Improved the sediment environment in the lake basin by conservation of the understory of the forest

Author(s): Toshiaki Mizuno
Email (s):
Institution or organization of origin: Lake Biwa Environmental Research Institute,Shiga
Country: Japan


The area of ​​Lake Biwa is about 670km2, and the area of ​​the catchment area is about 3170km2. There are coniferous and hardwood forests throughout the catchment area. The total forest area of ​​Shiga Prefecture, including almost the entire catchment area of ​​Lake Biwa, is about 2015km2. In recent years, in Shiga Prefecture, deer have eaten up forest floor vegetation, and the outflow of sand and mud from the forest has increased, deteriorating the habitat of freshwater fish such as endemic type char and Ayu. Therefore, we conducted a study with the aim of quantitatively measuring the effect of suppressing sediment production in forest understory.

As a result, it was found that with a vegetation coverage rate of 60% or more, there is an effect of suppressing the outflow of sediment by 97% compared to when there is no understory. For climate change adaptation based on the latest research, it is important to protect both understory vegetation and forest trees in order to control the amount of sediments flowing into rivers and lakes.

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