The Sengokuhara marshland is the only marshland found in Kanagawa Prefecture, worthy of recognition as it is rarely found in the Kanto region. Including the 17 hectares of northern gentle slope and 8 hectares on the slope of Mt. Daigadake side, the total area comprises 25 designated special protection areas, some of which are natural monuments of Japan .
There are many small animals living in the Sengokuhara marshland, small though it is. It provides a variety of plants and vegetation as a food source and habitat. The Sengokuhara marshland is the only habitat in the prefecture for Yellow bunting, a mountain grassland bird, and the Oorurihamushi (Chrysolina virgata) that feeds on marshland plants, Shirone (Lycopus lucidus).
As the original marshland gradually dried up, it began changing into forest. The very last open burning (Noyaki) took place at the Sengokuhara marshland in 1970, and since then, the total number of marshland plants has been decreasing, due to the overgrowth of Hakonedake (Pleioblastus chino f. vaginatus) and Hannoki (Japanese alder; Alnus japonica). In answer to this situation, “Sengokuhara marshland Conservation Plan” was established, and to conserve the remaining marshland, open burning and cutting have since been carried out.
At the foot of Mt.Daigatake, facing the Sengokuhara marshland, one sees fields of susuki (Miscanthus sinensis). The silvery-eared susuki swaying in the golden light of autumn, depicts the scene of Japanese fall. This same locality was chosen as one of the five most picturesque spots in Kanagawa Prefecture. A stone monument stands nearby to commemorate it.
The miscanthus grassland, where villagers could cut the grass, were to be commonly seen everywhere. However, the spread of city suburbs have been responsible for a decrease in the practice of utilising susuki, and now Sengokuhara is the only large scale susuki grassland in Kanagawa Prefecture
Originally, much of the existing area of grassland was used for thatching roofs, straws for the bedding for cattle and horses, and for their food. Forests were opened up to create fields of susuki. The practice of open burning enabled a continuation of grassland until recent times.
However, as cutting grass was no longer necessary, resulting in its return to a state of original forest. The movement designed to protect the landscape of susuki grassland has also been responsible for protecting flora and fauna, and animals.
In Sengokuhara, open burning resumed in 1988, and has continued ever since.
Sengokuhara Onsen (hot spring)
Sengokuhara onsen is a hot spring resort at an altitude of 700 meters that opened in an area of grassland. The use of the existing hot spring began in 1736 with the hot spring water drawn from Owakudani. At the present time, the hot spring water is centrally managed from Owakudani (white unclear water) and Ubako to supply various facilities. It also uses plentiful underground water from Lake Ashinoko.
Sengokuhara hot spring has been a Western-style summer resort since the Showa era. Sengokuhara hot spring compares favorably with other existing areas, characterised by its well-preserved natural surrounding.
The origins of Sengokuhara
Some 40,000 years ago, the pyroclastic flow that poured out of Mt. Kamiyama resulted in damming the Hayakawa River close to Mt. Kozuka. Later, lakes continued to form and disappear in successive eruptions within the caldera, thereby creating marshland. But around 3,000 years ago, Sengokuhara was temporarily dried up becoming a sugi(cedar) forest. This was the result of an avalanche of rocks that had exuded from Mt. Kamiyama. Influenced by its topography and natural environment of fog with an annual rainfall of 3,000 millimeters, the marshland has since managed to renew itself.