Floristic diversity and plant composition of the arid and Saharan zones of southern Tunisia Adel Dhief 1, 2, *, Samira Aschi-Smiti 2 and Mohamed Neffati 1 1 Institute of Arid Regions, Laboratory of Pastoral Ecology, 4119, Medenine, Tunisia. of Biology, Faculty of Sciences of Tunis, 1060, Tunis, Tunisia. 2 Department GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Publication history: Received on 17 January 2022; revised on 10 March 2022; accepted on 12 March 2022 Article DOI: https://doi.org/10.30574/gscbps.2022.18.3.0081 Abstract Spontaneous plants in arid and desert areas of Tunisia are now experiencing a resurgence of interest not only because of the possibilities of their use for multiple economic and ecological purposes, but also because of their great capacity for potential climate change adaptation. Often considered underused and neglected species, plants in arid and desert areas are of considerable importance. The purpose of this work is to provide knowledge relating to flora and Tunisian vegetation in arid zones. They are structured around various aspects relating to the characterization of this natural and biological wealth and its impact on the quality of the environment. In this work, we studied the flora of the different regions visited (Tataouine, Medenine, Tozeur, Gabes and Kebeli) in southern Tunisia and we surveyed the botanical composition and species diversity in the governorate of Tataouine region during the spring season of 2018. The flora contained about 279 species belonging to 58 families, with 54% annuals and 46% perennials. Keywords: South of Tunisia; Flora; Diversity; Species richness; Drylands 1. Introduction Located in North Africa, Tunisia is situated between longitudes 7° and 12°E and the latitudes 32° and 38°N. It is with the junction of the Western and Eastern Mediterranean, and covers a surface of 164 000 km 2, which is the three quarters of arid and desert regions including in particular the steppe zone in which the northern limit coincides appreciably with the isohyet of 350 mm [1-2]. Climate change and human activity represent a big threat to biodiversity [3-4-5]. In fact, the rangelands have been subjected to intensive anthropogenic and climatic disturbances, such as overgrazing and drought over a long period of time, and their overall condition is deteriorating [4–5]. The continuous damage to biodiversity increases the rate of species extinctions, which undermines our capacity to combat desertification, reduce poverty, increase food security, and exclude invasive species. The ongoing ecosystems degradation and increasing photogenetic erosion justify plans for restoration of arid areas. Loss of biodiversity is a major consideration in the phenomenon of desertification. For restoration activities to be successful, knowledge of local plant species is required because of the significant role their adaptation plays in the ecological context of restoration. The arid regions 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 * Corresponding author: Adel Dhief Institute des Régions Arides, Laboratoire d’Ecologie Pastorale, 4119, Medenine, Tunisia. Copyright © 2022 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 are also economically important given the tremendous richness of edible plant, forage, medicinal, and economic species [3-6]. The effects of any disturbance on the plant biodiversity of Arid areas are more apparent and deeper than in other ecosystems. Several studies have shown the negative effects of biotics and abiotics factors (grazing, drought and other human activities) on biodiversity of dryland plant species [7–8]. 