Soil development over millennial timescales - a comparison of soil chronosequences of different climates and lithologies

Soil Change Matters 2014

Sauer, D.^1 ; Schülli-Maurer, I.^2 ; Wagner, S.^3 ; Scarciglia, F.^4 ; Sperstad, R.^5 ; Svendgård-Stokke, S.^5 ; Sørensen, R.^6 ; Schellmann, G.^7

Institute of Geography, Dresden University of Technology, Dresden, Germany^1

Institute of Soil Science and Land Evaluation, Hohenheim University, Stuttgart, Germany^2

Institute of Crop Science and Resource Conservation, Soil Science Division, University of Bonn, Germany^3

Department of Biology, Ecology and Earth Sciences, University of Calabria, Arcavacata di Rende (CS), Italy^4

Norwegian Forest and Landscape Institute, Ås, Norway^5

Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, Ås, Norway^6

Institute of Geography, University of Bamberg, Bamberg, Germany^7

关键词: Environmental change;    Feedback systems;    Living organisms;    Logarithmic equations;    Semi-arid climate;    Silicate weathering;    Soil development;    Underlying soils;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/25/1/012009/pdf
DOI  :  10.1088/1755-1315/25/1/012009

来源: IOP

【 摘 要 】

This paper reports soil development over time in different climates, on time-scales ranging from a few thousand to several hundred thousand years. Changes in soil properties over time, underlying soil-forming processes and their rates are presented. The paper is based on six soil chronosequences, i.e. sequences of soils of different age that are supposed to have developed under the similar conditions with regard to climate, vegetation and other living organisms, relief and parent material. The six soil chronosequences are from humid-temperate, Mediterranean and semi-arid climates. They are compared with regard to soil thickness increase, changes in soil pH, formation of pedogenic iron oxides (expressed as Fed/Fetratios), clay formation, dust influx (both reflected in clay/silt ratios), and silicate weathering and leaching of base cations(expressed as (Ca+Mg+K+Na)/Al molar ratios) over time. This comparison reveals that the increase of solum thickness with time can be best described by logarithmic equations in all three types of climates. Fed/Fetratios (proportion of pedogeniciron Fed compared to total iron Fet) reflects the transformation of iron in primary minerals into pedogeniciron. This ratio usually increases with time, except for regions, where the influx of dust (having low Fed/Fetratios) prevails over the process of pedogeniciron oxide formation, which is the case in the Patagonian chronosequences. Dust influx has also a substantial influence on the time courses of clay/silt ratios and on element indices of silicate weathering. Using the example of a 730 kasoil chronosequence from southern Italy, the fact that soils of long chronosequences inevitably experienced major environmental changes is demonstrated, and, consequentially a modified definition of requirements for soil chronosequences is suggested. Moreover, pedogenic thresholds, feedback systems and progressive versus regressive processes identified in the soil chronosequences are discussed.