Biogeography of Spain and Portugal

International Journal of Geobotanical Research (Abbreviation: Int. J. Geobot. Res.) is a scientific journal published by the Asociación Española de Fitosociología (AEFA). It is published two issues a year (at least). It is open to papers on Bioclimatology, biogeography, phytosociology, plant biology, plant conservation, plant taxonomy, vegetation and climatic change and any other plant research projects related to geobotany. Chief editor Ángel Penas Merino Department of Biodiversity & Environmental Management (Botany) Faculty of Biology & Environment Science University of León. León. Spain Email: [email protected] Co-editors Salvador Rivas-Martínez Carlo Blasi Phytosociological Research Center. Department of Plant Biology Los Negrales (Collado-Villalba). Madrid, Spain University of Roma "La Sapienza". Roma. Italy Ulrich Deil Pavel V. Krestov Biologisches Institut II / Geobotanik. Freiburgi. Br. / Germany Institute of Biology & Soil Science. Vladivostok / Russia Andraž Carni Stephen S. Talbot Scientific Research Center. Slovenian Academy of Sciences and Arts US Fish and Wildlife Service. Anchorage. USA Ljubljana. Slovenia Tomás Emilio Díaz González Javier Loidi Arregui Department of Biology of Organisms & Systems Department of Plant Biology and Ecology University of Oviedo. Oviedo. Spain University of the Basque Country. Bilbao. Spain José Carlos Augusta da Costa José Alejandro Velázquez Montes Instituto Superior de Agronomía. Lisboa. Portugal Geografía Ambiental. UNAM. Mexico D.F. Mexico Francisco Alcaraz Ariza Frédéric Bioret Department of Plant Biology. University of Murcia. Murcia / Spain Université de Bretagne occidentale. Brest. France Luis Herrero Cembranos Department of Biodiversity & Environmental Management (Botany) University of León. León. León.. Spain International Editorial Board Ramón Álvarez Esteban Daniel Sánchez Mata Department of Economy & Statistic. University of León. León..Spain University Complutense of Madrid. Spain Michael G. Barbour Javier Amigo Vázquez Department of Plant Sciences. University of California. Davis.USA University of Santiago de Compostela.Santiago de Compostela. Spain Paloma Cantó Ramos Edoardo Biondi University Complutense of Madrid. Spain Universitá Politécnica delle Marche. Ancona. Italy Sara del Río González Bruno de Foucault University of León. León. Spain Département de Botanique.Université de Lille. France Nikolai Ermakov Blanca Díaz Garretas. Central Siberian Botanical Garden. Russia University of Málaga. Málaga. Spain Leopoldo García Sancho Mario Fernandes Lousã University Complutense of Madrid. Spain Instituto Superior de Agronomía. Portugal Carlos Francisco Gonçalves Aguiar Jorge Henrique Capelo Instituto Politécnico de Bragança. Bragança. Portugal National Institute of Biological Resources I.P. Oeiras.Portugal Jesús Izco Sevillano Pedro Luis Pérez de Paz Department of Botany. University of Santiago de Compostela. Spain Department of Plant Biology. University of La Laguna. Spain Paolo Mandrioli Ladislav Mucina Istituto di Scienze dell’Atmosfera e del Clima (CNR-ISAC). Bolonia. Department Enviromental & Aquatic Sciences. Curtin University of Tech- Italy nology. Perth. Australia Gonzalo Navarro Sánchez Yukito Nakamura Universidad Católica San Pablo de Bolivia. Cochabamba. Bolivia Department of Forest Science. Tokyo University of Agriculture. Japan Franco Pedrotti Jean Jacques Lazare Dipartimento de Scienze Ambientali. Universitá degli Studi di Came- Centre d’Etude et de Conservartion des Resources Végétales. Bayonne. rino. Camerino. Italy France Carlos José Pinto Gomes Richard Pott Department of Ecology. University of Evora. Portugal Institut für Geobotanik.Leibniz Universität Hannover. Germany Jesús Orlando Rangel Churio Martha Raynolds Instituto de Ciencias Naturales. Universidad Nacional de Colombia. Alaska Geobotany Center. Institute of Arctic Biology.University of Alaska. Bogotá. Colombia USA Technical Editors (Mapping) Ignacio Prieto Sarro Miguel Álvarez García Department of Geography. University of León. León. Spain Department of Geography. University of León. León. Spain ______ISSN: 2253-6302 (print)/ISSN: 2253-6515 (on line). © EDITAEFA. Asociación Española de Fitosociología. Depósito Legal: LE-280-2011. Published 1 December 2016. Printed by Gráficas CELARAYN S.A. International Journal of Geobotanical Research VOLUME 6 NUMBER 1 DECEMBER 2016

CONTENTS

Histo-anatomy of two Pistacia terebinthus L. leaflets galls induced by two enfeoffed aphids: Paracletus cimiciformis von Heyden and Geoïca utricularia Passarini of western Algerian region ...... 1-8 R. Mellah, H. Benhassaïni & R. Álvarez

Subhalophilous and halophilous geopermaseries and minoriseries of sandy and sandy gravel systems of Corsica: typology, bionomy and sequential analysis vegetation ...... 9-26 P. Delbosc, F. Bioret & C. Panaïotis

The Place of Geobotany in Geology ...... 27-36 B.D. Odhiambo

Plant biodiversity, phytosociology and latitudinal ranges in Sahara meridional and Sahelian regions .... 37-55 M. Costa, A. Santos, L. Llorens, P. Soriano & H. Boira International Journal of Geobotanical Research, Vol. nº 6. 2016. pp. 1-8

Histo-anatomy of Pistacia terebinthus L. leaflets galls induced by Paracletus cimiciformis von Heyden and Geoïca utricularia Passarini. Two aphids in western Algerian region.

(1) (1) (2) Rabha MELLAH , Hachemi BENHASSAÏNI & Rafael ÁLVAREZ

(1) Plants biodiversity: Conservation and valorization. Djilali Liabes university of Sidi BelAbbes ( Algeria). Email: [email protected], [email protected]. (2) Department of Cellular biology. University of León (Spain). Email: [email protected]

Abstract: Terebinth Pistachio tree (Pistacia terebinthus L.) is a typically Mediterranean, with very resinous odorous bark. In spring period, the leaflets of the tree are attacked by various types of aphids which transform them into galls. The aim of this study was to identify the histoanatomical characteristics of leaflets galls induced by Geoica utricularia Passerini and Paracletus cimiciformis von Heyden. The study site is under semiarid bioclimatic range and belong the western Algerian region. Histological cuts on galls and healthy leaflets are studied by using following colorations: Mayer hematoxylineosin and Safranin O Fastgreen. The results show that the anatomy of leaflets is common to those founding in dicotyledonous witch present a xeromorphic characters like a thick palisade parenchyma, a remarkable cuticle and the presence of numerous stomata. However, pathologic leaflets present a hypertrophy and hyperplasia of vascular bundles.This indicates the adaptation of the specie to the semiarid climatic conditions of the studied area and consequently the morphological modification of the leaflets in galls that serve ecological niche for aphids.

Keywords: Aphids, histology, galls, leaflets, Pistacia terebinthus L.

Introduction The Terebinth pistachio tree is particularly sensitive to this type of insects that transform leaflets to reddish The genus Pistacia contains eleven species including ecological niche with a distinctive architecture, artwork Terebinth pistachio tree (Pistacia terebinthus L.) of aphids which hem the leaflets (BLACKMAN & EASTOP (ZOHARY 1952). This taxon is characterized by alternate and composed leaves, deciduous, oblong and imparipin- 1994). This phenomenon attracts the attention of ecolo- nate or sometimes paripinnate (FOURNIER 1990). They gists and biologists since a long time. However, the gall often have yellow veins and grouped at the end of mechanism formation by the insects remains as yet un- branches, (SPICHIGER et AL. 2004). known (INBAR et AL. 2004). Some species of the genus Pistacia are circum-Medi- On P. terebinthus L., galls differ in shape, size, color terranean distribution (TRAVESET 1994). In these latitu- and structural changes with the affected organ. All the des, the Pistacia genus species leaflets are often invested Terebinth tree galls are smooth and without ornamenta- by several aphids that their are enfeoffed (INBAR et AL tions. Some galls are cylindrically shaped, while others 2004. ALVAREZ et AL 2008; 2011 ALVAREZ & ALVAREZ, are oval, elongated, and more or less wavy with thic- 2012). kening of the lamina with the exception of the gall pro- According to FORREST (1987), 700 species of aphids duced by G. utricularia and B. pistaciae (LECLANT on 4400 described species, causes during their life cycle, 2000). The Galls induced by Forda formicaria, Forda a gall within which they complete a part of their life marginata and Paracletus cimiciformis change the mar- cycle. The galls did not occur randomly. Each aphid is gins of the leaflets, however, Geoïca utricularia modi- associated with a genus or plant species called “host”. fies the midvein, while those of Baizongia pistaciae The aphid causes a gall that serves as refuge and to pro- reached the bud leaf primordial (INBAR et AL. 2004) and tect against bad weather, pesticides and predators. modify eventually the entire leaflet (ALVAREZ et AL (LOISELLE et AL 2013; ISAIAS et AL., 2000 and STONE & 2008;WOOL et AL, 1999 and INBAR et AL 2004). SCHONROGGE, 2003). Recent studies show that on the north shore of the These galls are results of the reaction of plants to this Mediterranean and in the Middle East, attacks by aphids parasitic attack or due to internal genetic factors change profoundly the histo-anatomy of leaflets on galls (YAMADA 1993) and highly dependent on food insect in P. terebinthus L. (INBAR et AL 2004, 2010; ALVAREZ activity (BRONNER 1992).

Corresponding author: Rafael Alvarez, Department of Cellular biology. University of León (Spain). email: [email protected]. ISSN: 22536302 (print)/ISSN: 22536515 (on line) ©Editaefa DOI: 10.5616/ijgr 160001 2 R. Mellah, H. Benhassaïni & R. Álvarez et AL 2008, 2011, 2013). In the same context, the aim of this work is to identify the histoanatomical characteristics of leaflets galls induced by G. utricularia and P cimiciformis on P. terebinthus L. in the western Algerian region and see if the environmental factors have an influence on the histological changes of the leaflets. Materials and methods: ● Plant Material Healthy leaflets and others with galls of pistachio Terebinth tree, (induced by P. cimiciformis and by G. utricularia) (Fig. 1) were collected randomly on the el- Figure 2: Location of P. terebinthus L. in western Algeria derly subjects in July 2013 during the morning, located (Google Earth, 2015). at Sidi BelAbbes Tessala mountain (west of Algeria) (Fig. 2). After dewaxing in xylene, rehydration cuts restarts with a series of ethanol baths with decreasing concentration (100%, 95%, 70%), then rinsed with distilled water. Finally, the slides were dried overnight in an oven at 37 ° C. The prepared cross sections were stained with Ma- yer's hematoxylineosin (HEMALUM coloring Masson- picroINDIGO CARMINE (ICP)) and Safranin Ofast green (ALVAREZ et AL. 2009) and dried both in two absolute ethanol baths followed by two xylene baths. The slides were permanently mounted with EntelLAN and observed under an optical microscope type OPTICA DM15 f20. Results: ● Anatomy and histology of leaflets The leaflets cross sections of Pistacia terebinthus L. show the following anatomical structures of lamina (Fig 3.): A layer of epicuticular wax with pleated appearance lined the epidermis which is constituted by of a layer of Figure 1: Samples taken for histoanatomical analysis elongated and geometrically similar cells. (Photo Mellah, 2013). (AC) Galls of Paracletus A few anomocytic stomata are met. Their number is cimiciformis; (BD) Galls of Geoica utricularia; (E) high on the adaxial face. We Note the presence of capi- Healthy leaflets of Pistacia terebinthus L. tates type trichomes on the abaxial surface, absent on the adaxial face. The palisade parenchyma is founded just The site rises to an average altitude of 933 m. It's un- beneath the epidermis and constituted by four rows of der semiarid bioclimatic influence with a cool winter. regularly aligned prismatic cells rich in chloroplasts (Fig. The soil is shallow sometimes rocky outcrop. Galls were 3 B). identified by Dr. Nicolas Pérez Hidalgo (University of Vascular bundles in secondary veins are located in León, Department of Zoology, Spain) as classified by the center of the leaf limb (leaf blade). The xylem is Kuste. oriented towards the adaxial side and phloem to the Samples (healthy leaflets and galls) were cut in half abaxial side of the leaflet. Both are surrounded by a and fixed in situ in the FAA (Formaldehyde 37% (50cc), perivascular sheath. pure acetic acid (50cc), 70% ethyl alcohol (900cc) for 48 We also note the presence of inorganic depots at sub- hours (ALVAREZ et AL. 2009). epidermal cells called calcium oxalate twins or "Druses" (Fig. 3C). ●● Sample preparation The same structures of dicotyledonous species cited The first step in the laboratory is to eliminate the above are present in the main rib. Annular collenchyma fixer samples by rinsing with distilled water, then dehy- is located under the upper epidermis. drated in a growing series of ethanol bath passing The vascular tissue is constituted by vascular bundles through the Isoamyl acetate as the intermediate liquid. whose the phloem is embedded in the center of secretor After that, these samples were impregnated in paraffin schizogenic ducts (23) (Fig. 3 AE). Xylem and phloem for 90 minutes in an oven at 64 ° C, for forming blocks are clearly identified and are surrounded by a perivascu- after. lar sheath. From these blocks, 12 μm cross sections were ob- Few spongy parenchyma noted. Again, collenchyma tained using a manual microtome type (LEICA) and appears followed by the lower epidermis there are no were put on slides with albumin. stomata at this face. Histo-anatomy of Pistacia terebinthus L. leaflets galls induced by two aphids in western Algerian region 3

