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Joshin’etsukogen NP, Nagano
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The name says 48, but the 3.8-hectare marsh holds more than 60 pondlets. They sit at 1,880 m in a basin between Shiga and Hachi mountains—so “Forty-Eight” is not an exact count.
Sundew grows in this marsh, where its insect-catching habit helps make up for scarce nutrients. It’s a clever survival trick in the acidic, nutrient-poor peat of a high moor.
Some of Shijuhachiike’s peat pools have floating islands. A Ministry of the Environment ranger documented them here—a small, unexpected detail in a marsh already dotted with more than 60 pools.
The pools are habitat for Japanese black salamanders and forest green tree frogs. Yamanouchi’s cultural-property record names both, showing that these little ponds are living habitat as well as beautiful reflections.
Shijuhachiike is included in the Shiga Kogen wetland group, identified by Japan’s Environment Ministry as the southernmost habitat of the yellow backswimmer. The group also supports several dragonflies and an aquatic beetle.
In ecology, a high moor is named for its raised peat—not simply its altitude. Peat builds up above the surrounding ground, leaving the wetland fed by rain and snowmelt rather than groundwater, and poor in nutrients.
Shiga Kogen’s volcanic deposits left an uneven landscape where many ponds and high moors developed in hollows. Shijuhachiike lies among those wetlands, between the volcanic peaks of Shiga and Hachi mountains.
Nagano Prefecture designated Shijuhachiike a Natural Monument on March 12, 1973. In 2016, the Environment Ministry also selected the wider Shiga Kogen wetland group—which includes this marsh—as an Important Wetland.
