Characteristics of stand structure and species composition in secondary stands regenerated after disturbance by 1954 typhoon
1990
Higo, M. (Gifu Univ. (Japan). Faculty of Agriculture)
In Tomakomai experiment forest of Hokkaido University, secondary stands with diverse composition covered the sites destroyed by the 15th typhoon in 1954. These secondary stands seemed to have different property from mature stands. In this paper, characteristics of species composition and structure were analyzed based upon data obtained from 39/100 centiare quadrates in secondary stands and 13 in mature ones. Average stem density of secondary stands was 69.09/100 centiare, although that of mature ones was 31.2/100 centiare. Average basal area was 2226.0 square cm/100 centiare in secondary 7472.8 square cm/100 centiare in mature stands. A greater difference in density and basal area between secondary and mature stands was observed in 5-20 cm DBH class. Species occurring in secondary stands were classified into two groups. One species group included species which occurred both in secondary and mature stands, but dominated understory (DBH5cm) in secondary stands. Another species group was characterized by more frequent occurrence in secondary than in mature stands. There were considered to be shade-intolerant, fast-growing species. Both the number of species and diversity index (Shonnon-Weaver's H) were higher in secondary stands, indicating the high species diversity of secondary stands. The number of dead stem was 19.5/100 centiare in secondary stands, which was four times as high as in mature stands (4.2/100 centiare). Most dead stems concentrated in the understory layer (0-5cm in DBH, 2-4m in height). From the above results it might be concluded that at 31 years after the disturbance, the secondary stands were in an earlier stage of secondary succession and would experience drastic change in species composition and stand structure for the future
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