Land use change effects on stratification and storage of soil carbon and nitrogen: Application to a Mediterranean nature reserve

Land use change from natural vegetation to agricultural land often affects the properties and quality of soils. A field study was conducted to determine the effects of land use change [Mediterranean evergreen oak woodland (MEOW-dehesa) to olive grove and cereal] on soil organic carbon (SOC) and nitrogen (N) concentrations and stocks, and on the soil quality in Cambisols in The Cardeña-Montoro Nature Reserve (South Spain). The land use change from MEOW-dehesa to olive groves increased the SOC concentration (MEOW-dehesa: 19.4 g kg−1; 7.2 g kg−1; olive grove: 41.8 g kg−1; 15.4 g kg−1 in the surface and subsurface layers respectively) and stock (22.3% higher in olive grove than in MEOW-dehesa and 17% higher in olive grove than in cereal), but did not affect the N concentration and decreased N stock in the surface layer. The conversion from MEOW-dehesa to cereal did not affect SOC stock and concentration; it only decreased the N concentration and stock in the surface layer (N: 1.6 g kg−1 and 1.1 g kg−1 in MEOW-dehesa and cereal respectively; N stock 4.2 Mg ha−1 and 2.9 Mg ha−1 in MEOW-dehesa and cereal respectively). After the land use change to olive grove stratification ratios increased, however in cereal they decreased. Comparing the different types of MEOW-dehesa, significant differences were found. It is important to point out that all the stratification ratios calculated were >2.