Karuizawa Forest Present
Today, most of Karuizawa is covered with forest. This is the result of the active planting of larch trees after World War II. Until then, there were few forests due to the effects of the eruption of Mount Asama over the years and the use of the land for grazing cattle and horses. The area was therefore in danger of landslides during heavy rains. Thanks to years of effort, most of Karuizawa’s forests are now planted with larch.
The forest is shifting (transition)
Karuizawa’s forests are greatly affected by the eruption of Mount Asama. When Mt. Asama erupts, the ground surface is covered with red-hot cinders, pumice and other ejecta, which nearly kill all vegetation in the area. After a time, mosses and other lichens grow in their place, followed by herbaceous plants. As these plants grow and die, soil is created, allowing shrubs and trees to grow, and the area is eventually transformed into a forest. This transition from an area with no vegetation to a forest with herbaceous vegetation is known as the vegetation succession (dry succession).
At the foot of Mt. Asama, after the eruption and the entry of lichen, first plants of the Poaceae and Kayazurigaceae families grow. Next, shrubs of about 10 cm in height, such as kokemomo and ganko-uran, began to grow, and gradually seeds of shrubs that grow in bright places, such as red pine and white birch, were carried by the wind, sprouted, and grew large, gradually transforming into a forest. At the foot of Mt. Asama, each stage of this transition process can be seen in Rokurigahara and other areas.
Tree of the town, Kobushi
The kobushi is the town’s designated tree. The kobushi is famous in northern Japan for being the first tree to bloom with white flowers in spring, and in Karuizawa they bloom from late April to early May. There is a theory that the name comes from the shape of the bumpy fruit in autumn, which resembles a fist, and another that the buds just before blooming resemble a child’s fist.
Recommended tree-watching courses
- ～Shinanoji Nature Trail
- A recommended course to observe the trees is the Shinanoji Nature Trail, which runs from Mine-no-chaya to Shiraito Falls and down to Oze and Mikasa. This 3-hour course follows a well-maintained wooden trail along the Yugawa River. Along the trail, visitors can see giant trees such as Japanese elm, mizunara oak, katsura, and sawagurumi.
Major trees found in Karuizawa
- Natural larch forest
- Karuizawa has many artificial larch forests, but natural forests can also be seen in many places. The first is a natural larch forest on the mountainside of Mt. Larch is a deciduous coniferous tree native to Japan, and although larch trees are planted throughout Japan, the number of natural larch trees is limited. Seedlings are produced from the seeds of the natural larch trees on Mount Asama and planted throughout the country.
- Harunire forest
- Haru elm forests remain around the Shinanoji Nature Trail, which runs from Shiraito Falls to Ryuukanashi Falls, and along the Yugawa River. Haru elm trees are a family of elm trees that are commonly found along rivers and other slightly moist flatlands where sandy soil has accumulated. Large elm trees can grow to 35 meters in height. Most of the trees in Nagano Prefecture have been cut down, and those remaining in the town are rare.
- Quercus crispula and Quercus crispula forests
- Other examples would be the Quercus mongolica var. mongolica forests at the foot of Mt. Both Quercus crispula and Quercus crispula bear acorns in the fall, providing valuable food for birds, mammals, and other animals. These forests play an important role in the ecosystem of the region.
Other typical trees found in Karuizawa
- Japanese red pine (Pinus densiflora)
- It is very common in mountainous areas throughout Japan and is characterized by its reddish-brown bark. It is widely planted at the foot of Mt. Asama because of its drought tolerance. In Rokurigahara and Oni-oshidashi, it is often seen growing in crevices in lava rocks.
- Japanese horse chestnut (Aesculus turbinata)
- Commonly found in slightly moist areas along streams. Large trees can be over 4 meters in circumference. In Karuizawa, large trees can be seen along the Yugawa River.
- Japanese white birch (Betula platyphylla var. japonica)
- Distributed in cold regions north of central Honshu, with conspicuous white bark. It grows in clusters in sunny mountainous areas. It is one of the representative trees of the highlands, and can be seen from around 1,000 meters above sea level.
- Japanese white fir (Abies mariesii)
- An evergreen coniferous tree native to Japan. It is usually 20 to 30 meters tall and 50 to 80 cm in diameter, but some of the larger trees can reach 40 meters in height. In Karuizawa, it is found scattered in villa areas and satoyama. It is used as a garden tree, Christmas tree, etc.