Late Quaternary environmental and landscape dynamics revealed by a pingo sequence on the northern Seward Peninsula, Alaska

Wetterich, Sebastian; Grosse, Guido; Schirrmeister, Lutz; Andreev, Andrei A.; Bobrov, Anatoly; Kienast, Frank; Bigelow, Nancy H.; Edwards, Mary E.

doi:10.1016/j.quascirev.2012.01.027

Cited by 35 publications

(38 citation statements)

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“…Aside from other permafrost paleo-records such as ice wedges (Siberia: Meyer et al [59]; Alaska: Meyer at al. [60] and terrestrial deposits (e.g., Siberia: Wetterich et al [84]; Canada: Murton et al [68], Fritz et al [28]; Alaska: Kanevskiy et al [48], Wetterich et al [83]), thermokarst lake sediments are important paleo-archives for reconstructing environmental changes on millennial time scales. Numerous studies have focused on general paleo-limnological investigations of Late Quaternary lake sediments by using various sediment and biogeochemical proxies (Lenz et al [55]; diatoms: Biskaborn et al [8]; plant macrofossils: Gaglioti et al [31]).…”

Section: Introductionmentioning

confidence: 99%

Impacts of shore expansion and catchment characteristics on lacustrine thermokarst records in permafrost lowlands, Alaska Arctic Coastal Plain

Lenz

Jones

Wetterich

et al. 2016

Arktos

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Arctic lowland landscapes have been modified by thermokarst lake processes throughout the Holocene. Thermokarst lakes form as a result of ice-rich permafrost degradation, and they may expand over time through thermal and mechanical shoreline erosion. We studied proximal and distal sedimentary records from a thermokarst lake located on the Arctic Coastal Plain of northern Alaska to reconstruct the impact of catchment dynamics and morphology on the lacustrine depositional environment and to quantify carbon accumulation in thermokarst lake sediments. Short cores were collected for analysis of pollen, sedimentological, and geochemical proxies. Radiocarbon and 210 Pb/ 137 Cs dating, as well as extrapolation of measured historic lake expansion rates, were applied to estimate a minimum lake age of *1400 calendar years BP. The pollen record is in agreement with the young lake age as it does not include evidence of the ''alder high'' that occurred in the region *4000 cal yr BP. The lake most likely initiated from a remnant pond in a drained thermokarst lake basin (DTLB) and deepened rapidly as evidenced by accumulation of laminated sediments. Increasing oxygenation of the water column as shown by higher Fe/Ti and Fe/S ratios in the sediment indicate shifts in ice regime with increasing water depth. More recently, the sediment source changed as the thermokarst lake expanded through lateral permafrost degradation, alternating from redeposited DTLB sediments, to increased amounts of sediment from eroding, older upland deposits, followed by a more balanced combination of both DTLB and upland sources. The characterizing shifts in sediment sources and depositional regimes in expanding thermokarst lakes were, therefore, archived in the thermokarst lake sedimentary record. This study also highlights the potential for Arctic lakes to recycle old carbon from thawing permafrost and thermokarst processes.

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Section: Introductionmentioning

confidence: 99%

Impacts of shore expansion and catchment characteristics on lacustrine thermokarst records in permafrost lowlands, Alaska Arctic Coastal Plain

Lenz

Jones

Wetterich

et al. 2016

Arktos

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“…A Berigian refugium for white spruce ( Picea glauca ) has been confirmed using phylogeography, pollen and macrofossils (Anderson et al ., ; Zazula et al ., ; Wetterich et al ., ; Edwards et al ., ). It is difficult to compare perceived migration rates for species which spread into their current distribution by colonizing the land from both the north side and south side of the glacial ice sheet.…”

Section: Discussionmentioning

confidence: 98%

Consideration of dispersal processes and northern refugia can improve our understanding of past plant migration rates in North America

