Mount Ibuki, a 1,377-meter-high mountain straddling Shiga and Gifu prefectures that is visited by many climbers, is now on the verge of a crisis — being seriously damaged by wild Japanese sika deer eating its plants.
In July last year, the mountain's slopes collapsed due to heavy rain, leading to the closure of trails.
The alpine flower field at the summit is listed as a national natural monument. The city of Maibara in Shiga Prefecture, which is mainly responsible for maintaining the mountain, calls the situation the “Mount Ibuki shock,” and is working to restore the mountain's ecological balance.
On April 20, the day the Ibukiyama Driveway toll road opened for the season, Noriaki Matsui, 66, of Maibara visited the mountain summit to repair fences that protect the plants. Matsui, who has lived at the foot of the mountain since his childhood, has been participating in the volunteer activity for about two years.
“It is regretful that plants unique to Mount Ibuki are disappearing,” Matsui said. “I want to lend a hand if I can do anything to help nature recover.”
The surface of the mountain is painfully bare, even considering the fact that new buds are only just starting to emerge.
Damage to plants by deer began roughly two decades ago. In the past, the deer population had been suppressed during winter when they lacked food due to snow. However, as the amount of snowfall has decreased, affected by global warming, the number of deer has increased and their area of activity has expanded.
It is believed that some 100 deer inhabit the summit and around 200 live in the area between the mountain's fifth and seventh stations. An adult deer is said to eat approximately 5 kilograms of grass a day. Since around 2016, the amount of plant cover on the mountain has been dropping sharply. The slopes have been increasingly denuded and have lost the ability to retain water, and rainfall has brought about soil erosion in wide areas.
Mount Ryozen, a 1,084-meter-high mountain located roughly 15 kilometers south of Mount Ibuki, has been known as one of the 100 best mountains for flowers in Japan, but many of the plants and flowers have disappeared as few measures were taken to tackle wildlife damage.
Naohiko Noma, a professor of plant ecology at the University of Shiga Prefecture, points out that while Mount Ibuki is not an exceptional case, deer started to gather on the mountain and eventually settled there because it had many grassy plains, providing a good feeding ground for them.
Volunteers and others involved in protecting Mount Ibuki's natural environment are continuing to make efforts, including setting up fences at the summit and also near the third station where plants such as yellow daily lilies grow.
However, there was heavy rain on the mountain in July last year, leading to landslides on the slopes and causing parts of the trails to collapse.
The trails remain closed. The Maibara Municipal Government and the Shiga Prefectural Government are conducting repair work with the aim of reopening them in the spring of 2025.
As a measure to reduce the number of deer, they set a 18-square-meter trap near the fifth station in September to lure the animals with feed and drop a net over them to capture many of them at once.
It is said that Oda Nobunaga, the 16th-century warlord who initiated the unification of Japan, gave Portuguese missionaries permission to establish a garden of medicinal plants on Mount Ibuki.
Haruki Kodera, 76, head of a nonprofit organization in Ibigawa, Gifu Prefecture, is working on a project to revive the medicinal plant garden. He said he started to see soil and sand flow into the field around 2017, and hopes the mountain will recover.
“I was raised by Mount Ibuki,” Kodera said. “I want to restore the place where I grew up to its original state.”
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