Mount Akaishi
Mountains of Akaishi
The mountains of Akaishi are within the Hooh mountains extending from Niihama City to Doi-cho, Uma-gun in eastern Ehime. It develops from the south of the mountain village in the west of Mount Hanezuru (altitude 1,282m) in eastern Gazo Ridge of the mountains of Ishiduchi. It is 15km long from east to west and 10km long from south to north.
The mountains of Akaishi belongs to the Ishiduchi mountains, with mountains around 1,400 to 1,700m high such as Mt. Nishiakaishi (altitude 1,626m), Higashiakaishi (altitude 1,706m), Futatsudake (altitude 1,647m), etc.
The mountains of Akaishi belongs to the Ishiduchi mountains, with mountains around 1,400 to 1,700m high such as Mt. Nishiakaishi (altitude 1,626m), Higashiakaishi (altitude 1,706m), Futatsudake (altitude 1,647m), etc.
Centering on Mt. Higashiakaishi, the ridge of the Akaishi mountains from the west of mount Maeakaishi to Mt. Gongen (altitude 952m) is formed by huge rocks called Kanrangan (peridotite) (*) constituted from the mantle (10km or move underground).
Centering on Mt. Higashiakaishi, the ridge of the Akaishi mountains from the west of mount Maeakaishi to Mt. Gongen (altitude 952m) is formed by huge rocks called Kanrangan (peridotite) (*) constituted from the mantle (10km or move underground).
The area of Mount Akaishi is historic with tens of thousands of five-needle pines around, it is a huge primeval pine forest indeed.
Mount Higashiakaishi
Mt. Higashiakaishi is the highest among all mountains of Akaishi, it lies on the border between Shikokuchuo City (former Doi-Cho, Uma-gun) and Niihama City (former Besshiyama Village, Uma-gun) at the center of the mountains of Akaishi.
The mountain is featured by wildly exposed peridotite with a huge number of conifers around its peak area. It has a unique shape and it is the treasury of alpine plants in Shikoku. It is selected as the top 200 mountains, top 100 flower mountains, and top 100 Shikoku mountains in Japan.
At the peak, there are triangulation stations used for creating maps and as surveying criteria.
The soil becomes reddish when the iron in peridotite gets acidified, when the color matches with the alpine plants, it forms a discernible combination. Especially in the autumn leaves season, the mountain is all covered by bright red make-up.
At the peak, visitors can take in the views of the famous mountains of Shikoku such as Mount Ishiduchi and Mount Tsurugi at Tokushima (altitude 1,995m), along with the bird eye view of the splendid islands of the Seto inland sea. Honshu is also visible on clear days.
Plants in the mountains Akaishi and Mt. Higashiakaishi
The mountains of Akaishi possesses an extremely wide range of botanical species including alpine and subalpine plants. It is especially famous for its abundant bean’s trees and ericaceae.
The distribution of alpine plants at altitudes below 1,700 m is due to the special geographical factors that produce a variety of minerals, including the peridotite geology appearing is most of the areas around Mt. Akaishi.
Also, It is commonly believed that the reason for so many alpine plants growing naturally in despite of the relatively low altitude above sea level is that the Akaishi mountains are exposed to strong south wind and have the same topography as the dry gravel peculiar to alpine areas.
Higashiakaishi is particularly the top treasury of alpine plants in Shikoku. In December 1957, the alpine plants, including five-needle pine, of Mt. Higashiakaishi were designed as the natural monument under article 37 of the Prefectural Cultural Asset Protection Law of Ehime.
“Akaishi five-needle pine” is called “Queen of bonsai”, giving out a strong feel of the primeval forest of Mount Akaishi.
The geographical distribution of the alpine and subalpine plants around the mountains of Akaishi is in fact affected by the host rocks.
For instance, bean’s trees and ericaceae are found on crystalline schist while Leontopodium and primula modesta are found on peridotite. “Akaishi five-needle pine” is unique to the peridotite zone of Mt. Higashiakaishi.
Meanwhile, Dozanho (altitude 1,300m) is famous for its large plant community of bean’s trees and shrubs (designed as national natural monument “Dozanho bean’s trees community” in 2019 for its high geobotanical, biological, and genetic value for its rich habitat at the south distribution).
Ericaceae grows naturally in a wide area with white flowers blooming in late May as a scenic view.
Regarding the vertical distribution of the plants, 0-500m is the as low mountain zone, 500-800m is the warm deciduous forest, and from 800m to the peak with an altitude of 1,706m is the evergreen pinophyta with the stratification of Japanese thuja, southern Japanese hemlock, Japanese cypress, Nikko fir, etc.
Geographically, from Dozanho to Maeakaishi through the peak of Mt. Nishiakaishi distributed the shrub layer or a mixture of the shrub and herb layer including deciduous broad-leaved forest, mizunara, willow, clethra, oval leaved lyonia, deciduous shrub, rhododendron lagopus, diabelia serrata, rhododendron, sasamorpha borealis, menziesia, enkianthus cernuus, and panicled hydrangea except Japanese larch and cypress. So, rhododendron can be seen in spring, and red leaves can be seen in fall.
The geology of Mt. Higashiakaishi
The mountains of Akaishi is at the upper stream of Sekikawa flowing from the Seto Inland Sea through Shikokuchuo City. Higashiakaishi contains of national rare rocks such as peridotite, “Iratsuryokurensekihen rock”, (*metamorphic rock formed under mid-level pressure and temperature with a greenish-yellow vision), eclogite arose with the highest metamorphic level in the Sanbagawa area (* metamorphic rock formed under high temperature and pressure), and garnet amphibolite (* rocks undergone metamorphism from basic igneous rocks)
The area of Mt. Higashiakaishi plays an important role in terms of geology and petrology.
The feature of peridotite at Mt. Higashiakaishi is the low level of silicon dioxide (a crucial material in crust formation), the high level of magnesium oxide, and the extremely low lower of calcium hydroxide when compared with other rocks. It is called “ultrabasic rock”.
Ultrabasic rocks are widely distributed in the Sanbagawa metamorphic area. It is called “Mt. Higashiakaishi peridotite” recognized as the largest scale in Japan. In the northern slope distributed the “Iratsuryokurensekihen rock”, which is arose from garnet amphibolite and eclogite under high pressure.
Moreover, serpentinite also arouse deep under peridotite under the reaction with water that the rock and the surrounding are petrified along the median tectonic line. All mountains of Akaishi generally shows such a same trend.
When rocks are oxidated, they turn red, and that’s the origin of the same Akaishi (it means “red rock” in Japanese literally).
The mountains of Akaishi, centering on Mt. Higashiakaishi, was designated as a nature conservation area in March 1976. 410ha out of the 1,790.34ha of conservation area possess particularly great natural environment being well preserved until now.
Higashiakaishi is constituted by peridotite that widely exposed. The phenomenon is fascinating in terms of both geology and petrology. The area is strong in its base with rich magnesium that could inculcate unique planes. In terms of an alpine plant treasury, the area is also precise in terms of botany.
The aera is designated as a special conservation area in Ehime with many rare alpine plants; serpentinite peridotites of Mt. Higashiakaishi are exposed as the reddish-brown mountain surface, also offering chance to take in scenic mountain views in the Shikoku region, it is a great spot not only for researchers and experts but also for mountain lovers and tourists.
"Akaishi five-needle pine" bonsai is, all in all, a unique natural product born from the rare natural world, natural activities, and history.
