火入れ地における炭素蓄積量の定量化

本研究の目的は岡山県真庭市蒜山地域の火入れ地において，土壌中に蓄積される炭素の蓄積過程と分布様式を明らかにし，その蓄積量を定量化することである．火入れ後に再生した植生は火入れで放出された炭素を吸収する，さらに火入れや野火によって生じた植物炭化物は微生物によってほとんど分解されないため，植物炭化物は炭素を長期間土壌中に蓄積する．したがって火入れの炭素収支は蓄積の方が多い可能性がある．バイオマスおよび土壌中の植物炭化物密度と火入れによる炭素蓄積量には正の相関がみえられた．また地形ごとの植物炭水化物量は尾根部よりも谷部において多く，さらに斜度と黒色土層の厚さに負の相関がみられた．本調査地における火入れによる炭素の蓄積量は尾根部よりも谷部において多かった．全体として，火入れによる炭素収支は蓄積の方が多かった．そのため，火入れが大気中の二酸化炭素を増加させないことが示唆された．The purpose of this study is to clarify accumulation and distribution processes of carbon contents into soil, and to analysis carbon mass quantitatively by prescribed burning at a grassland of Hiruzen area, Ｍａｎｉｗａ city, Okayama prefecture. Vegetation regenerated after prescribed burning could absorb carbon which emitted by prescribed burning. Futhermore, charcoal usually stores carbon in soil for a long time, because charcoal made by prescribed burning and wildfire is hardly decomposed by microorganism. Therefore, there is a possibility that accumulations would be more than emissions in carbon balance by prescribed burning. Charcoal mass was much at the valley than at the ridge, and there was a negative relationship between slope and thickness of dark soil layer. Carbon accumulations by prescribed burning were much at the valley than at the ridge. As a whole, accumulations could be more than emissions in carbon balance of prescribed burining. It is suggested that prescribed burning would not increase carbon dioxide in the atmosphere.