Soil Redox Controls CO2, CH4 and N2O Efflux from White-Rot Fungi in Temperate Forest Ecosystems.

Carolina Merino,Ignacio Jofré,Francisco Matus

doi:10.3390/jof7080621

Carolina Merino, Ignacio Jofré + Show 1 more

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https://doi.org/10.3390/jof7080621

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Abstract

Microaerophilic white-rot fungi (WRF) are impacted by oxygen depletion because of fluctuating redox occurrence in southern temperate forest soils of Chile (1500–5000 mm year−1). How these conditions influence WRF survival has been scarcely examined. We explored the contributions of WRF to greenhouse gas (GHG) emissions of N2O and CH4 and soil organic C oxidation (CO2) in five sterilized and inoculated forest soils derived from various parent materials and climates. The soil was incubated for 20 days following (i) oxic, (ii) anoxic, and (iii) fluctuating redox conditions. Fungi contributed to 45% of the total GHG under redox fluctuating conditions, including the contribution of bacteria, while the opposite (26%) was valid for oxic treatment. On average, the highest gas emission (62%) was N2O for WRF under redox treatment, followed by anoxic (22%) and oxic (16%) treatments, while CO2 and CH4 emissions followed oxic > redox > anoxic. These data suggest that indigenous microbial WRF communities are well adapted to fluctuating redox milieu with a significant release of GHG emissions in humid temperate forests of the southern cone.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
We found that white-rot fungi and bacteria Nitrous oxide (N2 O) production peaked at 62% of the total greenhouse gas (GHG) emissions with variable oxygen concentration, and Fungi contributed 70% of
Fluxes and other GHG such as CO2 and CH4 in a microcosm experiment under redox fluctuating conditions given the limited number of studies, in temperate humid forest soils

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Nitrous oxide (N2 O) is a powerful GHG~300 times more powerful than carbon dioxide (CO2 ) and 23 times than methane (CH4 ) [1,2]. Nitrification dominates over denitrification in mediating N2 O production [3]. Most nitrifiers are chemoautotrophic organisms (bacteria), abundant in organic matter-rich forest soils [4,5]. Denitrification is the most important for N2 O production [6]. Autotrophic nitrifiers (fungi) can reduce NO2 − to N2 O or N2 , following the oxidation of NH3 to NO2 − under sub-oxic conditions [7]. Lenhart et al [8] demonstrated that saprophytic fungi continuously released CO2 and CH4. Fungi are aerobic organisms in natural environments, they have been adapting their metabolic processes to reduced oxygen (O2 )

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