 0.2 kg respectively.

Compared with data reported for U.S. and European forest soils, Japanese methane consumption values per unit surface area were almost twice as high. Meantime, N2O emissions using the same measuring units were in the range of less than half as much. Among soil types, methane consumption rates for volcanic ash soil were significantly higher than for other types of soil, suggesting that porous volcanic ash soil, which has a wide distribution in Japan's forested lands, may have contributed to the higher methane uptake values.

As methane is known to trap heat, the FFPRI will do further studies to clarify the uptake mechanism in order to contribute to mitigating global warming.

http://ss.ffpri.affrc.go.jp/e_version/index-e.html

Posted: 2008/05/03 10:27:31 AM