Research report of Mt. Chokai Rakuten’s Forest Vol.1

Professor of Yamagata University, Doctor of Agriculture MITSUHIRO HAYASHIDA

Rakuten’s Forest

14.10.24

Survey begins at Rakuten’s Forest, at the foot of Mt. Chokai

Hello, my name is Hayashida and I am a professor student at Yamagata University.
This year, a project to protect the golden eagle in Yamagata was launched at Rakuten’s Forest at the foot of Mt. Chokai, in northern Yamagata Prefecture. We started monitoring surveys recently, once this year’s new work roads had been put through, and the forest thinning activities completed. Let me explain in simple terms the kind of survey we are carrying out.

The forest improvement carried out in Rakuten’s Forest will boost the numbers of hares, a key prey species for the golden eagle, with the goal of creating open spaces for golden eagles to hunt the hares. The plan is to thin the cedar plantation forest (felling trees to thin them out), which has been left unmaintained for many years. This will increase hare numbers because it will let sunlight onto the forest floor among the trees, boosting growth of grasses and shrubs in areas which had previously been completely shaded, allowing little grass to grow. In addition, open spaces for eagles to hunt hares have been created by the opening of new work roads and the upgrading of existing roads by cutting down cedars on either side.

This project is unique because it aims to conserve both the forest and the golden eagle. Traditionally, thinning activities have been a forestry technique involving the selective felling of trees to promote healthy growth among the remaining forest in crowded areas. However, the lack of forest thinning has become an issue nationwide recently due to the low price of timber. Thinning not only promotes tree growth and forest health, but also leads to the conservation of the golden eagle. It is our goal to establish this new forestry improvement technique.

So, how much will the conservation of the golden eagle benefit from this new forestry improvement technique trial? It is vital to validate the technique scientifically. The way to do that is monitoring surveys. We have three main validation techniques. The first is to monitor the changes in biomass by seeing the extent to which plants that hares feed on have increased among thinned cedars and along work roads. The second is to see whether hare numbers have increased, or if more hares are gathering in areas where forest has been thinned, combining the techniques of counting hare droppings within a set survey zone and filming animals moving around using an automatic camera. The third is direct observation of Rakuten’s Forest, where the thinning activities have taken place, to see whether golden eagles are in fact using the area.

For this observation, we requested the assistance of the Falconiforme Research Association, which has been monitoring Mt. Chokai for many years. We hope to clarify the kinds of benefits forest improvement can bring through monitoring surveys of plants, hares, and golden eagles. We also plan to build know-how about forest improvement as we examine the monitoring survey results coming in.

Autumn has truly come to the Mt. Chokai area, so we will start the plant survey and droppings monitoring in earnest next year. However, we will need to set the survey zones by the end of this year, because we have to remove all hare droppings from those areas. If we do this, we can establish a benchmark for hare activity in the survey zones by counting the droppings left between the day they were removed and the day of the first survey after the snow melts. We will set as many survey zones as possible before snow starts to settle on the ground in mid-November (this year could be earlier).

Automated camera set up in cedar forest

Monitoring has already begun using automatic observation cameras. There are eight cameras set up, four near developed work roads, and four in the forest. There is about one month before snow begins to settle. We will report back to you next month on the kinds of animals we have observed.

Automated camera set up in a broad-leafed forest clearing

Mitsuhiro Hayashida, Professor, Faculty of Agriculture, Yamagata University

Born in Kumamoto Prefecture. Graduated from the Faculty of Agriculture, Hokkaido University, where he then earned a doctorate in agriculture. After serving as a forestry assistant in seminars at the Faculty of Agriculture at Hokkaido University, he became an assistant professor at the Faculty of Agriculture at Yamagata University in 1993, and has held his current position since 2006.

Professor Hayashida's specialty is the study of forest biodiversity conservation and wildlife management. He elucidates the interrelationships of living things in the forests, and instructs how to establish technologies to preserve the diversity of living things in the forest. He conducts research in a variety of forests, including coastal forests, forests near villages, and mountain forests, and supports maintenance activities by locals for wetlands and village forests, as well as growing forests at elementary schools to provide education on the environment.

Professor Hayashida's public page

In Yamagata Prefecture, the forestry management activities are to encourage the reproduction of small animals like rabbits that the Golden Eagle can hunt. In collaboration with Yamagata University, the following monitoring surveys are conducted:
- Vegetation survey: plant presence before and after forestry maintenance
- Basic habitat survey: mammal presence recording with motion detector cameras
- Hare presence survey: hare feces monitoring
- Golden Eagle behavior survey: Golden Eagle flight monitoring, etc

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Rakuten's Forest