Details
| Original language | English |
|---|---|
| Pages (from-to) | 85-93 |
| Number of pages | 9 |
| Journal | Soil Biology and Biochemistry |
| Volume | 67 |
| Publication status | Published - Dec 2013 |
Abstract
Turbic Cryosols (permafrost soils characterized by cryoturbation, i.e., by mixing of soil layers due to freezing and thawing) are widespread across the Arctic, and contain large amounts of poorly decomposed organic material buried in the subsoil. This cryoturbated organic matter exhibits retarded decomposition compared to organic material in the topsoil. Since soil organic matter (SOM) decomposition is known to be tightly linked to N availability, we investigated N transformation rates in different soil horizons of three tundra sites in north-eastern Siberia and Greenland. We measured gross rates of protein depolymerization, N mineralization (ammonification) and nitrification, as well as microbial uptake of amino acids and NH4+ using an array of 15N pool dilution approaches. We found that all sites and horizons were characterized by low N availability, as indicated by low N mineralization compared to protein depolymerization rates (with gross N mineralization accounting on average for 14% of gross protein depolymerization). The proportion of organic N mineralized was significantly higher at the Greenland than at the Siberian sites, suggesting differences in N limitation. The proportion of organic N mineralized, however, did not differ significantly between soil horizons, pointing to a similar N demand of the microbial community of each horizon. In contrast, absolute N transformation rates were significantly lower in cryoturbated than in organic horizons, with cryoturbated horizons reaching not more than 32% of the transformation rates in organic horizons. Our results thus indicate a deceleration of the entire N cycle in cryoturbated soil horizons, especially strongly reduced rates of protein depolymerization (16% of organic horizons) which is considered the rate-limiting step in soil N cycling.
Keywords
- Arctic, Cryoturbation, Ecological stoichiometry, Nitrification, Nitrogen availability, Nitrogen mineralization, Nitrogen transformation, Protein depolymerization, Soil organic matter, Tundra
ASJC Scopus subject areas
- Immunology and Microbiology(all)
- Microbiology
- Agricultural and Biological Sciences(all)
- Soil Science
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In: Soil Biology and Biochemistry, Vol. 67, 12.2013, p. 85-93.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Nitrogen dynamics in Turbic Cryosols from Siberia and Greenland
AU - Wild, Birgit
AU - Schnecker, Jörg
AU - Bárta, Jiří
AU - Čapek, Petr
AU - Guggenberger, Georg
AU - Hofhansl, Florian
AU - Kaiser, Christina
AU - Lashchinsky, Nikolaj
AU - Mikutta, Robert
AU - Mooshammer, Maria
AU - Šantrůčková, Hana
AU - Shibistova, Olga
AU - Urich, Tim
AU - Zimov, Sergey A.
AU - Richter, Andreas
N1 - Funding information: This work was funded by the Austrian Science Fund (FWF) as a part of the International Program CryoCARB (Long-term Carbon Storage in Cryoturbated Arctic Soils; FWF – I370-B17). Jörg Schnecker received a Julius-Payer-Stipendium of the Austrian Society for Polar Research.
PY - 2013/12
Y1 - 2013/12
N2 - Turbic Cryosols (permafrost soils characterized by cryoturbation, i.e., by mixing of soil layers due to freezing and thawing) are widespread across the Arctic, and contain large amounts of poorly decomposed organic material buried in the subsoil. This cryoturbated organic matter exhibits retarded decomposition compared to organic material in the topsoil. Since soil organic matter (SOM) decomposition is known to be tightly linked to N availability, we investigated N transformation rates in different soil horizons of three tundra sites in north-eastern Siberia and Greenland. We measured gross rates of protein depolymerization, N mineralization (ammonification) and nitrification, as well as microbial uptake of amino acids and NH4+ using an array of 15N pool dilution approaches. We found that all sites and horizons were characterized by low N availability, as indicated by low N mineralization compared to protein depolymerization rates (with gross N mineralization accounting on average for 14% of gross protein depolymerization). The proportion of organic N mineralized was significantly higher at the Greenland than at the Siberian sites, suggesting differences in N limitation. The proportion of organic N mineralized, however, did not differ significantly between soil horizons, pointing to a similar N demand of the microbial community of each horizon. In contrast, absolute N transformation rates were significantly lower in cryoturbated than in organic horizons, with cryoturbated horizons reaching not more than 32% of the transformation rates in organic horizons. Our results thus indicate a deceleration of the entire N cycle in cryoturbated soil horizons, especially strongly reduced rates of protein depolymerization (16% of organic horizons) which is considered the rate-limiting step in soil N cycling.
AB - Turbic Cryosols (permafrost soils characterized by cryoturbation, i.e., by mixing of soil layers due to freezing and thawing) are widespread across the Arctic, and contain large amounts of poorly decomposed organic material buried in the subsoil. This cryoturbated organic matter exhibits retarded decomposition compared to organic material in the topsoil. Since soil organic matter (SOM) decomposition is known to be tightly linked to N availability, we investigated N transformation rates in different soil horizons of three tundra sites in north-eastern Siberia and Greenland. We measured gross rates of protein depolymerization, N mineralization (ammonification) and nitrification, as well as microbial uptake of amino acids and NH4+ using an array of 15N pool dilution approaches. We found that all sites and horizons were characterized by low N availability, as indicated by low N mineralization compared to protein depolymerization rates (with gross N mineralization accounting on average for 14% of gross protein depolymerization). The proportion of organic N mineralized was significantly higher at the Greenland than at the Siberian sites, suggesting differences in N limitation. The proportion of organic N mineralized, however, did not differ significantly between soil horizons, pointing to a similar N demand of the microbial community of each horizon. In contrast, absolute N transformation rates were significantly lower in cryoturbated than in organic horizons, with cryoturbated horizons reaching not more than 32% of the transformation rates in organic horizons. Our results thus indicate a deceleration of the entire N cycle in cryoturbated soil horizons, especially strongly reduced rates of protein depolymerization (16% of organic horizons) which is considered the rate-limiting step in soil N cycling.
KW - Arctic
KW - Cryoturbation
KW - Ecological stoichiometry
KW - Nitrification
KW - Nitrogen availability
KW - Nitrogen mineralization
KW - Nitrogen transformation
KW - Protein depolymerization
KW - Soil organic matter
KW - Tundra
UR - http://www.scopus.com/inward/record.url?scp=84883780718&partnerID=8YFLogxK
U2 - 10.1016/j.soilbio.2013.08.004
DO - 10.1016/j.soilbio.2013.08.004
M3 - Article
AN - SCOPUS:84883780718
VL - 67
SP - 85
EP - 93
JO - Soil Biology and Biochemistry
JF - Soil Biology and Biochemistry
SN - 0038-0717
ER -