Environment-dependent and intraspecific variations in leaf and size traits of a native wild olive (Olea europaea L.) along an aridity gradient in Morocco: a functional perspective

Abstract

Understanding plant adaptive strategies to aridity is crucial for ecological research, particularly in the current context of climate change and increasing drought. This study focuses on the intraspecific phenotypic variation of the wild olive (Olea europaea subsp. europaea var. sylvestris), one of the most emblematic species of the Mediterranean Basin, widely distributed in Morocco. The research is based on measuring nine leaf and plant-size related traits in 130 trees across 13 populations under varying climate conditions and vegetation covers. The study explores the adaptive strategies of wild olive trees in response to increasing aridity and aridification. The results indicate that the nine traits exhibit significant covariation trends along environmental gradients, reflecting plant strategies related to resource acquisition, resource investment, and water use. Wild olive trees demonstrate substantial intraspecific variation both among and within populations in response to these environmental gradients. Climate, altitude, and vegetation cover together explain 93.8% of the trait covariations. The study elucidates the mechanisms underlying the adaptive strategies of wild olive trees to cope with stressful conditions. The findings suggest that wild olive trees adapt to stressful environments by adopting a conservative strategy, characterized by lower resource investment and higher water-use efficiency. This research underscores the importance of considering intraspecific variation in plant responses to environmental stressors and demonstrates the utility of trait-based approaches in understanding plant strategies under such conditions.