Peatlands of Canada

Tarnocai, C.; Kettles, I M; Lacelle, B

doi:10.4095/211269

Cited by 42 publications

(19 citation statements)

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“…The properties of the topsoil (from surface to a depth of 0.5–4 m) were determined from the soil landscape of Canada database [ Shields et al , 1991; Tarnocai and Lacelle , 1996]. There are about 15,000 polygons in the database.…”

Section: Methodsmentioning

confidence: 99%

“…Where permafrost is present, most biological and hydrological processes are confined to the seasonally thawed active layer, across which exchanges of heat, moisture and gases occur between the atmosphere and terrestrial systems [ Anisimov et al , 2001]. A large amount of organic carbon has accumulated above and in the upper layers of permafrost because of the cold and wet conditions in permafrost regions and the soil‐mixing action of freezing and thawing (cryoturbation) [ Michaelson et al , 1996; Tarnocai and Lacelle , 1996]. Formation and changes of permafrost can greatly modify landscape and influence surface and subsurface hydrology, soil biogeochemistry, and ecosystems [ Williams and Smith , 1989; Chapin et al , 1992], and they can also influence the life of northern communities, and present challenges to development.…”

Section: Introductionmentioning

confidence: 99%

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Temporal and spatial changes of permafrost in Canada since the end of the Little Ice Age

2006

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[1] Climate warming was significant from the mid-19th century to the mid-20th century and in recent decades at most northern high latitudes. Climate warming could induce permafrost degradation, which may have important impacts on hydrological, ecological, and biogeochemical processes and on northern communities and infrastructure. To assess the effects of climate change on permafrost, a process-based model of Northern Ecosystem Soil Temperature (NEST) was developed and utilized to simulate the ground thermal regime of the Canadian landmass at a resolution of a half-degree latitudelongitude since the end of the Little Ice Age (circa 1850). The simulated southern boundary of the permafrost for recent decades is similar to that of the current published map, and the simulated active layer thickness and the depth to permafrost base are comparable to site measurements. Simulation results show that climate change since the end of the Little Ice Age, especially during the 20th century, has induced degradation of permafrost in most of Canada: From the 1850s to the 1990s, the area underlain by permafrost was reduced by 5.4%; for those areas where permafrost existed in all the years throughout the period 1850-2002, the mean depth to the base of permafrost decreased (became shallower) by 3 m; the mean active layer thickness increased by 0.21 m, or 34%; and the mean depth to permafrost table increased by 0.39 m. Results also show that suprapermafrost taliks were formed and became larger and more frequent with climate warming in the southern permafrost region, which greatly enhanced permafrost thaw from the top and could have severe impacts on the landscape, hydrology, and ecosystems.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temporal and spatial changes of permafrost in Canada since the end of the Little Ice Age

2006

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“…Research was conducted in a forested ombrotrophic peatland representative of forested bogs in the Boreal Plains (National Wetlands Working Group, ), where peatlands cover 27% of the landscape (Tarnocai et al ., ). The study site selected was partially disturbed by wildfire in 2006, with the remainder of the peatland last disturbed by wildfire in approximately 1935 (hereafter referred to as unburned).…”

Section: Study Areamentioning

confidence: 97%

Seasonal variation in albedo and radiation exchange between a burned and unburned forested peatland: implications for peatland evaporation

2015

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Forested boreal peatlands represent a precipitation‐dependent ecosystem that is prone to wildfire disturbance. Solar radiation exchange in forested peatlands is modified by the growth of a heterogeneous, open‐crown tree canopy, as well as by likely disturbance from wildfire. Radiation exchange at the peat surface is important in peatlands, as evaporation from the peat surface is the dominant pathway of water loss in peatlands of continental western North America. We examined shortwave and longwave radiation exchange in two forested ombrotrophic peatlands of central Alberta, Canada: one with (>75 years since wildfire; unburned) and another without a living spruce canopy (1–4 years since wildfire; burned) between the autumn of 2007 and 2010. Above‐canopy winter albedo was nearly two times greater in the recently burned peatland than the unburned peatland. Incoming shortwave radiation at the peat surface was much higher at the burned peatland, which increases the amount of energy available for evaporation. This is especially true for hollow microforms that are generally shaded by the tree canopy in unburned peatlands. Snow‐free albedo was similar between peatlands, although an increase in longwave losses at the burned site resulted in slightly greater net radiation at the unburned site. Copyright © 2015 John Wiley & Sons, Ltd.

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“…This study found that the median size of peat‐forming ecosystems was small (~30 m diameter) and that these systems occupied approximately 46% of the region (including lake area), 59% of the land surface (not including lake area), and 65% of the area within a 100 m buffer around lakes [ Umbanhowar et al , ]. Peat cover estimates of the same region (14.7–32.6%) using coarser‐resolution classification systems [ GeoBase , ; Tarnocai et al , ] are ~30–70% lower than those based on higher‐resolution classifications. To the extent that these systems store significant quantities of soil C in globally widespread physiographic provinces, we may be underestimating Northern Hemisphere pools of soil C [ Campeau et al , ].…”

Section: Introductionmentioning

confidence: 99%

The initiation and development of small peat‐forming ecosystems adjacent to lakes in the north central Canadian low arctic during the Holocene

Camill

Umbanhowar

Geiss

et al. 2017

J. Geophys. Res. Biogeosci.

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Small peat‐forming ecosystems in arctic landscapes may play a significant role in the regional biogeochemistry of high‐latitude systems, yet they are understudied compared to arctic uplands and other major peat‐forming regions of the North. We present a new data set of 25 radiocarbon‐dated permafrost peat cores sampled around eight low arctic lake sites in northern Manitoba (Canada) to examine the timing of peat initiation and controls on peat accumulation throughout the Holocene. We used macrofossils and charcoal to characterize changes in the plant community and fire, and we explored potential impacts of these local factors, as well as regional climatic change, on rates of C accumulation and C stocks. Peat initiation was variable across and within sites, suggesting the influence of local topography, but 56% of the cores initiated after 3000 B.P. Most cores initiated and remained as drier bog hummock communities, with few vegetation transitions in this landscape. C accumulation was relatively slow and did not appear to be correlated with Holocene‐scale climatic variability, but C stocks in this landscape were substantial (mean = 45.4 kg C m−2), potentially accounting for 13.2 Pg C in the Taiga Shield ecozone. To the extent that small peat‐forming systems are underrepresented in peatland mapping, soil organic carbon (SOC) stocks may be underestimated in arctic regions. Mean fire severity appeared to be negatively correlated with C accumulation rates. Initiation and accumulation of soil C may respond to both regional and local factors, and substantial lowland soil C stocks have the potential for biogeochemical impacts on adjacent aquatic ecosystems.

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Peatlands of Canada

Cited by 42 publications

References 0 publications

Temporal and spatial changes of permafrost in Canada since the end of the Little Ice Age

Temporal and spatial changes of permafrost in Canada since the end of the Little Ice Age

Seasonal variation in albedo and radiation exchange between a burned and unburned forested peatland: implications for peatland evaporation

The initiation and development of small peat‐forming ecosystems adjacent to lakes in the north central Canadian low arctic during the Holocene

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