Background and aims In the Mediterranean basin, reduction in cloudiness owing to climate change is expected to enhance solar ultraviolet (UV) levels and to decrease rainfall over the coming years, which would be accompanied by more frequent and intense wildfires. The aim of the present study was to investigate the role of solar UV-A and UV-B radiation in C and N pools of a Mediterranean shrubland and whether drier conditions could alter this role before and after a fire. Methods Over a three-year field experiment, 18 plots of 9 m 2 were subjected to three UV conditions (UV-A + UV-B exclusion, UV-B exclusion or near-ambient UV-A + UV-B exposure) combined with two rainfall regimes (natural or reduced rainfall). Several parameters related to C and N cycles in the soil and in the leaves and litter of two dominant plant species (Arbutus unedo and Phillyrea angustifolia) were measured before and after an experimental fire. Results UV-A exposure increased soil moisture throughout the study period, as well as respiration before the fire. The additional presence of UV-B decreased βglucosidase activity at 5-10 cm depth and soil respiration and pH. UV-B exposure also raised leaf C concentration in P. angustifolia and δ 15 N values in A. unedo. Reduced rainfall often emphasized the opposite effects of UV-A and UV-B on the studied parameters. After the fire, most of the UV and rainfall effects were lost. Conclusion UV-A exposure seems to stimulate soil biological activity and, thus, C and N turnover , while the effect of UV-B would be the opposite. At least in the short term, the Bhomogenizing influence^of fire would

Enhanced UV radiation levels and decreased rainfall in Mediterranean terrestrial ecosystems due to climate change might impact soil bacterial communities, significantly altering their structure and affecting biogeochemical cycles.The aim of this study was to evaluate the effect of UV-B and UV-A radiation on soil bacterial richness, abundance and community composition in a Typic Dystroxerept of Mediterranean shrubland and to determine whether these effects depend on reduced rainfall and/or soil physicochemical properties. Soils were subjected to long-term UV conditions: UV-A + UV-B exclusion (UV0

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Natural selection is the major force driving adaptive evolution in natural populations, varying in strength, direction, and form through space and time, especially in highly variable environments such as Mediterranean ecosystems. Although a conservative resource‐use strategy has been hypothesized to be adaptive in Mediterranean taxa, patterns of selection at the intraspecific level, that is, the suite of traits determining individual fitness, are largely unknown. Using a phenotypic selection experiment in natural semi‐arid conditions, we measured direct and indirect selection acting through two different fitness components (survival and reproduction), to assess the adaptive value of 20 ecophysiological traits on individuals of two gypsum endemic species, Centaurea hyssopifolia and Helianthemum squamatum, dwelling in environments with contrasting abiotic conditions (south‐ and north‐facing slopes) during two climatically contrasting years (dry and mesic). This allowed quantifying the magnitude and direction of natural selection at different spatiotemporal scales. Our results revealed that different abiotic conditions did not alter selection patterns, being the magnitude of selection more strongly affected by temporal environmental variation. Selection through reproduction indicated consistent selection for early phenology, low water use efficiency, high specific leaf area, low leaf dry matter content, and high leaf N across slopes and years in both species. In contrast, phenotypic trait variation was not linked to survival in either species. Furthermore, while individual reproductive output was higher or similar in environments with higher abiotic stress in both species and years, survival was similar across environmental conditions, and it was neither affected by plant size nor reproductive output. Contrary to our expectations, natural selection via reproductive fitness consistently favoured a drought‐escape, acquisitive resource‐use strategy in Mediterranean semi‐arid plants, rather than a conservative resource‐use strategy, even under conditions of higher abiotic stress (i.e. south slopes and dry year). Such acquisitive strategy could allow rapid development by maximizing resource assimilation and reproduction before the most limiting climatic conditions of mid‐late summer. Our results shed light on adaptive functional strategies of Mediterranean taxa at the intraspecific level, providing insight on future responses to environmental change, and highlight remarkable differences in selection acting through different fitness components. Read the free Plain Language Summary for this article on the Journal blog.