Riparian forests are known as hot spots of nitrogen cycling in landscapes. Climate warming speeds up the cycle. Here we present results from a multi-annual high temporal-frequency study of soil, stem, and ecosystem (eddy covariance) fluxes of N2O from a typical riparian forest in Europe. Hot moments (extreme events of N2O emission) lasted a quarter of the study period but contributed more than half of soil fluxes. We demonstrate that high soil emissions of N2O do not escape the ecosystem but are processed in the canopy. Rapid water content change across intermediate soil moisture was a major determinant of elevated soil emissions in spring. The freeze-thaw period is another hot moment. However, according to the eddy covariance measurements, the riparian forest is a modest source of N2O. We propose photochemical reactions and dissolution in canopy-space water as reduction mechanisms.
Bibliographical noteFunding Information:
This study was supported by the Ministry of Education and Science of Estonia (SF0180127s08 grant), the Estonian Research Council (IUT2-16, PRG-352, and MOBERC20), the Czech Science Foundation (17-18112Y) and project SustES— Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_019/0000797), the EU through the European Regional Development Fund (Centres of Excellence ENVIRON, grant number TK-107, EcolChange, grant number TK-131, and the MOBTP101 returning researcher grant by the Mobilitas Pluss program) and the European Social Fund (Doctoral School of Earth Sciences and Ecology). This work was also supported by the Academy of Finland (294088, 288494), and from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program under grant agreement No . We would like to thank Marek Jakubík for his technical support.
© 2021, The Author(s).
Data Availability StatementData used in this study are available from PANGAEA (https://doi.org/10.1594/PANGAEA.926331). All the data used in this study are available from the corresponding author upon reasonable request.
- climate change
- forest ecology