Abstract
Band-type dendrometers were installed on tree trunks of four species in the northern part of Okinawa, Japan. The monthly diameter growth was measured from 1986 to 1989, the data from 1988 being used in this paper. The seasonal diameter growth curves of sample trees were grouped into the following three types : Type A: the growth rate was high and the growth period was short; Type B: the growth rate was low and the growth period was long; Type C: there were two growth seasons per year. There was also a complex type, a combination of type A in the early growth season (in spring) and type B in the late growth season (in autumn). Type A included only Styrax japonicus, type B included Castannopsis sieboldii, Shima wallichii ssp. liukiuensis, and Cryptomeria japonica, and the type C included Styrax japonicus and Cryptomeria japonica. These tree species, which originated in the cool and temperate forest zones, showed similar seasonal diameter growth patterns that were the typical of the original area, even in the subtropical forest zone in Okinawa. The characteristics of the seasonal diameter growth of these tree species were recognized as being behavior adaptive for growth in autumn and winter seasons in the subtropical zone in Okinawa. The function of Richard was adapted to types A and B for one growth season per year, and to type C type for two growth seasons per year. The three types showed obvious differences among the coefficient "m," the growth rate, and the growth period.
