Permafrost Terrain Stability and Thermokarst Monitoring: - Arctic LCC

sites where were successfully established, and shrubs were taller and more dominated by tall
shrub species (for example, willow and shrub birch) than in other areas. The authors
speculated that tree and shrub advancement in the tundra depends on well-drained
microsites, such as microsites on thaw-pond banks, and, therefore, that treeline advancement
is contingent on further degradation of existing permafrost.
97. Lougheed, V.L., Butler, M.G., McEwen, D.C., and Hobbie, J.E., 2011, Changes in
tundra pond limnology—Re-sampling Alaskan ponds after 40 years: Ambio, v. 40,
no. 6, p. 589–599.
This paper documents the resampling of several ponds near Barrow, Alaska, that were
studied intensively in the 1970s, and found that the ponds had undergone a change in their
physical, chemical, and biological characteristics. Differences included higher daily mean
and maximum pond temperatures, higher concentrations of ammonia, nitrate, and soluble
reactive phosphorus, and a marginal increase in phytoplankton biomass. The authors noted
that it is difficult to make any broad statements regarding the effects of climate on these
ponds given the small amount of data, and suggested that these ponds represent a unique and
valuable long-term dataset and should be sampled more frequently and maintained as
Barrow expands.
98. MacLean, R., Oswood, M.W., Irons, J.G., and McDowell, W.H., 1999, The effect of
permafrost on stream biogeochemistry—A case study of two streams in the Alaskan
(USA) taiga: Biogeochemistry, v. 47, no. 3, p. 239–267.
This paper examines the effect of permafrost on stream chemistry by analyzing soils
chemistry in shallow organic soils and groundwater derived from springs and wells.
Extensive permafrost led to a greater hydrograph response to spring thaw and summer
storms, as well as a stronger signature of organic soil chemistry in the stream. Nitrogen
cycling appeared to occur independent of permafrost extent, as indicated by limited
correlations between nitrogen and discharge. A conceptual model is provided, indicating
different flowpaths through organic and mineral soils, depending on permafrost extent.
99. Mackay, J.R., 1970, Disturbances to the tundra and forest tundra environment of the
western Arctic: Canadian Geotechnical Journal, v. 7, no. 4, p. 420–432.
The e terms thermokarst and thermo-erosion are defined, and differences between these two
terms are highlighted, particularly the importance of thermal degradation and vertical
subsidence of thermokarst versus the importance of thermal degradation, mechanical
erosion, and lateral expansion under the influence of flowing water for thermo-erosion. The
author uses multiple examples from Northern Canada to explain his views of these
processes. Examples include the impact of man-made disturbances from seismic
exploration, a wildfire, a seepage in a channel, and a dog kennel patch on underlying
permafrost. Field-measured rates of thermokarst and thermo-erosion are reported for each of
these examples.
100. Mackay, J.R., 1972, The world of underground ice: Annals of the Association of
American Geographers, v. 62, no. 1, p. 1–22.
This paper provides an overview of the types and forms of ground ice. The paper includes a
map of permafrost distribution across the northern hemisphere, and a schematic indicating
how different processes lead to different forms of ground ice. The paper discusses many
forms of ground ice and how they originate and thaw, and describes the formation of three
pingos on the coastal plain at length. The potential for ice to exist beneath the ocean is also
noted.
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