Species richness in sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis> D. DON) plantations in southeastern Kyushu,Japan: the effects of stand type and age on understory trees and shrubs |
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Authors: | S Ito M Nakagawa G P Buckley K Nogami |
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Institution: | (1) Division of Forest Science, Faculty of Agriculture, Miyazaki University, Miyazaki 889-1702, Japan Tel./Fax +81-985-58-7178 e-mail: s.ito@cc.miyazaki-u.ac.jp, JP;(2) Tano Forest Science Station, Faculty of Agriculture, Miyazaki University, Tano, Miyazaki, Japan, JP;(3) Department of Agricultural Sciences, Imperial College, Wye, Ashford, Kent, UK, GB |
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Abstract: | The species richness of trees, shrubs and climbing plants was investigated in 41 sugi (Cryptomeria japonica D. Don) plantations of different stand age and area in southern Kyushu, southwestern Japan. Altogether 174 species were found,
of which 145 infrequent species were selected for analysis. Two groups were extracted from the species list according to their
occurrence in older (49 spp.) or younger (28 spp.) stands, the latter containing a higher percentage of climbing plants and
species with wind-dispersed seeds. In contrast, the older stand group contained major tree components typical of seminatural,
evergreen broadleaved forests in the region and was more heavily dependent on stand age, especially for species with gravity-
and frugivore-dispersed seeds, showing a gradual increase up to 60 years old. The species richness was less correlated with
edge perimeter facing seminatural forests and the years after latest thinning. The juxtaposition of plantation compartments
with stands of seminatural forest or other plantations, as well as the compartment's origin as former plantation site or a
seminatural stand, had relatively little influence on species richness. However, topographic variation was important in determining
the species composition, with valley stands having higher species richness and containing many plants typical of the regional
seminatural forests. These results suggest that (1) the major trend of species richness is determined by the presence of old
stand type species, (2) topographic variation of species richness remains even after establishment of plantations, and (3)
the normal rotation period of sugi plantations (35–40 years) may therefore be too short to conserve the maximum potential
species diversity within the working forest.
Received: June 4, 2001 / Accepted: August 26, 2002
Acknowledgments We wish to thank the staff of the Miyazaki University Forests for cooperation in the fieldwork. A part of this study was
supported by the Grant-in-Aid for Scientific Study from the Ministry of Education, Science and Culture of Japan (no. 09041071
and no. 10460068).
Correspondence to:S. Ito |
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Keywords: | Edge effects Stand ages Previous stand type Seed dispersal Sugi (Cryptomeria japonica D Don) |
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