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Buried soil organic inclusions in non‐sorted circles fields in northern Sweden: Age and Paleoclimatic context
Author(s) -
Becher Marina,
Olid Carolina,
Klaminder Jonatan
Publication year - 2013
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/jgrg.20016
Subject(s) - organic matter , context (archaeology) , soil water , total organic carbon , period (music) , geology , arctic , vegetation (pathology) , physical geography , soil organic matter , pedogenesis , soil horizon , earth science , soil science , geochemistry , geography , paleontology , ecology , environmental chemistry , chemistry , oceanography , physics , pathology , acoustics , biology , medicine
Abstract Although burial of surface organic soil horizons into deeper mineral soil layers helps drive the long‐term buildup of carbon in arctic soils, when and why buried horizons formed as result of cryoturbation in northern Sweden remain unclear. In this study, we used 14 C and 210 Pb dating to assess when organic matter was buried within non‐sorted circles fields near Abisko in northern Sweden. In addition, we used aerial photos from 1959 and 2008 to detect eventual trends in cryogenic activities during this period. We found that organic matter from former organic horizons (stratigraphically intact or partly fragmented) corresponds to three major periods: 0–100 A.D., 900–1250 A.D., and 1650–1950 A.D. The latter two periods were indicated by several dated samples, while the extent of the oldest period is more uncertainty (indicated by only one sample). The aerial photos suggest a net overgrowth by shrub vegetation of previously exposed mineral soil surfaces since 1959. This overgrowth trend was seen in most of the studied fields (92 out of 137 analyzed fields), indicating that the cryogenic activity has mainly decreased in studied non‐sorted circles fields since the 1950s. This latter interpretation is also supported by the absence of buried organic layers formed during the last decades. We suggest that the organic matter was buried during the transition from longer cold periods to warmer conditions. We believe these climatic shifts could have triggered regional scale burial of soil organic matter and thus affected how these soils sequestered carbon.