compost, the region has been jointly managed by every
village and sustainably maintained for a long time by
mowing, grazing, or burning. The burning-off of fields is
customarily carried out in early spring (Aso regional GIAHS
Executive Committee 2014).
A description of the Aso Grasslands is given in the
“Nihon Shoki,” which was edited around the eighth century,
and the “Engishiki,” edited around the tenth century, which
shows that the grasslands have been used as a pasture since
around these times (Otaki 1997). From these ancient documents, we can interpret that the Aso Grasslands have existed
for over one thousand years. However, Ogura et al. (2002)
suggested that the Aso Grasslands have been intentionally
burned for over 10,000 years based on the analysis of
microscopic charcoal in soil samples from the northern
caldera rim of Aso volcano. Similarly, Miyabuchi and
Sugiyama (2008) also suggested that sustainable maintenance of the Aso Grasslands by burning has continued over
10,000 years based on a phytolith analysis of a tephra
sequence.
The soil type of the Aso region is Andosol. Andosols are
formed from tephras or pyroclastic materials (Shoji et al.
1993). Matsuyama and Saigusa (1994) showed that Allophanic Andosols that have a clay fraction dominated by
allophane and imogolite are mainly distributed, while
Non-Allophanic Andosols are scattered, in this area. Additionally, Kubotera et al. (2015) analyzed the top 15 cm of
soil around the Aso region and showed that Non-Allophanic
Andosols were densely distributed on the northwestern Aso
somma. In Non-Allophanic Andosols, the clay fractions are
mostly dominated by 1:2 clay minerals and the active Al
consists largely or wholly of Al complexed with humus
(Shoji et al. 1985). In Allophanic Andosols, aluminum
toxicity does not occur frequently, but the large amount of
exchangeable Al in Non-Allophanic Andosols may lead to
acid injury to plants due to aluminum toxicity (Saigusa et al.
1980; Matsuyama et al. 2005).
Andosols in the Aso region have high carbon contents of
about 200 Mg C ha
−1 . Toma et al. (2010) indicated that ash
and charcoal formed by burning appeared to contribute to
carbon accumulation in soil. Furthermore, Toma et al.
(2013) suggested that the semi-natural, C4 (Miscanthus,
etc.)-dominated Aso Grassland system serves as an important carbon sink and is worthy of future conservation.
The Aso Grasslands have adapted to this low-fertility soil
and have contributed to local agriculture and the prevention
of global warming.
(3) Kunisaki Peninsula Usa
The Kunisaki Peninsula Usa area in Oita Prefecture is
located in the northeast of the island of Kyushu, and its
distinct geographical features, ecosystem, and agricultural
culture have been preserved and were consequently designated as a GIAHS by the FAO in 2013 (The Kunisaki
Peninsula Usa GIAHS Promotion Association 2017). In
particular, this area is characterized by low rainfall in winter,
steep rivers that extend in every direction from the mountains, and coverage by soil that is easily penetrated by
rainfall. These conditions pose a challenge for farmers, who
are constantly struggling with water shortages when trying to
irrigate rivers.
One of the important products in this GIAHS is dried log
wood-cultivated shiitake mushroom (Lentinula edodes) that
uses sawtooth oak (Quercus acutissima) as a log wood. This
traditional cultivation system depends on sustainable forestry by coppicing to produce enough log wood. In
broad-leaved forests in the mountainous part of the Kunisaki
Peninsula Usa area, even when cut down in autumn, fully
developed sawtooth oak trees have the characteristic of
shooting up from the stump in the next spring and
re-growing in 15–20 years with appropriate management
(Fig. 10.14a and b). Log woods that hosted shiitake mushroom were covered by twigs so as to avoid sunlight and
stacked on the mountainside for up to two years where the
sprouting of sawtooth oak would take place again. During
this period, the shiitake mycelium proliferates within log
wood, which is finally taken from the mountainside to a
scrap wood site where mushroom harvesting takes place
(Fig. 10.14b).
As the stumps of sawtooth oak can survive for more than
100 years and their roots grow further and faster in the soils
and absorb more nutrients year after year, the surface soil
continues to be full of vigorous growth. Due to the abundance of fallen leaves that accumulate on the soil surface
every year, dark Brown Forest soil occurs beneath the
abundant sawtooth oak broad-leaved forests in the Kunisaki
Peninsula Usa area which are rich in organic matter plus
inorganic nutrients and have a high water-holding capacity
that increases each year (Fig. 10.14c). By storing the rainwater that this sawtooth oak forest accumulates in roughly
1200 small-scale reservoirs, farmers can continue to farm
paddy fields and carry out forestry and fishery, and the
unique ecosystem can be permanently preserved (Hayashi
2014).
