Aokigahara Forest Wildlife and Plant Life

There is no soil here worth the name. Everything alive in this forest is a response to that one fact.

A forest with no soil to speak of

Everything unusual about the life here follows from one fact: the ground is rock. The lava of 864 has had a little over a millennium to weather, which in soil terms is almost nothing, so there is no deep layer for a root to descend into.

What grew instead is a forest that spreads sideways. Roots ride over the basalt hunting for cracks, pockets of grit and each other, and much of the floor is a woven tangle you step over rather than on. Trees blow down more readily here than in ordinary woodland because nothing anchors them deeply, and the fallen ones become the nursery for the next.

The trees that took the lava

Hemlock and Japanese cypress dominate, with mixed broadleaf species filling the gaps, and the canopy closes quickly enough that the light on the trail is green for most of the day. The trunks are not especially tall by the standards of Japanese forest, because growing on rock is slow work.

Look at any two neighbouring trees and you will usually find one rooted flat across the stone and the other upright in a pocket of accumulated debris. That difference is the whole story of the place in miniature, and it is the thing a guide will stop you to look at.

Moss, lichen and the fungi doing the soil's job

Moss covers almost everything that does not move, and it is the reason the forest photographs the way it does. Under and through it, fungi break down fallen wood into the thin organic layer that the next generation of roots will use, which is the process ordinary soil would otherwise handle.

Autumn brings the visible fruiting bodies out along the trail edges. This layer is also the fragile part: it is thin, slow to recover and easily scuffed away, which is one of the practical reasons the marked path matters.

Mammals you will probably not see

Asiatic black bears range across the wider Mount Fuji region, along with Japanese serow, sika deer, foxes, martens and squirrels. Encounters on the marked trails are rare, and the sensible precautions are ordinary ones: walk in company, keep to the signed route, and make a little noise as you go.

The one mammal you can be certain of is a bat. Saiko Bat Cave holds a hibernating colony, which is why it closes from 1 December to 19 March every year: waking a hibernating bat costs it fat reserves it cannot replace until spring. Outside those dates the cave is open and the animals are out at dusk over the lake shores.

Why the forest sounds the way it does

Visitors notice the quiet before they notice anything else. Porous lava absorbs sound rather than reflecting it, the moss layer absorbs more, and the closed canopy damps what is left, so there is very little echo and no carrying distance.

Birds are consequently heard far more often than seen: woodpeckers, tits and thrushes are all present, and in the breeding season the trail is louder than it looks. Stand still for a minute at any point on the walk and the forest fills in around you.

What is visible, season by season

For where to stand and look at all of it, see Things to Do; for what lies underneath, the three lava caves. Aokigahara Forest Tours compares every guided walk, and an Aokigahara guided tour is the difference between walking past this and having it pointed out.