Variations in phenological and functional traits in Thapsia garganica populations in Al Jebel Al Akhdar, Libya’

Abstract

Thapsia garganica is a herbaceous perennial in the Apiaceae, distributed around the Mediterranean and traditionally used in North Africa as a remedy for arthritis, herpes, hair-fall, hypertension, rheumatic, eczema and scabies. T. garganica is the source of thapsigargin: known for killing cancer cells. Seven populations were studied in sites differing in aspect and elevation within Al Jebel Al Akhdar in Libya. We studied the within-population size distribution of individuals, the timing of the phenological events, and vegetative and reproductive traits. Thapsia garganica showed high flexibility of functional traits and shifts in the timing of phenological events in response to elevation and aspect (north- or south-facing slopes). Local soil properties, together with effects due to altitude and aspect, could be direct causes of the observed differences in terms of population size and phenological traits. The phenological patterns detected also provide insights into the species response to climate change. Despite this phenotypic flexibility, and good growth in sites at 300–700 m a. s. l. on southfacing slopes, most sites in this study have an unstable size-structure, with few small individuals. This raises concerns about the long-term persistence of the other populations of this species in Al Jebel Al Akhdar.