10 Kyushu and Okinawa Regions
349
village and sustainably maintained for a long time by
mowing, grazing, or burning. The burning-off of fields is
customarily carried out in early spring (Aso regional GIAHS
Executive Committee 2014).
A description of the Aso Grasslands is given in the
“Nihon Shoki,” which was edited around the eighth century,
and the “Engishiki,” edited around the tenth century, which
shows that the grasslands have been used as a pasture since
around these times (Otaki 1997). From these ancient documents, we can interpret that the Aso Grasslands have existed
for over one thousand years. However, Ogura et al. (2002)
suggested that the Aso Grasslands have been intentionally
burned for over 10,000 years based on the analysis of
microscopic charcoal in soil samples from the northern
caldera rim of Aso volcano. Similarly, Miyabuchi and
Sugiyama (2008) also suggested that sustainable maintenance of the Aso Grasslands by burning has continued over
10,000 years based on a phytolith analysis of a tephra
sequence.
The soil type of the Aso region is Andosol. Andosols are
formed from tephras or pyroclastic materials (Shoji et al.
1993). Matsuyama and Saigusa (1994) showed that Allophanic Andosols that have a clay fraction dominated by
allophane and imogolite are mainly distributed, while
Non-Allophanic Andosols are scattered, in this area. Additionally, Kubotera et al. (2015) analyzed the top 15 cm of
soil around the Aso region and showed that Non-Allophanic
Andosols were densely distributed on the northwestern Aso
somma. In Non-Allophanic Andosols, the clay fractions are
mostly dominated by 1:2 clay minerals and the active Al
consists largely or wholly of Al complexed with humus
(Shoji et al. 1985). In Allophanic Andosols, aluminum
toxicity does not occur frequently, but the large amount of
exchangeable Al in Non-Allophanic Andosols may lead to
acid injury to plants due to aluminum toxicity (Saigusa et al.
1980; Matsuyama et al. 2005).
Andosols in the Aso region have high carbon contents of
about 200 Mg C ha
−1 . Toma et al. (2010) indicated that ash
and charcoal formed by burning appeared to contribute to
carbon accumulation in soil. Furthermore, Toma et al.
(2013) suggested that the semi-natural, C4 (Miscanthus,
etc.)-dominated Aso Grassland system serves as an important carbon sink and is worthy of future conservation.
The Aso Grasslands have adapted to this low-fertility soil
and have contributed to local agriculture and the prevention
of global warming.
(3) Kunisaki Peninsula Usa
The Kunisaki Peninsula Usa area in Oita Prefecture is
located in the northeast of the island of Kyushu, and its
distinct geographical features, ecosystem, and agricultural
culture have been preserved and were consequently designated as a GIAHS by the FAO in 2013 (The Kunisaki
Peninsula Usa GIAHS Promotion Association 2017). In
particular, this area is characterized by low rainfall in winter,
steep rivers that extend in every direction from the mountains, and coverage by soil that is easily penetrated by
rainfall. These conditions pose a challenge for farmers, who
are constantly struggling with water shortages when trying to
irrigate rivers.
One of the important products in this GIAHS is dried log
wood-cultivated shiitake mushroom (Lentinula edodes) that
uses sawtooth oak (Quercus acutissima) as a log wood. This
traditional cultivation system depends on sustainable forestry by coppicing to produce enough log wood. In
broad-leaved forests in the mountainous part of the Kunisaki
Peninsula Usa area, even when cut down in autumn, fully
developed sawtooth oak trees have the characteristic of
shooting up from the stump in the next spring and
re-growing in 15–20 years with appropriate management
(Fig. 10.14a and b). Log woods that hosted shiitake mushroom were covered by twigs so as to avoid sunlight and
stacked on the mountainside for up to two years where the
sprouting of sawtooth oak would take place again. During
this period, the shiitake mycelium proliferates within log
wood, which is finally taken from the mountainside to a
scrap wood site where mushroom harvesting takes place
(Fig. 10.14b).
As the stumps of sawtooth oak can survive for more than
100 years and their roots grow further and faster in the soils
and absorb more nutrients year after year, the surface soil
continues to be full of vigorous growth. Due to the abundance of fallen leaves that accumulate on the soil surface
every year, dark Brown Forest soil occurs beneath the
abundant sawtooth oak broad-leaved forests in the Kunisaki
Peninsula Usa area which are rich in organic matter plus
inorganic nutrients and have a high water-holding capacity
that increases each year (Fig. 10.14c). By storing the rainwater that this sawtooth oak forest accumulates in roughly
1200 small-scale reservoirs, farmers can continue to farm
paddy fields and carry out forestry and fishery, and the
unique ecosystem can be permanently preserved (Hayashi
2014).
10 Kyushu and Okinawa Regions
349