Sustainable forest management for adequate supply of nutrients to downstream areas


The importance of fish-breeding forests has been recognized since before modern times, but it was recognized that the logging of natural broadleaf forests and the planting of artificial coniferous trees in the process of expansion afforestation policies, resulted in a decline in the productivity of fishing grounds.


Fish-breeding forests have created excellent examples of watershed ecosystem management in many areas, showing us the importance of utilizing empirical knowledge, recognizing the continuity between forests and oceans, and linking forestry and fisheries.

Forests supply nutrients such as reduced iron to rivers through fallen leaves and branches. Eutrophication should be avoided, but oligotrophic conditions can also damage ecosystem functions. In Japan, empirical knowledge has been cultivated among fishermen and others since before the Meiji era (1868-1912) that active afforestation not only maintains forests but also enriches fishing grounds. Under Japan's Forest Law, 54,000 hectares of forest throughout Japan are designated and protected as fish-breeding forests. Although the mechanism of this practice remains scientifically unexplained and its effectiveness as a climate change adaptation measure remains to be verified, it is drawing attention as an empirical and traditional knowledge that can realize sustainable forest management.


Fish-breeding forest in a mountain stream in Maze River, Gifu, Japan

SINCE 1994

Gero City has designated the entire area of the former Maze Village as Maze District Nature Park, and has designated it as a fish-breeding forest for mountain streams. In the Heisei era, as a new depopulation countermeasure to replace the conventional policy of expanding afforestation, the city promoted tourism promotion utilizing the clear waters of the Maze River and the rich nature of the area, and the Maze Village Forest and Mountain Village Revitalization Study Group was formed by the municipal office staff and people involved in forestry and inland waterway fishery. Ayu fish anglers have paid attention to the relationship between the quality of ayu fish in the area and the forests of Maze, and people have come to share a common understanding of the importance of utilizing the natural ecosystem of the forests, rivers, farmland, and people in the watershed area. Therefore, the concept of a fish-breeding forest was born with the aim of preserving the beautiful mountain streams and the fish that live there, including iwana (char) and amago (red spotted masu trout), that are also the village’s heritage. Today, community members are increasingly aware that in order to protect the water, the entire mountain must be protected.


Northern fish-breeding Forest

SINCE 2002

After World War II, the forests of Cape Erimo were cut down and the area was known as the “Erimo Desert”. At the same time, coastal kelp production declined, but the forest was later regenerated, and production and quality of the coastal kelp are said to have recovered. Based on this recognition, the Hokkaido Government established a certification system called “Northern fish-breeding Forest” in FY2002 to promote voluntary forestation activities by local residents. 9 sites throughout Hokkaido have been certified these days (As of FY2023).


"Ohayashi" (former clan property forest) in Manazuru Peninsula

SINCE 1904

After the Great Meireki Fire in 1657, the Odawara planted pine trees on the Manazuru Peninsula and protected them as a clan property  (“Ohayashi”) forest. These forests were designated as fish-breeding forests in 1904, and in combination with the abundance of seaweed and benthic animals on the rocky coast, set-net fishing flourished in the area around the peninsula. The area became a prefectural natural park in 1954, and in 1979 the “clownfish and coral sea anemones along the coast of Manazuru Peninsula” in the lower reaches of the peninsula were designated as natural monuments by Kanagawa Prefecture. The tip of the Manazuru Peninsula, including the Ohayashi forest, is recognized to have an ecosystem that combines the sea, the coast, and the forest, containing elements of a rich natural environment.

(Credit: Hakone Geopark