Tanashiro Wetland
The Tanashiro Wetland is a secluded marshland located at the northern foot of Mt. Fujisato-Komagatake (1,158 m). It was formed thousands of years ago when part of the mountain collapsed, creating a flat meadow where rainwater collected. Many plants that grow here are rare or absent in other parts of Shirakami Sanchi, including the insectivorous common sundew (Drosera rotundifolia), pogonia orchids (Pogonia japonica), bog cranberry (Vaccinium oxycoccos), cotton grass (Eriophorum vaginatum), and Asian skunk cabbage (Lysichiton camtschatcensis). Tanashiro is best known, however, for the beautiful orange Amur daylilies (Hemerocallis middendorffii) that cover most of the wetland in early summer. Unfortunately, in recent years global warming and other environmental factors are causing the wetland to dry up, and the daylilies are now in decline.
As the borders of the marsh dry, trees from the surrounding forest have begun to encroach. Erman’s birch (Betula ermanii), Japanese alpine cherry (Prunus nipponica), and Japanese rowan (Sorbus commixta) are able to tolerate boggier conditions, so they are the first to expand into the wetland. Once established, they dry out the soil enough that beech, pine, and Japanese cedar are able to take root. As the drying trend continues, trees that would normally grow on the edges of the wetland have begun to spring up throughout Tanashiro.
Boardwalks are installed across the wetland to protect the fragile ecosystem from foot traffic and to limit the introduction of non-native seeds tracked in on visitors’ shoes.