Hamura-Kusabana Kyuryo

Hamura-Kusabana Kyuryo is a Tokyo Metropolitan Natural Park spanning the wooded hills along the upper Tama River in western Tokyo, across the municipalities of Akiruno, Fussa, and Hamura. ^[1] The park covers approximately 553 hectares (5.53 km²) and was designated on March 12, 1953, protecting a strip of hills roughly 200-300 meters in elevation on the western edge of the Tokyo metropolitan area. ^[2] Despite its name, 'Kusabana' does not mean 'flower grass' -- it is a place name within Akiruno City that the hills are named after, not a description of the park's vegetation. ^[3] The park's rounded, forested ridgeline appears as a dense, thickly wooded hill when viewed from below, while its summits open onto expansive views across the Kanto Plain. It serves both as a satoyama woodland conservation area and as a recreational destination for urban residents seeking respite from the city. ^[3]

Hamura-Kusabana Kyuryo's wooded hills support wildlife typical of Musashino secondary woodland rather than grassland habitat. Resident birds documented on the park's official species page include the Japanese pygmy woodpecker (Kogera, Yungipicus kizuki), Japan's smallest woodpecker, which favors the park's evergreen and deciduous broadleaf stands; the varied tit (Yamagara, Sittiparus varius); and the Oriental turtle dove (Kijibato, Streptopelia orientalis). ^[1] Along the Tamagawa Aqueduct and streamside sections of the park, both Genji and Heike firefly species (Luciola cruciata and Luciola lateralis) emerge in late June, though their numbers have declined with surrounding urbanization. ^[1] Small mammals and woodland-edge insects, including butterflies typical of the wider Kanto uplands, are also present across the park's forest and trail-margin habitats.

The vegetation of Hamura-Kusabana Kyuryo is dominated not by grassland but by secondary deciduous woodland (zoki-bayashi) typical of the Musashino uplands: roughly 5km of the main ridge trail runs continuously through stands of kunugi (Quercus acutissima), konara oak (Quercus serrata), and akamatsu (Japanese red pine). ^[1] Along the ridge paths, the white flowers of marubauzuki (Deutzia scabra) are conspicuous, and the sweet fragrance of egonoki (Styrax japonicus) blossoms carries through the woods. ^[2] In spring, cherry trees bloom along the Tama River at Hamura Weir and along the Tamagawa Aqueduct at the park's edge. ^[2] Woodland-margin species such as hornbeam and understory wildflowers also occur, contributing seasonal color changes across the hills.

The hills of Hamura-Kusabana Kyuryo are underlain by Quaternary terrace deposits of the Tama River, consisting primarily of gravels, sands, and silts accumulated during repeated cycles of river aggradation and incision over the past several hundred thousand years. These Tama River terrace formations, known locally as the Musashino Uplands, represent a staircase of ancient floodplain surfaces now elevated well above the modern river channel. The soils developed on these terraces are Kanto loam, a distinctive reddish-brown volcanic ash deposit (andosol) that accumulated from repeated eruptions of Mt. Fuji and other Hakone-region volcanoes during the Pleistocene and Holocene. This well-drained, moderately acidic loam substrate is characteristic of the western Tokyo uplands and strongly influences the park's vegetation composition.

Hamura-Kusabana Kyuryo experiences a humid subtropical climate (Köppen Cfa) typical of the Kanto region, characterized by hot, humid summers and mild, relatively dry winters. Average temperatures range from approximately 3-8°C in January to 25-30°C in August, with the annual mean around 14°C. The park receives abundant precipitation, averaging 1,400-1,600 mm annually, much of which falls during the tsuyu (rainy season) in June and July and again during autumn typhoon season. Winters are generally sunny with occasional cold dry winds from the northwest (Siberian high-pressure system), and snowfall is infrequent but possible from December through February. Spring conditions bring mild temperatures and cherry blossom season from late March to early April, while autumn foliage peaks in November. The open hilltop location of the park can experience stronger winds than surrounding lowland areas.

