Toward eco‐sustainable afforestation in arid lands: key lessons from a 23‐year‐old arboretum of native and non‐native trees in Jordan

Abstract Introduction Afforestation is a key restoration strategy for mitigating land degradation and desertification in semiarid regions. However, evaluating the ecological impacts of tree species used for sustainable dryland restoration is crucial. For example, non‐native tree species may become invasive, with negative effects on native understory biodiversity. Objectives This study identifies drought‐tolerant tree species suitable for sustainable arid‐land afforestation. Methods Using 23 years of data from the Jordan University of Science and Technology arboretum, we recorded survival rates and performance (i.e. canopy height and area) of 28 native and 78 non‐native tree species under arid conditions. We also assessed their potential for natural spread into surrounding areas; quantified understory species richness and cover. Results Native and non‐native trees showed comparable survival rates and tree performance, but Eucalyptus species outperformed other trees. Four native and 13 non‐native species, including seven Eucalyptus species, had survival rates above 50% and were designated drought‐tolerant. Most native ( Ceratonia siliqua , Pistacia atlantica , and P. palaestina ) and non‐native ( Acacia farnesiana , Prosopis chilensis , and Tetraclinis articulata ) species had minimal negative impacts on understory diversity. In contrast, Eucalyptus species dramatically reduced understory diversity, possibly due to allelopathic effects. Acacia cyclops had the highest potential for natural spread. Conclusions Our study underscores the importance of balancing drought tolerance with ecological impacts when selecting species for dryland afforestation. Prioritizing native species in restoration efforts can help minimize disruptions to non‐forest dryland ecosystems and promote long‐term ecological sustainability.