Widespread global peatland establishment and persistence over the last 130,000 y

Abstract

Glacial−interglacial variations in CO2 and methane in polar ice cores have been attributed, in part, to changes in global wetland extent, but the wetland distribution before the Last Glacial Maximum (LGM, 21 ka to 18 ka) remains virtually unknown. We present a study of global peatland extent and carbon (C) stocks through the last glacial cycle (130 ka to present) using a newly compiled database of 1,063 detailed stratigraphic records of peat deposits buried by mineral sediments, as well as a global peatland model. Quantitative agreement between modeling and observations shows extensive peat accumulation before the LGM in northern latitudes (>40°N), particularly during warmer periods including the last interglacial (130 ka to 116 ka, MIS 5e) and the interstadial (57 ka to 29 ka, MIS 3). During cooling periods of glacial advance and permafrost formation, the burial of northern peatlands by glaciers and mineral sediments decreased active peatland extent, thickness, and modeled C stocks by 70 to 90% from warmer times. Tropical peatland extent and C stocks show little temporal variation throughout the study period. While the increased burial of northern peats was correlated with cooling periods, the burial of tropical peat was predominately driven by changes in sea level and regional hydrology. Peat burial by mineral sediments represents a mechanism for long-term terrestrial C storage in the Earth system. These results show that northern peatlands accumulate significant C stocks during warmer times, indicating their potential for C sequestration during the warming Anthropocene.

Dispersal limitations and historical factors determine the biogeography of specialized terrestrial protists

“…Holarctic Sphagnum ‐dominated peatlands have experienced considerable changes in their extent due to the repeated advances and retreats of ice sheets during the Quaternary. Many of the largest areas covered by peatlands today were under ice during the Last Glacial Maximum (e.g., Fennoscandia, boreal Canada), while peatlands may have persisted in others (e.g., Pacific coast of Canada) (Treat et al, ). These successive glacial expansions and contractions are known to have shaped genetic diversity in multicellular taxa (Schönswetter, Stehlik, Holderegger, & Tribsch, ), whose dispersal is assumed to be slow in contrast to eukaryotic micro‐organisms (Bahram et al, ).…”

Peatland initiation and carbon accumulation in the Falkland Islands

“…Using both new and published basal peat radiocarbon dates we constructed a cumulative Summed Probability Distribution (cSPD) to quantify the timing of peat initiation in the Falkland Islands (Reyes and Cooke, 2011). To place these results in context we also constructed cSPDs for global and extratropical South American peatlands based on the database of Treat et al (2017). For each site containing at least two dated depths we constructed a Bayesian age-depth model using Bacon with default priors for accumulation rate and memory, accepting alternate suggestions where initial screening suggested these were inappropriate (Blaauw and Christen, 2011;Goring et al, 2012).…”

“…3). While considerably older peatlands are present around the world (Treat et al, 2019), many of these are in the tropics and Falkland Islands peatlands are atypically old for the temperate/boreal realm. This may relate to the limited extent of late Quaternary glaciation, which appears to have been restricted to cirques and small mountain glaciers, particularly in West Falkland (Clapperton, 1971;Clapperton and Suggern, 1976;Roberts, 1984).…”

Genetic structure and phylogeographic relationships of the Bellamya complex: A nascent aquacultural snail in the Pearl River basin, China

“…A relatively constant population size was maintained in the Pearl River basin for Neosalanx taihuensis, whereas population expansion occurred in the Yangtze River and Huaihe River basins during the mid-Pleistocene (Zhao et al, 2008). In the Pearl River basin, the relatively mild Pleistocene climate in southern China (Ju, Wang, & Jiang, 2007;Weaver, Eby, Augustus, & Wiebe, 1998) (Figure 2), coinciding with a period of cooling during MIS 4 (∼0.071 to 0.057 mya; Treat et al, 2019) in the last glacial period. In particular, during the Last Glacial Maximum (LGM, 0.021-0.018 mya), the sea level was 130 ~ 150 m lower than that today, resulting in strengthened downcutting processes of the rivers (Shen, 2013;Treat et al, 2019;Yu, Xue, Liu, & Chen, 2003).…”

“…In the Pearl River basin, the relatively mild Pleistocene climate in southern China (Ju, Wang, & Jiang, 2007;Weaver, Eby, Augustus, & Wiebe, 1998) (Figure 2), coinciding with a period of cooling during MIS 4 (∼0.071 to 0.057 mya; Treat et al, 2019) in the last glacial period. In particular, during the Last Glacial Maximum (LGM, 0.021-0.018 mya), the sea level was 130 ~ 150 m lower than that today, resulting in strengthened downcutting processes of the rivers (Shen, 2013;Treat et al, 2019;Yu, Xue, Liu, & Chen, 2003). Cooler and drier climates further intensified during this period, and the Bellamya habitats in rivers and lakes were fragmented or even lost.…”