Figure 3: Serial cross sections performed in Pistacia terebinthus L. leaflets (Photo Mellah, 2013). (AE) Midvein of Pistacia terebinthus leaflets. (BC) Lamina of Pistacia terebinthus leaflets. (DF) Leaflets edge. Colorations: (AB) hematoxylineosin; (CDEF) SafraninFast green. Observations: (ABD) Light Field Optical Microscopy; (EF) Optical Microscopy under U.V Light Field; (C) Polarization microscope. Abbreviations: cu, cuticle; co, collenchymas; ep B, abaxial epidermis; ep D, adaxial epidermis; t, trichome; LA, Lamina; ph, phloem; pp, palisade parenchyma; lp. Lacu- nae parenchyma; s, stomata; vb, vascular bundles; sd, schizogenic duct; t, tannins; V, Vein; x, xylem; ph, phloem; p, prism; pvs. perivascular sheath; (1, 2, 3, 4) the floors of the palisade parenchyma. Scale bars: (ADEF) = 200 µm; (BC) = 50µm. ●● Histo-anatomy of galls due to Paracletus cimici- the limb, the phloem is oriented centripetally in the upper formis and Geoica utricularia aphids: wall of the gall while the xylem is oriented towards the inner skin. Stomata are absent in this zone. ► Galle due to Paracletus cimiciformis The Figure 4E shows that the main vein remains un- Cross sections galls caused by the P. cimiciformis changed. The upper epidermis becomes a structure lining aphid sting on leaflets shows the following structures the inside of the chamber. This latter is elongated and (Fig. 4): slightly elliptical. In sporadic basis a suberized layer of From outside inwards, we note the presence of an cells arises. No histoanatomical difference was observed outer epidermis lined with a thick layer of epicuticular between the two walls (Fig. 4 D). wax. It is decorated all along by anomocytic stomata The contact of the both ends (upper and lower) of the type. Just below the epidermis, a set of isodiametric leaflet represents the closing zone (Fig. 4 A). The reac- parenchyma cells arises (Fig. 4 ABF). tion zone takes position just before (Fig. 4 AF). The vascular bundles consist of equidistant secretor schizogenic ducts occupy the middle of the limb. From ► Gall due to Geoica utricularia simple origin; these vascular bundles are developed G. utricularia aphids cause on the leaflets of P. tere- especially in areas of curvature. Always at the level of binthus L. the following deformations (Fig. 5) 4 R. Mellah, H. Benhassaïni & R. Álvarez

Figure 4: Cross-sections performed in serial Terebinth pistachio tree galls, caused by aphid Paracletus cimiciformis (Photo Mellah, 2013). (A-F) The closure and the reaction zones of galls caused by P. cimiciformis aphids. (B) Curvature and lumen of gall. (C) Upper Wall; (D) Suberized zone on the epidermis lumen; (E) Healthy midvein. Colorations: (A-B-C-D) hematoxylin-eosin; (E-F) Safranin-Fast green. Observations: Light Field Optical Microscopy. Abbreviations: Ep D. Adaxial epidermis; Ep B. Abaxial epidermis; el. epidermis lumen; ea. epidermis air; cu. cuticle; pa. parenchyma; L. lumen; st. Stomata; UW. Upper Wall; LW. Lower Wall; xy: xylem; sd. Schizogenic duct; P. Prism; pvs: perivascular sheath; vb: vascular bundles; ph: phloem; Ra. Remains of aphids; CZ. Closure Zone; RZ: Reaction Zone; SZ. Suberized Zone. Scale bars: (A-B) = 200 µm; (D-F) = 100 µm ; (C-E) = 50µm. The center line of the main rib incurs deformation The results of the crosssections of healthy leaves of after histological changes. Hypertrophy is visible after P. terebinthus L. showed a simple structure of dicotyle- development of conductive bundles (both phloem are donous leaves. They reveal a set of various tissues of a oriented forward adaxial and abaxial epidermis, while primary structure by their meristematic origin. the xylem occupy the center of the midvein). (Fig. 5 A). The adaxial and abaxial sides of leaflets are lined by Note the presence of a parenchyma between the two a single layer of epidermal cells. All primary structures conductor bundles. of a leaf are from the protoderme (RAVEN et AL. 2007). Unicellular trichomes capitates and ciliate types are A thick cuticle abundantly decorated with epicuticular present at the inner epidermis of the room gall (Fig. 5 striations or ridges settles on the epidermis. This CD) where a suber layer starts (Fig. 5 E). corroborates the work of SIMPSON (2006) and ALVAREZ et AL. (2008) on Pistacia terebinthus. The thickness of Discussion: the cuticle is considered as a stress response since it ● Healthy leaflets reduces sweating and reflection of light (ROLAND et AL. 2008). Sometimes the cuticle is very absent or thin in P. terebinthus L. (ALSAGHIR et AL. 2006). Histo-anatomy of Pistacia terebinthus L. leaflets galls induced by two aphids in western Algerian region 5

Figure 5: Serial cross sections made at the Terebinth pistachio tree galls, caused by aphid Geoica utricularia (Photo Mellah, 2013). (A) The midvein deformations; (B) Curvature and lumen of gall; (CD) the presence of trichomes in lumen is a reaction caused by P. cimiciformis aphids ; (E) the suberized zone on the epidermis lumen. Colorations: SafraninFast green. Observations: (ABCE) Light Field Optical Microscopy; (D) Optical Microscopy under U.V Light Field. Abbreviations: el. epidermis lumen; ea. epidermis air; ph. phloem; xy. xylem; cu. Cuticle; p. parenchyma; g tr. glandular Trichome ; Tr c. trichome ciliated ; tr b. trichome birth ; L. lumen ; pa b. parenchyma between bundles; SZ. Suberized Zone. Scale bars: (B) = 200 µm; (ADE) = 100 µm ; (C) = 50µm.

According to our results, the stomata found in P. At the midvein, the xylem and phloem are oriented terebinthus L. are anomocytic type and are on along the adaxial and abaxial sides, respectively. These conductors main vein. Their distributions indicate the amphistomatal beams are surrounded by a thick layer of fibers forming type. This is in accordance with the work of ALSAGHIR the sheath perivascular around which is located the & PORTER (2005) and ÖZEKER & MISIRLI (2001). collenchyma. This sheath mediates transport of com- However, hypostomatal type may be present in P. tere- pounds mesophyll to vascular bundles (FERNANDEZ et binthus (ALVAREZ et AL. 2008). AL. 2003 and COSTA et AL. 2001). The fundamental tissues of the leaflet take place bet- The presence of secretors bundles associated with ween the upper and lower epidermis, in the mesophyll. phloem is a general characteristic of the Pistacia genus The mesophyll becomes thicker when the leaflets beco- (Watson & Dallwitz 2008). In the case of P. terebinthus, me older (SIMPSON, 2006; ALVAREZ et AL. 2008). these bundles accumulate an oleoresin, which in addition Our results show that the P. terebinthus mesophyl is to tannin plays an insect deterrent role (COSTA et AL. characterized by a palisade parenchyma with four strata. 2001 & ALVAREZ et AL. 2009). Moreover, both are the This is an apparent photosynthetic tissue in the lamina repellents of herbivores (COSTA et AL. 2001). (ALVAREZ et AL. 2008), which represents almost 40% of The presence of twins (spherical crystals) of calcium the limb (ALSAGHIR et AL. 2006). This parenchyma oxalate in parenchyma cells is also noted. development is an adaptive trait to environmental aridity In general the characteristics of P. terebinthus leaves and stress that accompany dryness of the air and / or the indicate the traits of a sclerophyll species (METCALFE & growing lack of water (STOCKER 1961). It is a common CHALK 1985; SIMPSON 2006). xerophytes’ character in the genus Pistacia (ALSAGHIR et Leaflets with galls AL. 2006). This is likely the case in our study area which is under semiarid bioclimatic with cool winter. The terebinthus tree is widely recognized by its re- The spongy lacunars parenchyma is constituted by of markable reddish galls (BLACKMAN & EASTOP 1994). shorter cells, than those of palisade parenchyma, and The causes and the adaptive significance of this feature developed in a very dense manner especially at the ends has not been determined although some authors explai- of the leaflets. This is also confirmed by the work of ned by the accumulation of pigments in response to ALSAGHIR et AL. (2006) and ALVAREZ et AL. (2008). abiotic and biotic factors (DIAS et AL. 2013). 6 R. Mellah, H. Benhassaïni & R. Álvarez

The environment inside closed galls is more stable ces resulting in crispation, depigmentation of the leaves and prevents aphids suffer drought periods. The and the formation of galls. protection against the enemies is due to the walls of the The growing of a heavily infested plant can also be gall, by its physical or chemical components and external disrupted due to the removal of nutrients by aphids structures, including coating hair and sticky resin (STONE (MILES 1989). During this transit, aphids carry out inter- & SCHÖNROGGE 2003). cellular punctures, but also intracellular in most encoun- P. cimiciformis and G. utricularia settled at the young tered cells. leaflets because aphids tend to emerge before bud break (WOOL Nearby cells phloem bundles are much more punc- & MANHEIM 1986). Macroscopically galls respectively show tured than those of epidermis or mesophyll, indicating the flattened and cylindrical appearance. that the phloem search is performed by sampling and The anatomical sections of the gall caused by P. aphids is able to recognize the chemical composition of cimiciformis show that there is a similarity in the structure different types of encountered cells. Aphids are sensitive and the thickness between the upper and lower wall. In to certain types of compounds which act as either their study ALVAREZ et AL. (2009), note that this same stimulants or inhibitors or antiappetizing (TJALLINGH & gall due to the same aphid has a thicker upper wall. HOGENESCH 1993). Among internal compounds only Usually this gall is preceded by the folding of the leaflet; protease inhibitors (PIs) and lectins have been identified it is a simple pseudogall within the meaning of in the phloem sap of the plant which is the aphid’s food WOROBEY & CRESPI (1998). The marginal end of the (Kehr 2006). leaflets is slightly curved towards the adaxial side. However, upon folding of the leaflet by P. cimici- While that due to G. utricularia form a sphere at the formis several vascular bundles originate. Thus phloem abaxial surface of the leaflet of the Terebinth pistachio departs attracting towards him the xylem. The xylem is tree. Both galls studied are singlethalamic, because they directed to the epidermis of the room and phloem to the have a single room and are initially occupied by a single outer epidermis of the gall. This is already confirmed by type of aphid (MANI 1964). ALVAREZ et AL. (2009) which mention that this reaction KRAUS & ARDUIN (1995) indicate that gall caused by requires the stylus aphids to move around this beam to P. cimiciformis is like most zoocediciae of histioide type eat. At the level of the gall produced by G. utricularia, with protoplasmic form (as classified by Kuste). we note the development of vascular tissue at the Diversification of the internal structure of the galls midvein. must be commensurate with nutrition of their occupants Otherwise, the observation of secretors canals at both because the gall creates an "aspirate force" that pumps galls shows that they are large and well developed. Pre- nutrients from the plant, while changes of the external sumably, this should be linked to the general develop- structure are related to defense against enemies (STONE ment of the phloem. Such conduits are part of the & SCHÖNROGGE 2003). phloem (ALVAREZ et AL. 2009). One hypothesis is that a The tissues that compose the gall provide aphids a water deficit suffered by the host plant alters the bio- nutritious efficiency greater than that of a non parasitized chemical composition of the phloem sap of the plant section of the plant (FORREST 1987). WOOL & BAREL (food substrate aphids), resulting in a change in the rate (1995), reported that the increase in the number of aphids of multiplication aphids (GIROUSSE 1996), which proves within the gall is accompanied by an increase of the the fabulous replica of phloem in the body of all the gall. thickness of the wall. The walls of the gall are occupied In the closed area of the gall due to P. cimiciformis, by cells of the parenchyma marking the intercellular we note a formation of calcium oxalate twins attributed spaces. These parenchyma cells occupy the wall showing to low levels of hormones; in particular, a decrease in hyperplasia and hypertrophy of the leaflets. auxin (DORCHIN et AL. 2002). On both galls, a thick cuticular ornamentation takes The presence of sclerenchyma fibers in healthy leaf- place (ALVAREZ et AL. 2008). It lines the surface of the let and their absence in the gall suggest that the initiali- leaflet allowing insects to recognize the host plant zation of the gall is formed when the leaflets are young. (ISAIAS et AL. 2000). Stomata which are in all cases This joins the results found by ALVAREZ et AL. (2009). anomocytic and absent within the galls are filled by this The initiation of the uncontrolled proliferation of pa- cuticle. This is perfectly in line with the work of renchyma cells may be internal or external origin. Indeed ALVAREZ et AL. (2009). several authors showed its external origin and that the Within the walls of galls, parenchyma cells are in epidermal cells are not included (HAENSCH 2007). The greater number than in healthy leaflets. Their sizes are various observations made on our histological sections very large.We also observe a rich vascular network in the performed at the galls show that the initiation of this structures of the two galls. This is in line with the results multiplication is externally (aphid sting). of WOOL et AL. (1999) indicates that there is a marked Furthermore, and sporadically the results of anatomi- increase in wall thickness due to the presence of many cal sections show suberized area that settles on the inner phloem elements very close to the epidermis. This wall of studied young galls. According to ALVAREZ change of tissue occurs to promote access aphids to their (2011), this area is only present in mature galls caused source of food. by F. formicaria aphid. With few exceptions, the founder is the only one able Resistance in the leaflets of P. terebinthus L. is also to induce gall (WOOL 2005). The perforation leaflets and expressed by the hypersensitivity reaction. Thus, thanks injecting liquid saliva in plant tissues can have toxic to the signals transmitted by the cells that are in contact effects responsible for physiological nature of disturban- with the aphid, more distant cells die and form necrosis to stop the pathogenic progression (HAENSCH 2007). Histo-anatomy of Pistacia terebinthus L. leaflets galls induced by two aphids in western Algerian region 7

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International Journal of Geobotanical Research, Vol. nº 6. 2016. pp. 9-26

Subhalophilous and halophilous geopermaseries and minoriseries of sandy and sandy gravel systems of Corsica: typology, bionomy and sequential analysis vegetation

(1,2) (1) (1) Pauline DELBOSC , Frédéric BIORET & Christophe PANAÏOTIS

(1) EA 2219 Géoarchitecture, Université de Bretagne Occidentale, Institut de Géoarchitecture, UFR Sciences et Techniques, 6 bd. Victor le Gorgeu, 29200 Brest, France (2) Conservatoire botanique national de Corse, 14 avenue Jean Nicoli 20250 Corte, France

Abstract: The coast of Corsica arouses for more than half a century, botanists and phytosociologists interest, revealing the diversity and the originality of its terrestrial vegetations. Sandy and sandy-gravelly systems punctuate the coast of Corsica, mostly over the eastern plain, between Bastia and Porto-Vecchio. Moreover, these systems can be found in sandy bays, offshore bars and mouth of coastal rivers. From a bioclimatic point of view, geopermaseries of sandy coastal systems are located within the limits of the inframediterranean belt (Thermicity index IT> 470). Due to their location on the coast and wind exposure, sandy systems, are distributed according to two climatic patterns: the west coast pattern, cooler and the east coast pattern, drier. Sandy vegetation systems are characaterized by the granulometry of the substrate: ● sandy beach dunes (coastal or continental geomorphological formations, constituted by wind accumulations); ● river-marine terraces (extent of aeolian sands, heterometric sediment, with a dominance of gravel (grain diameter greater than 2 mm); ● shingle beaches (beaches and beads pebbles deposited by marine currents). Geosymphytosociological investigations were conducted in 2013 and 2014 on sandy systems of Corsica, over 33 sites representing 175 hectares. A phytosociological and geosymphytosociological typology have been proposed according to dynamico-catenal phytosociological method, illustrated by schemes representing profiles of the natural vegetations succession (not influenced by human factors). The analysis of the geosynrelevés, combined with the geomorphological analysis of sandy coastal landscape, allow to identify four geopermaseries, according to a chorological [1 and 2] and to a granulometry substrate [3 and 4] determinism: [1] sandy beaches dune geopermaserie of the east coast [Echinophoro spinosae-Ammophileto arundinaceae geopermasigmetum]; [2] sandy beaches dune geopermaserie of the west coast [Sileno corsicae-Ammophileto arundinaceae geopermasigmetum]; [3] sandy-gravelly terraces geopermaserie [Salsolo kali-Euphorbieto peplis geopermasigmetum]; [4] pebble beaches geopermaserie [Glaucio flavi-Crithmeto maritimi geopermasigmetum]. These results will be integrated within the future catalog of vegetation series and geoseries of Corsica.

