Tropospheric ozone (O3) and rising temperatures are significantly altering key developmental stages for plant population maintenance in Mediterranean mountains. In this study, we assessed the effects of these stressors on the growth, flowering, and seed production of six Mediterranean mountain species. Using an Open-Top Chamber (OTC) facility, plants were subjected to four O3 treatments, representing pre-industrial, current, and projected future levels, and a temperature treatment. Vegetative growth was enhanced by O3 in Erodium paularense and by temperature in Silene ciliata . However, a critical “tug-of-war” was observed in reproductive phenology: O3 generally delayed flowering onset and peak while reducing flowering duration, whereas temperature advanced and extended these stages respectively. While O3 exposure reduced seed numbers in Erysimum penyalarense and E. paularense , it increased them in Jurinea humilis and S. ciliata , the latter also showing enhanced seedling survival. Despite an apparent tolerance in vegetative growth, the contrasting effects of O3 and temperature on flowering phenology could impair the species ability to track climatic shifts, such as early-season soil water deficits. Furthermore, reductions in seed quantity and weight in specific species may exacerbate population declines, potentially threatening the biodiversity of these fragile alpine ecosystems. Copyright © 2026. Published by Elsevier B.V.
Tropospheric ozone (O3) and rising temperatures are significantly altering key developmental stages for plant population maintenance in Mediterranean mountains. In this study, we assessed the effects of these stressors on the growth, flowering, and seed production of six Mediterranean mountain species. Using an Open-Top Chamber (OTC) facility, plants were subjected to four O3 treatments, representing pre-industrial, current, and projected future levels, and a temperature treatment. Vegetative growth was enhanced by O3 in Erodium paularense and by temperature in Silene ciliata . However, a critical “tug-of-war” was observed in reproductive phenology: O3 generally delayed flowering onset and peak while reducing flowering duration, whereas temperature advanced and extended these stages respectively. While O3 exposure reduced seed numbers in Erysimum penyalarense and E. paularense , it increased them in Jurinea humilis and S. ciliata , the latter also showing enhanced seedling survival. Despite an apparent tolerance in vegetative growth, the contrasting effects of O3 and temperature on flowering phenology could impair the species ability to track climatic shifts, such as early-season soil water deficits. Furthermore, reductions in seed quantity and weight in specific species may exacerbate population declines, potentially threatening the biodiversity of these fragile alpine ecosystems. Copyright © 2026. Published by Elsevier B.V. Read More
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