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Article Dans Une Revue Global Change Biology Année : 2020

Total organic carbon concentrations in ecosystem solutions of a remote tropical montane forest respond to global environmental change

Résumé

The response of organic C concentrations in ecosystem solutions to environmental change changes the release of dissolved organic matter from forests to surface and groundwaters. We determined the total organic C (TOC) concentrations (filtered <1‐7 µm) and the ratios of TOC/dissolved organic N (DON) concentrations, electrical conductivity (EC), and pH in all major ecosystem solutions of a tropical montane forest from 1998 to 2013. The forest was located on the rim of the Amazon basin in Ecuador and experienced increasing numbers of days with >25°C, decreasing soil moisture, and rising N deposition from the atmosphere during the study period. In rainfall, throughfall, mineral soil solutions (at the 0.15‐ and 0.30‐m depths), and streamflow, TOC concentrations and fluxes decreased significantly from 1998 to 2013, while they increased in stemflow. TOC/DON ratios decreased significantly in rainfall, throughfall, soil solution at the 0.15‐m depth, and streamflow. Based on Δ14C values, the TOC in rainfall and mineral soil solutions was 1 yr old and that of litter leachate 10 yr old. The pH in litter leachate decreased with time, that in mineral soil solutions increased, while those in the other ecosystem solutions did not change. Thus, reduced TOC solubility because of lower pH values cannot explain the negative trends of TOC concentrations in most ecosystem solutions. The increasing TOC concentrations and EC in stemflow pointed at an increased leaching of TOC and other ions from the bark. Our results suggest an accelerated degradation of dissolved organic matter (DOM), particularly of young DOM, associated with the production of N‐rich compounds simultaneously to changing climatic conditions and increasing N availability. Thus, environmental change increased the CO2 release to the atmosphere but reduced DOM export to surface and groundwater.
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Dates et versions

hal-02945318 , version 1 (19-06-2021)

Identifiants

Citer

Wolfgang Wilcke, Andre Velescu, Sophia Leimer, Simon Blotevogel, Pablo Alvarez, et al.. Total organic carbon concentrations in ecosystem solutions of a remote tropical montane forest respond to global environmental change. Global Change Biology, 2020, 26 (12), pp.6989-7005. ⟨10.1111/gcb.15351⟩. ⟨hal-02945318⟩
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