PINE AFFORESTATION IMPROVES THE BIOLOGICAL SOIL ATTRIBUTES LINKED TO METHANE OXIDATION IN A TEMPERATE ZONE OF ARGENTINA

Abstract

Background: Atmospheric methane (CH₄) is responsible for approximately 20% of global warming since the preindustrial era. Forests are land ecosystems whose role is crucial for mitigating the greenhouse effect due to their capacity to capture and store C and preserve other processes such as CH₄ oxidation in the soil. On the other hand, there are contradictory results about the magnitude of CH₄ uptake in afforestation. This land conversion implies changes in microenvironmental conditions and modifications in vegetation tissue chemistry entering the soil, with changes in soil life forms.

Results: The averaged potential CH₄ oxidation rate in the laboratory (MOL) of afforested soil was 186% greater than that of the grassland, which could be marginally attributed to differences in soil physicochemical parameters like bulk density, pH and organic matter. MOL’s seasonal pattern was observed at both plots, with the highest values at the warm and rainy season. MOL magnitude increased with soil depth up to 10-15 cm, which corresponds with the mineral layer.

Conclusions: MOL were higher in afforested soils than in those covered by grasses. However, in spite of the differences, MOL followed similar patterns following the season’s climatic characteristics, showing their maximum MOL value at the same soil depth. Pine afforestation would improve the biological soil attributes linked to methane oxidising bacteria compared to the grassland systems.