Invasive species pose a major threat to biodiversity and forest ecosystem services, and are expected to benefit from climate change, becoming even more impactful in the future. This thesis investigates the physiological strategies of Trachycarpus fortunei, an invasive palm increasingly spreading in sub-Mediterranean forests south of the Alps. The main objective was to assess how light, temperature, and water availability influence its performance compared to native tree species, to understand the mechanisms underpinning its invasion, and to anticipate its future spread under climate change. In the first study, I compared the light-use efficiency of T. fortunei and co-occurring natives in naturally invaded forests. The invasive T. fortunei maintained photosynthetic rates comparable to native evergreens but outperformed them in autumn, when deciduous trees had shed their leaves. This ability to extend carbon uptake later into the season likely facilitates reproduction and spread, especially in mixed deciduous forests. The second study examined the photosynthetic temperature responses of the same species through a transplant experiment along a European gradient combined with a soil-plant-atmosphere model. Contrary to the expectation that invasive species profit from strong acclimation, T. fortunei showed similar or lower thermal acclimation of photosynthesis than native species. Yet it maintained a stable carbon balance across broad temperature ranges, reflecting a conservative but resilient strategy. Warming alone is thus unlikely to confer a strong advantage but may still extend the growing season under favorable conditions. The third study tested the drought resilience of T. fortunei by inducing hydraulic failure in leaves, stems, and roots. While T. fortunei's leaves were highly resistant, the invasive palm was unable to recover after intense drought, unlike the native competitors, suggesting that prolonged or severe droughts represent a key physiological limit to the palm's expansion. Taken together, these studies reveal that T. fortunei does not follow the classic resource-acquisitive strategy often associated with invasive plants. Instead, its success stems from extended seasonal carbon gains and reduced carbon losses in the absence of herbivory and parasites. However, frost and poor drought recovery highlight important constraints that may restrict further spread in colder or drier regions. More broadly, this thesis demonstrates the importance of experimental trait-based approaches for understanding invasion mechanisms. Physiological measurements provide direct insights into species' trade-offs and limits, avoiding confounding effects such as propagule pressure or incomplete niche filling that bias observational studies. By clarifying both the advantages and vulnerabilities of T. fortunei, this work contributes to predicting its trajectory under climate change and provides a mechanistic basis for developing proactive management strategies to protect sub-Mediterranean and other vulnerable ecosystems.