Evaluation of Topsoil Carbon Content and Quality in a Peatland and Reforested Soil after 50 Years of Soil Restoration in the Sierra de Guadarrama National Park (Spain)

Abstract

The increase in atmospheric CO2 levels and the advance of desertification due to soil degradation across our planet is becoming one of humanity’s most serious concerns. The restoration and development of soil management techniques are becoming widespread tools to protect soils. The Sierra de Guadarrama National Park (Spain) is an area that has suffered historically severe deforestation, but it was reforested in an extensive program 50 years ago. In this study, an evaluation of the soils in the restored area was carried out. For this purpose, the chemical composition of the different soil organic matter fractions was characterized using infrared and UV-vis spectroscopies. The results showed a large increase in carbon stocks in the topsoil (0–10 cm) (about 30 Mg·ha−1 more than the area not reforested) after reforestation 50 years ago. There was also an increased level of transformation of organic carbon into resilient humic structures, which are resistant to degradation. Reforestation activities within the National Park have greatly increased the humification rates of organic matter, resulting in the accumulation of high-quality organic carbon.