DISTRIBUTION AND CHEMICAL CHARACTERISTICS OF CATIONS IN ANNUAL RINGS OF JAPANESE CEDAR

The objectives of this study were to investigate the distribution and chemical characteristics of cations in annual rings of Japanese cedar (Cryptomeria japonica D. Don) grown in a healthy stand of an unindustr ialized region in Japan and discuss the possibility of using cations i n tree-rings as a chronological index of acidic deposition, Radial dis tributions of some cations and P at different vertical positions of th e stem were analyzed for five trees from the same mountain, Each catio n and P in all trees showed a specific distribution in its radial patt ern but similar distribution trends were observed at all vertical posi tions, The cations and P were classified into three groups: (I) consta nt radial concentrations (Ca2+, Sr2+, N+, and probably Ba2+), (II) hig h concentrations in the heartwood and low in the sapwood (Mg2+, K+, Rb +, Cs+), and (III) increasing concentrations in the sapwood (P, Mn2+, Cu2+). Th, total concentration of cations exceeded the calcium-binding capacity (CBC) of the wood, and the excess was attributed to K+ in a salt form, The CBC increased from the sapwood/heartwood heartwood boun dary toward the pith in the heartwood but remained constant in the sap wood, The increase of CBC in the heartwood was consistent with the pro file of Mg2+, indicating a transfer of Mg2+ into heartwood and fixatio n on the acquired binding site. The radial distribution of Sr-90 was c losely related to the cumulative deposition of fallout from the nuclea r weapon tests, but that of Cs-137 was unrelated, This suggests immobi lity of Sr2+ and mobility of Cs+ in the horizontal direction of wood, The conservation of the historical Sr-90/Sr2+ change indicated that no influence of heartwood formation on the chemical environment of Sr2in cedar xylem and a possibility of using Sr2+ as a chronological inde x of nutrient availability. A steady-state in nutrient availability is speculated for trees growing in this mountain because all of the tree s analyzed show constant radial distributions of Sr2+ for decades.