Key Words: Bioclimatology, Biogeography, Endemism, Iberian, Phytosociology Introduction synthesis work was conducted between 2013 and 2014 on psammophilous vegetations. According to the phyto- For more than a half of a century, numerous botany sociological dynamico-catenal methodology, a typology and phytosociology publications highligted the diversity of geopermaseries and minoriseries is proposed. and the originality of Corsican terrestrial vegetations This paper highlights the typological outcomes and (Paradis & Piazza 1988a, 1988b, 1989, 1991, 1992a, presents a structural, causal and phenomenological des- 1992b, 1999a, 1999b, 2003, Piazza & Paradis 1988, cription of geopermaseries, minoriseries and series. Ve- 1995, Paradis & Géhu 1990, Paradis & Orsini 1992, getation sequences are directly dependant to the substrate Gamisans & Piazza 1992, Gamisans & Paradis 1992, nature (sand, dune, sand-gravel, gravel). Lorenzoni et al. 1994, Paradis & Pozzo di Borgo 1998, Lorenzoni & Paradis 2000a, 2000b, Géhu & Biondi Study area 1994). Corsica has 802 km of coastlinegeomorphologically Sandy and sandy-gravelly systems punctuate much of diversified (Castelnau 1920, Piazza 1994 Paradis the coastline of Corsica (Géhu & Biondi 1994), repre- 2014Gauthier et al. 2002, Palmieri 2004). Geomorpho- senting approximately 39% of the coastline of the island logical landforms are characterized by steep reliefs often (Piazza 1994). Because of their accessibility and tourist interspersed with valleys, and a Quaternary accumulation frequentation, these vegetation systems are subject to zone corresponding the Eastern Plain. Two main frequentation and increasing urbanization. Within the categories are distinguished: ablation coast (rocky objective of improving the phytocoenotic knowledge, a

Corresponding author: D. Pauline. EA 2219 Géoarchitecture, Université de Bretagne Occidentale, Institut de Géoarchitecture, UFR Sciences et Techniques, 6 bd. Victor le Gorgeu, 29200 Brest, France. e-mail: [email protected] ISSN: 2253-6302 (print)/ISSN: 2253-6515 (on line) ©Editaefa DOI: 10.5616/ijgr 160002 10 P. Delbosc, F. Bioret & C. Panaïotis coasts) and accumulation coast (sandy-gravelly shores). level (permaserie, minoriserie and serie) and geoserial Our study focused on accumulation forms which are level (geopermaserie, geominoriserie and geoserie). represented by sandy beaches, dune beaches, sandy- «Vegetation series or sigmetum is the basic typologi- gravelly terraces, and cobble beaches (Figure 1). cal unit of dynamic phytosociology. This geobotanical notion attempts to express all the plant communities, or collection of stages that can be found in similarteselar places as a result of their succession processes. There- fore, it includes not only the representative vegetation type of the mature stage, or head series, but also the initial or subserial communities replacing it. The vegetation series is the fundamental unit of dynamic phytosociology (science of vegetation series and of sigmataxa that it encompasses) » (Rivas-Martínez 2005). Three types of vegetation series can be distinguished (Lazare (2009) and Rivas-Martínez et al. (2011): ● climatophilous series, developed on mature soils according to the mesoclimate and receiving only rain- water ; ● edaphoxerophilous series, developed on xerophytic soils (leptosoils, arenosoils, gyptosoils, serpentinite soils ...) such as dunes, lithosols, rocky slopes, ridges, cliffs ... ; ● edaphohygrophilous series, occupying the hydromor- phic soils as fluviosoils, halosoils, histosoils. They develop in the river beds, shores of lakes and ponds, marshes, salt steppes, bogs... Minoriserie and permaserie Minoriserie is defined by Rivas-Martínez (2007) as truncated dynamic serie under ecological stress linked to climatic constraints so that dynamic vegetation is Figure 1. Location of coastal dunes and sandy gravel studied blocked at the shrub stage without allowing forest sites implantation. In some sectors, main ecological constraints (halophilous gradient, substrate, wind exposure…), block The bioclimate of Corsica is characterized by two the natural dynamics of vegetation: plant communities, rainfall sets: on the west coast, the annual rainfall varies stabilized at one stage represent permanent series or between 690 and 840 mm (Bastia, Aleria and Sisco), permaseries. while on the east coast, the average annual rainfall is below 600 mm per year (Ajaccio Airport and Parata, Methodological choice Bonifacio Saint-Florent). The east winds (Grecale, Siro- Studying these permaseries equals to a classical cco and Levante) provide a significant moisture that phytosociological study. All the permaseries present flows across the eastern coast (Simi 1964). However on within an homogeneous geomoprhological unit are the east coast, cold and dry winds like Libecciu and gatered into a geopermaserie (Fig. 2). Ponente, provide a smaller amount of rain. Temperatu- Geopermasynrelevés could answer to a double res, meanwhile, are uniform throughout the coast and are requirement of homogeneity and representativeness. The characterized by sea influence that softens temperatures delimitation of an individu of geopermasigmetum depends on homogeneous orotopographic, geological (15-16 °C). According to Del Río Gonzáles (2005), and geomorphological context Rocky coasts are present ombrotype varies from dry to sub-humid and thermotype over several kilometers on the west coast, while on the varies from thermo to inframediterranean. east coast, they are present on small areas and are Methods regularly interspersed by other geomorphological Symphytosociological conceptual approach systems (dunes, pebble beaches, sandy beaches, salt marsh). The methodology follows the sigmatist phytosocio- Numerous typological and geomorphological synthe- logical and the symphytosociological methods (Braun- sis (Piazza 1994, Paradis & Piazza 1996, Piazza & Para- Blanquet 1928, Guinochet 1973, Géhu & Rivas-Martínez dis 1997, 1998, 2002, Paradis et al. 1999, Paradis 2014) 1981), in order to characterize dynamic trajectories and combined with ecological data collected in the field phenomenological processes of vegetation series. between 2013 and 2014, allowed to establish the vegeta- Landscape phytosociology or dynamico-catenal tion zonation according to the geomorphological system phytosociology, relies on many concepts, distinguished and the halophilous gradient. by levels of organization of the landscape: the serial

Subhalophilous and halophilous geopermaseries and minoriseries of Corsica 11

Figure 2. Typical spatial sequence of sandy coastal dune vegetation Geopermaserie: Echinophoro spinosae-Ammophilo arundinaceae geopermasigmetum [(1) Salsolo kali- Cakiletum maritimae; (2) Sporoboletum arenarii; (3) Sporobolo pungentis-Elymetum farcti; (4) Eryngio maritimi- Elymetum farcti; (5) Sileno corsicae-Elymetum farcti otanthetosum maritimi; (6) Echinophoro spinosae-Ammophiletum arundinaceae; (7) Pycnocomo rutifolii-Crucianelletum maritimae]. Géominorisérie: Pistacio lentisci-Junipero macrocarpae geominorisigmetum [(8) Helichryso italici-Cistetum salviifolii; (9) Pistacio lentisci-Juniperetum

Geopermaserie

Figure 3. Delimitation of a geomorphological unit (sandy dune beach) according to the type of serie (geopermaserie and minoriserie).

The individualization and the delimitation of geo- Geosymphytosociological nomenclature morphological features based on a first mapping work The geoserie is named with the name of the most carried out upstream of the field phase. dominant syntaxon of the serie’s head ; the ending indi- Besides the consideration of orthophotography (true cating the rank is added to the end of the second taxon (- and infrared color) and of National Geographic Institute geosigmetea, -geosigmetalia, -geosigmion, -geosigme- maps, ecological information is collected: tum) ; a connecting vowel is added to the end of the first ● ecological data: geology, geomorphology, soil, topo- taxon (Lousã et al. 2001, Bacchetta et al. 2009, Blasi graphy... (Dupias et al. 1965, Rossi & Rouire 1980a, 2010, Loidi et al. 2011). 1980b, Demartini & Favreau 2011); The connecting vowel, in most cases like phytoso- ● vegetation data (Gamisans & Grüber 1979, Gamisans et ciology is an "o"; the connection vowel is the "i" for the al. 1981a, 1981b, Paradis & Tomasi 1991, Gamisans & third declination latin words (Weber et al. 2000). Paradis 1992, Paradis 1992, Lorenzoni et al. 1993, Citer Izco 2014 Lorenzoni & Paradis 1996, Paradis & Piazza 1996, Pa- Example for coastal geopermaserie nomenclature radis et al. 1999). Geopermaseries - geoseries type - geomorphology - Each geomorphological unit, can then be divided into geography-names of the two characteristics of the one or more subentities, in order to distinguish geoper- dominant species permasigmassociation [latin name maseries, geominoriseries and possible geoseries (Fig. 3). géopermasigmetum]

12 P. Delbosc, F. Bioret & C. Panaïotis

Example: topographic geopermaserie dune sandy ● CRUCIANELLETALIA MARITIMAE G. Sissingh 1974 beaches of the east coast of Corsica to Echinophora ♦ Crucianellion maritimae Rivas Goday & Rivas Mart. spinosa and Ammophila arundinacea: Echinophoro 1958 spinosae-Ammophilo arundinaceae geopermasigmetum. Helichryso italici-Scrophularietum ramosissimae Géhu et al. 1987

Results: Crucianello maritimae-Armerietum pungentis Zevaco

1969 Syntaxonomic synopsis Pycnocomo rutifolii-Crucianelletum maritimae Géhu et al. 1987 The syntaxonomic synopsis is presented following ● HELICHRYSETALIA ITALICI Géhu & Biondi 1994 the alphabetical order of phytosociological classes: ♦ Euphorbion pithuysae Géhu & Biondi 1994 CAKILETEA MARITIMAE Tüxen & Preising in Tüxen 1950 Scrophulario ramosissimae-Genistetum salzmannii (Mal- cuit 1926) Géhu & Biondi 1994 ● EUPHORBIETALIA PEPLIS Tüxen 1950 Helichryso italici-Cistetum salviifolii Paradis & Piazza ♦ Euphorbion peplis Tüxen 1950 1998

