In situ carbon and nitrogen turnover dynamics in topsoils: a climate warming simulation study in an alpine ecosystem

Autor(en): I. Djukic, F. Zehetner, M. Horacek, M. H. Gerzabek
Abstrakt: Context. Climate change may affect ecosystem carbon (C) and nitrogen (N) cycling by accelerating C and N transformations in soil, which in turn can feed back to the climate system. These effects may be especially pronounced in cold regions, which are particularly sensitive to climate change, store significant amounts of soil organic C and harbour N-poor ecosystems. Still it is debated how C and N dynamics in high-elevation ecosystems will respond to rising temperatures. Aims. We investigated the effects of climate warming and shifting vegetation zones on litter C and N turnover in a high-elevation ecosystem of the Austrian Alps. Methods. We used high-to-low elevation soil translocation to simulate the combined effects of changing climatic conditions and shifting vegetation zones, and combined this with an in-situ decomposition experiment using ¹³C and ¹⁵N double-labelled litter material. Key results. In our experiment, plant litter decomposition raised soil pH by up to one pH unit (5.7 to 6.7) within 15–20 weeks, followed by a decrease below the initial pH values until the end of the experiment. Simulated mean annual soil warming of 1.5 and 2.7°C resulted in a significantly accelerated turnover of added maize-C, whereas maize-N persisted longer in the soils. The more resistant C pool (half-life 1–2 years) responded much more strongly to experimental warming (100–190% increase in decomposition rate) compared to the labile pool (half-life 1–2 weeks; 5–20% increase in decomposition rate). In contrast, simulated warming led to a significant decrease of N loss by mineralisation for both pools (change in half-life for labile maize straw N pool, 5.9 to 10.5 and 19.1 days, respectively; and stabile maize straw N pool, 1386 to 1733 and 3466 days, respectively). Conclusions. Our results show that rising temperatures in alpine ecosystems may have contrasting effects on C and N dynamics in the short to medium term. This reflects very tight N cycling and underlines the importance of soil hydrological processes, such as water percolation and leaching, on the fate of N in such N-poor ecosystems. Implications. The linkage between N cycling and soil hydrological processes should be accounted for in ecosystem modelling efforts.
Organisation(en): Institut für Geographie und Regionalforschung, Department für Lithosphärenforschung
Externe Organisation(en): Universität für Bodenkultur Wien, Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft, Austrian Institute of Technology, Austrian Agency of Health and Food Safety (AGES)
Journal: Soil Research
Band: 61
Seiten: 766-774
Anzahl der Seiten: 9
ISSN: 1838-675X
DOI: https://doi.org/10.1071/SR23053
Publikationsdatum: 09-2023
Peer-reviewed: Ja
ÖFOS 2012: 401902 Bodenkunde
Schlagwörter
ASJC Scopus Sachgebiete: Environmental Science (miscellaneous), Soil Science, Earth-Surface Processes
Sustainable Development Goals: SDG 13 – Maßnahmen zum Klimaschutz
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/16a2ab89-6c71-4a0b-bbf9-8604e73e526b