| Title | Distribution and activity of ice wedges across the forest-tundra transition, western Arctic Canada |
| |
| Author | Kokelj, S V; Lantz, T C; Wolfe, S A ; Kanigan, J C; Morse, P D; Coutts, R;
Molina-Giraldo, N; Burn, C R |
| Source | Journal of Geophysical Research vol. 119, issue 9, 2014 p. 2032-2047, https://doi.org/10.1002/2014jf003085  Open Access |
| Image |  |
| Year | 2014 |
| Alt Series | Earth Sciences Sector, Contribution Series 20130468 |
| Publisher | Wiley-Blackwell |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Northwest Territories |
| NTS | 107B; 107C |
| Area | Mackenzie River Delta; Richards Island; Garry Island |
| Lat/Long WENS | -136.0000 -133.0000 69.7500 68.4167 |
| Subjects | surficial geology/geomorphology; Nature and Environment; ice wedges; remote sensing; ground temperatures; ground ice; vegetation; permafrost |
| Illustrations | photographs; location maps; tables; graphs; plots |
| Program | Climate Change Geoscience |
| Released | 2014 09 30 |
| Abstract | Remote sensing and a regional network of ground-temperature and ground-ice observations have been used to investigate the size and distribution of ice wedges in different soil types across the tree line
in uplands east of the Mackenzie Delta. In the northern most dwarf-shrub tundra, up to 50% of the ground surface is polygonal, with ice wedges commonly exceeding 3 m in width. The largest ice wedges are in peatlands where thermal-contraction cracking
occurs more frequently than in nearby hummocky terrain with fine-grained soils. There are fewer ice wedges, rarely exceeding 2-m in width, in uplands to the south, and none have been found in mineral soils of the tall-shrub tundra, although active
ice-wedges are found there throughout peatlands. In the subarctic forest, relict wedge ice is restricted to peatlands where the saturated organic active layers above permafrost may not freeze back each year. At tundra sites, winter temperatures at
the permafrost surface are lower in organic than mineral soils because of the shallow permafrost table and high thermal conductivity of frozen peat. In combination with the high coefficient of thermal contraction of ice in the highly porous peat,
ice-wedge cracking and growth is more common in peatlands than in mineral soil. However, the high volumetric water content of a saturated organic active-layer may inhibit freezeback, particularly where thick snow accumulates, making the permafrost in
polygonal peatlands susceptible to degradation following the alteration of drainage or climate warming. |
| Summary | (Plain Language Summary, not published)
We examined the size and distribution of ice wedges in different soil types across the tree line in uplands east of the Mackenzie Delta. These are
largest in peatlands in the north, where thermal-contraction cracking occurs most frequently. They are smaller and fewer in the southern tundra, with active ice wedges found only within peatlands. In the subarctic forest, only relict wedge ice is
found and is restricted to peatlands. Ice-wedge cracking and growth is more common in peatlands than in mineral soil. However, the high volumetric water content of saturated peat may inhibit freezeback, particularly where thick snow accumulates,
making permafrost in polygonal peatlands susceptible to degradation following the alteration of drainage or climate warming. |
| GEOSCAN ID | 293674 |
|
|