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 conservation [9]. Restoration efforts for natural diversity are important and result in high species diversity [9–11]. Some efforts have been made to restore the functions of drylands. Floristic wealth is considered particularly valuable and a prime target for establishing conservation priorities [12-14]. The economic, medicinal and ecological value of desert plants requires knowledge of their botanical composition and their richness in spontaneous species. During the period between 2008 and 2011 the flora of the arid and desert areas of southern Tunisia was assessed (Tataouine, Medenine, Tozeur, Gabes and Kebeli) and the botanical composition of Tataouine region was studied during the spring of 2017-2018, during which the area received an average rainfall (100 mm) and 135 species was recorded. [10]. Under these conditions, arid and desert rangelands show a great resilience illustrated through a very high plant diversity. These rare favorable conditions offer a golden opportunity to record the greatest plant diversity in arid and desert zones and identify key species that can survive in this ecosystem. Specifically, the objectives of our study are to examine the diversity in the flora of the arid and desert areas of southern Tunisia (Tataouine, Medenine, Tozeur, Gabes and Kebeli) and the botanical composition, including plant family, life form, habitat class, palatability, and medicinal and aromatic plants, and to determine the relevance of plant diversity to arid and desert. It is important to understand the significance of these rangelands in terms of providing several ecosystem services of vital importance for the local communities. Our findings could contribute towards developing holistic and sustainable rangelands management practices and finding innovative solutions to protect key natural habitats in southern Tunisia and similar arid environments. 2. Material and methods 2.1. Study Area Figure 1 Map of the study sites of the flora of the arid and desert areas of southern Tunisia (Tataouine, Medenine, Tozeur, Gabes and Kebeli). The study of the flora of the arid and Saharan zones of Tunisia was carried out directly by several field visits during the period between 2008-2011 (Figure 1). All species were photographed using a digital camera, showing structure, leaf, stem, flower, and fruit, if existing. All recorded plants were then identified with the help of available Tunisian flora of Pottier-Alapetite [14-15] and by collaboration with botanists. The coordinates of the study sites are determined by a GPS device (Table 1). The five sites of the region of Tataouine (Bir zar, ElBorma, Tiert, Oued Jnein, El Ouera) were chosen to determine the floristic composition during the year 2008 which was very rainy. The total annual average rainfall in 251 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 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. Table 1 Geographical distribution of study sites in southern Tunisia Sites Altitude (m) regions Coordinates GPS Jbil 169 kebeli Bir zar 334 Tataouine 33°141’020’’N/09°250’508’’E ElBorma 242 Tataouine Tiert 392 Tataouine ElFjé 15 Medenine Oued Jnein 280 Tataouine Oued Dhabaa 249 kebeli Ksar Ghilane 240 kebeli Oued Zridib 369 Medenine El Ouera 188 Tataouine Djerba 3 Medenine Nefta 52 Tozeur Matmata 380 Gabes 31°293’535’’N/10°004’597’’E 32°033’006’’N/09°072’698’’E 30°464’235’’N/10°111’545’’E 33°295’905’’N/10°382’999’’E 31°482’265’’N/10°161’592’’E 36°776’793’’N/03°253’147’’E 32°593’606’’N/09°390’184’’E 33°151’601’’N/09°584’911’’E 32°562’928’’N/10°274’946’’E 33°807'600’’N/ 10°845'200''E 33°550'100’’N/08°080’00’’E 33°320'400’’N/09°580'170’’E 2.2. Data Collection As a consequence of the favorable rainfall conditions recorded in southern Tunisia during 2008-2009 (Figure 2), vast rangeland areas were covered by hundreds of bloomed plant species. The present inventory represents the highest species richness recorded in the regions of (Tataouine, Medenine, Tozeur, Gabes and Kebeli) and in the five sites of Tataouine. The inventory was conducted through frequent field visits made to various rangeland sites from March 2008 to April 2008 to identify different plant species (Figure 3 and table 2). Since the areas is huge, we had to rely on expert knowledge, including herders who practice transhumance, as well as elderly