Steppe-tundra

Steppe-tundra is a sparse dry-climate vegetation type which was widespread during Pleistocene times at mid-latitudes of North America and Eurasia, but no longer exists today. The characteristics of steppe-tundra are inferred indirectly from knowledge of the habitat preferences of the individual plant species that were present in this vegetation, and from related zoological and sedimentological evidence.cite web|title=Steppe-tundra|work=Estimates of preanthropogenic carbon storage in global ecosystem types|url=http://www.esd.ornl.gov/projects/qen/carbon11.html|publisher=Oak Ridge National Laboratory|lastaccess=2007-09-04]

The terms steppe and tundra tend to imply a dense sward with organic-rich soils, and so in this sense the term is misleading. For convenience, the steppe-tundra can be divided into two types, a more 'steppe-like' variant and a more 'tundra-like' variant.

For the tundra-like vegetation, analogies have been drawn with a treeless vegetation that presently occurs in scattered patches on well drained south-facing hillslopes in north-eastern Siberia, although the modern-day equivalent is thought to have too dense a ground cover of vegetation.cite book|last=Khotinsky|first=N.A.|date=1984|chapter=Holocene vegetation history|pages=179-200|title=Late Quaternary Environments of the Soviet Union|editor=A.A. Velichko|publisther=Longman|location=London] Ground cover amounted to no more than about 50%, with mainly herbaceous plants but a few scattered low shrubs and occasional stunted trees in sheltered spots. Peat accumulation would have been negligible, and the soil would have had a much lower organic content than most present-day tundra such as Ubsunur Hollow .

The more steppe-like variant, containing a higher proportion of steppic species, would seem if anything to have had an even sparser vegetation cover. The best analogy would be with semi-desert transitional steppes that occur today at the northern fringes of the central Asian desert.

The steppe-tundra supported grazing megafauna such as bison, horses, and mammoths.

References

External links

* [http://cogweb.ucla.edu/ep/Frost_06.html Possible link between steppe-tundra habitat and human eye, skin and hair color]