An analysis of carbon storage protected areas with relation to agroforestry management and biodiversity

This work investigated the role of land cover and land use change (LUC) as a soil ability to store carbon and reduce carbon dioxide emission in a Mediterranean area. Using a paired site approach we estimated the effect of land cover change on the carbon stock from 1972 to 2008 in a natural reserve (Grotta di S. Ninfa) in the West of Sicily. Fifteen paired sites representative of five land use change were selected. We studied the effect of land use on soil organic carbon (SOC) content in bulk soil and 2000-1000 µm, 1000-500 µm, 500-250 µm, 250-63 µm, 63-25 µm and <25 µm size fractions. Furthermore, laboratory incubation of the soil samples was conducted to measure carbon dioxide evolution in bulk soil at two different depth from each paired site. Our results showed that the conversion of natural vegetation to orchard (vineyard and olive grove) resulted in SOC decrease from 27% up to 50%. The conversion from vineyard to arable land led to 9% decrease, while the opposite caused a 105% SOC gain. Finally when arable land is replaced by eucalyptus afforestation a 40% SOC increasing was observed. SOC decline occurred mainly in coarser fractions, while the finest one are not influenced by land use. An overall reduction in the study area of 63% of SOC was calculated, corresponding to a 58 Mg ha-1 SOC loss in less than 30 years. Our results indicated that land use conversion, vegetation type and management practices, which control biogeochemical and physical soil properties, could help to reduce carbon dioxide emissions and sequester SOC.