The Mammoth Steppe
The “mammoth steppe” ecosystem existed approximately 11 thousand years ago, during the Pleistocene epoch (University of California Museum of Palaeontology, 2011). This ecosystem was typified by high species densities, highly productive vegetation and high levels of nutrient cycling. (Pleistocene Park, 2017). In appearance it was very similar to the modern tundra ecosystem seen in northern latitudes such as Iceland and Northern Canada. Within these ecosystems the predominant species were large herbivores; Steppe Bison (Bison priscus), Horses (Equus lambei), Musk ox (Boothrium bombifrons) and Mammoths (Mammuthus primigenius) (Guthrie, 1989; Merck, 2011) but other large herbivorous species included the woolly rhino and giant deer (Van Kolfschoten, 2007) were also present in less abundance.
Whilst this is not an exhaustive list of the species present, as exemplified by the fossil record presented in Cooper (2008), this megafaunal community provides a good example of the prevalent community assemblage of the ecosystem. An example of this ecosystem is “Beringia” the landmass present when the bed of the Bering sea was exposed linking Siberia and North America.
How The Mammoth Went Extinct And Took Its Habitat With It
There are two prevalent theories as to how species within these ecosystems went extinct; The impacts of Climate change and the impacts of overhunting by humans. In terms of “biogeographic population theory” these constitute the environmental and biotic constraints; the limits placed upon a species by the environment and by other species, however both are driven by a change in climate. The direct impact of environmental change was increased seasonal variation and widely fluctuating climates, putting stress on many species and limiting populations. Indirectly this increased the pressure between species, with declines in food sources due to altered growing seasons resulting in resident humans relying more heavily on large mammal hunting. The combination of environmental and biotic pressures it is thought, resulted in the extinction of many large grazing species in this ecosystem and it is argued, resulted in a shift away from the tundra and towards higher productivity systems (Pleoistocene Park, 2017).
Why Does It Matter?
When applied to modern tundra ecosystems, which share much of the same range as the “Mammoth steppe”, these theories could have several implications. With modern human driven climate change, species that are highly sensitive to changes like snow cover reduction and rising temperatures in the modern day tundra ecosystems could be at risk. This is visible in Caribou populations, which show a decline correlated with rising temperature and rainfall (Vors and Boyce, 2009) and who’s populations may be influenced by plant community shifts driven by abiotic changes.
Musk ox populations also show variability as a result of forage ability, habitat availability, and infectious diseases. increasing temperature and humidity (Ytrehus, et al., 2008).
With the loss of such prevalent grazing herbivorous species could come a resultant ecosystem shift as seen during the Pleistocene quaternary extinction, and result in the loss of the modern tundra ecosystem.
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Bibliography
Cooper, C.L. (2008) Pleistocene Fauna. Available at: http://www.uky.edu/OtherOrgs/KPS/poky/files/pokych10-01-29.pdf (Accessed: 1 March 2017).
Lenart, E.A., Bowyer, R.T., Hoef, J.V. and Ruess, R.W. (2002) ‘Climate change and caribou: Effects of summer weather on forage’, Canadian Journal of Zoology, 80(4), pp. 664–678. doi: 10.1139/z02-034.
Merck, J. (2011) Alaska 2007 – the mammoth Steppe. Available at: https://www.geol.umd.edu/~jmerck/alaska/alaska11pleistocene.html (Accessed: 1 March 2017).
Pleistocene Park (2017) Pleistocene park: Restoration of the mammoth Steppe Ecosystem. Available at: http://www.pleistocenepark.ru/en/background/ (Accessed: 1 March 2017).
University of California Museum of Paleontology (2011) The Pleistocene epoch. Available at: http://www.ucmp.berkeley.edu/quaternary/pleistocene.php (Accessed: 1 March 2017).
Van Kolfschoten, T. (2007) The collapse of the mammoth Steppe ecosystem. Available at: http://www.nwo.nl/en/research-and-results/research-projects/i/57/3357.html (Accessed: 1 March 2017).
Vors, L.S. and Boyce, M.S. (2009) ‘Global declines of caribou and reindeer’, Global Change Biology, 15(11), pp. 2626–2633. doi: 10.1111/j.1365-2486.2009.01974.x.
Ytrehus, B., Bretten, T., Bergsjø, B. and Isaksen, K. (2008) ‘Fatal pneumonia Epizootic in musk ox (Ovibos moschatus) in a period of extraordinary weather conditions’, EcoHealth, 5(2), pp. 213–223. doi: 10.1007/s10393-008-0166-0.
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