Organic matter dynamics along a salinity gradient in Siberian steppe soils

Medientyp: E-Artikel; Sonstige Veröffentlichung

Titel: Organic matter dynamics along a salinity gradient in Siberian steppe soils

Beteiligte: Bischoff, Norbert [VerfasserIn]; Mikutta, Robert [VerfasserIn]; Shibistova, Olga [VerfasserIn]; Dohrmann, Reiner [VerfasserIn]; Herdtle, Daniel [VerfasserIn]; Gerhard, Lukas [VerfasserIn]; Fritzsche, Franziska [VerfasserIn]; Puzanov, Alexander [VerfasserIn]; Silanteva, Marina [VerfasserIn]; Grebennikova, Anna [VerfasserIn]; Guggenberger, Georg [VerfasserIn]

Erschienen: Göttingen : Copernicus GmbH, 2018

Ausgabe: published Version

Sprache: Englisch

DOI: https://doi.org/10.15488/3372; https://doi.org/10.5194/bg-15-13-2018

ISSN: 1726-4170

Schlagwörter: soil fertility ; carbon isotope ; persistence ; bacterium ; grassland soil ; sugar ; organic matter ; saline soil ; microbial community ; Siberia ; soil moisture ; Fungi ; organic carbon ; salinity ; fatty acid ; water stress ; environmental gradient ; aboveground biomass ; fungus ; sodicity ; soil organic matter ; steppe ; matric potential ; Kulunda Steppe ; [...]

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Beschreibung: Salt-affected soils will become more frequent in the next decades as arid and semiarid ecosystems are predicted to expand as a result of climate change. Nevertheless, little is known about organic matter (OM) dynamics in these soils, though OM is crucial for soil fertility and represents an important carbon sink. We aimed at investigating OM dynamics along a salinity and sodicity gradient in the soils of the southwestern Siberian Kulunda steppe (Kastanozem, non-sodic Solonchak, Sodic Solonchak) by assessing the organic carbon (OC) stocks, the quantity and quality of particulate and mineral-associated OM in terms of non-cellulosic neutral sugar contents and carbon isotopes (δ13C, 14C activity), and the microbial community composition based on phospholipid fatty acid (PLFA) patterns. Aboveground biomass was measured as a proxy for plant growth and soil OC inputs. Our hypotheses were that (i) soil OC stocks decrease along the salinity gradient, (ii) the proportion and stability of particulate OM is larger in salt-affected Solonchaks compared to non-salt-affected Kastanozems, (iii) sodicity reduces the proportion and stability of mineral-associated OM, and (iv) the fungi:bacteria ratio is negatively correlated with salinity. Against our first hypothesis, OC stocks increased along the salinity gradient with the most pronounced differences between topsoils. In contrast to our second hypothesis, the proportion of particulate OM was unaffected by salinity, thereby accounting for only < 10% in all three soil types, while mineral-associated OM contributed > 90%. Isotopic data (δ13C, 14C activity) and neutral sugars in the OM fractions indicated a comparable degree of OM transformation along the salinity gradient and that particulate OM was not more persistent under saline conditions. Our third hypothesis was also rejected, as Sodic Solonchaks contained more than twice as much mineral-bound OC than the Kastanozems, which we ascribe to the flocculation of OM and mineral components under higher ionic strength ...

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Organic matter dynamics along a salinity gradient in Siberian steppe soils - [published Version]

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