Linking Soil Organic Carbon Stocks to Land-use Types in a Mediterranean Agroforestry Landscape

In agroforestry landscapes, land use, and the associated management practices exert strong impacts upon soil organic carbon stocks. Data on the soil organic carbon were collected for different land-use types within a small watershed, El Salado, located in Lanjaron (SE Spain). Eight land-use types namely: farmland planted in olive, almond, and cereals; forest with Pinus halepensis Mill. and Pinus sylvestris L. stands; shrubland; grassland; as well as abandoned farmland were taken into consideration. Of the land-use types investigated, forest, shrubland, as well as grassland exhibited the highest average soil organic C stocks (100-63 Mg ha(-1)) in contrast with the abandoned farmland (28 Mg ha(-1)), with farmland representing a go-between situation (51-49 Mg ha(-1)). The environmental factors precipitation, temperature, and elevation significantly influenced (P< 0.01) the soil organic C stock, with the contents tending to be higher in mountain soils with respective intermediate values of 600-800 mm, 10-15 degrees C, and 1,000-1,500 m asl. Thus, the present approach offers a comparison of C-sequestration patterns as related to the land-use types in a Mediterranean agroforestry landscape, where the main challenge is to integrate the forest trees and the crops within their harmonious interacting combinations.