The eastern and middle parts of Gunma Prefecture are hilly areas up to 600 m above sea level. So these areas belong to the warm temperate zone. Natural vegetation there would be evergreen broad-leaved forests. But the vegetation there has almost totally disappeared, due to human activities since ancient times. Remnants of natural vegetation are found as forests in the precincts of temples and shrines, or on steep slopes. Plains and plateaus are used as urban areas, farms or paddies. Dandelions, tall goldenrods and other naturalized species account for a significant part of vegetation on the plains and plateaus. The foothills are mostly planted with Japanese cedars and cypresses. However, coppices, mostly consisting of Sawtooth oak and Conara oak, remain in some areas.
These coppices are secondary forests formed artificially, as sources of firewood. There, plants of northern origin (e.g. dogtooth violets) coexist with those of southern origin (e.g. “Shunran” orchid).
The diorama shows a coppice in early spring. Leaves of tall trees have not emerged. Evergreen trees―such as “Shirakashi” oaks and spearflowers―exist as remnants of natural vegetation. Dogtooth violets, anemones and violets flower on the ground. The flowering season of “Shunran” orchid has ended. The season of fresh green leaves is about to arrive, and soon the call of japanese pheasants will be heard.
Small gifu butterflies are found in the Hokkaido, Tohoku and Shinetsu regions of Japan. In the Kanto region, they live only in the Mt. Akagi area. The butterflies grow wings in early spring, in coppices in the cool temperate zone. They mate and lay eggs before tree leaves grow thick. Larvae grow rapidly, eating “Usubasaishin” (a variation of Dutchman’s-pipe), and become chrysalides, at about the time when forests are darkened by thickly grown leaves. Like dogtooth violets, the butterflies are called spring ephemeral, due to their life cycle.
Since the characteristics (e.g. wing pattern) of the small gifu butterflies vary widely according to region, and they have a peculiar life cycle,the butterflies have decreased rapidly due to unrestrained collecting. In Gunma Prefecture, they are designated a Natural Monument, for protection.
Some areas in Gunma Prefecture are mountain areas 600 to 1,600 meters above sea level. The weather in these areas is favorable for the development of deciduous broad-leaved forests. In the past, beech forests (of the type characteristic of the Pacific side of Japan) were found in mountain areas in Gunma, such as those in the Tano Mountains, Mt. Asamakakushi, Mt. Sukai, and the Ashio Mountains. At present, partly as a result of tree planting, beech forests remain only in a small number of areas, such as on Mt. Suwa. In areas on Mt. Akagi, beech forests have been superseded by natural oak forests.
The exhibits, in a 12 m-high room, show the view of a beech forest (of the type characteristic of the Japan Sea side of Japan) on the northern side of Mt. Hotaka. Beech trunks were transported from the site of the Naramata Dam, located deep in the mountain. You see Acanthopanax sciadophylloides and Acer japonicum in the sub-tree zone; and Viburnum furcatum (white flowers), rowans, and Lindera umbellata var. membrancea in the shrub zone. Viola brevistipulata and other flowers are found on the forest bed.
Areas in Gunma Prefecture, more than 1,600 meters above sea level, belong to the subalpine zone. Some of these areas are mature coniferous forests where firs predominate. On the other hand, Abies Mariesii predominate in some areas with heavy snowfalls (mountain areas near Oze, or east of the Shiga Heights), whereas Abies Veitchii are dominant in areas with less snowfall (those on Mt. Kusatsu Shirane or Nikko Mountains).
The diorama represents a forest of Abies Veitchii and Abies Mariesii on Mt. Nikko Shirane (in Katashina Village). Besides Abies Veitchii and Abies Mariesii (both variations of fir), the forest includes Japanese hemlocks and Japanese spruces (both also belonging to the pine family). Found on the forest bed are white flowers, such as cornelian cherries and Oxalis Acetosella. In addition, you can see Oplopanax japonicus, with thorns thickly growing on their leaves and stems. All of these plants characterize the subalpine zone
The Ozehagara moor is about 1,400 m above sea level. Surrounded by mountains, it extends about 6 km east-west, and about 2 km north-south.
The moor comprises bog, mire and fen, classified according to vegetation. At the moor, visitors can observe plants of each level.
The diorama shows the Ozegahara moor in late July. Skunk cabbages and rabbit ear irises can be seen at the fen, and day lilies at the mire. Moorworts can be seen in the raised topography called Bult, and insectivorous sundew plants in a basin of another type, called Schlenke. Among the sundew plants, one is capturing a dragonfly. The diorama also shows the underwater portion of a candock, growing in a pool called Chito.