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Göteborgs universitets publikationer

Microbial nitrogen dynamics in organic and mineral soil horizons along a latitudinal transect in western Siberia

Författare och institution:
Birgit Wild (Institutionen för geovetenskaper); J. Schnecker (-); A. Knoltsch (-); M. Takriti (-); M. Mooshammer (-); N. Gentsch (-); R. Mikutta (-); R. J. E. Alves (-); A. Gittel (-); N. Lashchinskiy (-); A. Richter (-)
Publicerad i:
Global Biogeochemical Cycles, 29 ( 5 ) s. 567-582
Artikel, refereegranskad vetenskaplig
Sammanfattning (abstract):
Soil N availability is constrained by the breakdown of N-containing polymers such as proteins to oligopeptides and amino acids that can be taken up by plants and microorganisms. Excess N is released from microbial cells as ammonium (N mineralization), which in turn can serve as substrate for nitrification. According to stoichiometric theory, N mineralization and nitrification are expected to increase in relation to protein depolymerization with decreasing N limitation, and thus from higher to lower latitudes and from topsoils to subsoils. To test these hypotheses, we compared gross rates of protein depolymerization, N mineralization and nitrification (determined using N-15 pool dilution assays) in organic topsoil, mineral topsoil, and mineral subsoil of seven ecosystems along a latitudinal transect in western Siberia, from tundra (67 degrees N) to steppe (54 degrees N). The investigated ecosystems differed strongly in N transformation rates, with highest protein depolymerization and N mineralization rates in middle and southern taiga. All N transformation rates decreased with soil depth following the decrease in organic matter content. Related to protein depolymerization, N mineralization and nitrification were significantly higher in mineral than in organic horizons, supporting a decrease in microbial N limitation with depth. In contrast, we did not find indications for a decrease in microbial N limitation from arctic to temperate ecosystems along the transect. Our findings thus challenge the perception of ubiquitous N limitation at high latitudes, but suggest a transition from N to C limitation of microorganisms with soil depth, even in high-latitude systems such as tundra and boreal forest.
Ämne (baseras på Högskoleverkets indelning av forskningsämnen):
Geovetenskap och miljövetenskap
tundra, permafrost, boreal forest, protein depolymerization, ARCTIC TUNDRA, TERRESTRIAL ECOSYSTEMS, CARBON AVAILABILITY, FOREST, ECOSYSTEMS, ALASKAN TUNDRA, USE EFFICIENCY, PLANT-GROWTH, N UPTAKE, PERMAFROST, MATTER, Environmental Sciences, Geosciences, Multidisciplinary, Meteorology &, Atmospheric Sciences, ST WM, 1985, NATURE, V317, P613
Postens nummer:
Posten skapad:
2015-08-07 13:02
Posten ändrad:
2015-08-07 13:02

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