Salsolo kali-Cakiletum maritimae Costa & Mans. 1981 corr. Rivas Mart. et al. 1992 HELIANTHEMETEA GUTTATI (Braun-Blanq. ex Rivas Goday 1958) Rivas Goday & Rivas Mart. 1963 euphorbietosum peplis Paradis et al. 2004 ● TRACHYNIETALIA DISTACHYAE Rivas Mart. 1978 Salsolo kali-Euphorbietum peplis Géhu et al. 1984 ♦ Trachynion distachyae Rivas-Martínez 1978 Atriplicetum hastato-tornabeni O. Bolòs 1962 ● MALCOLMIETALIA RAMOSISSIMAE Rivas Goday 1958 ♦ Maresio nanae-Malcolmion ramosissimae (Rivas Mart. CISTO LADANIFERI-LAVANDULETEA STOECHADIS Braun-Blanq. 1978) Rivas Mart., Costa & Loidi 1992 in Braun-Blanq., Re. Molinier & He. Wagner 1940 Ononidetum variegatae Piazza & Paradis 2002 ● STAURACANTHO GENISTOIDIS-HALIMIETALIA COMMUTATI Rivas Cutandietum maritimae Piazza & Paradis 1994 Mart., Lousã, T. E. Díaz, Fernández-González & J. C. Sileno gallicae-Corynephoretum articulati Géhu & Biondi Costa 1990 1994 ♦ Stauracantho genistoidis-Halimion halimifolii Rivas Sileno sericeae-Matthioletum tricuspidatae Paradis & Piazza 1992 Mart. 1979 Corrigiolo telephifoliae-Corynephoretum articulati Géhu Cisto salviifolii-Halimietum halimifolii Géhu & Biondi et al. 1987 1994 Laguro ovati-Vulpion fasciculatae Géhu & Biondi 1994 Sileno sericeae-Vulpietum fasciculatae Paradis & Piazza EUPHORBIO PARALIAE-AMMOPHILETEA AUSTRALIS Géhu & 1992 Géhu-Franck 1988 corr. Géhu 2004 ● AMMOPHILETALIA AUSTRALIS Braun-Blanq. 1933 NERIO OLEANDRI-TAMARICETEA AFRICANAE Braun-Blanq. & O. ♦ Ammophilion australis Braun-Blanq. 1921 corr. Rivas Bolòs 1958 Mart., M. J. Costa & Izco in Rivas Mart., Lousã, T. E. ● TAMARICETALIA AFRICANAE Braun-Blanq. & O. Bolòs 1958 Diáz, Fern.-Gonz. & J. C. Costa 1990 ♦ Tamaricion africanae Braun-Blanq. & O. Bolòs 1958 ♦♦ Sporobolenion arenarii Géhu 1988 QUERCETEA ILICIS Braun-Blanq. in Braun-Blanq., Roussine & Sporoboletum arenarii (Arènes 1924) Géhu & Biondi 1994 ♦♦ Sporobolo arenarii-Elymenion farcti Géhu 1988 Nègre 1952 Sporobolo pungentis-Elymetum farcti (Braun-Blanq. 1933) ● PISTACIO LENTISCI-RHAMNETALIA ALATERNI Rivas Mart. 1975 Géhu et al. 1984 ♦ Juniperion turbinatae Rivas Mart. 1975 corr. 1987 Echinophoro spinosae-Elymetum farcti Géhu 1988 Pistacio lentisci-Juniperetum macrocarpae Caneva et al. typicum Géhu 1988 1981 othanthetosum maritimi Géhu & Biondi 1994 Sileno corsicae-Elymetum farcti (Malcuit 1926) Bartolo et SAGINETEA MARITIMAE V. Westh., C. Leeuwen & Adriani 1962 al. 1992 ● SAGINETALIA MARITIMAE V. Westh., C. Leeuwen & Adriani typicum Géhu & Biondi 1994 1962 otanthetosum maritimi Bartolo et al. 1992 ♦ Saginion maritimae V. Westh., C. Leeuwen & Adriani medicaginetosum marinae Géhu & Géhu-Franck 1993 1962 Eryngio maritimi-Elymetum farcti Géhu 1986 (race corso- Catapodio marini-Parapholisetum incurvae Géhu & B. sarde) typicum Foucault 1978 race méditerranéenne otanthetosum maritimi Piazza & Paradis 1997 Catapodio marini-Evacetum rotundatae Géhu et al. 1989 Inulo crithmoidis-Elymetum farcti Piazza & Paradis 1994 frankenietosum intermediae Géhu et al. 1989 Plantagino humilis-Lotetum cytisoidis Paradis & Piazza Galio halophili-Senecietum transientis Paradis & Piazza 1993 1992 ♦♦ Ammophilenion australis Rivas Mart. & Géhu in Rivas Catapodio marini-Mesembryanthemetum nodiflori Paradis, Mart., M. J. Costa, Castrov. & Valdés Berm. 1980 corr. Rivas Mart., Lousã, T. E. Diáz, Fern.-Gonz. & J. C. Costa Panaïotis & Piazza 2014 1990 Catapodio marini-Senecietum transientis Paradis, Panaïo- Echinophoro spinosae-Ammophiletum arundinaceae Géhu tis & Piazza 2014 & Biondi 1994 SISYMBRIETEA OFFICINALIS Gutte & Hilbig 1975 Sileno corsicae-Ammophiletum arundinaceae Géhu & ● BROMETALIA RUBENTI-TECTORUM Rivas Mart. & Izco 1977 Biondi 1994 ♦ Laguro ovati-Bromion rigidi Géhu & Géhu-Franck ex Glaucio flavi-Crithmetum maritimi Paradis & Piazza 2011 Géhu 2004 Elytrigio juncei-Crithmetum maritimi Paradis & Piazza Sileno gallicae-Brometum gussonei Géhu & Biondi 1994 2011

Subhalophilous and halophilous geopermaseries and minoriseries of Corsica 13

Symphytosociological and geosymphytosociological This minoseries appearing occasionally (Tizzano, outcomes Barcaggio, Roccapina, Palombaggia...) is most frequent on the eastern side between Bastia and Porto-Vecchio. ► Corsican psammophilous and edaphoxerophilous The most representative units are located on Ostriconi, minoriserie, thermomediterranean dry to subhu- Saleccia and Roccapina sites. This minoriserie develops mid of Pistacia lentiscus and Juniperus oxycedrus at the back of psammophilous geopermaseries of Corsi- subsp. macrocarpa can coastal dunes and at the lower contact of Galio- [Pistacio lentisci-Junipero macrocarpae minorisig- scabri Querco ilicis sigmetum. metum] Regarding to the distribution of Pistacio lentisci-Ju- Sigmaecology niperetum macrocarpae, it is highly likely that the dis- The Pistacio lentisci-Junipero macrocarpae minor- tribution area of this minoriserie extends across the Ty- isigmetum forms the last coastal stripe of sandy dune rrhenian and Adriatic area. Complementary surveys systems (Cap Corse, Bonifacio). It develops on sandy could allow to refine its chorology. beaches and is very haloresistant. Ombrotype: dry-sub- Sigmastructure (Tab. I) humid below. Thermotype: thermo-inframediterranean. Sigmasystematic [holotypus: rel. 6 du Tab. II]

Physiognomy of végétation Plant community Bioindicator species Pistacio lentisci-Juniperetum Juniperus oxycedrus subsp. Shrub thickets macrocarpae macrocarpa, Pistacia lentiscus

Helichrysum italicum subsp. italicum, Schrubland Helichryso italici-Cistetum salviifolii Cistus salviifolius, Genista corsica

Cutandia maritima, Maresio nanae-Malcolmion Vulpia fasciculata, Therophytic grass ramosissimae Lolium rigidum subsp. rigidum, Medicago littoralis

Table I. Bioindicator species of Pistacio lentisci-Junipero macrocarpae minorisigmetum

PISTACIO LENTISCI-JUNIPERO MACROCARPAE ► Corsican psammophilous geopermaseries of coastal MINORISIGMETUM. dunes When the Pistacio lentisci-Junipero macrocarpae Sigmaecology minorisigmetum is submitted to regular fires, it is re- Sandy systems are present in the funds of bay, off- placed by Cisto salviifolii-Halimietum halimifolii [Tab. shore bars, clogging coves and estuaries of coastal rivers. II-B]. This shrubland usually develops on sandy gravel Bioclimatically, sandy systems depends on their position on the coast and wind exposure: a cooler regime of the substrates but is also found on fixed dune, at the contact west coast and a drier regime of the east coast. Geomor- of Pistacio lentisci-Junipero macrocarpae minorisig- phologically, sandy vegetation systems are distinguished metum. according to the substrate granulometry: Conservation issues ● dune beach (coastal or continental geomorphologi- This minoriserie presents a major heritage value: cal formation, formed by the accumulation of sand transported by wind) [1, 2] ● presence of a Juniperus oxycedrus subsp. macrocarpa protected at the regional level; ● river-marine terrace (extent of aeolian sand, very heterometric sediments, with a gravel dominance ● presence of two habitats of Community interest (grain size greater than 2 mm). [3] (HCI) among which one is prioritary (*) (2250 * - Ombrotype: dry upper, lower dry to lower sub-humid. Juniper thickets on dunes -Pistacio lentisci-Juni- Thermotype: thermo and inframediterranean. peretum macrocarpae ; 2260 -Dunes to scle- rophyllous vegetation Cisto-Lavanduletalia - Cisto Sigmachorology salviifolii-Halimietum halimifolii) ; Sandy and sandy-gravelly systems punctuate much of the coast (Géhu & Biondi 1994, Piazza 1994, Paradis ● only a few dunes beaches have this minoriserie 2014) of the Eastern Plain, between Bastia and Porto- ● presence of the most spectacular dune systems on Vecchio. Ostriconi and Roccapina. The main threats are fires that may lead to a total Sigmastructure destructuration of the minoriserie. In Corsica, cutting Sandy gravel geopermaseries are composed by open represents a historical reason of disappearance of Juni- grassland vegetations. Vegetation sequence is expressed perus oxycedrus subsp. macrocarpa (Paradis 1991, Para- in general over a length of 15 to 25 m. The transect may dis Piazza & 1995). be truncated due to urbanization or geomorphological context fixed dune (rocky cliffs, coastal wetlands...).

Table II. Pistacio lentisci-Junipero macrocarpae minorisigmetum

A B C Synrelevé number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Surface (ha) 0.19 0.56 2 2.67 0.85 0.26 0.07 0.16 0.61 1.07 2.09 0.24 5.4 5.4 1.89 1.09 3.04 1.39 Phanerogamic total recovery (%) 95 95 95 100 95 100 90 80 100 90 95 80 100 100 100 70 100 95 Average altitude (m) 2 1-2 1-2 2 2 2-3 2 2 1-2 1-2.5 1-2 2 3-5 3-5 1 1 1 1 Dominant exposition E SE SE SW N SE E E SE S SW - E E E SE - E Number of syntaxa 6 6 6 6 6 6 6 6 6 6 6 6 6 6 5 6 6 6 Characteristics syntaxa of the progressive dynamic

Pistacio lentisci-Juniperetum macrocarpae O5 O5 O5 O5 O5 O5 O2 O4 O3 O3 O3 O3 O3 O5 - - - - Helichryso italici-Cistetum salvifolii - - - - - O2 O4 ------Therophytic grass of Maresio nanae-Malcolmion ramosissimae - - - - - …+ …1 …1 …+ …+ …+ - …1 …2 - O2 …1-

Characteristics syntaxa of the regressive dynamic

Cisto salvifolii-Halimietum halimifolii ------O4 O4 O4 O2 O4 - O5 O4 O5 O5 Localities: 1, 7 y 18 Prunete-Canniccia. 2,6 y 9 Palombaggia. 3, 4 y 10 Roccapina. 5. Campomoro. 8 Pinarellu. 11 Traolicetu. 12 Benedettu. 13, 14 y 17. Mucchiatana. 15 Biguglia y 16 Lavu Santu F. Bioret & C. Panaïotis & C. Bioret F. , P. Delbosc

Table III A. Sileno corsicae-Ammophilo arundinaceae geopermasigmetum

Geopermasynrelevé number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Surface (ha) 0.8 1.5 0.7 2 3.7 1.2 4.8 0.4 0.1 1.05 6.2 2.03 1.6 2.3 5.3 2.6 0.4 6.4 1.6 12.8 0.9 Phanerogamic total recovery (%) 60 70 60 70 45 70 70 65 90 90 80 80 90 100 70 95 70 90 80 80 60 Number of permasigmataxa 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 Characteristics permasigmataxa

Sileno corsicae-Ammophiletum arundinaceae O2 O4 O2 O3 …1 .+ o1 o1 O1 O2 R O1 .+ .+ .+ O3 o1 O3 /2 O3 O2 Subhalophilous halophilous and geopermaseries minoriseriesand of Corsica Permasigmataxa of sandy beaches Salsolo kali-Cakiletum maritimae O2 o1 o+ o1 …1 O3 O1 O2 O1 O2 O2 O2 O2 O2 O3 O2 O3 O2 O+ O2 O2 Sporoboletum arenarii - - O2 O2 - o1 O2 O3 O1 - O2 O1 O1 - - r - o1 r - - Permasigmataxa of embryonic dunes Sporobolo pungentis-Elymetum farcti o1 ------O+ O2 O2 - O4 O2 - - - O2 - - o1 Sileno corsicae-Elymetum farcti typicum - O2 O2 - - - O2 O2 O4 ------O2- - - - Sileno corsicae-Elymetum farcti totanthetosum maritimi ------O3 - Sileno corsicae-Elymetum farcti medicaginetosum marinae ------O2 - O3 ------Eryngio maritimi-Elymetum farcti (race corso-sarde) - O2 O2 O2 O2 O2 - - - O2 O3 O2 O2 O2 O3 O2 O3 O2 - O2 - Eryngio maritimi-Elymetum farcti (race corso-sarde) otanthetosum maritimi ------O2 - - O2 - .1 - O1 - - - - - Permasigmataxa of fixed dune Sileno gallicae-Brometum gussonei ------+ - - - - Cutandietum maritimae …1 - - - - O2 - - - o1 o1 o1 ------…+ Sileno sericeae-Vulpietum fasciculatae - - - - - O1 - - O2 O3 O2 O2 O2 O2 - O2 O2 …1 O4 O1 - Another permasigmataxa Sileno sericeae-Matthioletum tricuspidatae ------o+ O3 - - - Plantagini humilis-Lotettum cytisoidis ------O2 - - O2 ------Catapodio marini-Parapholietum incurvae ------.+ o1 …1 - - - Sileno gallicae-Corynephoretum articulatae - - - - - o+------.+ - - - .+

Catapodio marini-Parapholietum incurvae race méditerranénne ------+ ------Catapodio marinae-Evacetum rotundatae frankenietosum intermediae ------Corrigiolo telephiifoliae-Corynephoretum articulati ------o1 O2 - - - Elytrigio juncei-Crithmetum maritimi ------Groupement of Carpobrotus edulis - - - - - + ------.+ - - O2 - - - - Ononidetum variegatae ------O3 ------

Localities: 1.Plage d’Argenta. 2,3,4 , 5,7 y 8. Cap Corse . 6 Benedettu. 9 Baie de Satgnolu. 10 y 20 Roccapina. 11 y 21 Plage de Tralicetu. 12 y 13 Tizzano. 14 Verghia. 15 San Giusseppe.16 Anse 15 de Minaccia.17 Golfe de Lava. 18. Plage de Liamone.. 19 Campomoro.