Snell

Cowling

2015

Journal of Biogeography

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Aim According to the palynological record, rapid plant migrations following the retreat of the last glacier were common in North America and Europe. However, providing an explanation for these rapid migration rates has been challenging considering modern-day seed dispersal distances. We used the newly developed seed dispersal functionality in a hybrid dynamic global vegetation model (DGVM) to simulate two theories that have been proposed to explain rapid plant migrations: long-distance seed dispersal and northern refugial populations.Location Idealized landscapes representing temperate and boreal regions of North America.Methods Vegetation migration rates for three species (Acer rubrum, Fagus grandifolia and Picea glauca) were simulated in response to climate change across a landscape. All simulations included long-distance seed dispersal; however, we compared landscape colonization rates both with and without the presence of northern refugial populations.Results For all three species, the colonization rates were faster when there was a northern refugial population. Increasing the number of locations of refugia further increased the rate of landscape colonization, and this was most effective when refugial populations were spatially separated. The perceived migration rates (i.e. the time it took to spread the furthest distance away from the southern refugium) were approximately twice as fast when a refugium was present. For example, A. rubrum had a perceived migration rate of 119 m yr À1 without refugia and a perceived migration rate of 204 m yr À1 with a northern refugium.Main conclusions The simulated migration rates that matched the rapid migration rates observed in the pollen record for Acer were only achieved when both long-distance dispersal and northern refugial populations were included in the simulations. Even with refugial populations, migration rates for P. glauca and F. grandifolia were slower than historical rates. The results of this study are consistent with the hypothesis that plant migration rates calculated from the pollen record overestimate the ability of most species to track rapid climate change.

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“…In northwest Alaska, peat layers and elevated percentages of spruce pollen suggest that paludification accompanied the intermittent presence of forests there between 40 and 60 calendar ka B.P. (49). On Siberia's Lena River Delta, buried peat layers date to 32-52 calendar ka B.P.…”

Section: Discussionmentioning

confidence: 99%

Life and extinction of megafauna in the ice-age Arctic

Mann

Groves

Reanier³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Understanding the population dynamics of megafauna that inhabited the mammoth steppe provides insights into the causes of extinctions during both the terminal Pleistocene and today. Our study area is Alaska's North Slope, a place where humans were rare when these extinctions occurred. After developing a statistical approach to remove the age artifacts caused by radiocarbon calibration from a large series of dated megafaunal bones, we compare the temporal patterns of bone abundance with climate records. Megafaunal abundance tracked ice age climate, peaking during transitions from cold to warm periods. These results suggest that a defining characteristic of the mammoth steppe was its temporal instability and imply that regional extinctions followed by population reestablishment from distant refugia were characteristic features of ice-age biogeography at high latitudes. It follows that long-distance dispersal was crucial for the long-term persistence of megafaunal species living in the Arctic. Such dispersal was only possible when their rapidly shifting range lands were geographically interconnected. The end of the last ice age was fatally unique because the geographic ranges of arctic megafauna became permanently fragmented after stable, interglacial climate engendered the spread of peatlands at the same time that rising sea level severed former dispersal routes. (10,000-45,000 calendar y ago) when some 65% of terrestrial megafauna genera (animals weighing >45 kg) became globally extinct (1). Based on what we know about recent species extinctions, the causes of extinction are usually synergistic, often species-specific, and therefore, complex, which implies that there is no universal explanation for end-Pleistocene extinctions (2, 3). Globally and specifically in the Arctic (3-10), megafaunal extinctions have been variously blamed on overhunting, rapid climate change, habitat loss, and introduced diseases (3-10). Further complicating a clear understanding of the causes of ice-age extinctions is that the magnitude and tempo of environmental change during the last 100,000 y of the Pleistocene were fundamentally different than during the Holocene (11), and these differences had far-reaching implications for community structure, evolution, and extinction causes (12).A recent survey comparing the extinction dates of circumboreal megafauna with ice-age climate suggests that extinctions and genetic turnover were most frequent during warm, interstadial events (13). However, the mechanisms for these extinctions remain unclear, partly because this previous study considered multiple taxa living in many different ecosystems. Here, we focus on five megafaunal species that coinhabited a region of the Arctic with an ecological setting that is relatively well-understood. To avoid the methodological problems involved in pinpointing extinction dates (13), we infer population dynamics from changes in the relative abundance of megafauna over time. Using a uniquely large dataset of dated megafaunal bones from one particular area, we t...

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Late Quaternary environmental and landscape dynamics revealed by a pingo sequence on the northern Seward Peninsula, Alaska

Cited by 35 publications

References 105 publications

Impacts of shore expansion and catchment characteristics on lacustrine thermokarst records in permafrost lowlands, Alaska Arctic Coastal Plain

Impacts of shore expansion and catchment characteristics on lacustrine thermokarst records in permafrost lowlands, Alaska Arctic Coastal Plain

Consideration of dispersal processes and northern refugia can improve our understanding of past plant migration rates in North America

Life and extinction of megafauna in the ice-age Arctic

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