Carbon balance in soils under conifers and broadleaved species within La Sierra, Dominican Republic

Abstract

Our research assesses the effects of four forest species, namely, Swietenia macrophylla King, Swietenia mahagoni (L.) Jack., Pinus occidentalis Swartz, and Pinus caribaea Morelet var. Caribaea, on the soil and litter organic carbon (C) stocks, C dioxide equivalent balance (BCO2 Eq.) diurnal, and periodic dynamics beneath these species. Reforestation projects in the study region cover 1200, 543, 770, and 1152 hectares, respectively, with these four species being the most relevant in reforestation projects within the country. To determine the BCO2 Eq. per unit area, we compared the greenhouse gas (GHG) fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) expressed as CO2 Eq. units with the organic C stocks found in the mineral soil to a depth of 30 cm and in the forest litter. In four measurement periods over 18 months, we conducted field measurements in sixteen stands, four per species. Our results indicate that S. mahagoni emitted the lowest CO2 Eq., while S. macrophylla released the highest amount into the atmosphere. At the end of the 18 months, BCO2 Eq. from S. macrophylla soils was 299.70 metric tons ha−1 year−1, while for P. occidentalis, P. caribaea, and S. mahagoni, the corresponding quantities were 103.64, 146.41, and 72.34, respectively. All species showed a general upward pattern in soil respiration from September 2020 to March 2022. The average CO2 Eq. flux rates to the atmosphere were approximately 65.4, 51.1, and 75.9 percent higher in S. macrophylla soils compared to the respective rates of P. occidentalis, P. caribaea, and S. mahagoni.