Table III B. Sileno corsicae-Ammophilo arundinaceae geopermasigmetum Geopermasynrelevé number 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 13. 2.0 Surface (ha) 0.58 1 5.43 0.9 2.2 0.4 1.9 3.8 1.1 1.1 0.2 1.4 0.21 0.4 6 2 Phanerogamic total recovery (%) 30 70 80 70 40 50 10 50 40 40 80 20 20 15 15 60 Number of permasigmataxa 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 Characteristics permasigmataxa Sileno corsicae-Ammophiletum arundinaceae ------Permasigmataxa of sandy beaches Salsolo kali-Cakiletum maritimae O2 O1 O3 /2 O2 O2 o2 O2 O2 …r o1 - O2 O2 O2 - Sporoboletum arenarii o1 o2 o1 - O2 - O2 ------Permasigmataxa of embryonic dunes Sporobolo pungentis-Elymetum farcti O2 - O2 ------O1 Sileno corsicae-Elymetum farcti typicum - O2 O1 ------Sileno corsicae-Elymetum farcti totanthetosum maritimi ------Sileno corsicae-Elymetum farcti medicaginetosum marinae ------Eryngio maritimi-Elymetum farcti typicum(race corso-sarde) - - O2 O3 O2 O2 ------Eryngio maritimi-Elymetum farcti (race corso-sarde) otanthetosum maritimi ------Permasigmataxa of fixed dune Sileno gallicae-Brometum gussonei - - - - O2 - - O3 O3 O2 ------Cutandietum maritimae ------Sileno sericeae-Vulpietum fasciculatae - - O2 ------Another permasigmataxa

Sileno sericeae-Matthioletum tricuspidatae - O3 - - - o2 - - - - O4 - - - - - Plantagini humilis-Lotettum cytisoidis - - O1 ------Catapodio marini-Parapholietum incurvae - - o1 ------O2- - - - - Sileno gallicae-Corynephoretum articulatae ------Catapodio marini-Parapholietum incurvae race méditerranénne ------Catapodio marinae-Evacetum rotundatae frankenietosum intermediae - - - - o1 ------Corrigiolo telephiifoliae-Corynephoretum articulati ------F. Bioret & C. Panaïotis & C. Bioret F. , Elytrigio juncei-Crithmetum maritimi - - O1 ------O1 - - - - O3 Groupement of Carpobrotus edulis - - o+ - - - - o+ - Ononidetum variegatae ------P. Delbosc Localities: 22.St-Florent. 23, 25,26,27,28,29,30,31,32,33,34,35,y 36. Cap Corse. 24. Chiumi. 37. Plage d’Argent

Table IV. Echinophoro spinosae-Ammophilo arundinaceae geopermasigmetum A B Geopermasynrelevé number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Surface (ha) 6.95 1.43 5.4 4.3 6 6 1.71 1.86 6.05 1.8 2.05 8 6.09 0.44 Phanerogamic total recovery (%) 90 95 80 90 80 70 85 70 100 20 90 70 90 95 Number of permasigmataxa 27 27 27 27 27 27 27 27 27 27 27 27 27 27 Characteristics permasigmataxa Echinophoro spinosae-Ammophiletum arundinaceae O1 O2 O1 r O2 O2 o1 r ------Subhalophilous halophilous and geopermaseries minoriseriesand of Corsica Permasigmataxa of sandy beaches Salsolo kali-Cakiletum maritimae O2 O2 O2 O3 r /+ o2 O4 O3 O2 O3 - o1 o…1 Sporoboletum arenarii + r O1 - - /1 …1 O2 O1 O1 - /+ O2 o+ Permasigmataxa of embryonic dunes Sporobolo pungentis-Elymetum farcti - + ------O3 - - - - - Sileno corsicae-Elymetum farcti ------O2 - O2 - O5 O2 Eryngio maritimi-Elymetum farcti (race corso-sarde) O1 O2 O2 O2 - - O2 …+ o1 - O2 O2 - - Eryngio maritimi-Elymetum farcti (race corso-sarde) otanthetosum maritimi O2 - - - - - O2 - r - - - - - Permasigmataxa of fixed dune Pycnomonio rutifolii-Crucianelletum maritimae O3 O2 O3 O2 O2 O3 O3 - O/1 - - - - - Echinophoro spinosae-Elymetum farcti typicum O2 - - - O1 OI2 - - o1 O3 - - - - Echinophoro spinosae-Elymetum farcti t) otanthetosum maritimi O2 O3 O3 O2 ------O2 - - - Sileno nicaensis-Vulpietum fasciculatum typicum O2 + - - - - O4 - o1 - o1 - - - Sileno gallicae-Brometum gussonei ------… o1 - Cutandietum maritimae o/2 O2 - O2 - Another permasigmataxa Groupement à Carpobrotus edulis - O2 - - - - O2 - - O2 - - - r Plantagini humilis-Lotettum cytisoidis ------o1 - Catapodio marini-Parapholietum incurvae race méditerranénne ------…2 ------Ononidetum variegatae ------O2 - O2 - - - Localities: 1. Mucchiatana. 2,3,4 y 9. Prunete-Cannicia . 5 y 6 ëtang de Palo. 7. Palombaggia. 8 Pinarellu. 10. Fium’Alto. 11. Biguglia. 12. Santa-Giulia. 13 y 14. Bonifacio

18 P. Delbosc, F. Bioret & C. Panaïotis

Sigmasystematic 1994). In table 5, some relevés characterize impove- Analysis of geopermasynrelevés combinated with the rished facies of this geopermaserie in trampled areas (A. sandy system geomorphological analysis helped to hig- Tab. V). hlight three geopermaseries according to a chorological Bacchetta et al. (2010) identified a unique psammo- determinism [1 and 2] and size [3]. philous halophilous and dunegeosigmetum. The geomorphological approach of the authors is based on the con- [1] west coast of Corsica dunes beaches geoperma- sideration of plant units which grow on the dune sys- series, thermomediterranean subhumid to dry of the tems, without taking into account the dynamic type of Sileno corsicae-Ammophilo arundinaceae geoperma- each unit. sigmetum [holotypus: rel. 2; tab. III] The shape and space occupied by sandy systems de- This endemic corsican psammophilous geoperma- pends primarily on the geomorphological configuration serie, heliophilous and salt-tolerant, , grows on the west of the coastline. When systems are interspersed with coast of the island and is characterized by the Sileno sandy rocky coast or located in front of a rocky coast, corsicae-Ammophiletum arundinaceae. It is composed of

vegetation sequence may be truncated. In this case, it foreshore vegetations (Salsolo kali-Cakiletum maritimae, matches the concept of fractogeosigmetum (Géhu 2006). Sporoboletum arenarii, Sporobolo pungentis-Elymetum farcti, Eryngio maritimi-Elymetum farcti). Vegetation Conservation issues sequence grows about twenty meters but may exceptio- Although frequent along the coastal zone of Corsica, nally develop over a hundred meters, for example on the dune geopermaseries appear ponctually. They are regu- Roccapina site. Tables analysis shows that the geoper- larly subjected to human pressures: human use and tram- maserie presents an impoverished facies (B. Tab. III) pling of sandy gravel sites have change the vegetation characterized by the absence of Sileno corsicae-Ammo- sequence and favorr the development of secondary veg- philetum arundinaceae and a higher frequency of Sileno etation. Refering to the European Habitats Directive, gallicae-Brometum gussonei (zoo-anthropogenic grass- these geopermaseries include many HCI: land). This geopermaserie is often located on the lower contact to Pistacio lentisci-Junipero macrocarpae mi- ● (1210) annual vegetation foreshore (Salsola kali- norisigmetum. Cakiletum aegyptiacae) ● (2110) embryonic dunes (Sporoboletum arenarii, [2] East coast of Corsica dune beach geopermaserie, Sporobolo pungentis-Elymetum farcti, Echinopho- thermomediterranean subhumid to dry of the ro spinosae-Elymetum farcti, Sileno corsicae- Echinophoro spinosae-Ammophilo arundinaceae geo- Elymetum farcti, Eryngio maritimi-Elymetum farcti, permasigmetum [holotypus: rel. 1; tab. IV] Inulo crithmoidis-Elymetum farcti, Plantagino- This psammophilous, heliophilous and halophilous Lotetum cytisoidis humilis) geopermaserie is endemic of Corsica. It is common on ● (2120) mobile dunes along the shoreline with Am- the east coast of the island and is characterized by the mophila arenaria (white dunes) (Echinophoro spi- Echinophoro spinosae-Ammophiletum arundinaceae. nosae-Ammophiletum arundinaceae, Sileno corsi- Ammophila vegetation constitute an almost continuous cae-Ammophiletum arundinaceae) fringe on all sites. Vegetation sequence is present over Bacchetta et al. (2007, 2010) described a Sardinian twenty meters and is replaced by Clematido cirrhosae- halophilous pasmmophilous geosigmetum whose catenal Pistacietum lentisci smilacetosum asperae. On the subs- arrangement is similar to those identified in Corsica trates of fixed dune, it is located at the lower contact of (Salsolo kali-Cakiletum maritimae, Atriplicetum hastato- Cisto salviifolii-Halimietum halimifolii. The tables ana- tornabaeni, Sporobolo pungentis-Elymetum farcti, Sileno lysis shows an impoverished facies (B. Tab. IV) marked corsicae-Elymetum farcti, Sileno corsicae-Ammophile- by the absence of the Echinophoro spinosae-Ammo- tum arundinacea, Crucianellion maritimae, Maresio philetum arundinaceae and a lower frequency of fixed nanae-Malcolmion ramosissimae, Pistacio lentisci-Juni- dune vegetation including the Pycnocomo rutifolii-Cru- peretum macrocarpae). cianelletum maritimae. Symphytosociological and geosymphytosociological [3] South of Corsica dune beache geopermaserie, results of sandy-gravel terraces thermomediterranean dry ► Corsican edaphoxerophilous, thermomediterra- Crucianello maritimae-Armerio pungentis geoperma- nean dry of gravel terraces of Pinus pinaster sigmetum [holotypus: rel. 3 tab. V] Sigmaecology This heliophilous and halophilous geopermaserie, This acidiphilous series grows on fixed sand and endemic to Corsica, is characterized by the Crucianello gravel dune in adlittoral position. It is the last fringe of maritimae-Armerietum pungentis, pioneer low shrubland the sequence of vegetation sandy-gravelly systems. Om- dominated by Armeria pungens which distribution is brotype: lower dry Thermotype: thermo inframediterra- strictly limited to Bonifacio and the island of Piana nean. (Lavezzi). Geopermaserie expresses on a small width (less than 10 meters). Sigmachorology This geopermaserie is at the lower contact of rocky coast It appears in several places of Corsica (Lavu Santu, on which develops Euphorbio pithyusae-Helichryso Bay of Calvi, Palombaggia) but still on small areas (less microphylli minorisigmetum or of Juniperion turbinatae than 2 hectares). bushes on the island of Piana (Lavezzi) (Paradis et al .

Subhalophilous and halophilous geopermaseries and minoriseries of Corsica 19

Table V. Crucianello maritimae-Armerio pungentis geopermasigmetum

A B Geopermasynrelevé number 1 2 3 4 5 Surface (ha) 1.89 6.3 0.5 0.58 0.27 Phanerogamic total recovery (%) 70 70 70 60 100 Number of permasigmataxa 20 20 20 20 20 Characteristics permasigmataxa Crucianello maritimae-Armerietum pungentis O4 O4 O4 O2 O2 Permasigmataxa of sandy beaches Salsolo kali-Cakiletum maritimae /2 - O2 O1 O2 Sporoboletum arenarii O2 O3 o+ .+ .1 Permasigmataxa of embryonic dunes Sporobolo pungentis-Elymetum farcti - - O1 - - Inulo crithmoidis-Elymetum farcti - o1 - .+ - Sileno corsicae-Elymetum farcti - - O3 - - Eryngio maritimi-Elymetum farcti (race corso-sarde) - - - - .+ Permasigmataxa of fixed dune Echinophoro spinosae-Elymetum farcti o/2 O2 - O2 - Sileno sericeae-Vulpietum fasciculatae - - - - O3 Another permasigmataxa Groupement à Carpobrotus edulis - - - .1 - Tamaricion africanae - - - O2 O3 Plantagini humilis-Lotetum cytisoidis - - O2 - O2 Localities: Bonifacio

This series is located at the upper contact of the Heli- Natural dynamic progressive stages have not been chryso italici-Scrophulario ramosissimae minorisigme- identified yet. The shrubland of Cisto salviifolii-Hali- tum and lower contact of the Galio-scabri Querco sube- mietum halimifolii is part of a secondary dynamic, as it is ris sigmetum. favorised by frequent fires. Complementary surveys could allow to better typify the dynamic trajectories Sigmatructure Sigmasystematic [holotypus: rel. 1 du tab. VI] It is characterized by scarce and clear groves of Pinus pinaster subsp. hamiltonii which some individuals may Conservation issues be sculpted by wind and salt spray. The undergrowth is This series is rare in Corsica where it is present on the Cistus salviifolius and Halimium halimifolium small areas (1 to 2 hectares). Situated on the fringe of shrubland whose height may reach 2 m and has important sandy and sandy-gravelly systems, it is the subject to a recovery (about 95%). The herbaceous layer is sporadic regression due to increasing urbanization. The head of and its floristic composition is very diversified: Brachy- serie represents a priority HCI: (2270-2) "dunales forests podium retusum, Jasione montana subsp. montana, maritime pine (Pinus pinaster subsp hamiltonii)" which Sixalix atropurpurea subsp. maritima. is of major interest in landscape of the Corsican coast.