pastoralists, to guide us to the exact locations where certain species were resurfacing during such an exceptional favorable year. All recorded plants were then identified with the help of available Tunisian flora of Pottier-Alapetite [1415]. The nomenclature for inventoried species was updated using the synonymic index of the flora of North Africa by [16] and POWO (Plants of the World Online) [17] and by collaboration with botanists. Once plants were identified, family, life form, habitat and class of each species were determined. Figure 2 Variation of monthly precipitation (mm), the average monthly temperature (° C), humidity of the monthly average air (%) and the average monthly wind speed (Km / h) during the season of 2008 in Tataouine, southern Tunisia [18] 252 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 253 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 254 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Figure 3 The Flora identified during the visits to the study sites of the southern Tunisia. 255 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Table 2 The list of species identified during visits to study sites in southern Tunisia Halophilic vegetation Aeluropus littoralis Anacyclus monanthos subsp. cyrtolepidioides Artemisia herba-alba Arthrocnemum macrostachyum [= indicum] Atriplex glauca subsp. mauritanica Atriplex halimus (planté) Atriplex lindleyi subsp. inflata Atriplex mollis Bromus madritensis Casuarina cf. equisetifolia Diplotaxis simplex Erodium glaucophyllum, Filago mareotica Frankenia thymifolia Halocnemum strobilaceum Hyparrhenia hirta Plantago coronopifolium Launaea resedifolia Limoniastrum monopetalum Limonium pruinosum Lycium shawii [= L. Arabicum] Lygeum spartum Medicago minima Mesembryanthemum cristallinum Nitraria retusa Ononis angustissima subsp. filifolia Peganum harmala Picris coronopifolia Plantago albicans Polygonum equisetiforme Reichardia tingitana Retama raetam Rostraria salzmannii [= Koeleria salzmannii] Salsola tetrandra Sueda vermiculata [= mollis] 256 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Trigonella maritima Zygophyllum album [= Tetraena alba] Aeluropus littoralis Arthrocnemum macrostachyum [= glaucum] Juncus acutus Limoniastrum monopetalum Limonium tunetanum Lycium shawii Reaumuria vermiculata Salsola tetrandra Tamarix africana Zygophyllum album Gypsophyl steppe with Erodium arborescens Anabasis oropediorum Anarrhinum brevifolium Argyrolobium uniflorum Asparagus albus Asparagus stipularis [= horridus] Asphodelus tenuifolius Asteriscus hierochunticus (= Odontospermum pygmaeum) Atractylis cancellata Atractylis serratuloides Coris monspeliensis Deverra chlorantha [= Pituranthos chloranthus] Didesmus bipinnatus Diplotaxis harra Erodium arborescens Fagonia cretica Fagonia glutinosa Globularia alypum Gymnocarpos decander Hammada scoparium Hedysarum spinosissimum Helianthemum crassifolium Helianthemum intricatum Helianthemum lippii Helianthemum sessiliflorum 257 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Herniaria fontanesii Kickxia aegyptiaca Lygeum spartum Plantago albicans Reichardia tingitana Retama raetam Salsola tetrandra Thymelaea hirsuta Thymelaea microphylla Steppe with Rhantherium suaveolens Acacia saligna Anacyclus monanthos subsp. Cyrtolepidioides Apteranthes europaea [= Caralluma] Artemisia campestris subsp. cinerea Asparagus stipularis Astragalus armatus subsp. tragacanthoides Atractylis serratuloides Cenchrus ciliaris Centaurea dimorpha Cistanche phelypaea Deverra chlorantha [= Pituranthos tortuosa] Echiochilon fruticosum Eragrostis papposa Kickxia aegyptiaca Launaea mucronata [= L. resedifolia] Lycium shawii Lygeum spartum Opuntia ficus-indica subsp. inermis Peganum harmala Picris coronopifolius Polygonum equisetiforme Reaumuria vermiculata Retama raetam Rhantherium suaveolens Salsola villosa Stipagrostis ciliata [= Aristida] Vegetation of the Oases and beaches Cakile maritima subsp. aegyptiaca 258 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Centaurea