Effects of Shrub Identity and Abiotic Factors on Understory Richness and Occurrence in Mediterranean Arid Pseudo Savanna of South Tunisia

Abstract This research was carried out in the national park of Bou-Hedma, South Tunisia. The purpose of the study was to determine whether shrub variety characteristics and abiotic factors were relevant in predicting the distribution of understory species. To evaluate the relative roles of shrubs in vegetation composition and diversity patterns under pseudo-savanna conditions, soil water content and nutrient concentrations were collected from various shrub canopies and open spaces. Herbaceous similarity (species density, richness, and biomass) and soil attributes were sampled using the quadrat method beneath and between different shrubs and in open areas. The results show that all studied shrubs enhance soil water availability as well as the nutrient status of the soil. It is expected that Retama raetam has the greatest positive impact on soil fertility and understory vegetation, given the findings that it was the most effective shrub among those studied. In this pseudo-savanna, environmental management strategies should encourage the preservation of surviving shrubs and promote their restoration through targeted efforts. The study recommends using Retama raetam as a key restoration species in Tunisia’s arid ecosystems.