20 P. Delbosc, F. Bioret & C. Panaïotis

Table VI. Edaphoxerophilous corsican series, thermomediterranean dry,

coastal gravel terres of Pinus pinaster

Synrelevé number 1 2 Surface (ha) 12.71 14.37

Phanerogamic total recovery (%) 85 80 Average altitude (m) - 0-2 Slope (%) - 4 Dominant exposition - E Number of syntaxa 3 3 Characteristics syntaxa of the progressive dynamic

Wood of Pinus pinaster subsp. hamiltonii O2 O2 Therophytic grass of Maresio nanae-Malcolmion ramosissimae …1 …+ Characteristics syntaxa of the regressive dynamic

Cisto salvifolii-Halimietum halimifolii O5 O5 Localities: 1 Lavusantu y 2 Pinarellu

Table VII. Scrophulario ramosissimae-Genisto salzmanii minorisigmetum

Synrelevé number 1 Surface (ha) 3.21 Phanerogamic total recovery (%) 100 Average altitude (m) 4 Number of syntaxa 4 Characteristics syntaxa of the progressive dynamic

Scrophulario ramosissimae-Genistetum salzmanii O5 Maresio nanae-Malcolmion ramosissimae O2 Characteristics syntaxa of the regressive dynamic

Catapodio marini-Evacetum rotundatae …o+ Localities: 1 Plage du Ricanto

Table VIII. Helichryso italici-Scrophulario ramosissimae minorisigmetum Synrelevé number 1 2 3

Surface (ha) 1.27 1.09 3.02 Phanerogamic total recovery (%) 100 100 80 Average altitude (m) - 1-3 4 Dominant exposition - E -

Number of syntaxa 4 4 4 Characteristics syntaxa of the progressive dynamic

Helichryso italici-Scrophularietum ramosissimae O5 O5 o4 Therophytic grass of Maresio nanae-Malcolmion ramosissimae …2 …1 …2 Characteristics syntaxa of the regressive dynamic

Corrigiolo telephifoliae-Corynephoretum articulati - - o1 Localities: 1 y 2 Lavusantu. 3 Plage du Ricanto

Subhalophilous and halophilous geopermaseries and minoriseries of Corsica 21

► Corsican edaphoxerophilous minoriserie, medite- tic interest is linked to the presence of Scrophularia rranean dry to heat, coastal gravel terraces ramosissima, rare in Corsica. The characteristic associa- [Scrophulario ramosissimae-Genisto salzmannii mi- tion of this minoriserie is related to the HCI (2210) norisigmetum] "fixed dunes mediterranean coastal Crucianellion maritimae". Frequentation and trampling are the major an- Sigmaecology thropogenic pressures. This minoriserie grows on gravel terraces in the su- pralittoral fringe. The substrate, semi-stabilized, consists ► Corsican geopermaserie, thermomediterranean of gravel and coarse sand. Ombrotype: lower dry. Ther- dry-subhumid of sablo-gravelly terraces motype: thermo inframediterranean. [Salsolo kali-Euphorbio peplis geopermasigmetum] Sigmachorology Sigmaecology This minoriserie is present in two locations: Ajaccio This geopermaserie differs from the previous one by and Ostriconi. Due to the endemic nature of the head its coarser substrate and geomorphology terrace. When serie, the minoriserie is also endemic to Corsica. the influence of the salt spray decreases, this geoperma- Sigmastructure serie is replaced by Helichryso italici-Scrophularietum This minoriserie is a shrubland dominated by Genista ramosissimae or Scrophulario ramosissimae-Genistetum salzmannii var. salzmannii and Scrophularia ramosissi- salzmannii). Ombrotype: dry sub-humid. Thermotype: ma, which height varies from 30 to 60 cm. The grassland below thermo inframediterraneen. stage is represented by the Maresio nanae-Malcolmion Sigmachorology ramosissimae, disparately expressed and characterized Salsolo kali-Euphorbio peplis geopermasigmetum by Jasione montana subsp. montana, Reichardia picroides and Carlina corymbosa subsp. corymbosa. remains punctual (Lavu Santu, Baraci, Ajaccio, Ricanto, Lava, Liamone, Stagnoli SE, Lozari). Due to the presen- Sigmasystematic [holotypus: rel. 1 tab. VII] ce of Salsolo kali-Euphorbietum peplis in the Eastern Conservation issues Mediterranean (Cyprus, Turkey and Greece) (Gehu et al. The remarkable character of this minoriserie lies in 1984, Bioret & Géhu 2015), this geopermasigmetum the floristic combination of Scrophularia ramosissima seems to be present in other mediterranean areas. and Genista salzmannii var. salzmannii. This minorise- Sigmastructure rie, endemic to Corsica, represents a HCI (2210) “Medi- The sandy-gravelly terraces geopermaserie is compo- terranean coast dunes of Crucianellion maritimae” sed of low and open grassland vegetation. Vegetation (Scrophulario ramosissimae-Genistetum salzmannii). sequence is expressed in general over a length of 10 to ► Corsican edaphoxerophilous minoriserie, thermo- 20 m. The transect may be truncated due to urbanization mediterranean dry, of Scrophularia ramosissima (Ajaccio, Ricanto) or geormophological context fixed and Helichrysum italicum subsp. Italicum dune (coastal wetlands such as on Ovu Santu site). [Helichryso italici-Scrophulario ramosissimae minorisigmetum] Sigmasystematic [holotypus: rel. 1 du tab. IX] Two geopermasynreleves (B) are characterized by Sigmaecology the absence of Salsola kali-Euphorbietum peplis, they This minoriserie grows back of sandy gravel bars. It constitute an impoverished facies. is strictly linked to the substrates of coarse-grained. Om- brotype: lower dry. Thermotype: thermo inframediterra- Conservation issues nean. This geopermaserie is characterized by the association of Salsola kali-Euphorbietum peplis Gehu et al. Sigmachorology 1984 ; its originality is based on the presence of protec- This minoriserie is located on several sites (Lavu ted species Euphorbia peplis. The geopermaserie inclu- Santu, Benedettu, Golfo di Sagno (Porto-Vecchio), des a significant number of the HCI: Verghia Campo del Oro, Galeria, Ostriconi). This mino- ● (1210) annual vegetation foreshore (Salsolo kali- riserie is at the upper contact of the Salsolo kali-Euphor- Cakiletum aegyptiacae- kali- Salsolo kali- Euphor- bio peplis geopermasigmetumand lower contact of the maritime pine serie. bietum peplis, Galio halophili-Senecietum transientis) Sigmastructure ● (2110) embryonic dunes (Sporoboletum arenarii, This minoriserie includes two dynamic stages: Sporobolo pungentis-Elymetum farcti, Sileno cor- ● a chamephytic stage dominated Scrophularia ra- sicae-Elymetum farcti, Eryngio maritimi-Elymetum mosissima and Helichrysum italicum subsp. itali- farcti) cum (Helichryso italici-Scrophularietum ramo- ● (2210) fixed dunes Crucianellion maritimae (Pyc- sissimae) nocomo rutifolii-Crucianelletum maritimae) ● a therophytic grassland stage: Maresio nanae-Mal- ● (1310-4) annual subhalophilous garssland (Cata- colmion ramosissimae which appears punctually podio marini-Senecionetum transientis) and regularly, imbricated in the previous stage ● (2230) dunes with Malcolmietalia (Sileno sericeae- Sigmasystematic [holotypus: rel. 3 tab. VIII] Vulpietum fasciculatae, Sileno sericeae-Matthio- letum tricuspidatae) Conservation issues The limited distribution of geomorphological context The minoriserie originality is linked to the singularity (sandy-gravelly terraces) reinforces the heritage value of of ecological conditions (sandy-gravelly terrace) and its this unit. 15

distribution limited in some points of Corsica. Its floris-

22 P. Delbosc, F. Bioret & C. Panaïotis

Table IX. Salsolo kali-Euphorbio peplis geopermasigmetum

A B Geopermasynrelevé number 1 2 3 4 5

Surface (ha) 4.55 8.98 1.68 4.55 4.12 Phanerogamic total recovery (%) 70 90 30 50 60 Number of permasigmataxa 26 26 26 4 26 Characteristics permasigmataxa Salsolo kali-Euphorbietum peplis O2 O2 O2 - - Permasigmataxa of sandy beaches

Salsolo kali-Cakiletum maritimae euphorbietosum peplis O2 O2 - O2 .1 Sporoboletum arenarii …+ - - …+ - Permasigmataxa of ressaut terraces Sporobolo pungentis-Elymetum farcti - - O2 - - Galio halophili-Senecietum trasientis - or- …1 - …2 Glaucio flavi-Crithmetum maritimi - - .1 o2 O3 Catapodio marini-Senecietum trasientis - .+ - - - Eryngio maritimi-Elymetum farcti O2 O3 - …1 - Pycnocomo rutifolii-Crucianelletum maritimae O3 - - - - Permasigmataxa of the top of terraces Elytrigio juncei-Crithmetum maritimi - - .+ - - Cutandietum maritimi o1 .o2 - - - Sileno sericeae-Vulpietum fasciculatae O2 o1 - - - Sileno sericeae-Matthioletum tricuspidatae - o2 - - - Sileno gallicae-Corynephoretum articulatae …+ - - - - Another permasigmataxa

Catapodio marini-Parapholietum incurvae race méditerranénne - o+ - - - Corrigiolo telephiifoliae-Corynephoretum articulati - O” - - - Catapodio marini-Mesembryanthemetum nodiflori - .+ - - -- Localities: 1 y 4 Lavu-Santu. 2 Plage de Ricanto. 3 y 5 Baracci

Figure 5. Typical spatial sequence of sandy-gravel terrace vegetation. (1) Salsolo kali-Cakiletum maritimae Costa & Mans. 1981 corr. Rivas Mart. et al. 1992; (2) Salsolo kali-Euphorbietum peplis Géhu et al. 1984; (3) Galio halophili-Senecietum transientis Paradis & Piazza 1992; (4) Helichryso italici- Scrophularietum ramosissimae Géhu et al. 1987; (5) Groupement à Pinus Pinaster.

Subhalophilous and halophilous geopermaseries and minoriseries of Corsica 23

Symphytosociological and geosymphytosociological Sigmastructure resultats of pebble beaches This unit is composed of foreschore vegetation very sparse vegetation where recovery rarely exceeds 30%. ► Corsican edaphoxerophilous minoriserie, thermomediterranean subhumid of pebbles beaches Sigmasystematic [holotypus: rel. 1 tab. XI] [Helichryso italici-Cisto salviifolii minorisigmetum] This geopermaserie contains only three syntaxa. It is characterized by the Glaucio flavi-Crithmetum maritimi Sigmaecology Paradis & Piazza 2011. The geopermasynrelevé realized This heliophilous minoriserie grows on a pebble on Porto's pebble beach is an impoverished facies (B) beaches which sandy interstitial matrix and regularly due to anthropic pressure. accompanied by organic debris. Ombrotype: lower sub- Conservation issues humid. Thermotype: thermo inframediterraneen. This geopermaserie has no plant species or groups of Sigmachorology high heritage value. Helichryso italici-Cisto salviifolii minorisigmetum Discussion and conclusion: has a very limited distribution but is common in some parts of the west coast between Calvi and Propriano. On This work allows to present the conceptual, metho- catenal point of view, this minoriserie develops at the dological and typological principles of landscape phyto- upper contact of Glaucio flavi-Crithmo maritimi geo- sociology while adapting the methodological approach to permasigmetum and at the lower contact of Galio scabri- the Mediterranean coastal vegetations. This method Querco ilicis sigmetum. requires a good knowledge of the mechanisms governing the progressive or regressive dynamic trajectories of Sigmastructure vegetations. It provides a better understanding of cœnoti- This minoriserie has a physiognomy of a low shrub- cal diversity and naturalness of a landscape, according to land (0,3 to 0,6 m) and is structurally dominated by a pluristructural approach from the plant communitis to Genista corsica. This shrubland is accompanied by Heli- the vegetation geoseries (Beguin et al. 1979; Biondi, chrysum italicum subsp. italicum, Cistus salviifolius, 2011). Cistus monspeliensis. Grassland elements appear spora- This study contributes to improve ecological dically and are composed of species Euphorbio paraliae- knowledge, structural and phenomenological of geoper- Ammophiletea australis (Ammophila arenaria, Elymus maseries, minoriseries of sandy gravel coast of Corsica. farctus, Eryngium maritimum). Future investigations will complete the proposed typolo- Sigmasystematic [holotypus: rel. 1 tab. X] gy. The confrontation of our typological results with other areas of the Mediterranean basin would be useful Conservation issues in order to refine the typology of sigmetal or geosigmetal The limited distribution of this minoriserie and the units (chorology, syntaxa differentials, syntaxonomical presence of Genista corsica, endemic corso-Sardinian, depletion of sigmataxons in range limits). confers it a major heritage value. The minoriserie head Future research will be oriented on two main direc- corresponds to fixed dunes Crucianellion maritimae tions: (2210). No major threat seems to weigh on this minorise- ● characterization of coastal soils. rie. On dune systems, soils factors are predominant in ► Corsican geopermaserie, thermomediterranean the zonation of vegetation (Fenu et al. 2012) as subhumid of pebble ridges wind influence seems to be a secondary factor, [Glaucio flavi-Crithmo maritimi geopermasigme- The project to establish a soil referential in Corsica tum] by ODARC (Office of Agricultural and Rural De- velopment of Corsica) is an important issue that Sigmaecology will facilitate the characterization of vegetation se- This heliophilous and hyperhalophilous geoperma- ries and geoseries ; serie grows on pebble beaches. The substrate is regularly ● patrimonial assessment of serial and geoserial removed by the sea and has a unstable character. It is units. necessary to distinguish the pebble beaches by their Some sectors could be selected based on their geomorphological origin: Fango and Porto beaches are ecological and anthropogenic originalities, in order natural ; those of Cap Corse, Nonza and Farinole, are to achieve a vegetation monitoring at a finer scale. linked to anthropogenic releases of a former asbestos This could contribute to a better understanding of quarry. Ombrotype: lower subhumid. Thermotype: human impacts and spatial and temporal scales of Thermo inframediterranean. plant succession based on disturbance degrees. Sigmachorology Acknowledgments: This geopermaserie is limited to some areas of Corsi- ca (Fango Crovani, Porto, Cap Corse). At the island The authors thank the scientific team of the Botanical scale, it grows on beaches including some pebbles from Conservatory of Corsica, especially Carole Piazza, Lae- the adjacent rivers. Vegetation sequence is expressed on titia Hugot, Alain Delage, Kevin O'Deye-Guizien, Julie a wide strip of ten meters. In the Fango, this geopermase- Reymann, Paula Spinosi and Caroline Favier Vittori ; rie is located on the lower contact of Helichryso italici- thanks to Guilhan Paradis for his help to interpret the Genistetum corsicae. ecology of vegetation.

24 P. Delbosc, F. Bioret & C. Panaïotis

Table X. Helichryso italici-Cistetum salvifolii minorisigmetum

Synrelevé number 1 2 Surface (ha) 7.89 4.35 Phanerogamic total recovery (%) 70 95

Average altitude (m) 6 2 Dominant exposition - SW Number of syntaxa 3 2 Characteristics syntaxa of the progressive dynamic

Helichryso italici-Cistetum salvifolii O4 O5 Therophytic grass of Maresio nanae-Malcolmion ramosissimae …2 …2

Characteristics syntaxa of the regressive dynamic

Groupement à Brachypodium retusum …2 - Localities: 1 Fango y 2 Liamone

Figure 6. Typical spatial sequence of pebble beaches vegetation. (1) Salsolo kali-Cakiletum maritimae; (2) Sporoboletum arenarii; (3) Glaucio flavi-Crithmetum maritimi; (4) Scrophulario ramosissimae-Genistetum salzmanii; (5) Galio scabri-Quercetum ilicis.

