The Norwegian Mugwort and other glacial tidbits

Norwegian Mugwort

Northern Hemisphere Glacial Relict distributions were often modified by the northward retreat of great ice sheets that extended south to the Great Lakes in North America.   One example is the Norwegian Mugwort, a small alpine plant now restricted to Norway, Ural Mtns and isolated areas of Scotland, a plant that was widespread during the last glaciation.  Such disjunct Distribution can not be explained by the flight of birds and seed dispersal. A genuine break is the definition of disjunct distribution and it is also the definition of a relict distribution.  


The Arctic Springtail - a face only a mother could love

The Artic Springtail (Tetracanthella arctica) is a tiny 1.5mm long insect living among mosses and existing on plant detritus and fungi. It resides in isolated Arctic locales such as Greenland, Iceland & Spitzbergen to Northern Canada (see map above) but also is found further south in the alpines of the Pyrenees and Tatra mountains.  As it cannot tolerate high temperatures and humidity, it is likely they are climatic relicts.
The Springtail's distribution is believed to be the survival of small relict populations after the end of the last glacial, a shrinking and fragmentation of what was once an extensive distribution during colder glacial climes Cox, C.D. and Moore, P.D..   


However, according to the International Polar Foundation, an amazing study published by the Archives of Insect Biochemistry and Physiology reveals that some Arctic Springtails (Megaphorura arctica) use hydrogen peroxide to cope with cold temperatures by dehydrating themselves and freezing themselves cryogenically.  Maybe freezing themselves was a survival technique to combat the LGM!   

The footprint of the last glaciation left its imprint on the Northern Hemisphere and also on the topography of the United Kingdom .  In a warming world it is clear that vegetation distributions - including agriculture - will be impacted in unpredictable ways.  Stay tuned....

Habitats for Tetracantella Arctica