|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1993 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1992 : ¥1,000,000 (Direct Cost : ¥1,000,000)
According to out investigation, in the soils beneath Sugi stands more than 30 to 40 years olds, Ca and other base has increased repidly at the upper layr, and the layr of exchangeable Ca accumulation moves to the lower layr. In addition, the accumulation of N and P and an increase in soil pH were evident in the soils beneath Sugi stands, but not in the Hinoki and broad leaved stands. These results suggested that the multi storied and the mixed stands containing Sugi increase soil fertility. While the effect of a multi storied and a mixed stands on soil fertility differed according to the mixed state of Sugi and the stand density of reserved Sugi, the above presumption was confirmed. The results obtained were as follows.
(1) Six mixed stands of Sugi with Hinoki and of Akamatsu with broad leaved trees were chosen in Tochigi and Iwate Prefecture. In the mixed stands with the high stand density of Sugi, the dry weight and the contents of nutrrents such as N, P, K and Ca of A_0 horizon were abundant compared to the other stands. In mineral forizon also, exchangeable Ca and P have increased and soil pH rose. These characteristics was obvious in Andosols with low base-saturation.
(2) Eight multi storied stands were chosen in Tochigi, Chiba and Gifu Prefecture. Upper trees were consisted of Sugi, Hinoki and broad leaved trees, the age of Sugi or Hinoki underplanted was less than 30 years olds. In stands which upper trees are Sugi and more than 40 years old, the dry weight and the contents of nutrients such as N, P, Ca of A_0 horizon were abundant compare to Hinoki and broad leaved trees. These nutrients increased in mineral horiaon. These characteristics was obvious in Andsols with low base-saturation and in soils with the low content of coarse fragment.