Livestock systems with scattered trees in paddocks reduce soil CO₂ fluxes compared to grass monoculture in the humid tropics

The incorporation of trees in livestock systems can influence the fluxes of CO₂ from soil to the atmosphere. The aim of this study was to evaluate the diurnal and seasonal variations of soil CO₂ fluxes in grazing livestock systems with and without trees in the State of Tabasco, southern Mexico. We selected two livestock systems, one with scattered trees in paddocks (STP) and the other pasture monoculture (PM) without trees. We measured the soil CO₂ fluxes, soil temperature, and moisture in the winter-rainy, dry and summer-rainy seasons. Measurements were made five consecutive days a month from 06:00 to 14:00, with an infrared gas analyzer and a closed dynamic chamber (LI-COR). Pasture monoculture showed a higher soil CO₂ flux, compared to the STP (6.72 vs. 4.30 μmol m⁻² s⁻¹). Soil moisture to 5 cm depth was higher in the PM, while soil temperature did not differ between these systems. Soil CO₂ fluxes were higher in the summer rainy season compared to the winter-rainy and dry seasons in both livestock systems. Soil temperature and moisture also differed between seasons for both systems. Soil CO₂ fluxes were higher in the afternoon, while soil moisture was lower in both livestock systems. Soil temperature did not differ between livestock systems (ANOVA, p > 0.05). Soil CO₂ fluxes in STP showed significant positive correlations with soil temperature and soil moisture. We conclude that STP system is an alternative, with a high potential to mitigate CO₂ emissions from the soil, and to promote the sustainable development of livestock farming in the tropics.