Differential Adaptation of Eucalyptus Species through Morpho-physiological and Hydraulic Adjustments to Climate Variability

Regenerating forests must adapt to prevailing climatic conditions for several decades, and possibly over a century. Climate change is profoundly altering tree productivity and ecophysiological responses, with major impacts on forest ecosystems. Understanding the capacity of forest tree species to adapt to climate change, particularly drought, is therefore crucial for sustainable forest management. This study investigates variability in the physiological behavior of three Eucalyptus species ( E. camaldulensis , E. maculata , E. paniculata ) growing under two bioclimates (humid and sub-humid). Gas exchange, hydraulic traits, morphological characteristics, and water availability were monitored to evaluate species performance. Significant differences in adaptive behavior were observed across species and sites ( p < 0.05 ). The Sejnane provenance (humid) showed superior water status and physiological tolerance to drought compared with Rimel (sub-humid), reflecting better adaptation with lower evapotranspiration and water deficit. Morphological adjustments contributed to improved physiological performance under limited water. E. paniculata displayed strong acclimation to both sites, maintaining efficient water control under stress, while E. camaldulensis showed limited adaptive capacity. These findings are essential for identifying drought-resilient tree species suited for reforestation, supporting sustainable forest management and ecosystem restoration under changing climatic conditions.