Soil Organic Carbon Changes in an Umbrisol under Different Silvicultural Treatments in a Temperate Forest in Northwestern Mexico

Soil organic carbon (SOC) is of most importance for the development of all ecosystems, specifically carbon forest stock, as it is affected by climate, tree species and forest management. The aim of this study is to determine SOC changes in an Umbrisol under forest management in a temperate forest in Mexico. Three silvicultural forest stands were analyzed (Clear cutting, Seed-trees and Selection) and compared with a Post-fire area and a Reference stand. At each stand, 4 composite soil samples were collected at two depths (0-20 and 20-40 cm) to determine SOC; the values obtained from these samples were then used as inputs for the RothC 26 model. The ANOVA indicated differences in the SOC between stands and depths. Seed-trees showed highest content of SOC (0-20 cm), with an increase of 63% with respect to Reference. At depth 20-40 cm, Clear cutting presented the highest SOC, with increase rates above 100% with respect to Reference. Differences in the SOC can be attributed to litter deposition from forest harvesting and fires. Forest management contributes to improving and increasing the capacity of Umbrisols as carbon reservoirs. The modeled scenarios for both depths showed that SOC reservoirs reach an equilibrium after 50-60 years.