thumb|upright=1.3|Avaste Nature Reserve|Avaste Fen, Estonia. Sedges dominate the landscape. Woody shrubs and trees are sparse. thumb|upright=1.3|Wicken Fen, England. Grasses in the foreground are typical of a fen.
thumb|upright=1.3|Avaste Nature Reserve|Avaste Fen, Estonia. Sedges dominate the landscape. Woody shrubs and trees are sparse. thumb|upright=1.3|Wicken Fen, England. Grasses in the foreground are typical of a fen.
A fen is a type of peat-accumulating wetland fed by mineral-rich ground or surface water. It is one of the main types of wetland along with marshes, swamps, and bogs. Bogs and fens, both peat-forming ecosystems, are also known as mires. The unique water chemistry of fens is a result of the ground or surface water input. Typically, this input results in higher mineral concentrations and a more basic pH than found in bogs. As peat accumulates in a fen, groundwater input can be reduced or cut off, making the fen ombrotrophic rather than minerotrophic. In this way, fens can become more acidic and transition to bogs over time.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).