Factors influencing the stability of organic carbon pool in some Mediterranean soils

Soils from pine, fir and chestnut woods, Mediterranean maquis at different successional stages, mixed area of maquis with pines introduced by foresters, Pteridium grasslands, garigue and clearing area in southern Italy were compared for microbial biomass and activity as well as for the stability of carbon reserve. Cluster analysis and principal component analysis showed that carbon turnover was influenced in decreasing order by soil age and both soil origin (volcanic or non-volcanic) and anthropic activity, with mature volcanic undisturbed soil being characterised by a low rate of carbon mineralization and the highest content of organic and microbial carbon. A long history of grazing, cutting and burning of vegetation, resulting in a garigue, as well as frequent fires or the introduction of pine to the maquis had a higher impact on the soil than the management of the chestnut orchards or coppice.