| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1999: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The purpose of this study was to clarify the regeneration characteristics of Quercus communities (Q.dentata and Q. salicina) in Sado Island from the view points of the regeneration process estimated from the stand structure, the limiting factors in regeneration process from flowering to seedling establishment, the function of seed dispersing predator of wood mouse, and the safe site of seedling.
1. Regeneration process : The frequency distribution patterns of height and diameter at breast height of Q. salicina in study stand show the J-shape and bell-shape, respectively. From this patterns, there were few saplings in the Q. salicina stand and it seem to be failed to continuous regeneration after simultaneous regeneration following the large-scale disturbance like clear cutting. Q. dentata stand had the same tendency about stand structure and regeneration process.
2. Limiting factor : Pre-dispersal insect damage was the most critical limiting factor in the regeneration process of Q. dentata. As there was no fluctuation of female flower production, Q. dentata population could not escape the insect predation pressure.
3. Function of wood mouse : In Sado Island, Apodemus speciosus was main seed dispersing predator of Quercus acorns. Dispersing acorns by wood mouse were once scatter-hoarded, but all caching acorns were predated until next spring.
4. Safe site : There was significant correlation between the number of over five years old Q. salicina seedling and the rPPFD in winter season (from November to April). Q. salicina seedling was able to establish and grow under the deciduous tree canopy or forest margin where light intensity would be increase in winter season.
Though above results are very important and useful to manage the Quercus communities in Sado Island, time and space fluctuation of acorn production and dispersion, that would be effective on the regeneration characteristics, must be continuously monitored for long time.
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