Importance of Internal Proton Production for the Proton Budget in Japanese Forested Ecosystems

Abstract

Annual biogeochemical fluxes (bulk precipitation, throughfall, stem flow, soil solution and vegetation uptake) of inorganic elements were observed in eight cool temperature forested ecosystems in Hokkaido, northern Japan, in order to determine the mechanisms of acid neutralization in Japanese forest ecosystems. We compared our results with the other biogeochemical studies in Japan, north Europe and US from the literature. In many Japanese forests, the internal proton production (IPS) by base cation accumulation into the vegetation was a major proton source, rather than external acidic deposition, and the IPS also affected the base cation fluxes from the mineral. IPS in Japanese forest tended to be larger than that in north Europe and US. Our results suggested that the high acid neutralizing ability of Japanese forests could be attributed to the strong relationship between the base cation buffering of the soil and the larger contribution of IPS as a proton source. acidic deposition|biogeochemical cycling|forest ecosystem|Japan|proton budget