Abstract
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.
Highlights
The role of forests in regulating greenhouse gas (GHG)[1] budget, in particular for nitrous oxide (N2O), is still largely unknown[2]
N2O is responsible for approximately 6% of global radiative forcing from anthropogenic GHGs, (ii) N2O is the ruling stratospheric ozone-layer depleting agent in the 21st century[4], and (iii) N2O the third most important GHG with a global warming potential 296 times that of CO23 (100-year lifetime adjustment, with feedbacks)
There are several hypotheses explaining the impact of freeze-thaw cycles on soil N2O emissions[14,16,17], a generally accepted theory of the impact of freeze-thaw on N2O fluxes is still missing
Summary
The role of forests in regulating greenhouse gas (GHG)[1] budget, in particular for nitrous oxide (N2O), is still largely unknown[2]. An SWC value of 0.5–0.8 m3 m−3 has been shown to be optimal for soil N2O emissions in forests on both mineral soils[8] and organic soils[9]. Depending on the initial moisture, both flooding and drought can induce hot moments in forests[10]. Drought decreases soil N2O emissions or even turns the soil into a sink of N2O11. Another mechanism that creates hot moments of soil N2O emission is freeze-thaw cycles[12,13,14,15]. There are several hypotheses explaining the impact of freeze-thaw cycles on soil N2O emissions[14,16,17], a generally accepted theory of the impact of freeze-thaw on N2O fluxes is still missing
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
