Natural Water Sanctuary Minami Alps Initiatives

Greening a Landslide Site and Restoring a Rich Forest

The mountains where our Natural Water Sanctuary Minami Alps is located are composed of granite. In mountains where granite becomes weathered, slope collapses are more likely to occur.

Unweathered granite is hard and often used for stone materials, but once it is exposed to the elements, it becomes fragile and crumbles easily

The photo below shows a collapsed area in one part of this sanctuary.

The ground is exposed and covered in sandy soil created by the weathering of granite. Because this surface sand is easily carried away, seeds blown in from the surroundings can’t take root, and plants can’t grow. Left untreated, the slope collapse would likely have worsened.

Ground affected by surface erosion (slope collapse)

In these heavily weathered areas, we build terraces using thinned Japanese larch timber from the surrounding forest to hold the soil in place. The slope is then covered with nets made of coconut fiber, which will eventually decompose and return to the earth. Seedlings are planted—grown from seeds of tree species naturally found nearby—to help regenerate the forest.

Roughly 10 years later, greenery has gradually returned to what once looked like a sandy beach. Suntory will continue these efforts, aiming for even more abundant forests.

Learn about the initiative policy and structure