Carmina Sirignano

Tree-ring carbon and oxygen isotopes indicate different water use strategies in three Mediterranean shrubs at Capo Caccia (Sardinia, Italy)

Key messageVariations in stable carbon and oxygen isotope compositions of co-occurring plant species reflect their different water use strategies and indicate the importance of screening species’ WUEito plan climate change adaptation strategies.AbstractThe different abilities of plant species to cope with drought have been associated with structural and ecophysiological constraints. In this paper, we evaluate interspecific differences in intrinsic water use efficiency (WUEi) and the ratio of photosynthesis (A) to stomatal conductance (gs) in three co-occurring Mediterranean shrubs: two broad-leaved evergreen (Pistacia lentiscus and Phillyrea angustifolia) and one needle-like-leaved evergreen (Juniperus phoenicea). We used δ13C in rings to assess inter-annual changes in WUEi while the influence of the stomatal conductance was explored through δ18O. Our results indicate consistent differences in WUEi in the three species, largely determined by leaf traits and differences in stomatal conductance control. Juniperus phoenicea could be the most threatened by the current trend of increasing temperature and summers drought. Phillyrea angustifolia and P. lentiscus seem to be less affected by drought stress because of their tighter stomatal control and high survival rate under field conditions. Our study shows that shrubs with different leaf traits employ different plant ecophysiological strategies under drought stress.

Radiocarbon Chronology and Paleodiet Studies on the Medieval Rural Site of Zaballa (Spain): Preliminary Insights into the Social Archaeology of the Site

The archaeological site of Zaballa is a Medieval rural site located in the province of Álava (Basque Country, northern Iberia). The site has been excavated during a rescue archaeology project, over an area of about 4.5 ha, where human occupation has been documented ranging from the 6th to 15th century. The archaeological operations have shown the transformation of the village, in diachronic terms, by unearthing the structure of production areas (agricultural lands, storage areas, and craft activities), the shape of domestic spaces, and the Saint Tirso monastery, with its adjacent cemetery. Much of the evidence and features related to a peasant community are small and disturbed by recent agricultural activities, and are therefore difficult to be interpreted in social terms. Studying dietary patterns has helped to fill this gap by providing a protein-rich diet of the elitist population and by highlighting the existence of hierarchies separating the inhabitants of Zaballa. In this paper, we discuss the reconstruction of the chronological sequence of the site inhabitation, with a multidisciplinary approach. The archaeological evidences and the critical use of radiocarbon dating have been integrated with stable isotope analysis on human remains found in the cemetery of the church of San Tirso, resulting in a first attempt to find evidence of the social structure of the rural community of Zaballa.