TY - JOUR
T1 - Mediterranean riparian zones as hotspots of greenhouse gases
T2 - effects of vegetation, distance to the riverbank and wet periods
AU - Velázquez, Eduardo
AU - Lassaletta, Luis
AU - Galea, Carmen
AU - Vallejo, Antonio
AU - Hurtado, Juliana
AU - Garnier, Josette
AU - Butterbach-Bahl, Klaus
AU - González-Murua, Carmen
AU - Fuertes-Mendizábal, Teresa
AU - Estavillo, José María
AU - Zaman, Mohammad
AU - Sanz-Cobena, Alberto
N1 - Publisher Copyright:
© 2025 The Authors
PY - 2026/1
Y1 - 2026/1
N2 - The ability of riparian forests to reduce nutrient flows from crops to streams is well known. However, their role as sources and sinks of greenhouse gases (GHGs) has been less studied, particularly in Mediterranean environments. We assessed the changes in daily soil N2O and CH4 fluxes between 2021 and 2023 in a riparian zone located in Central Spain. We also evaluated if cumulative fluxes of such GHGs depended on soil NO3−, NH4+ and DOC contents, and water-filled pore space (WFPS). Their dependence to different vegetation types and distances to the riverbank, as well as on the existence of wet periods, which include occasional floods, was also analysed. Daily N2O and CH4 fluxes were both low. Those of N2O were positive whereas those of CH4 were mostly negative, but positive fluxes of this GHG were nevertheless observed in late autumn 2021 and in spring 2022. Cumulative fluxes were mainly driven by soil NH4+ contents in the case of N2O and by WFPS in the case of CH4, and influenced by the distance from the riverbank in both cases. The relationships between cumulative fluxes of N2O and its major drivers were positively and significantly influenced by the wet periods. Our results indicate that our riparian zone acted as a net source of N2O and a net sink of CH4, but it became a net source of CH4 in cold and wet periods, where anoxic conditions in which methanogenesis occurs are favoured. Soil N2O emissions mainly originate as a by-product of nitrification but also from incomplete denitrification after heavy rainfall events in warm months. Thus, we advocate for preventive strategies to reduce nitrogen flows from cropping systems to reduce soil N2O emissions in Mediterranean riparian zones.
AB - The ability of riparian forests to reduce nutrient flows from crops to streams is well known. However, their role as sources and sinks of greenhouse gases (GHGs) has been less studied, particularly in Mediterranean environments. We assessed the changes in daily soil N2O and CH4 fluxes between 2021 and 2023 in a riparian zone located in Central Spain. We also evaluated if cumulative fluxes of such GHGs depended on soil NO3−, NH4+ and DOC contents, and water-filled pore space (WFPS). Their dependence to different vegetation types and distances to the riverbank, as well as on the existence of wet periods, which include occasional floods, was also analysed. Daily N2O and CH4 fluxes were both low. Those of N2O were positive whereas those of CH4 were mostly negative, but positive fluxes of this GHG were nevertheless observed in late autumn 2021 and in spring 2022. Cumulative fluxes were mainly driven by soil NH4+ contents in the case of N2O and by WFPS in the case of CH4, and influenced by the distance from the riverbank in both cases. The relationships between cumulative fluxes of N2O and its major drivers were positively and significantly influenced by the wet periods. Our results indicate that our riparian zone acted as a net source of N2O and a net sink of CH4, but it became a net source of CH4 in cold and wet periods, where anoxic conditions in which methanogenesis occurs are favoured. Soil N2O emissions mainly originate as a by-product of nitrification but also from incomplete denitrification after heavy rainfall events in warm months. Thus, we advocate for preventive strategies to reduce nitrogen flows from cropping systems to reduce soil N2O emissions in Mediterranean riparian zones.
KW - Agricultural landscapes
KW - Climate change mitigation strategies
KW - Dissolved organic carbon
KW - Floods
KW - Soil NO and CH fluxes
KW - Soil NO and NH contents
KW - Water-filled pore space
UR - https://www.scopus.com/pages/publications/105025190821
U2 - 10.1016/j.geoderma.2025.117632
DO - 10.1016/j.geoderma.2025.117632
M3 - Journal article
AN - SCOPUS:105025190821
SN - 0016-7061
VL - 465
JO - Geoderma
JF - Geoderma
M1 - 117632
ER -