Deer Foraging Pressure Control

Across Japan, populations of deer, monkeys, and wild boars have increased excessively, causing various types of damage. Our Natural Water Sanctuary Tokyo Hinohara is also experiencing foraging pressure with an overpopulation of deer consuming all the vegetation that once covered the forest floor.

The soil, left bare after the vegetation is eaten, becomes easily eroded by rain, significantly increasing the risk of landslides on steep slopes. In the photo below, soil erosion has already begun, and tree roots are becoming exposed.

Area where soil erosion has begun

The next photo shows what might appear to be a well-maintained broadleaf forest. However, on closer inspection, you can see that not only grasses and shrubs, but even the lower branches and leaves within a deer's reach have been completely eaten.

Broadleaf forest stripped by deer

Deer don't just eat grass and leaves—they also consume tree bark. Even the majestic Japanese cedars in this forest have suffered bark-stripping damage by deer. When bark is completely stripped around the trunk, a tree can no longer absorb water and nutrients from its roots, eventually leading to the tree’s demise.

A tree with its bark consumed by deer

Even newly sprouted broadleaf saplings can be eaten before they have a chance to grow, making forest regeneration difficult.

Newly sprouted Japanese Oak

To enhance biodiversity in our Natural Water Sanctuary Tokyo Hinohara, we are gradually converting small areas of conifer plantation into broadleaf stands by clear-cutting and replanting. Before replanting, we always install protective fencing to prevent deer from damaging young plants.

Learn more about wildlife damage prevention measures