contracta Erodium arborescens Frankenia pulverulenta Globionis [= Chrysanthemum] coronarium Hyoscyamus albus Launaea resedifolia Lotus creticus s. l. Posidonia oceanica Senecio glaucus subsp. coronopifolius Silene succulenta Tamarix sp. White Sagebrush Steppe: (Artemisia herba-alba) Ajuga iva subsp. pseudoiva Anabasis oropediorum (2 pts poils) Anacyclus monanthos subsp. cyrtolepidioides Argyrolobium uniflorum [= Genista uniflora] Artemisia campestris Astragalus armatus Astragalus caprinus Atractylis carduus (Forssk.) C. Christ [= A. flava ], Calendula aegyptiaca [= C. sancta] Caralluma europaea Carrichtera annua [= Vella annua] Catananche arenaria Convolvulus supinus Cuscuta sp. sur Argyrolobium uniflorum Deverra tortuosa Didesmus bipinnatus Del. Diplotaxis harra Echium humile subsp. pycnanthos Echium trygorrhizum Erodium crassifolium [= E. hirtum] Erodium glaucophyllum Erodium pulverulentum Fagonia cretica Gymnocarpos decander Forssk. Haloxylon scoparium Pomel [= Hammada scoparia] Helianthemum kahiricum 259 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Helianthemum virgatum Herniaria fontanesii Kickxia aegyptiaca [= Linaria] Launaea resedifolia Limonium pruinosum, accidental presence here! Lycium shawii Roem. & Schult. [= L. arabicum] Lygeum spartum Matthiola longipetala Muricaria prostrata Pallenis hierochuntica [= Odontospermum pygmeum] Paronychia arabica Pistacia vera, roadside, planted, ground beetles are planted on the thorns, it is a "shrike" "lardoir"! Plantago ovata Polygonum equisetiforme Pteranthus dichotomus Reaumuria vermiculata Reichardia tingitana Retama raetam Rumex vesicarius Salsola brevifolia Salvia verbenaca Seriphium herba-album [= Artemisia herba-alba ]. Stipa capensis (= S. tortilis) Volutaria crupinoides Volutaria lippii [= Amberboa lippii] Vegetation of the Matmatas Mountains Anagallis arvensis Astragalus armatus Bromus madritensis Calicotome villosa . Coris monspeliensis Coronilla scorpioides Dactylus glomerata subsp. hispanica Deverra chloranthus Didesmus bipinnatus Ephedra altissima Euphorbia cornuta 260 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Gymnocarpos decander Helianthemum intricatum Helianthemum sessiliflorum Helianthemum virgatum Helichrysum stoechas Hippocrepis ciliata ? Rhus tripartita Koelpinia linearis Kickxia aegyptiaca Lycium shawii Lygeum spartum Marrubium vulgare Medicago minima Moricandia arvensis Onopordon espinae Piptatherum miliaceum Phagnalon rupestre Pallenis hierochuntica Pallenis spinosa Papaver hybridum Paronychia chlorothyrsa Peganum harmala Plantago albicans Plantago ovata Plantago psyllium Pteranthus dichotomus Reseda decursiva Retama raetam Rhus tripartita Rosmarinus officinalis var. troglodytorum Scandix pecten-veneris Scilla peruviana Scorzonera undulate Seriphium herba-album Sisymbrium erysimoides Stipa tenacissima Teucrium alopecurus Thymelea hirsuta 261 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Thymus capitatus Thymus hirtus subsp. algeriensis Trigonella stellata Vaillantia sp. Valerianella sp. Steppe at Genista microcephala, near Tougène Anabasis oropediorum Astragalus armatus Dittrichia viscosa [= Inula viscosa] Genista microcephala Plantago albicans Plantago ovata Ruta chalepensis Stipa parviflora Teucrium alopecurus Vegetation of Foum Tatouine Anacyclus clavatus Anacyclus cyrtolepidioides Anchusa hispida [= Gastrocotyle hispida] Andrachne telephioides Arnebia decumbens Artemisia herba-alba Asteriscus hierochuntica Astragalus falciformis ? Astragalus pseudosinaicus ? Carrichtera annua Cenchrus ciliaris [= Pennisetum] Convolvulus supinus Cuscuta sp. Daucus sp. Deverra chlorantha Dipcadi serotinum Diplotaxis harra Echinops spinosus Ephedra altissima Erodium arborescens Erodium crassifolium Erodium pulverulentum var. tunetanum 262 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Fagonia cretica Filago germanica s. l. Gymnarrhena micrantha Gymnocarpos decander Hammada scoparia Helianthemum kahiricum Lamarckia aurea Lappula spinocarpos [= Sclerocaryopsis] Matthiola kralikii Moricandia arvensis Papaver hybridum Peganum harmala Picris coronopifolia Pinus halepensis Plantago ovata Pteranthus dichantomus Rhanterium suaveolens Reseda decursiva Retama raetam Rhus tripartita Richardia tingitana Scilla peruviana Scorzonera undulata S. glaucus subsp. coronopifolius Sinapis alba Stipa capensis Stipa parviflora Stipagrostis plumosa Thesium humile Trigonella polyceratia Volutaria lippii Steppe to Anthyllis henoniana, from Chenini Aegilops triaristata Allium roseum subsp.odoratissimum Anthyllis sericea subsp.henoniana Argylobium uniflorum Artemisia herba-alba Astragalus caprinus 263 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Atractylis serratuloides Bromus madritensis Calendula arvensis Convolvulus supinus Cutandia dichotoma Deverra chorantha Diplotaxis harrra Diplotaxis simplex Echium trygorrhizum Enarthrocarpus clavatus Echiochilon fruticosum Fagonia glutinosa Gagea fibrosa Gymnocarpos decander Hedypnois cretica Helianthemum crassifolium subsp. glaucum Helianthemum intricatum Helianthemum ledifolium Herniaria fontanesii Matthiola longipetala subsp. kralikii Morea sisyrinchium [= Gynandriris] Paronychia arabica subsp. cossoniana Paronychia gr. kapela Picris coronopifolia Plantago albicans Reaumuria vermiculata Rostraria salzmannii Scabiosa arenaria [= Sixalix arenaria] Schismus barbatus Scilla peruviana Scorzonera undulata Stipa capensis Stipa parviflora Stipa tenacissima Tetrapogon villosus Asparagus refractus Asphodelus refractus Calligonum polygonoides subsp. comosum 264 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Cutandia dichotoma Daucus sahariensis Haloxylon schmittianum Ifloga spicata Koelpinia linearis Salsola brevifolia Stipagrostis pungens Steppe to Stipagrostis pungens, by Ksar Ghilane Anthyllis sericea subsp. henoniana Asphodelus refractus Centaurea furfuracea Cutantia dichotoma Daucus sahariensis Gymnocarpos decander Rhanterium suaveolens Savigna parviflora subsp. longistyla Stipagrostis pungens – Psammophile whose roots clump together and fix the sand. These lateral ramifications can follow the prevailing winds. They thus promote the development of Rhanterium Anthemis stiparum Asphodelus tenuifolius Atractylis carduus [= A. flava] Cleome amblyocarpa Helianthemum lippii var. sessiliflorum Henophyton deserti [= Oudneya africana] Koelpinia linearis Matthiola longipetala Nolletia chrysocomoides Savignya parviflora subsp. longistyla Stipagrostis pungens Steppe to Euphorbia guyoniana, by Ksar Ghilane Anthemis stiparum Asphodelus tenuifolius Astragalus hamosus Astragalus saharae Centaurea purpurea Cutandia divaricata Erodium chevallieri Guitt. [= E. glaucophyllum var. cinerascens Chevallier] 265 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Euphorbia guyoniana Herniaria fontanesii Koelpinia linearis Launaea capitata [= L. glomerata] Lotus pusillus [= L. halophilus] Plantago ciliata Savignya parviflora subsp. longistyla Boiss Vulpiella stipoides Dunes in Ephedra alata, south of Douz Anabasis articulata Bassia muricata Cistanche violacea Ephedra alata subsp. alenda The presence of this chlamydosperm species is the main feature of the resort. For the alenda subspecies, the fruiting cones are 10-16 mm, with bracts without tab at the base, male flowers with 6-7 anthers are grouped into a dense head (Ozenda, 2004). It is common throughout Western Sahara. Halocnenum strobilaceum Haloxylon schmittianum Pomel Helianthemum confertum Dun. Ifloga spicata Limoniastrum guyonianum Lotus pusillus Maresia nana Moltkiopsis ciliata Retama raetam Senecio gallicus Traganum nudatum Zygophyllum album et à 4 km au sud de Douz : Calligonum polygonoides subsp. comosum Casuarina equisetifolia Salsola brevifolia Suaeda mollis Tamarix africana Planting of "saxoul" Haploxylon persicum Acacia karroo Anabasis articulata Arnebia decumbens 266 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Diplotaxis harra Erucaria vesicaria Haloxylon persicum (introduit en 1969 par Schoenenberger