String bog

{{Short description|Bog consisting of ridges and islands}}

File:Kepler Mire - Dead Marshes.JPG, a string bog in New Zealand.]]

A string bog or string mire is a bog consisting of slightly elevated ridges and islands, with woody plants, alternating with flat, wet sedge mat areas. String bogs occur on slightly sloping surfaces, with the ridges at right angles to the direction of water flow. They are an example of patterned vegetation.

String bogs are also known as aapa moors or aapa mires (from Finnish aapasuo) or Strangmoor (from the German).{{cite book |editor1-last=Evert |editor1-first=Klaus-Jürgen |title=Encyclopedic Dictionary of Landscape and Urban Planning: Volume 1 |date=2010 |publisher=Springer Science & Business Media |isbn=9783540764557 |page=984}}

A string bog has a pattern of narrow (2–3m wide), low (less than 1m high) ridges oriented at right angles to the direction of drainage with wet depressions or pools occurring between the ridges. The water and peat are very low in nutrients because the water has been derived from other ombrotrophic wetlands, which receive all of their water and nutrients from precipitation rather than from streams or springs.{{Clarify|reason=Finnish Wikipedia says the opposite about 'aapasuo' – is there a difference between string bogs in different regions?|date=February 2016}} The peat thickness is greater than 1m.

String bogs are features associated with periglacial climates, where the temperature results in long periods of subzero temperatures. The active layer exists as a frozen ground for long periods and melts in the spring thaw. Slow melting produces characteristic mass movement processes and features associated with specific periglacial environments.