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Land-use change is considered likely to be one of main drivers of biodiversity changes in grassland ecosystems. To gain insight into the impact of land use on the underlying soil bacterial communities, we aimed at determining the effects of agricultural management, along with seasonal variations, on soil bacterial community in a Mediterranean ecosystem where different land-use and plant cover types led to the creation of a soil and vegetation gradient. A set of soils subjected to different anthropogenic impact in a typical Mediterranean landscape, dominated by Quercus suber L., was examined in spring and autumn: a natural cork-oak forest, a pasture, a managed meadow, and two vineyards (ploughed and grass covered). Land uses affected the chemical and structural composition of the most stabilised fractions of soil organic matter and reduced soil C stocks and labile organic matter at both sampling season. A significant effect of land uses on bacterial community structure as well as an interaction effect between land uses and season was revealed by the EP index. Cluster analysis of culture-dependent DGGE patterns showed a different seasonal distribution of soil bacterial populations with subgroups associated to different land uses, in agreement with culture-independent T-RFLP results. Soils subjected to low human inputs (cork-oak forest and pasture) showed a more stable bacterial community than those with high human input (vineyards and managed meadow). Phylogenetic analysis revealed the predominance of Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes phyla with differences in class composition across the site, suggesting that the microbial composition changes in response to land uses. Taken altogether, our data suggest that soil bacterial communities were seasonally distinct and exhibited compositional shifts that tracked with changes in land use and soil management. These findings may contribute to future searches for bacterial bio-indicators of soil health and sustainable productivity.

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Globe artichoke is a vegetable native to the Mediterranean basin. Its commercial production is mainly based on perennial cultivation of vegetatively propagated clones, which are highly heterozygous and segregate widely when progeny‐tested. The aim of this study was to measure genetic variation using random amplified polymorphic DNA (RAPD) in five populations of ‘Spinoso sardo’, the most widely grown and economically important cultivar in Sardinia (Italy). Analysis of molecular variance (amova) gave highly significant differences between populations (28.1% of the total genetic diversity); substantial within‐population variation was detected (71.8% of total genetic diversity). The RAPD results show the need to apply clonal selection to narrow the broad genetic variability within the cultivar and to address important questions on the most suitable strategies for germplasm preservation.

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