Abstract
We discovered a 50-cm-thick peat deposit near Cape Rasmussen (65.2°S), in the maritime Antarctic. To our knowledge, while aerobic ‘moss banks’ have often been examined, waterlogged ‘peatlands’ have never been described in this region before. The waterlogged system is approximately 100 m2, with a shallow water table. Surface vegetation is dominated by Warnstorfia fontinaliopsis, a wet-adapted moss commonly found in the Antarctic Peninsula. Peat inception was dated at 2750 cal. BP and was followed by relatively rapid peat accumulation (~0.1 cm/year) until 2150 cal. BP. Our multi-proxy analysis then shows a 2000-year-long stratigraphic hiatus as well as the recent resurgence of peat accumulation, sometime after 1950 AD. The existence of a thriving peatland at 2700–2150 cal. BP implies regionally warm summer conditions extending beyond the mid-Holocene; this finding is corroborated by many regional records showing moss bank initiation and decreased sea ice extent during this time period. Recent peatland recovery at the study site (<50 years ago) might have been triggered by ongoing rapid warming, as the area is experiencing climatic conditions approaching those found on milder, peatland-rich sub-Antarctic islands (50–60°S). Assuming that colonization opportunities and stabilization mechanisms would allow peat to persist in Antarctica, our results suggest that longer and warmer growing seasons in the maritime Antarctic region may promote a more peatland-rich landscape in the future.
Highlights
The maritime Antarctic biogeographic region has been experiencing one of the most rapid rates of warming worldwide in recent decades[1]
Noteworthy is that moss banks are aerobic, lacking a water table, and are not considered wetlands; the thickest banks tend to support permafrost in their deepest layers
The reported peat deposit on Cape Rasmussen conforms to the ‘peatland’ definition: it is characterized by a peat deposit in excess of 40 cm in depth, its soil is saturated, it supports a prevalence of hydrophytic vegetation, and its peat layer consists of at least 80% of dead organic material
Summary
Julie Loisel[1,2], ZichengYu 2, David W. Multiple lines of evidence suggest an extended warm episode that ended during the late Holocene (Fig. 3) These include: (1) Cape Rasmussen peatland, with its initiation and subsequent rapid development between 2700 and 2150 cal. While the effects of warmer and wetter conditions on Antarctic terrestrial ecosystems remain speculative, it is projected that many organisms and communities will be able to take advantage of, and benefit from, the ongoing changes by either expanding their range, growing their biomass, and possibly increasing trophic complexity[34] To this effect, several studies have reported 4- to 5-fold increases in moss growth rates from moss banks over the past few decades across the maritime Antarctic region, from Elephant Island (61°S) to Lazarev Bay (69°S)[6,8,35]. Assuming that colonization opportunities and stabilization mechanisms would allow peat to persist in Antarctica, our results suggest that longer and warmer growing seasons in the maritime Antarctic region may lead to a peatland-rich landscape in the future
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