Dynamics of carbon, water, and energy fluxes in pasture and eucalyptus plantations in the Brazilian Cerrado

In recent decades, a significant portion of the Cerrado ecosystem has been replaced by pasture. Due to the low level of technology used in pasture management – such as the absence of corrective soil practices and inadequate fertilization – this has resulted in degraded lands characterized by weed predominance and increased erosion. These areas are currently being used for planting eucalyptus. This land-use transition promotes changes in the partitioning of sensible and latent heat fluxes and increases carbon and water uptake. Few eddy covariance studies have been dedicated to understanding soil change in the Brazilian Cerrado ecosystem, where a large part of the country’s agriculture takes place. Thus, this study's main objective was to compare the magnitudes and the influence of the seasonality of carbon, water, and energy fluxes observed in a eucalyptus and pasture areas in the Cerrado ecosystem. The research was carried out in two hydrological years (2016–2017 and 2017–2018) in Três Lagoas, Mato Grosso do Sul, Brazil. The experimental sites acted as a carbon sink, with annual fixation between -1057.5 (±24) and -821.4 (±44) g C m -2 in the eucalyptus area and -208.9 (±9.6) and -171.8 (±15.8) g C m -2 in the pasture area. Average evapotranspiration at the eucalyptus stand (3.8 mm d -1 ) was higher than that at the pasture site (2.0 mm d -1 ), even during the dry season, resulting in higher latent heat flux values at the eucalyptus site (9.30 MJ m -2 d -1 ) over the study period. Both vegetation types had strategies for maintaining growth in the dry season, such as increased average water use efficiency (4.0–4.5 g C kg -1 H 2 O). In general, the replacement of degraded pasture areas by eucalyptus plantations increased carbon fixation in biomass, contributing to reducing effects associated with climate change, in addition to improvements in the region’s microclimate conditions.