The Aokigahara “sea of trees” that spreads across the northwest base of Mt. Fuji is a forest growing atop lava that flowed during the eruption of Mt. Fuji in 864 (the great eruption of the Jougan era), some 1,200 years ago.
Although the lava that flowed from Mt. Fuji turned the Hokuroku belt into a burnt-out wasteland, it cooled down in the course of time, and atop it, trees began to bud anew and the forest was regenerated.
For a forest, which thrives for ages upon ages, 1,200 years is but a brief moment in time. The Aokigahara woodlands is thus still a very young forest.
The Aokigahara woodlands spans some 3,000 hectares but has a soil depth of a mere dozen-plus centimeters. It is also a highly unusual forest in that it is comprised primarily of hemlock fir, Japanese cypress, and other evergreen needleleaf trees, yet also contains broadleaf trees such as longstalk holly, Japanese andromeda, Mongolian oak, Fuji cherry, and maple.
In addition, plants, shrubs, and mosses developed on the forest floor, resulting in one-of-a-kind scenery. The thickly-wooded forest is also a good home to such living things as bats that live in the lava caves, small animals such as mice and moles, various birds including the great spotted woodpecker and the Japanese bush warbler, and insects such as ground beetles.