to fix the dunes: currently in the process of invasive expansion. Ifloga spicata Launaea resedifolia Maresia nana Matthiola longipetala subsp. kralickii Plantago albicans subsp. laniginosa Reaumuria vermiculata Senecio gallicus subsp. coronopifolius Tamarix amplexicaulis [= T. pauciovulata] Traganum nudatum Zygophyllum album Vegetation of the Edge of the Chotts (chott El Djerid, de Douz) Cistanche violacea Halocnemum strobilaceum Limoniastrum guyonianum Salsola tetragona Tamarix africana Zygophyllum album Vegetation of the north-east of Tozeur Aizoon canariense Anabasis articulata Asteriscus pygmaeus Citrillus colocynthis [= Colocynthis vulgaris] Echiochilon fruticosum Filago pygmaea [= Evax pygmea] Hammada schmittiana Linaria laxiflora Neurada procumbens Peganum harmala Polycarpaea repens Retama raetam Stipagrostis pungens Tamarix gallica (cultivé) Volutaria lippii 267 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Other species of flora have been observed Atriplex suberecta Bassia indica Bromus catharticus Caesalpinia gilesii Casuarina stricta [= quadrivalvis] Cionura erecta Fumaria capreolata Fumaria mirabilis Heliotropium currassavicum Hordeum murinum Hornungia procumbens [= Hymenolobus procumbens] Lawsonia inermis, le henné Malva parviflora Nicotiana glauca Ocymum basilicum Rubia tinctoria Sphenopus divaricatus Dunes in Calligonum arich (Grand Erg Oriental) Calligonum arich Astragalus gombiformis, Calligonum. azel, Cleome arabica, Cornulaca monocantha, Euphorbia gugoniana, Helianthemum confertum, Retama raetam, Spartium saharae Stipagrostis pungens 3. Results and discussion The plant species identified during the visits to the study sites in the southern of Tunisia are represented by Figure 3. Several studies have claimed that precipitation has a significant impact on the vegetation dynamics of arid zones [1920]. More particularly, rainfall variability has a great impact on plant phenology [21–22], plant life cycles [23–24], and therefore species richness [25–26]. Rainfall distribution and quantity play important roles in encountering the maximum number of plant species that can grow in arid and desert zones. 268 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 The favourable conditions of 2009/2008 resulted in a large number of plant species . Many of which were not recorded in recent decades, such as Helianthemum crassifolium, Helianthemum ruficomum, Helianthemum virgatum subsp. africanum, Plantago afra, Dactylis glomerata, Andrachne telephioides, Catananche arenaria, Coris monspeliensis, and Teucrium alopecurus. Concerning the floristic composition of the five chosen sites of tataouine, the altered climate conditions in the south of Tunisia were associated with increased species richness. a total of 558 species were recorded, belonging to 58 families (Table 2). The families with the highest number of species were Asteraceae with 86 species (30.70%), Poaceae with 60 (22%), Fabaceae with 48 (17.14%), Amaranthaceae with 32 (11.42%), Brassicaceae with 32 (11.42%), and Boraginaceae, Caryophyllaceae, and Lamiaceae with 24species each (8% each). These families were the most diverse of the flora in the arid zones of Tunisia. Overall, 54% of the species were annual (301 species) and 46% were perennial (257). Several annual plant species can be found exclusively in improved microsite conditions (e.g., lower temperatures, reduced solar radiation, or increased organic matter) in Rocky Mountains and benefit from higher rainfall. For example, the presence of Lamarckia aurea and Umbilicus rupestris indicates favorable environmental conditions, which may be the result of available microsites for plant establishment under higher rainfall conditions. During the extremely wet year, the arid and desert rangelands, with all their different habitats (mountain, plain, wadi, dune), tended to be dominated by therophytes (ephemerals and annuals) [27]. These species germinate on conditions that are favorable and thrive under heavy rainfall. The