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| Titel |
Physical and chemical properties of young soils of the Icelandic highlands |
| VerfasserIn |
Guðrún Gísladóttir, Utra Mankasingh |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250113784
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| Publikation (Nr.) |
 EGU/EGU2015-14007.pdf |
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| Zusammenfassung |
| Most of the Icelandic soils are of volcanic origin, classified as andisols (carbon content
1-12%), many of which are strongly affected by erosion and so, formation of new soils is of
great interest. The effect of land cover type on the weathering patterns and the formation of
new soils are of interest. The southern Icelandic highlands are characterised by harsh climate,
shallow soils and limited vegetation cover. We hypothesise that in the highland regions of
Iceland the progression of land cover from unvegetated to vegetated sites will impact soil
development. This study describes the physical and chemical properties of highland soils in
Iceland. Soil samples were collected from 12 sites in September 2013, nine sites
were fully vegetated and three unvegetated: grassland (G1-G8), with moss, Carex
Bigelowii and dwarf shrubs, sandy fluvial wetland (S) and unvegetated gravels
(M1-M3).
All soils with vegetative cover were characterized by weak or structureless soil ranging in
texture from loamy sand to silty clay loam, while at unvegetated sites soil texture was
structureless and sandy. On average, the bulk density of soils (range 0.53 – 1.16 g cm-3)
were lower at vegetated sites than unvegetated sites. The soil depth is greater in the vegetated
sites, indicating greater soil development. The average % carbon (%C), % nitrogen (%N),
overall % soil organic matter (%SOM), of vegetated sites were higher than for
unvegetated sites, indicating the difference in soil development: vegetated sites
(mean), 1.60%C, 0.10%N, 4.9%SOM; unvegetated sites (mean), 0.27%C, 0.02%N,
1.81%SOM.
All soils had significant amounts of amorphous clay minerals such as allophone,
imogolite, ferrihydrite or aluminium-humus complexes and also high aluminium and
iron percentages, and high phosphate retention. All of which are characteristic for
andisols. There were strong associations between Fe and Al and the soil C, which are
indicative of Al and Fe complexed with humus or allophane and ferrihydrite clays.
The allophane and ferrihydrite content was 3.5-7.7% and 2.4-5.3%, respectively.
The soils in the study had a high clay content, generally greater than 10% for all
soil types. However, selective dissolutions with oxalate and with pyrophosphate
indicate that more organic carbon was associated with the Fe and Al of vegetated
sites than observed for the vegetated sites. These results also indicate more organic
associations in sites with vascular plants and mosses vs mosses only. The %C, %SOM,
Fe/Al associations, soil structure and soil depth all indicate that there is gradient
of increasing soil genesis form unvegetated to vegetated sites, with evidence of
greater organic associations in sites with vascular plants. Even though the soils at
the vegetated sites are andisols, they are still immature , while the less developed
soils at the unvegetated sites are vitrisols ( |
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