land Article Botanical Composition and Species Diversity of Arid and Desert Rangelands in Tataouine, Tunisia Mouldi Gamoun and Mounir Louhaichi * International Center for Agricultural Research in the Dry Areas (ICARDA), 2049 Ariana, Tunisia; [email protected] * Correspondence: [email protected]; 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. Citation: Gamoun, M.; Louhaichi, M. Keywords: vegetation; species richness; drylands; south of Tunisia Botanical Composition and Species Diversity of Arid and Desert Rangelands in Tataouine, Tunisia. Land 2021, 10, 313. https://doi.org/ 1. Introduction 10.3390/land10030313 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- Academic Editors: dermines our capacity to combat desertification, reduce poverty, increase food security, Krish Jayachandran and Eddie J. and exclude invasive species [4–7]. The arid rangelands are among the most important B. van Etten 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 Received: 22 January 2021 are also economically important given the tremendous richness of edible plant, forage, Accepted: 12 March 2021 Published: 19 March 2021 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 Publisher’s Note: MDPI stays neutral studies have shown the negative effects of grazing, drought, and other human activities on with regard to jurisdictional claims in biodiversity and plant species of arid rangelands [8–11]. In the face of the degradation of published maps and institutional affil- natural resources and the progress of desertification, maintenance of biodiversity through iations. 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 Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. considered to be particularly valuable and a prime target for establishing conservation This article is an open access article priorities [18–20]. An essential part of many studies on rangelands restoration and sustain- distributed under the terms and able management is the medicinal use of plants and their economic value, which requires conditions of the Creative Commons knowledge of the botanical composition and species richness present in natural rangelands. Attribution (CC BY) license (https:// In 2017, the botanical composition of the arid and desert areas of southern Tunisia creativecommons.org/licenses/by/ was assessed, during which the area received an average rainfall (100 mm) and recorded 4.0/). 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 Land 2021, 10, x FOR PEER REVIEW 2 of 12 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 exceptional wet season, causing a magnificent phenomenon called the “flowering of desert rangelands”, which led to the blossoming of a wide range of flowers during the month of March 2018. Under these conditions, arid and desert rangelands show a great resilience illustrated through a very high plant diversity. Land 2021, 10, 313 These rare favorable conditions offer a golden opportunity to record the greatest2 of 12 plant diversity in arid and desert rangelands and identify key species that can survive in this ecosystem. Specifically, the objectives of our study are to examine the botanical com- position, including plant family, life form, habitat class, palatability, and medicinal and exceptional wet season, causing a magnificent phenomenon called the “flowering of desert aromatic plants, and to determine the relevance of plant diversity to arid and desert range- rangelands”, which led to the blossoming of a wide range of flowers during the month of lands stability and functioning. It is important to understand the significance of these March 2018. Under these conditions, arid and desert rangelands show a great resilience rangelands in terms of providing several ecosystem services of vital importance for the illustrated through a very high plant diversity. local communities. Our findings could contribute towards developing holistic and sus- These rare favorable conditions offer a golden opportunity to record the greatest tainable rangelands management practices and finding innovative solutions to protect key plant diversity in arid and desert rangelands and identify key species that can survive natural habitats in southern Tunisia and similar arid environments. in this ecosystem. Specifically, the objectives of our study are to examine the botanical composition, including plant family, life form, habitat class, palatability, and medicinal 2. Materials and Methods and aromatic plants, and to determine the relevance of plant diversity to arid and desert 2.1.rangelands Study Area stability and functioning. It is important to understand the significance of theseTataouine rangelands is inlocated terms in of the providing extreme severalsouth of ecosystem Tunisia and services it has ofa unique vital importance geographical for locationthe local bordering communities. Libya Our and findings Algeria could(32°55 contribute′32″ N, 10°26 towards′39″ E). developing It is the largest holistic gover- and noratesustainable of the rangelands country, covering management an area practices of 38,889 and km finding2. Tataouine innovative shares solutions borders to with protect the governorateskey natural habitats of Medenine in southern and Kebili Tunisia to the and north, similar Libya arid and environments. the governorate of Medenine to the east, and Algeria to the west (Figure 1). 2. MaterialsThe total and annual Methods average rainfall in the area is below 100 mm, with cold, dry, and windy2.1. Study winters Area and hot and arid summers. Sand dunes and sandy, limestone, and gypsum soils Tataouineare the most is locatedcommon in soils the extreme in the desert south ar ofea. Tunisia A total and of 38% it has of a Tataouine unique geographical consists of ◦ 0 ◦ 0 naturallocation rangelands bordering Libya(1,500,000 and ha), Algeria representing (32 55 32” more N, 10than26 27%39” E).of the It is total the largestrangelands gover- in Tunisia,norate of grazed the country, by an coveringestimated an 390,000 area of head 38,889 of sheep, km2. Tataouine goats, and shares camels borders [21]. The with vege- the tationgovernorates is scattered of Medenine and dominated and Kebili by to shru thebs north, adapted Libya to and drought the governorate and extreme of Medenine tempera- tures.to the east, and Algeria to the west (Figure1). Figure 1. Map of the governorate of Tataouine and its location in Tunisia; picturespictures takentaken duringduring springspring 20182018 showingshowing the different natural habitats exploding with flowers in a rare phenomenon. different natural habitats exploding with flowers in a rare phenomenon. The total annual average rainfall in the area is below 100 mm, with cold, dry, and windy winters and hot and arid summers. Sand dunes and sandy, limestone, and gypsum soils are the most common soils in the desert area. A total of 38% of Tataouine consists of natural rangelands (1,500,000 ha), representing more than 27% of the total rangelands in Tunisia, grazed by an estimated 390,000 head of sheep, goats, and camels [21]. The vegetation is scattered and dominated by shrubs adapted to drought and extreme temperatures. Land 2021, 10, x FOR PEER REVIEW 3 of 12 Land 2021, 10, 313 3 of 12 2.2. Data Collection 2.2. Data Collection As a consequence of the favorable rainfall conditions recorded in southern Tunisia As a