Climate change is intensifying heat and water stress across Mediterranean ecosystems, threatening the success of forest restoration and reforestation efforts. Artificial shading has been proposed as a silvicultural practice to reduce early establishment stress in native tree seedlings, although its effectiveness may vary among species with contrasting ecological strategies.

We assessed the effects of artificial shading on microclimate, survival, early growth, and physiological performance in three Mediterranean tree species: strawberry tree (Arbutus unedo), carob tree (Ceratonia siliqua), and cork oak (Quercus suber). A field experiment was established at Companhia das Lezírias, Portugal, comparing shaded and unshaded planting conditions. Survival, growth, photosynthetic active radiation, leaf and soil temperature, chlorophyll fluorescence, and relative leaf water content were monitored during early establishment.

Shading consistently reduced incident radiation and leaf and soil temperatures, creating a less thermally stressful microenvironment. Shaded seedlings generally showed improved photochemical efficiency, indicated by higher Fv/Fm values, particularly in Q. suber and C. siliqua. Relative leaf water content also increased under shading in these two species, while A. unedo showed little physiological response.

Despite these physiological benefits, survival responses were species-dependent. Although C. siliqua showed reduced survival under shade, Q. suber and A. unedo did not present significant differences between treatments. These contrasting responses indicate that short-term physiological improvement does not necessarily translate into higher establishment success.

Overall, artificial shading can alleviate early-stage thermal physiological stress in Mediterranean tree seedlings, but its effectiveness in improving survival depends strongly on species-specific light requirements and ecological strategies. Restoration practices should therefore apply shading selectively, aligning microclimatic interventions with the functional traits and establishment requirement of target species. Future studies should also evaluate different shading intensities to identify species-specific thresholds and optimal levels of protections.