Natural Water Sanctuary Tennozan Initiatives

Controlling Encroaching Bamboo to Restore Abundant Mixed Forests

Across Japan, the problem of bamboo encroaching on mixed forests and causing trees to wither has become a growing concern. Our Natural Water Sanctuary Tennozan is not immune to this problem. If left unchecked, bamboo could cause diverse plant life in this sanctuary to disappear, leading to the loss of a rich forest ecosystem.

Bamboo encroaching on a mixed forest

To halt the spread of bamboo, we are implementing a method called waist-high harvesting. This involves harvesting bamboo about one meter above the ground during winter, when the underground rhizomes (subterranean stems) are dormant. By cutting at this time, the dormant rhizomes do not notice the loss of aboveground growth. In spring, the sap rises and leaks out from the cut end of the bamboo, depleting stored nutrients and eventually causing the bamboo to die off.

Cut bamboo leaking sap

After the bamboo are harvested, various trees and grasses begin to grow in their place, and the mixed forest gradually regenerates. We will continue to monitor the forest’s progress and help it become an ideal environment for life and groundwater replenishment.

Learn about the Bamboo Forest Issue

Rhinoceros Beetle Forest Project for Children

In places where new seedlings are slow to appear after the bamboo has died off, we carry out activities under the Rhinoceros Beetle Forest Project. Local elementary school students help grow and plant seedlings of trees like sawtooth oak that produce the sap rhinoceros beetles favor

Local students planting saplings

This is the growth process of the planted trees. Since it will take a while before the oaks mature enough to produce sap, other measures are taken to support the beetles. A large wooden enclosure was built at the same site, and filled with bamboo chips. These are decomposed by mushrooms and other fungi to create egg-laying beds for the rhinoceros beetles.

Forest a few years after planting

Learn about rhinoceros beetles living in Natural Water Sanctuaries