life-form spectrum of these recorded species showed that 48% were therophytes, 20% were chamaephytes, 20% were hemicryptophytes, 5% were nanophanerophytes, 3% were geophytes, 2% were macrophanerophytes, 1% were phanerophytes, and 1% were parasites (Figure 4). The dominance of therophytes can be attributed to the large number of microsites suitable to annual plants that have rapid germination and growth, thus increasing their abundance [46– 48]. Chamaephytes can survive in arid zones because they are highly adapted to arid conditions [28–29]. Figure 4 Life form distribution of plant species in the arid and desert zones of Tataouine, Tunisia (spring 2008). The perennial shrubs were mainly chamaephytes, such as Haloxylon schmittianum, Haloxylon scoparium, Helianthemum kahiricum, Helianthemum lippii, Rhanterium suaveolens, and Gymnocarpos decander, which characterize the dry and desert rangelands. Hemicryptophytes were very common plants in large areas of arid rangelands, with more than some species, most of which were Poaceae that emerge from seeds and propagate vegetatively from plant parts [30]. During the rainy season, the growth of herbaceous plants in the rangelands of Tataouine was very important (Figure 5). Herbaceous vegetation was dominant, with 73% of species, followed by shrubs 25%, and trees 2%, with climbers represented by only one species: Convolvulus supinus. Not surprisingly, herbaceous species were very abundant because the majority of herbaceous species are therophytes and hemicryptophytes, which dominate the rangelands. 269 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 Figure 5 Habitat class of plant species in the arid and desert zones of Tataouine, Tunisia (spring 2008). The inventoried rangelands had a relatively high species richness, due to its diverse plant communities combined with favorable rainfall conditions. Additionally, rangelands are characterized by a large number of palatable species belonging to Poaceae, such as Oloptum miliaceum, Dactylis glomerata, Stipagrostis plumosa, Cynodon dactylon, and Cenchrus ciliaris. Annual plants that grow mainly in spring are an important component of arid rangelands. They include, for example, many species that are very palatable, such as Astragalus asterias, Astragalus hamosus, Astragalus arpilobus, Sulla carnosa, Hippocrepis areolata, and Medicago laciniata of the Fabaceae. Moreover, in addition to its pastoral value, these rangelands have many valuable medicinal and aromatic plants [31]. Many traditional species remedies derived from pastoral plants that originated in natural rangelands have become modern medicines.[32] These species include the following : Allium roseum, Allium ampeloprasum, Searsia tripartita, Periploca angustifolia, Capparis spinosa, Herniaria fontanesii, Haloxylon scoparium, Artemisia herba-alba, Artemisia campestris, Henophyton deserti, Diplotaxis harra, Citrullus colocynthis,Calligonum comosum, Ephedra alata, Ephedra altissima, Hyparrhenia hirta, Rosmarinus officinalis, Thymus algeriensis, Thymbra capitata, Ajuga iva, Daucus carota, Marrubium deserti, Teucrium polium, Calicotome villosa, Retama raetam, Cymbopogon schoenanthus, Calligonum polygonoides, Polygonum equisetiforme, Ziziphus lotus, Thymelaea hirsuta, Thapsia garganica, Deverra denudata, Deverra tortuosa, Nitraria retusa, Peganum harmala, and Zygophyllum album. Some species have high culinary value [33], such as Rosmarinus officinalis, Thymus algeriensis, Capparis spinosa, Allium roseum, and Allium ampeloprasum. Some species, such as Ziziphus lotus and Nitraria retusa, have small edible fruits used by the local population [34]. A few species are poisonous or toxic to animals, such as Peganum harmala, Euphorbia terracina, Euphorbia retusa, and Adonis microcarpa. The floristic survey conducted on the study sites revealed a high number of endangered species. The endangered forage species were Anabasis oropediorum, Anarrhinum fruticosum, Calligonum comosum, Echiochilon fruticosum, Eragrostis