Soil water content drives spatiotemporal patterns of CO2 and N2O emissions from a Mediterranean riparian forest soil

• Published in: Biogeosciences Vol. 14; no. 18; pp. 4195 - 4208
• Main Authors: Poblador, Sílvia, Lupon, Anna, Sabaté, Santiago, Sabater, Francesc
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 21-09-2017; European Geosciences Union (EGU); Copernicus Publications
• Subjects: Availability; Biogeochemical cycle; Biogeochemical cycles; Biogeochemistry; Canvis climàtics; Carbon dioxide; Carbon dioxide emissions; Catchment area; Catchments; Climate change; Climate Research; Climatic changes; Denitrification; Emissions; Forest soils; Gasos d'efecte hivernacle; Greenhouse effect; Greenhouse gase; Greenhouse gases; Groundwater; Groundwater levels; Groundwater table; Hydrologic regime; Hydrology; Klimatforskning; Markvetenskap; Microorganisms; Mineralization; Moisture content; Nitrification; Nitrogen; Nitrous oxide; Precipitation; Respiration; Riberes; Riparian forests; Riparian land; Riparian zone; Shorelines; Soil conditions; Soil properties; Soil Science; Soil temperature; Soil water; Soils; Water availability; Water content; Water table
• ISSN: 1726-4170; 1726-4189; 1726-4189
• DOI: 10.5194/bg-14-4195-2017

Riparian zones play a fundamental role in regulating the amount of carbon (C) and nitrogen (N) that is exported from catchments. However, C and N removal via soil gaseous pathways can influence local budgets of greenhouse gas (GHG) emissions and contribute to climate change. Over a year, we quantified soil effluxes of carbon dioxide (CO2) and nitrous oxide (N2O) from a Mediterranean riparian forest in order to understand the role of these ecosystems on catchment GHG emissions. In addition, we evaluated the main soil microbial processes that produce GHG (mineralization, nitrification, and denitrification) and how changes in soil properties can modify the GHG production over time and space. Riparian soils emitted larger amounts of CO2 (1.2–10 gCm-2d-1) than N2O (0.001–0.2 mgNm-2d-1) to the atmosphere attributed to high respiration and low denitrification rates. BothCO2 and N2O emissions showed a marked (but antagonistic) spatial gradient as a result of variations in soil water content across the riparian zone. Deep groundwater tables fueled large soil CO2 effluxes near the hillslope, whileN2O emissions were higher in the wet zones adjacent to the stream channel. However, both CO2 and N2O emissions peaked after spring rewetting events, when optimal conditions of soil water content, temperature, and N availability favor microbial respiration, nitrification, and denitrification. Overall, our results highlight the role of water availability on riparian soil biogeochemistry and GHG emissions and suggest that climate change alterations in hydrologic regimes can affect the microbial processes that produce GHG as well as the contribution of these systems to regional and global biogeochemical cycles.