Table XI. Glaucio flavi-Crithmo maritimi geopermasigmatum

A B Geopermasynrelevé number 1 2 3 4 5 6 7 8 9 10 11 12 Surface (ha) 7.89 1.4 V 1.8 0.6 21.6 3.8 0.5 1.6 8.04 2.02 3.22 Phanerogamic total recovery (%) 40 20 15 60 30 40 50 50 80 80 60 80 Number of permasigmataxa 13 13 13 13 13 13 13 13 13 13 13 13 Characteristics permasigmataxa Glaucio flavi-Chritmetum maritimi O2 O1 O2 O2 O2 O2 O2 O1 o1 O3 O3 - Permasigmataxa of pebbles beaches Salsolo kali-Cakiletum maritimae O2 O2 O2 O2 O2 O2 o2 O3 O2 O2 - O2 Sporobolo pungentis-Elymetum farcti ------O1 - Eryngio maritimae-Elymetum farcti - - - O2 - - - - - .+ - - Galio halophili-Senecientum trasientis ------…+ - Another permasigmataxa Sileno gallicae-Brometum gussonei - - - - o2 O2 O2 O2 - - - - Cutandietum maritimae ------O4 Groupement à Carpobrotus edulis - - - - o+ - o1 - - O2 - O2 Tamaricion africanae ------O4 O2 - O2 Localities: 1-11 Cap Corse. 12 Porto

Subhalophilous and halophilous geopermaseries and minoriseries of Corsica 25

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International Journal of Geobotanical Research, Vol. nº 6. 2016. pp. 27-36

The Place of Geobotany in Geology

(1) Beneah D. ODHIAMBO

(1) University of Venda, Private Bag X5050, Thohoyandou, 0950; Limpopo Province, South Africa. Tel: +27159628587, Mobile: +27607786672,E-Mail: [email protected]; [email protected]

Abstract: Geobotany is the study of plants as related to the geological substrate. In this article, the term geobotany is defined as it is understood and used among the geological fraternity. It is the visual survey and analysis of vegetation in order to discriminate geological differences in the subsurface. This chapter demonstrates the place of geobotany in geology by giving a reflective historical perspective on the use of plants in geology. Geobotany is significant in exploration of mineral resources and is of strategic importance in geologic mapping in vegetated terrain. For this purpose, the uses of plants in mineral exploration, and the entry levels at which plants are used to discriminate geological differences in the landscape are presented. These entry levels include the use of plants for general geological mapping (regional geobotany) purposes, and for specific identification of mineral deposits (indicator or target geobotany). How mineral uptake influences the spectral reflectance characteristics of plants (spectral geobotany) is presented in the last section of the chapter as a geobotanical technique that uses remote sensing technology. This historical review of the place of geobotany in geology, underscores the genesis and paradigmatic shift in research and development through which the discipline has evolved over time.

Keywords: Geobotany, element uptake, spectral reflectance, bioremediation, Kenya.

Introduction research and development through which the discipline has evolved over time. ‘Rocks produce soils in which plants grow’. Geobotany is the study of plants as related to the Definition of Geobotany geological substrate. In this article, the term geobotany is Geobotany encompasses the linkage between geology defined as it is understood and used among the geo- and plants; and specifically how plants as an interphase logical fraternity. It is the visual survey and analysis of are or can be used in geological studies, for example in vegetation in order to discriminate geological differences mineral exploration, in biogeochemical studies, in me- in the subsurface. This chapter demonstrates the place of dical geology and in remote sensing studies, to mention a geobotany in geology by giving a reflective historical few application areas. perspective on the use of plants in geology. Geobotany is In this chapter, geobotany is defined and used from a significant in exploration of mineral resources and is of strategic importance in geologic mapping in vegetated geological point of view; it is the science that deals with terrain. For this purpose, the uses of plants in mineral the visual survey of vegetation in order to identify geolo- exploration, and the entry levels at which plants are used gical differences in the landscape (Malyuga, 1964; Rai- to discriminate geological differences in the landscape nes and Canney, 1980). This visual survey often includes are presented. These entry levels include the use of observations of physiological modifications in plants, plants for general geological mapping (regional such as dwarfism, morphological deformities, and chlo- geobotany) purposes, and for specific identification of rosis (Kovalevsky, 1987). These teratological (Raines mineral deposits (indicator or target geobotany). How and Canney, 1980) changes can occur in individual mineral uptake influences the spectral reflectance plants or whole plant communities. In this regard, geobo- characteristics of plants (spectral geobotany) is presented tany is also concerned with the relationships between the in the last section of the chapter as a geobotanical form, composition and distribution of vegetation com- technique that uses remote sensing technology. This munities and their relationship to environmental factors, historical review of the place of geobotany in geology, particularly in undisturbed terrain (Cole, 1984). Since underscores the genesis and paradigmatic shift in vegetation type and characteristics can change with rock type, vegetation has been used to derive geological infor-

Corresponding author: Beneah D. Odhiambo University of Venda, Private Bag X5050, Thohoyandou, 0950; Limpopo Province, South Africa. e-mail: [email protected] ISSN: 22536302 (print)/ISSN: 22536515 (on line) ©Editaefa DOI: 10.5616/ijgr 160003

28 B.D. Odhiambo mation and to discriminate parent rock material. This is human eye), a realisation that led to the development of because vegetation reflects the interplay of many envi- remote sensing applications in geobotanical studies. It is ronmental factors including the geochemistry of the soil noteworthy that the remote sensing concept was first at the rooting depth, the type of soil, the aspect, and even envisaged by Socrates in c.400 BC, when he observed variations of micro-relief. It is therefore useful for geolo- that “man must rise above the earth's surface, to the top gical mapping and mineral exploration. of the atmosphere, in order to understand the environ- Geobotanical prospecting utilizes the principle of ment in which he lives" (in Odhiambo, 1993). selective adaptation by plants to variations in geological When vegetation becomes stressed and develops a conditions in the subsurface. This includes observations distinct spectral characteristic in the infrared part of the of the presence or absence of certain plant species or electromagnetic spectrum, identification of “spectral vegetation assemblages, observations of changes in anomalies" at the red edge has enabled researchers to abundance and vigor around a dispersion halo, and identify mineralized areas using remote sensing identification of conspicuous morphological modifi- (Singhroy, 1989, and Odhiambo, 1993). cations in individual plants or in a group of plants (Dorr Historical Development of Geobotany et al., 1971). Thus, geobotany is based on the premise that plants, through their root systems, absorb The use of plants in the search for subsurface mineral geochemically available elements from the subsurface resources has been in practice since ancient times. In and thereby reflect the underlying geological conditions Rome, during the reign of Augustus Caesar (63 BC to (Siegel, 1974). 14 AD) the architect Vitruvius stated that water is to be It is important to realize that the term geobotany is sought in areas where certain trees are to be found frequently used to include biogeochemistry. While bio- growing naturally and not artificially planted (Agricola, geochemistry is concerned with the detection of biogenic 1556). Physiological effects of metal on vegetation were haloes of ore indicator elements in living organisms and also observed by Agricola (1556), while Barba described their remains (Kovalevsky, 1987) using rapid and the use of plants for mineral prospecting in Potosi, sensitive analytical instruments (Brooks, 1972), in Bolivia in 1637 (Cannon, 1979). Other significant stu- practice it is difficult to treat geobotany and biogeo- dies that formed the fundamental basis for geobotanical chemistry as being mutually exclusive. This is because in methods of mineral prospecting include the works of virtually all geobotanical investigations it is common Lomonosov (1763) and Kapinsky (1941), both quoted in practice to sample and analyse the vegetal component for Malyuga (1964). In all these studies, emphasis was its constituent metallic elements when attempting to placed on observation of the depauperating effects of determine the “composition" of the subsurface geology. mineralization on whole plant communities. However, it In other words, to ascertain that a plant is indeed a was not until the early parts of the 19th Century that geobotanical indicator species, trace element analysis geobotanists propounded the notion of indicator species must be done in order to correlate the elemental for specific mineral types. Today, more descriptive terms concentration in the plant species with the substrate such as accumulators, specialists, or super tolerant plants geochemistry. Consequently, this trend of thought has are used more freely, caution being taken in declaring reached the point where most researchers consider and plants as indicators of specific mineral types (Cannon, treat geobotanical and biogeochemical methods of 1979). prospecting as constituting a single discipline. This is It is important to underscore what geobotany is appropriate since the absence or excess availability of a understood to mean among geological fraternity. Ques- certain mineral element may result in the anomalous tioning whether ecology, plant geography, and geobota- appearance and/or development of a plant, or even whole ny are three different sciences, or three different view- plant communities. Malyuga (1964) referred to the use of points of the same science and whether one is a part of plants for mineral exploration as the biogeochemical or the others, or if all three are synonymous, Rübel (1927) geobotanical method. The technique is used widely in strived to correct the misunderstandings by non-ecolo- the exploration for ore deposits, in the study of the gists, by discussing what ecology includes in the minds character and depth of groundwater, and even in the of ecologists, what plant geography means to plant geo- determination of the presence of geological structures, graphers, and what geobotany comprehends. Rübel which are often associated with ore deposits. In this (1927) recognized geobotany as that part of botany chapter these terms are used interchangeably. which has to do with gea, the earth, the action of all According to Raines and Canney (1980), the appli- earthly factors, all changes of plants on the earth, and all cations of geobotany can be summarized into three distributional questions over the earth. Essentially what conceptual approaches. First, is the study of plant com- Rübel stated is that geobotany (plant ecology-plant geo- munities, including characteristic florae and specific graphy) is the science of the relationship of plants to the indicator species; second, is the study of vegetation environment, the earth. The article by Tadros (in Vege- density, which includes extreme cases of complete tatio, 1949) entitled, Geobotany in Egypt (A historical absence or presence of vegetation; and third, is the study review) does not attempt to define the term, but proceeds of plant morphology. Each approach involves to use it from a botanical perspective. investigations of the various ways in which individual In the 3rd Edition of the Great Soviet Encyclopedia plants or whole plant communities respond to mineral (1970-1979; in Free Dictionary, 2010) geobotany is re- concentrations in the geochemical environment. It should ferred to as phytogeography, a science concerned with be noted that the response can also affect plants in a non- the Earth’s vegetation as an aggregate of plant commu- visual fashion (i.e., in ways that are not detectable by the nities, or phytocoenoses. Essentially, these positions

The Place of Geobotany in Geology 29 stem from the statement of the German naturalist A. and the caution necessary when attempting to interpret Humboldt, which dates back to the beginning of the 19th the geology of an area using vegetation, particularly with Century, that vegetation is a unique element of nature. It the aid of remote sensing data with little or no ground should be pointed out that in these studies and academic truth and auxiliary data. It is evident from this figure that discourses the use of plants from a geological perspec- a given vegetation community can represent several tive as originally envisaged by architect Vitruvius (in geological conditions. Agricola, 1556) is not addressed. The term geobotany Thus, regional geobotanical remote sensing studies cannot be stretched to include palaeobotany; a view pro- have been met with varying degrees of success. This is pounded in the Great Soviet Encyclopaedia. because the success of the technique depends to a large Recent geobotanical studies have been undertaken in extent on plant response to the varied and complex several countries, especially in New Zealand and environmental factors, from the species level to the Australia (Brooks, 1972), in the Scandinavian countries community level. From the many case studies on (Rune, 1953; Talvite, 1979), USSR (Lomonosov, 1763; regional geobotanical remote sensing research carried Kapinsky, 1941), Canada (Fortescue, 1980; Wagner, et out in different parts of the world, some general trends al., 1989; Singhroy, 1989), and in the USA (Siegel, that can be grouped into three main categories have been 1974, 2013). In Africa, indicator ground-based identified. geobotanical work has been done in Botswana and Namibia (Cole, 1980; 1984; Cole et al., 1986), Zaire (Duvigneaud and Brenan, 1966), and in Zimbabwe (Wild, 1974; Brooks and Yang, 1984). In the East African region, similar studies have also been undertaken with respect to fluorite and chromite mineralization (Odhiambo, 1988; Odhiambo et al., 1989) and in Burundi (Singhroy, pers. comm., 1990). Chromite indicator plants were identified in Zimbabwe by Wild (1974). These plants aided greatly in the exploration and delineation of chromite deposits in that region. The levels at which plants are used to discriminate geological differences in the landscape include the use of plants for general geological mapping (regional geobotany) purposes, and for specific identification of mineral deposits (indicator or target geobotany). How mineral uptake influences the spectral reflectance characteristics of plants is an attribute of spectral geobotany. It should not be over emphasised that these entry levels are at the forefront of the developments in geobotanical applications. These entry levels are briefly discussed in the following sections. Regional Geobotany The term regional (or background) geobotany was introduced by Singhroy (1987) and adopted by Bruce Figure 1: Hypothetical vegetation zonation patterns in Alaska (After, Fortescue, 1980) and Hornsby (1987) in attempts to make the geobotanical concept more applicable in an exploration setting. It relies on the geobotanical concept at the community First is the use of vegetation for general geological level, rather than at the species level. As a result, it does mapping; this is based on the structural factors of not require the use of special sensors onboard an aircraft vegetation response. Second are analyses of the spectral and instead, satellite imagery can be used, thereby response characteristics of whole vegetation commu- reducing exploration costs in terms of data acquisition nities to excess availability (or absence) of certain mi- and processing. The regional concept is based on the neral elements in the subsurface - which leads to spectral premise that the nature and distribution of plant anomalies in the vegetation. Third are observations of communities occur as a result of environmental the taxonomic factors of vegetation response to different conditions and therefore variations in distribution from geological conditions. the established norm for an area may be indicative of The application of remote sensing data and different anomalous changes in the geology. The model, therefore, image enhancement techniques has been used by several requires an understanding of the general ecological researchers in attempts to identify suitable enhancements conditions of an area in terms of the relationships for the digital data that best depict distinct lithological between the bedrock units, the sacrificial materials units. (including soils, topography and plant communities) and In a study undertaken in the Spanish-Portuguese py- the resulting spectral patterns observed on remotely rite belt, Banninger (1985) made a comparison between sensed imagery. Landsat MSS and TM data for geobotanical prospecting. Figure 1 show five hypothetical case studies by In a similar study, Aranoff et al. (1986) used an integra- Fortescue (1980) designed to illustrate the complexity ted approach in which a deposit model, Landsat imagery,