papposa, Sulla carnosa, Stipa parviflora, and Stipa lagascae. Likewise, the majority of the medicinal plants are considered seriously threatened due to overuse. For example, Allium roseum is threatened with extinction because of overexploitation; the harvesting of this plant is very destructive because the bulbs are torn off during harvesting [35]. Of the medicinal species recorded in our survey, eight are classified as critically endangered: Allium roseum, Allium ampeloprasum, Ephedra alata, Ephedra altissima, Rosmarinus officinalis, Thymus algeriensis, Thymbra capitata, and Cymbopogon schoenathus. Out of the 558 species that have been identified, some species are endemic to the country, which are Anarrhinum fruticosum subsp. brevifolium,Calligonum arich, Helianthemum virgatum subsp. africanum, Limonium tunetanum, Onopordum espinae, and Teucrium Alopecurus [36]. This inventory has devoted a great deal of attention to the botanical composition and species diversity of arid and desert rangelands in Tataouine that provide important ecosystem services, yet they are still neglected. Nevertheless, a great number of plant species are still vitally important for human health, as well as livestock and wildlife feeding. The recorded wide range of species reflects the significant resilience and adaptation of these arid rangeland ecosystems. Among the strategies adopted by the arid plants to overcome such harsh conditions is their 270 GSC Biological and Pharmaceutical Sciences, 2022, 18(03), 250–273 ability to go dormant and cope with extreme heat and recurrent drought to ensure that neither internal temperatures nor tissue dehydration reach low levels [36]. The degree of floristic importance varies from one species to another and is based on spatial distribution across the region. Interesting enough, south Tunisia’s flora includes some species endemics to the country that are classified as endangered. There is solid evidence that greater botanical diversity is essential to sustainable land use by increasing forage yield, pollinators, as well as weed and pest suppression [37]. Certainly, high botanical diversity also plays a key role in soil aggregate stability. The root system of the plant improves soil structure and increases the soil organic matter [38-39]. Furthermore, plant diversity and root traits also benefit essential soil physical properties [38-39]. In recent years, advanced research in ecological conservation, combined with greater focus on ecosystem services, have enhanced our understanding of these complex ecosystems but also highlighted several challenges, calling for innovative measures to preserve our natural resources. 4. Conclusion In addition to the ecological importance of safeguarding the stability of the natural environment, the rich and diverse flora of arid and desert rangelands in Tunisia provide essential ecological services to the livestock and human population. They provide a great variety of native forage and medicinal plants with modern pharmacological uses. Because the rangelands are not protected, a serious threat to floral diversity, caused by human activity, has occurred in a large area of the arid rangelands, while climate conditions are creating significant transformation through favorable years. Although the rangelands of Tataouine are dry, they are the native habitat of more than 10% of the total flora of Tunisia. The recorded species are mainly annuals and perennials characteristic of dry ecosystems. The main families are the Asteraceae, Poaceae, Fabaceae, Amaranthaceae, Brassicaceae, Boraginaceae, Caryophyllaceae, Lamiaceae, Apiaceae, and Cistaceae, which together account for 65% of the flora. Therophytes comprised the highest number of species, followed by chamaephytes and hemicryptophytes. These rangelands are rich in foraging. Species of high nutritional value for livestock feeding and many important plants used in both traditional and modern medicine. 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