Peatlands:

 

My last column was about wetlands in general; this column will deal with only three very important wetland types which, collectively, can be called peatlands. They are fens, bogs, and swamps. Most of the information here was taken from the book I mentioned last time: Fen, Bog & Swamp by Annie Proulx. She admits she is not a scientist, but she has done an excellent job of reviewing the massive amount of literature on this topic which is very pertinent to the current climate crisis as these wetland types store huge amounts of the greenhouse gases CO2 and methane.

People often refer to any specific wetland type by the correct name for a different wetland type. Perhaps they do not realize that the names are not interchangeable or perhaps they have never been exposed to an appropriate description of each type. Therefore, I will provide a description for each of the 3 involved in this column. The 3 are a gradual ecological succession of one to the next (fen to bog to swamp) over time. Sometimes all 3 can occur in different locations within the same large wetland basin.

Fen: A peat accumulating wetland that receives some drainage from surrounding mineral soil and usually supports marsh-like vegetation such as water lilies, reeds, bulrushes, etc. Fen waters contain minerals from the runoff from the mineral soil and are often deep enough to support some fish life. The plants eventually fill the fen with partially decayed vegetable matter, and over thousands of years it becomes peat.

Bog: A peat making wetland with a water source that is not in contact with mineral soil (for example, rain and snow that falls on its surface). Therefore, bog water is extremely low in mineral content and tends to be shallower than in fens. If, or when, a fen gets a raised surface that loses contact with the mineral-rich ground water and then must depend on rainwater, it then becomes a bog. Primary vegetation is often sphagnum moss as its spores can be carried by the wind for many miles; it is a plant that prefers wet, acidic, nutrient-poor water.

Swamp: A peat making wetland that can support shrubs, trees, and even forests. Typically, a specific one is referred to as a swamp with the blank being filled in by the name of the dominant tree or shrub species. Waters entering them contain minerals picked up from adjacent soils. Waters tend to be shallower than those of fens and bogs. As with all peatlands, as the layers of dead vegetation become thicker, they compress and eventually become peat. Wooded swamps are the end of the succession of fen to bog to swamp. The next stage would be dry forest.

Plant species diversity is greater in fens than in bogs due to greater nutrient availability in fen waters than in bog water. Few plant species can survive, let alone thrive, in the nutrient poor and acidic bog water.

Peat is composed of partially rotted vegetation because the water has locked out oxygen which is necessary for decay to occur. These deposits then build up over many centuries/millennia. Europeans cut and dried peat for thousands of years to burn for home heating. The European Union prohibited the cutting of peat in 2011 in an effort to reduce the flow of CO2 and methane from harvested peatlands. Many of these areas are being converted back to fens, bogs, and swamps.

People lived in peatland areas which were a mixture of these three wetland types and uplands for thousands of years. Their homes were on land, but they especially utilized fens for hunting and fishing and ate the starchy rhizomes of reeds which were a stable food source. Walking through fens, bogs and swamps can be difficult so the inhabitants-built paths (called trackways) with planks, poles, brush, etc. to support their weight. They then could access much more of the area. The Sweet Trackway is the oldest known road in Britain and was built in 3807 BC.

Many artifacts have been found in peatlands; many of them radiocarbon dated as being from 8000 to 6000 BC. One notable artifact was an antler point “harpoon” that dated 11,740 BC plus or minus a few hundred years. Peat cutters and wetland ecologists have found coins, jewelry, pots, tools, carved wood, and well-preserved human bodies.

In 1952, peat-cutters in Denmark found a human body. They cleared the peat away from it and found it had hardly decomposed. They felt he could not have been dead for long. Radiocarbon dating found it had died over 1600 years ago.

Bodies have been found in both fens and bogs. In fen bodies, the soft tissues had decomposed but the skeleton remained; whereas in bog bodies the soft tissues were preserved, and the bones had been dissolved. Most bog bodies became brown bags of skin after several thousand years. Bogs not only tanned the skin, but it also saved hair, beards, and fingernails; even fingerprints remained after thousands of years submerged in bogs. Several bog bodies were able to be fingerprinted.

Alfred Dieck (1906 – 1989), a German archaeologist gathered information on as many bodies found in peat as he could from 1939 until 1986. His final total was 1,850 bodies. There has been considerable speculation as to why there were so many bodies and why they were in the peat. A number of the bodies had been subjected to considerable trauma, so some people wondered if they were murder victims that had been hidden. Others thought perhaps they had been criminals or other undesirable individuals that were executed and placed there for convenience of disposal. One must be cautious in ascribing motive for the deaths of people who lived and died many centuries (even thousands of years) ago. Perhaps they were placed there for reasons we will never know.