Effect of cactus pear cultivation after Mediterranean maquis on soil carbon stock, δ13C spatial distribution and root turnover
Abstract Mediterranean ecosystems are characterized by nearly complete replacement of natural vegetation by intensive croplands and orchards leading to strong soil degradation. Organic carbon is usually accumulated in soils under maquis leading to partial regeneration of fertility for future agricultural use. The aim of this work was to investigate the effect of land use change from maquis to agriculture on soil organic carbon (SOC) stock and its spatial distribution in a Mediterranean system. Three Mediterranean land use systems (seminatural vegetation, cactus pear crop and olive grove) were selected in Sicily and analysed for soil C stocks and their δ13C. Total SOC and δ13C were measured …
Turnover and availability of soil organic carbon under different Mediterranean land-uses as estimated by13C natural abundance
Summary Soil organic matter (SOM) is an important factor in ecosystem stability and productivity. This is especially the case for Mediterranean soils suffering from the impact of human degradation as well as harsh climatic conditions. We used the carbon (C) exchange resulting from C3-C4 and C4-C3 vegetation change under field conditions combined with incubations under controlled conditions to evaluate the turnover and availability of soil organic C under different land-uses. The 40-year succession of Hyparrenia hirta L. (C4 photosynthesis) after more than 85 years of olive tree (Olea europaea L.; C3 photosynthesis) growth led to the exchange of 54% of soil organic C from C3 to C4 forms. In …
Dynamics of soil organic carbon pools after agricultural abandonment
Abandonment of agricultural land and the subsequent recolonization by natural vegetation is known to cause increases in C contents, contributing to reduction in atmospheric CO2 concentrations. Assessment of the possible mitigation of CO2 excess requires understanding the SOC dynamics, the origin of C pools and the pathways of their transformation. The aims of this work were to assess, by using the δ13C signature, the changes of old and new organic C in total (soil organic carbon, SOC) and labile (microbial biomass C, MBC, dissolved organic C, DOC, CO2 efflux from soil) pools after vegetation change from vineyard (C3) to grassland (C4) under semiarid Mediterranean climate. Colonization of ab…
How do microbial communities in top-and subsoil respond to root litter addition under field conditions?
Abstract Contrasting microbial community composition and activity at different soil depths may affect root litter decomposition. These effects have up to now been investigated mainly in laboratory studies, which may not be able to take into account complex in situ conditions. Our study aimed to analyze the composition and activity of microbial communities after addition of 13 C labeled wheat root litter to a loamy soil under grassland at 30, 60 and 90 cm depths, during a three-year field experiment. We investigated the dynamics of bacterial and fungal abundances and community structures by DNA genotyping and pyrosequencing of 16S and 18S rDNAs. The genetic structures of bacterial and fungal…