Effects of Japanese cedar (Cryptomeria japonica D. Don) and Japanese cypress (Chamaecyparis obtusa Sieb. et Zucc.) needles in the soil on nitrogen accumulation in forest soil
2016
Ichikawa, T. (Tochigi Agroforestry Club (Japan))
The aim of the present study was to investigate the effects of Japanese cedar and Japanese cypress needles in the soil on nitrogen accumulation in forest soil according to stand age in the Kanto region of Japan. We determined nitrogen content of litterfall, forest floor, needle leaves in the soil, and soil in cedar and cypress forests. The study sites were located in forests planted with Japanese cedar and Japanese cypress trees that were adjacent to each other on the same slope with different stand ages (13, 21, 34, 48, 66, and 93 years). In cypress forests, the C/N ratio of needle leaves in the soil was intermediate between that of forest floor and soil nitrogen content at a depth of 0-10 cm. The contribution of nitrogen by needle in the soil to the soil nitrogen content at a depth of 0-10 cm in the cypress forests was larger than that in the cedar forests. The easily decomposed cypress litter entered the soil at a depth of 0-10 cm, and increased soil nitrogen content in the cypress forest. On the other hand, the nitrogen content of litterfall decreased more than 21 years old in the cedar forests. However, litterfall of decomposed with difficulty was increasing with stand age in the cedar forest. This suggest that the soil nitrogen content at a depth of 0-10 cm remains unchanged with stand age in the cedar forests.
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