Most of the Tunisian rangelands are suffering from overgrazing and land degradation. Conserving and restoring these natural vegetation cover through the designation of protected areas is one of the main used tools. However, fencing period has rarely been examined. This study seeks to enhance understanding of the causes and effects of changes in plant communities, particularly under dryland conditions. This study evaluates vegetation dynamics in protected areas using some ecological indicators such as plant cover, species density, flora richness and diversity. Field measurements were conducted using the quadrat-point method, during two growing seasons (springs of 2022 and 2023) both inside and outside the protected zone of Zarat (southern Tunisia). Results showed that protection improves significantly the measured indicators. However, long-term protection may lead to reduced biomass production, plant density and floristic diversity decreases. Some fodder species such as Rhanterium suaveolens Desf. and Echiochilon fruticosum Desf. are predominant in the protected area. However, grazing pressure reduces vegetation cover and species richness in the grazed areas, with less palatable species such as Astragalus armatus Willd. and Thymelaea microphylla Coss. & Durieu becoming more prevalent. Since the results showed that short-term protection provides greater benefits to plant species than long-term protection, the fencing period should considered for sustainable management of protected areas.