The Hamura area along the Tama River has been inhabited since prehistoric times, with archaeological evidence of Jomon-period settlements in the broader river valley region. During the Edo period (1603-1868), the Musashino uplands on which the park now sits were used for farming, charcoal production from coppiced woodland, and grazing of horses and cattle -- traditional satoyama practices that shaped the secondary deciduous woodland the hills are covered in today, not open grassland. In the Edo period the lower slopes became the source point of the Tamagawa Josui, a 43km aqueduct built to carry drinking water to Edo, which drew the surrounding villages into close, frequent contact with the shogunate. Tokyo Metropolitan Government incorporated the wooded hills into the park system in 1953 as part of its postwar program of suburban greenspace conservation. ^[1]

Hamura-Kusabana Kyuryo was designated a Tokyo Metropolitan Natural Park on March 12, 1953, as part of Tokyo Metropolitan Government's program to establish green open spaces accessible to residents of the western suburbs. ^[1] The park's establishment responded to the rapid postwar urbanization of the Tama region, which converted agricultural land and forest into residential and industrial development. Management has emphasized conserving the secondary deciduous woodland (satoyama) that dominates the hills -- stands of konara oak, kunugi (sawtooth oak), and akamatsu (red pine) -- and maintaining the hiking-trail network, rather than any grassland-restoration program; official park descriptions do not mention meadow or grassland management. The area also contains archaeological remains spanning the Jomon through Kofun periods, and its lower slopes mark the historic starting point of the Tamagawa Josui aqueduct, built in the Edo period to supply drinking water to Edo. ^[1]

The park's main hiking route, the Kataraiino-michi Hamura-Kusabana Course, runs roughly from Hamura Weir on the Tama River, through Manji Pass, to the summit of Sengen-dake (235m), before looping back -- following about 5km of ridge trail through continuous secondary woodland. ^[1] From Sengen-dake, hikers are rewarded with panoramic views across the Tama River's terraced forests and the surrounding towns; a second summit, Daisumi-yama (192m), has an observation pavilion overlooking Fussa. ^[1] Along the route, hikers pass the Tamagawa Weir and its 'two brothers' memorial statue, the distinctive spiral-shaft Maimaizu well, and stretches of the historic 43km Tamagawa Aqueduct, which is lined with cherry trees that bloom in spring. Birdwatching is popular during spring and autumn migration, when the ridge woodland serves as a stopover site for migratory passerines.

Hamura-Kusabana Kyuryo is managed by Tokyo Metropolitan Government and is freely accessible to the public during daylight hours. Facilities include marked trailheads, informational signage describing the park's natural features and seasonal highlights, and basic amenities such as benches and rest areas at key viewpoints. Restroom facilities are available within or adjacent to the park grounds. The park is most conveniently reached from Hamura Station on the JR Ome Line, which connects to Tachikawa and central Tokyo via frequent services; the station is approximately 15-25 minutes on foot from the main park area. Bus services from Hamura Station provide an alternative for visitors. Cycling to the park is popular, and the Tama River cycling path provides a scenic route from central Tokyo. The park does not charge an entrance fee and is open year-round, though facilities may be limited during winter months.

Conservation management at Hamura-Kusabana Kyuryo focuses on maintaining the secondary deciduous woodland (satoyama) that covers the hills, a habitat type under pressure from surrounding suburban development in the Tama region. Trail and forest maintenance by Tokyo Metropolitan Government aims to keep the ridge woodland corridor intact rather than to preserve open grassland, since official park descriptions characterize the park's core habitat as mixed deciduous forest rather than meadow. ^[1] Volunteer programs organized through Tokyo Metropolitan Government and local nature groups engage community members in habitat maintenance activities including manual removal of invasive plant species such as Kudzu (Pueraria montana) and management of encroaching shrub species. The park contributes to regional biodiversity conservation by maintaining habitat connectivity within the Tama River green corridor, supporting movement of insects, birds, and small mammals across an otherwise fragmented suburban landscape.