Photo: Jay Mather.

Fun Fen Facts

Oct 02, 2018 by Sarah Mowry
The Land Trust’s new Metolius River Preserve is home to a rare fen. Ever wonder what a fen is and how it differs from a bog? Read on!

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The Land Trust’s new Metolius River Preserve is home to a rare fen, or wetland. In honor of this super cool natural feature, we offer a chance to learn more about fens with these fun fen facts (say that 3 times fast!):

First some terminology:

  • What is a fen? A fen is a type of alkaline wetland that is fed from groundwater. Common along the coast or in subalpine regions, mid-elevation fens are rare and found infrequently throughout Central Oregon. Fens tend to appear on slopes, flats, or depressions.

  • What’s the difference between a fen and a bog? A bog is an acidic wetland that receives most of its moisture from rainfall. Bogs tend to be on dome shaped landmasses.

  • What’s a mire? Both fens and bogs are kinds of mires. A mire is a wetland type that is dominated by peat.

  • What is peat? Peat is a mixture of decomposed plant material that has developed over time. Yes, this is the same kind of peat that is harvested all over the world as a source of fuel. Learn LOTS more about peat from ... wait for it ... the International Peatland Society.

  • What’s a peatland? Peatland is a term that refers to wetlands dominated by peat.

  • Why are there so many different names for wetlands? Because biologists and ecologists love to classify things!

Fun fen facts:

  • Fens are biological hot spots and are home to a high percentage of rare or uncommon plant species.

  • Fens stay wet year-round and can remain in the same location for thousands of years.

  • The peat in fens takes a long time to form! It is estimated that peat accumulates in our area at the rate of ~1 inch per century!

  • Because peat accumulates over thousands of years, it preserves a record of past climatic conditions as well as fire frequency history. We are hoping to one day core our fen to learn this history!

  • Peatlands are helping combat climate change! Peatlands are the largest natural terrestrial carbon store. They store more than all other vegetation types in the world combined!

  • New peatlands are still being discovered today! In 2017, scientists discovered the world’s largest tropical peatland under the forests of the Congo.

  • Our fen has been called a Cascade Mountain Mire! No, this is not the name of a Led Zeppelin song, but rather a categorization for the kind of fens we have in this region. Most of those tend to be higher elevation fens, so our more accurate Led Zeppelin song title might be Mid-Cascade Mire.

  • Fens have some super fun references in literature! The Lord of the Rings by J.R.R. Tolkien finds Aragon saying “'But north lies our road between down and fen when day returns” and Shakespeare used the term "fen-sucked" to describe the fog rising from marshes in King Lear.



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