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<p><strong>Background: </strong>Climate change will increase temperature and reduce rainfall across temperate forests of Mexico. This can alter tree establishment dynamics within forest and in neighbouring man-made clearings.</p><p><strong>Hypotheses:</strong> Climate change will reduce emergence and survival of tree seedlings, and surviving plants will display functional responses matching with these changes. These effects should be more noticeable in clearings due to the lack of canopy cover.</p><p><strong>Studied species</strong>: <em>Quercus eduardii</em> (Fagaceae, section <em>Lobatae</em>) an oak species endemic to Mexico.</p><p><strong>Study site and years of study</strong>: Tree growing season 2015-2016 (rainy season) in a mature oak forest and a neighbouring clearing in Sierra de Álvarez, state of San Luis Potosí.</p><p><strong>Methods: </strong>In both habitats, we established control plots (under current climatic conditions) and climate change simulation plots (increased temperature and reduced rainfall). At the beginning of the growing season, we sowed acorns of <em>Q. eduardii</em> in these plots and monitored the emergence, survival and growth of seedlings. At the end of the growing season, we assessed functional responses on surviving seedlings.</p><p><strong>Results:</strong> Seedling emergence and survival were lower in climate change plots from both habitats. However, differences in survival between climate treatments were larger within the forest. Seedlings from climate change plots displayed functional responses indicating higher levels of thermal and water stress.</p><p><strong>Conclusions: </strong>This study indicates that climate change will constrain tree recruitment in Mexican oak forests. However, contrary to our expectations, it seems that these effects will be higher within forests than in man-made clearings.</p>

Background and Aims: Tree recruitment in seasonally dry forests occurs during the rainy season. However, higher temperatures and reduced rainfalls are expected in these ecosystems because of climate change. These changes could induce drought conditions during the rainy season and affect tree recruitment. Plants subjected to thermal or water stress often display morphological and physiological shifts addressed to prioritize their survival. If recently emerged tree seedlings display these responses, this could improve their development during the rainy season and increase their survival chances. Our aim was to test whether recently emerged oak seedlings display these responses.Methods: We performed a field experiment with Quercus ariifolia, an oak species endemic to seasonally dry forests of central Mexico. At the beginning of the rainy season (September 2016), we sowed acorns of this species in control plots under the current climate and plots in which climate change was simulated by increasing temperature and reducing rainfall (CCS plots). Seedling emergence and survival were monitored every seven days during the rainy season (until January 2017). At the end of the experiment, we measured several functional traits on surviving seedlings and compared them between controls and CCS plots.Key results: Higher temperature and lower rainfall generated water shortage conditions in CCS plots. This did not affect emergence of seedlings but reduced their survival. Seedlings that survived in CCS plots displayed shifts in their functional traits, which matched with those of plants subjected to thermal and water stress.Conclusions: Our results suggest that climate change can increase the extinction risk of Q. ariifolia in seasonally dry forest of Mexico by reducing the survival of its offspring. Nevertheless, the results also suggest that seedlings developed under climate change conditions can display functional shifts that could confer them tolerance to increased drought.

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