Estimates of Soil Organic Carbon in the Ojos de Agua and El Quinillal Forests in the Central Huallaga of Peru

Abstract

The Peruvian Amazon has experienced large losses of forest cover due to changes in land use, contributing to increases in CO2 in the atmosphere. This study estimated the organic carbon content of forest soil in two forests “Ojos de Agua” and “El Quinillal” in the Central Huallaga of Peru, establishing three types of cover: (i) primary, (ii) intervened, and (iii) deforested. For this purpose, 24 plots of 100 m2 were established and samples were extracted at a depth of 0–20 cm. The effect of the type of forest cover on soil carbon (Organic Carbon-SOC, Inorganic Carbon-SIC, Saturated Carbon-SC, Critical Carbon-CC, Saturated Carbon Deficit-SCD, and Organic Carbon-OC) was analyzed by means of an Analysis of Variance, correlation. Likewise, the relationship between carbon (C) and soil properties was evaluated by principal component analysis and correlation network. The results indicated that the highest SOC averages were found in the primary forests of Ojos de Agua and El Quinillal with 3.54% and 2.51%. The lowest values were found in the deforested forests with 1.34% and 1.46%. The calculation of the saturated C levels of the soil showed an average of 28.63% ± 2.14% and the saturated carbon deficit of 26.63% ± 2.45%, whereas the critical threshold of C showed an average of 2.21% ± 0.18%. The highest SOC content found in the Ojos de Agua primary forest is due to the presence of dominant forest species such as Manilkara bidentata and Brosimum alicastrum. Likewise, the C deficit in the soils of the study area is very alarming because it is very close to saturation levels, especially in deforested forests.