Senjogahara (Battlefield)

Senjogahara originates from a myth that the gods of Nantaiyama and Akagiyama fought over Lake Chuzenji. It used to be a lake, but now it is a vast marshland covering 400 hectares. The marshland is home to 350 species of plants and a large number of wild birds, and has been recognized as a “wetland of international importance” and registered under the Ramsar Convention.

A nature study trail surrounds the marshland, and there is a hiking course that can be completed in about two hours. From the observation point with Mt. Nantai in the background, visitors can enjoy a panoramic view of the vast marshland and feel the beauty of nature. The area can be enjoyed all year round, but the best times to visit are from mid-June to early August, when cotton grass and hozakimotsuke are at their best, and from late September to early October, when the autumn leaves of the grasses are beautiful.

Outline

This is a 400-hectare marshland located in Nikko National Park. This marshland extends over flat land at an elevation of approximately 1,390 to 1,400 meters, and is surrounded by Nantai-yama, Taro-yama, Sannobashira-yama, and Mitake on the east side, and Odashirogahara and Sotoyama on the west side. Yugawa River runs through the area from north to south.

The Yugawa River was dammed by the eruption of Mt. Nantai about 20,000 years ago, forming Lake Kosenjogahara. Later, earth, sand, and volcanic ejecta piled up, plants grew, and peat turned into peat, creating a marshland. Parallel to the Yugawa River, the Senjogahara Nature Study Path has been developed and wooden paths have been established.

National Route 120 runs through the Senjogahara area, and the Akanuma Nature Information Center and the Sanbonmatsu Tea House have been established. Ryuzu Falls and Yudaki Falls are also bases for hikers, and beautiful views can be enjoyed from their observation platforms.

The northern side across National Route 120, which crosses the marshland, has been converted to grassland and is used as farmland for upland cultivation and mountain climbing cultivation. Strawberries, kalanchoe, shakoba cactus, and atsuzakura are cultivated here.

The method of “mountain top culture” in Senjogahara is to temporarily grow seedlings in a cooler area after they have sprouted and grown in a warmer area during seedling cultivation. While this can speed up the agricultural harvest, it requires advanced farming techniques due to the risks associated with the harsh environment of the highlands.

The success of Yamagamiage cultivation and the availability of Nikko strawberries on the market during the Christmas season have made Tochigi Prefecture known as the top strawberry producing prefecture in Japan. Currently, the cultivation of ornamental plants is thriving in Yamaage.

History

The “Senjogahara Shinseitan” describes the legend of the origin of the marshland’s name. It is said to be the place where Nantai-san (Mt. Futara) from Shimono-no-kuni (present-day Tochigi Prefecture) and Akagi-san (Mt. Akagi) from Ueno country (mainly Gunma Prefecture) fought each other, transforming into a giant snake and a giant centipede. The conflict is said to have been caused by a territorial dispute over Lake Chuzenji, which Nantai-san (Mt. Futara) won.

From B.C., before the writing of the Kojiki and Nihonshoki, the province of Meno was divided into Ueno and Shimono provinces, and this area was the center of the Kenu nation, a powerful and powerful tribe. Therefore, it has been pointed out that there may have been actual warfare in the area. There is a theory that the name of the place originated from a dispute between Mt. Nantai and Mt. Akagi, and another theory that the name is derived from “Senjo-ga-hara.

After the Meiji Era, farmland development in Senjogahara was promoted, and in 1934 the area was designated as part of “Nikko National Park,” but the value of the marshland was not fully understood at first; in the late 1940s, forests were cleared and sediments were introduced into the area as a result of logging. In particular, the 1949 Typhoon Kitty caused the marshland to shrink, as the influx of sediment temporarily turned the marshland into a lake. In addition, with the construction of the national highway, the number of park users increased from the 1960s to the 1970s, causing some destruction of the marsh vegetation.

In the 1960s, the drying out of the marshlands was recognized as a problem, and in the 1970s, marshland conservation measures were initiated. In 2005, part of Senjogahara became a Ramsar wetland.

Senjogahara Nature Study Path

Senjogahara Nature Study Path is a north-south trail along the Yugawa River, managed by the Ministry of the Environment. It is part of the Yugawa River Trail and has a wooden path.

The southern entrance to this nature trail is located along Route 120 in the Akanuma area, and the northern entrance is located around Senjogahara’s Senmon Pond. The northern entrance is located around Senjogahara’s Senmon Pond. From the entrance in the Akanuma area, there is a branch to Ryuzu Falls, Odashirogahara, and Yudaki. Choose this branch and cross the Akanuma River in the direction of Yudaki. The northern entrance is located around Senjogahara’s Senmon-ike Pond. The wooden path has observation spots and benches that offer a panoramic view of Senjogahara.

The route is mostly flat, except for the Yudaki area, and allows hikers to feel the natural environment of Oku-Nikko up close. For this reason, the trail is visited by many hikers and is also used as a school excursion course for elementary schools in the Kanto region.

Flora and Fauna

According to the Ministry of the Environment’s list of 500 Important Wetlands in Japan, the vegetation of Senjogahara is mainly “Numagaya-Warty Moss Community” and “Ooazesuge Community. The majority of the marshland is a mid-level marshland where numagaya, Japanese knotgrass, and cotton grass grow, and in the center of the marshland, Japanese watermoss forms a community of high-level marshland. In the grassland area, there are herbaceous plants such as Ibuki-torano-o, Japanese honeysuckle, and Japanese larch, as well as woody plants such as Japanese linden and Renge-tsutsuji. In the forests along the Yugawa River, larch, mizunara oak, Japanese elm, white birch, and other trees grow in abundance. In winter, the frozen soil in the meadow area is deep, making it difficult for the woody plants to take root.

Flowers bloom from June to August, starting with the black-eyed blackbird, followed in turn by cotton grass, zomi, azalea, azalea, Ibuki-turano-o, larch, Japanese honeysuckle, and hozakimotsuke.

Birds are abundant in the area, including yellow-throated flycatcher and white-throated bunting in the tinned forests, northern flycatcher and white-throated redstart in the marshlands, wagtail and brown-headed cowbird in the forests, and red-cockaded woodpecker, titmouse, and bush warbler in the forests.

Black bears are also frequently seen in the forests.