Outline of the Aya Research Site
The Aya Research Site is located on the north slope of a ridge running east from Mt.Ohmori (32 degrees 04'N, 131 degrees 09'E), Miyazaki Prefecture, 860 km west of Tokyo. This site is under the management of the Kumamoto Regional Forestry Office as Compartment No. 93 of the Takeno National Forest (109 ha) and has no record of logging and artificial disturbances.
In 1989, we established a 4-ha plot (200m x 200m) in the site. To observe seed dispersal and litterfall production, a 1.2-ha core plot (120 m x 100 m) was set up within the 4-ha plot.
2. Climate and Microtopography
Annual mean temperature :17.3 C degrees
Annual precipitation : 2,457 mm
Parent rock : shale and sanstone of Mesozoic formation
Dominant Soil Type : moderately moist brown forest soil type
(FAO-Unesco : Dystric Cambisol, USA : Dystrochrept)
The plot is on steep north-facing slope. The elevation of the 4-ha plot ranges from 380 m to 520 m (See below).
According to phytosociological studies, this site belongs to a transitional zone between Distylio-Quercetum salicinae and Lasiantho-Quercetum gilvae associations.
We enumerated 115 tree species in 49 families at the site, of which 5 were conifer, 41 were deciduous broad-leaved and 69 were evergreen broad-leaved species.
4. Research Design
In the 4-ha plot, we have conducted researches based on research design as followed.
For all trees above 5 cm in DBH (Diameter at Brest Height), we recorded species name, locationand DBH in the 4-ha plot.
The first census was conducted in 1989. We have conducted recensus every two years during 1989-1997, and every four years since 1997.
All trees above 30 cm in height and below 5 cm in DBH in the quadrats were recorded in the same manner as the tree census. During 1994-2004, sapling census was conducted every two years.
In 1991, we set a 1.2-ha core plot. There were 263 traps with seedling census quadrats in the 1.2-ha core plot.
We cunducted seedling census at the 263 quadrats during June 1991-March 1997, at the 142 quadrates during April 1997-March 2001, and at the 42 quadrates during April 2001-March 2004.
We have cunducted monthly sample collection of trap contents at the 263 traps during June 1991-March 1997, at the 142 traps during April 1997-March 2001, and at the 42 traps since April 2001.
5. Distributional Pattern of Major Tree Species
c) Distylium racemosum (HAMAMELIDACEAE)
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