Patterns of permafrost formation and degradation in relation to climate and ecosystems

Abstract

We develop a permafrost classification system to describe the complex interaction of climatic and ecological processes in permafrost formation and degradation that differentiates five patterns of formation: ‘climate‐driven’; ‘climate‐driven, ecosystem‐modified’; ‘climate‐driven, ecosystem‐protected’; ‘ecosystem‐driven’; and ‘ecosystem‐protected’ permafrost. Climate‐driven permafrost develops in the continuous permafrost zone, where permafrost forms immediately after the surface is exposed to the atmosphere and even under shallow water. Climate‐driven, ecosystem‐modified permafrost occurs in the continuous permafrost zone when vegetation succession and organic‐matter accumulation lead to development of an ice‐rich layer at the top of the permafrost. During warming climates, permafrost that has formed as climate‐driven can occur in the discontinuous permafrost zone, where it can persist for a long time as ecosystem‐protected. Climate‐driven, ecosystem protected permafrost, and its associated ground ice, cannot re‐establish in the discontinuous zone once degraded, although the near surface can recover as ecosystem‐driven permafrost. Ecosystem‐driven permafrost forms in the discontinuous permafrost zone in poorly drained, low‐lying and north‐facing landscape conditions, and under strong ecosystem influence. Finally, ecosystem‐protected permafrost persists as sporadic patches under warmer climates, but cannot be re‐established after disturbance. These distinctions are important because the various types react differently to climate change and surface disturbances. For example, climate‐driven, ecosystem‐modified permafrost can experience thermokarst even under cold conditions because of its ice‐rich layer formed during ecosystem development, and ecosystem‐driven permafrost is unlikely to recover after disturbance, such as fire, if there is sufficient climate warming. Copyright © 2007 John Wiley & Sons, Ltd.

Land Cover Change in the Lower Yenisei River Using Dense Stacking of Landsat Imagery in Google Earth Engine

“…Thaw propagation into ice-rich near-surface permafrost can be accompanied by ground subsidence (e.g., [60]) and/or formation or expansion of thermokarst depressions (e.g., [61]). Lowering of the permafrost table may result in the formation of taliks, enhancing underground drainage and resulting in dryer surface conditions (e.g., [24,25]).…”

Derivation and analysis of a high-resolution estimate of global permafrost zonation

“…This is mostly due to the effects of topography (Gruber and Haeberli, 2007), vegetation cover (Shur and Jorgenson, 2007), ground material (Gubler et al, 2011), water bodies and flow (Burn, 2005;Endrizzi et al, 2011) or snow distribution (Zhang, 2005;Sturm and Benson, 2004;Liston, 2004). Consequently, point (borehole) measurements in any but the most homogeneous conditions do not suffice to describe conditions over an area, making their use for model calibration and validation difficult.…”

Sources and sinks of carbon in boreal ecosystems of interior Alaska: A review

“…The thick organic layer in permafrost-impacted environments actively protects permafrost from thawing as part of the "ecosystem-protected permafrost" identified by Shur and Jorgenson (2007). The type of moss groundcover exerts an important control on the soil thermal regime since mosses with higher moisture content, such as Sphagnum mosses, protect the soil from warm summer temperatures better than feather mosses, which have a higher thermal conductivity .…”