Pine afforestation improves the biological soil attributes linked to methane oxidation in a temperate zone of Argentina

Abstract

Background: Atmospheric methane (CH 4 ) 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 CH 4 oxidation in the soil. On the other hand, in the particular case of afforestation, there are contradictory results about the magnitude of CH 4 uptake variation due to changes in methanotrophic bacteria activity and its relationship with micro-environmental conditions. Results:The average potential CH 4 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. A seasonal pattern in MOL was observed in both land uses, 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. Conclusion:Pine afforestation would improve the biological soil attributes linked to methane oxidising bacteria compared to the grassland systems.

Natural grassland conversion to agriculture or pine plantations: Effects on soil methane uptake

“…Several studies show that [CH 4 ] drops to values less than 50% of C 0 below 20 cm depth in various land uses (crops, pastures, grasslands, afforestation) (De Bernardi et al., 2019; Nan et al., 2020; Price et al., 2003; Wang et al., 2014; Wu et al., 2010) as it was observed in this work too. Moreover, it is between 5 and 15 cm depth where the largest methanotrophic activity is located (Terán et al., 2022), coinciding with the highest decrease in [CH 4 ] measured along the soil profile for all studied land uses (Figure 3); [CH 4 ] only decreased 10% of C 0 in A, but 20% in NG and between 20% and 30% in the afforested sites coinciding with differences in the magnitude of CH 4 uptake between land uses.…”

“…Moreover, studies in the same Pinus plantations have already reported higher CH 4 uptake and a potential biological contribution (i.e. methanotrophic activity) under this land use than under grassland and cropland (De Bernardi et al., 2021; Terán et al., 2022). This work aimed to contribute with new data about land‐use change effects on CH 4 flux measurements in two periods of one‐year long (non‐ consecutive) in four land uses located in a temperate region of the Southern Hemisphere in order to grow global knowledge.…”