land Article Botanical Composition and Species Diversity of Arid and Desert Rangelands in Tataouine, Tunisia Mouldi Gamoun and Mounir Louhaichi *   Citation: Gamoun, M.; Louhaichi, M. Botanical Composition and Species Diversity of Arid and Desert Rangelands in Tataouine, Tunisia. Land 2021, 10, 313. https://doi.org/ 10.3390/land10030313 Academic Editors: Krish Jayachandran and Eddie J. B. van Etten Received: 22 January 2021 Accepted: 12 March 2021 Published: 19 March 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). International Center for Agricultural Research in the Dry Areas (ICARDA), 2049 Ariana, Tunisia; M.Gamoun@cgiar.org * Correspondence: M.Louhaichi@cgiar.org; Tel.: +216-7175-2099 Abstract: Natural rangelands occupy about 5.5 million hectares of Tunisia’s landmass, and 38% of this area is in Tataouine governorate. Although efforts towards natural restoration are increasing rapidly as a result of restoration projects, the area of degraded rangelands has continued to expand and the severity of desertification has continued to intensify. Any damage caused by disturbances, such as grazing and recurrent drought, may be masked by a return of favorable rainfall conditions. In this work, conducted during March 2018, we surveyed the botanical composition and species diversity of natural rangelands in Tataouine in southern Tunisia. The flora comprised about 279 species belonging to 58 families, with 54% annuals and 46% perennials. The Asteraceae family had the greatest richness of species, followed by Poaceae, Fabaceae, Amaranthaceae, Brassicaceae, Boraginaceae, Caryophyllaceae, Lamiaceae, Apiaceae, and Cistaceae. Therophytes made the highest contribution, followed by chamaephytes and hemicryptophytes. Of all these species, 40% were palatable to highly palatable and more than 13% are used in both traditional and modern medicine. Keywords: vegetation; species richness; drylands; south of Tunisia 1. Introduction Climate change and human activity represent a big threat to biodiversity [1–3]. The continuous damage to biodiversity increases the rate of species extinctions, which un- dermines our capacity to combat desertification, reduce poverty, increase food security, and exclude invasive species [4–7]. The arid rangelands are among the most important ecosystems and provide a great variety of services and homes to pastoral and agro-pastoral communities. In particular, they cover diverse habitats and ecological communities. They are also economically important given the tremendous richness of edible plant, forage, medicinal, and economic species. The effects of any disturbance on plant biodiversity of arid rangelands are more apparent and more profound than in other ecosystems. Several studies have shown the negative effects of grazing, drought, and other human activities on biodiversity and plant species of arid rangelands [8–11]. In the face of the degradation of natural resources and the progress of desertification, maintenance of biodiversity through active management has recently become an important challenge for biodiversity conserva- tion [12]. Restoration efforts for natural rangelands are important and result in high species diversity [13–17]. Some efforts have been implemented to restore rangelands functions, and resting is the most widely and successfully used practice in arid rangelands restora- tion and represents an ideal still applied in rangelands management. Floristic richness is considered to be particularly valuable and a prime target for establishing conservation priorities [18–20]. An essential part of many studies on rangelands restoration and sustain- able management is the medicinal use of plants and their economic value, which requires knowledge of the botanical composition and species richness present in natural rangelands. In 2017, the botanical composition of the arid and desert areas of southern Tunisia was assessed, during which the area received an average rainfall (100 mm) and recorded 135 species [16]. More recently, the arid and desert areas of southern Tunisia witnessed an Land 2021, 10, 313. https://doi.org/10.3390/land10030313 https://www.mdpi.com/journal/land