30 B.D. Odhiambo and sacrificial geochemistry were used to develop a in Africa and in the United Kingdom. In this study, procedure for locating tungsten mineralization associated imagery was also used in monitoring the seasonal with shallow buried intrusions. Although in these studies vegetation changes related to water stress in Botswana it was found that the mineralized sites with distinct and the UK. It was found that the detection of mineral geological units and mineralization could be delineated deposits on remotely sensed images depends on the using satellite data, it should be noted that in the identification of the geobotanical anomalies at the classifications used the pixels that were known to fall on community level. In Botswana, it was found that large mineralized areas were given distinct values during geobotanical anomalies that are confined to the ground image classification in order to locate the known sites of layer can be identified on satellite-based remotely sensed the mineral deposits. All the data were represented in the images if the tree canopy is sufficiently open and if form of co-registered images which constituted an image uptake of a toxic element by the trees causes contrasts in data base. reflectance with that of the neighbouring vegetation. Cole et al. (1986) used imagery of differing spectral They also concluded that the size of a deposit is an and spatial resolutions from Landsat MSS, Landsat TM, important factor for detection mineral anomalies in these SPOT and airborne Daedalus II line scanner for studies areas using remotely sensed data. of lithological units and the location of mineralized sites

presented in Plate 2. In this classification most of the

Plate 2: Unsupervised classification Landsat TM in Plate 1: FCC Landsat TM showing the structural geo- which natural vegetation classes (Geobotanical Units) are morphology and geobotanical units West Pokot, Kenya identified unclassified pixels correspond to shadowed areas. Bedell (1987) used edge-detection analysis of satellite imagery for detecting gold deposits in Tanzania. Indicator Geobotany He found that remote sensing can assist the exploration Indicator geobotany recognizes the vegetation com- geologist by differentiating structures both temporally position and/or communities that occur on mineralized and spatially when investigating the frequency and areas as indications of associated mineral deposits. From geometry of edges in plan view. He found that this is a historical perspective, it is emphasised that indicator particularly important when use is made of different geobotany has evolved to include elemental analysis of Gaussian filters and false colour composites of the mineral composition in plants that are associated with multitextural data, as they provide suitable images for specific mineral deposits. In this regard, vast literature lineament interpretation. However, lithological units exists with respect to indicator geobotany. Many works were not discriminated in the study. that have been published by the USSR (Russian) Regional geobotanical techniques have also been Academy of Sciences were extensively reviewed by used for traversing un-mapped geological terrain Cannon (1960); Malyuga (1964); Chikishev (1965); (Singhroy, 1989; Bruce and Hornsby 1987; Bruce, pers. Brooks (1983); Kovalevsky (1987); Cwick (1987); comm., June, 1992) during helicopter surveys in Guyana. Odhiambo (1993). In this regard, the advancements in geobotanical The uptake of chromium and its influence on techniques using remote sensing data for geological vegetation is used in this section to demonstrate the applications lies in the identification of lithological units realm of indicator geobotany. Several researchers (Rune, which have been correlated to distinct vegetation 1953; Proctor and Woodell, 1971; Morton, 1992; Lamb, communities (Plate 1). Image classification can involve 1993) have noted that serpentine rocks have distinct application of standard statistically based decision rules vegetation communities. Indeed, the presence of unu- in order to identify the land cover types for pixels in the sually sparse flora over ultramafic rocks has led to many image. Unsupervised classification can be undertaken studies of the reasons for this apparent infertility. Dating prior to the fieldwork with the objective being of back as far as the 16th Century (in 1583), Caesalpino identifying natural classes that can be recognised and (cited in Proctor and Woodell, 1971) described a plant described in the field. The result of the classification is restricted to the Upper Tiber Valley in Tuscany near Florence, Italy. Such vegetation is sometimes referred to

The Place of Geobotany in Geology 31 as the serpentine barrens (Lamb, 1993). Serpentine soils occurs on the mineralized geobotanical unit, which can have been shown to have very toxic effects on vegetation also be clearly identified on remotely sensed data. The (Malyuga, 1964; Lyon et al., 1968). The chromium species Protea kilimandischarica is a characteristic content of non-serpentinic soils is in the order of indicator of the area around the chromite mineralization. 100µg/g (ppm), whereas in serpentinic soils, chromium It is an evergreen and does not shed its leaves. Satureja values around 5000µg/g (0.5%) are common; however, abyssinica is closely associated with the chromite de- the range varies from 1000 to 25,000µg/g, with the latter posits in the area; its tiny purplish-pink flowers together commonly found in heavily leached tropical serpentine with its sweet minty smell, makes it a conspicuous herbal soils (Jaffre, cited in Brooks, 1987). As a result, these species. The Acacia - Dodonea - Combretum - Ficus ve- soils develop distinct vegetation communities. For getation community surrounding the chromite mine- example, Mouat (1982) observed that the foothills of the ralization is similar to that recorded by Brooks and Sierra Nevada are covered by an open Ceanothus Malaisse (1985) around the Great Dyke in Zimbabwe. chaparral with scattered digger pine (H. sabiniana), They also noted this vegetation community as not being while surrounding metasediments and metavolcanics are exclusive to the known chromium and nickeliferous covered by an oak woodland and grassland. Similarly soils. Miekel (in Mouat, 1982) described serpentine and non- Plate 3 shows a water lily which belongs to the plant serpentine vegetation in the Appalachian Piedmont. family Nymphaeaceae, growing in the mine water in Miekel noted that the serpentine is characterized by a abandoned Pb-Zn mine water was found to contain stunted tree flora with an open canopy dominated by concentration value of more than 10,000ppm lead Virginia pine (Pinus virginiana), post oak (Quercus (Odhiambo, 2014). Since water lily is an apparent stelleta), and blackjack oak (Q. Marilandica). Non- accumulator of lead, it can be effectively used in serpentine flora on the other hand is dominated by a bioremediation of the mine waters that have high lead robust tree flora with a closed canopy often dominated concentrations. The analytical data obtained from the by chestnut oak (Q. prinus L.) and white oak (Q. alba). study justifies detoxification of the mine waters. Proctor and Woodell (1971) stated that the most conspicuous feature of the Lizard Peninsula in Cornwall is the restriction of Minuartia verna to serpentine soils. In the serpentine endemic plants of the Great Dyke in Zimbabwe, Brooks and Yang (1984) reported a maximum chromium concentration of 77µg/g (ppm). Similarly, Jaffre et al. (1979) reported a mean of 45µg/g in 17 species (132 specimens) of Geissois from New Caledonia, where Lee et al. (1977) found less than 10µg/g chromium in plants growing in soils containing up to 1% (10,000µg/g) of this element. Wild (1974a) also recorded high concentration of chromium (2400µg/g) in dried and upto 48,000ppm in ashed leaves of Sutera fodina, a Zimbabwean serpentine endemic. Wild (1974) also found 30,000ppm in the leaves of Plate 3: Water lily (family Nymphaeaceae) in Dicoma niccolifera, and up to 15,000ppm in the leaves Pb-Zn mine waters. of Pearsonia metallifera. Brooks (1987) believed that the very high concentration values of chromium in plant ash Spectral Geobotany could be due to contamination by wind-blown dust from This section elucidates the historical advancement of the Noro chrome mine, since other specimens of the the remote sensing concept that was first envisaged by same species from other parts of the Great Dyke gave a Socrates in c.400 BC. Spectral geobotanical approach in 1 leaves maximum value of only 2µg/g chromium in dried geobotanical remote sensing has also been referred to as (Brooks and Yang, 1984). It should be noted that the target geobotany (Singhroy, 1987). It crystallizes the geochemical conditions (mainly pH and Eh values) may relationships between spectral properties of plants and be completely different in the area where Wild's (1974) the geochemical stress phenomenon. There is a need samples were collected, when compared with the sites therefore to establish an understanding that the where Brooks and Yang (1984) sampled. These geochemical condition of the substrate influences environmental conditions are not stated in either study. spectral reflectance properties of plants (Odhiambo, How the samples were prepared (i.e., whether ashed, or 1993). just dried and then digested) is also not indicated. Today, spectral geobotanical investigations are Geobotanical results, presented by Odhiambo (1993) widely used in geobotany since leaves of healthy, reveal a clear decrease in species diversity from non- actively growing plants produce broadly similar spectral mineralized Precambrian Basement gneisses to mine- reflectance curves (Horler et al., 1980; Goetz et al., ralized serpentine host rocks. Variation in species com- 1983; Milton and Mouat, 1984; Singhroy, 1989). position is exemplified by the characteristic Protea - Spectroradiometers with narrow spectral band working Faurea - Maerua - Satureja vegetation community that in the vegetation reflectance edge (the near infrared

portion, also called the red-edge) of the electromagnetic 1 Researches tend to express results differently (e.g. ppm or µg/g). Samples are also prepared differently. spectrum have been developed in order to measure and

32 B.D. Odhiambo quantify the distinct spectral changes. The variations in identify locations for collecting samples. Transects absorption and spectral reflectance characteristics of should be established in a direction perpendicular to the plants have been related to pigment content, cellular general strike of the lithological units. The data used in structure, and to the moisture content of leaves (Cwick, geobotanical sampling research should be collected 1987). Odhiambo (1993; 2008) used the SE590 during two field seasons that should be selected to Spectroradiometer to analyse spectral reflectance coincide with the driest time (months) of the year when characteristics (from 380nm to 1200nm) of vegetation in vegetation is most stressed, and mineral concentrations relation to mineral concentrations. in the subsurface are at their highest (Cole, 1983; Lyon Hyperspectral (imaging spectroscopy) remote sensing et al., 1982). In both cases the sampling period should is currently being investigated by researchers with regard take as short a time as possible in order to minimise to the detection and identification of minerals, terrestrial climatic variations that might influence element uptake vegetation, and man-made materials. The concept of by plants. Sampling should be during the same time of hyperspectral remote sensing began in the mid-80 and is day to avoid any diurnal climatic impacts on the currently being used widely by geologists for the vegetation. mapping of minerals. In hyperspectral imaging, actual Wet seasons should be avoided since leaching of detection of materials is dependent on the spectral elements from plant leaves may occur (Brooks, 1983), coverage, spectral resolution, signal-to-noise ratio of the and concentrations in the subsurface may be diluted by spectrometer, on the abundance of the material and the the excess water available in the soil due to heavy strength of absorption features for that material in the rainfall. A second reason for the dry season being ideal wavelength region measured (Lee and Landgrebe, 1993). for geobotanical studies is that the atmosphere is rela- The degree of association between chromite tively cloud-free. As a result, conditions for collection of pathfinder elements and independent spectral parameters spectral data are ideal and cloud free satellite imagery is at the red edge of the electromagnetic spectrum raises the easily selectable (Odhiambo, 1993). Finally, fieldwork is question as to whether or not a purely prospective (as not impeded by impassable roads, which can occur opposed to a retrospective) approach to mineral during wet seasons in most tropical environments. exploration using geobotanical methods is feasible. The results presented by Odhiambo (1993) indicate that it is Geobotanical Samples possible both at the general level of interpretation and at the species specific level. In either case, a positive Geobotanical samples should be separated (where correlation implies that as the concentration of an applicable) into twigs and leaves; the reason being that element increases in the sample, the value of the the two plant parts (organs) are known to concentrate independent spectral parameter also increases. different amounts of trace elements. In addition, each Conversely, a negative correlation implies a decrease in sample should be split several times to provide the value of the independent spectral parameter as the replicates. This enables repeated determinations to test concentration of the element increases. the repeatability of analytical results obtained. Standard plant material should be used (or prepared) with which to General Methodology for Geobotanical Studies compare the results from the analyses. Sample preparation in geobotanical trace element The historical aspects of the methodologies used in analysis is of utmost importance, since, for example, the geobotanical studies for mineral exploration are not ashing technique preconcentrates the elements in plant clearly elucidated in the literature surveyed. The material. The concentration levels so obtained are methodology is to be found only in the contemporary usually much higher (sometimes by a factor of about 20 studies summarized in this section. fold) than the values obtained for the same samples when In planning a geobotanical study, the sampling the material has simply been dried and then digested procedures adopted should take into account the (Odhiambo, 1993). potential differences in metal uptake by different plant Several studies (Brooks et al., 1985; Odhiambo, 1988; species and plant parts. In addition, the stages of and Odhiambo, 2015) have shown that strong corre- maturity and seasonal cycles should be considered, as lations exist between soil and plant element conce- recommended by Thornton (1986). This is of practical ntrations. So, when preparing for fieldwork and data importance because in temperate countries the maximum collection, one should endeavour to find out if any "elemental peak" in plants is restricted to the first week previous mineral evaluation studies around the study of spring (Canney et al., 1979; Banninger, 1985). In area had been done. If the results of such a mineral these regions, this factor greatly limits the timing of assessment program are available and the quality of the fieldwork for geobotanical studies. The timing of the results are acceptable for the purposes of the research, studies also has a bearing on the spectral discrimination then no additional geochemical analysis of the soils and of annual and perennial plants in both temperate and rock samples is necessary. It is recommended that only a tropical climates. During the dry season in the tropics, few soil samples may be collected from selected sample annual plants are absent and spectral reflectance from sites (from soil sampling pits) in order to determine the perennial plants becomes more conspicuous on satellite soil pH and Eh, soil organic matter content and soil images. texture, since these physicochemical factors control uptake mineral elements by plants. Normally, a brief reconnaissance survey where Although Malyuga (1964) and Brooks (1972) have transects and sampling plots are established on the recommended that two or three of the more dominant geobotanical units map should be undertaken in order to

The Place of Geobotany in Geology 33 plant species be sampled so that at least one of them is In the chromite mineralization studies undertaken in present at each sample point, experience using a pre- West Pokot District of Kenya, Odhiambo (1993) found selected sampling grid has shown (Malyuga, 1964; that with the exception of manganese, the other mineral Kapinsky, 1941 cited in Brooks, 1972; Brooks, 1984; elements that are associated with the chromite Cole, 1986; Kovalevsky, 1987; Odhiambo et al., 1989; mineralization (the pathfinder elements, namely nickel, Odhiambo and Howarth, 1993a) that geobotanical cobalt, and chromium) are non-essential plant micro- indicator plants are not necessarily the dominant species. nutrients. These heavy trace elements are not known to Thus, all species should be sampled indiscriminately be essential for normal development of vascular plants from each sample point, during the first field season. (Siegel, 1974; Raven et al., 1976 cited in Singhroy, This biogeochemical approach to mineral prospecting 1989). The non-essentiality in plant nutrition is an im- using vegetation is based on the continuum concept portant factor in geobotanical studies since it has also (Elliot, 1983), where vegetation can be used as been shown that the uptake of essential elements (such as biogeochemical samples without the need for mapping calcium, potassium, sodium, phosphorous, and sulphur) vegetation units. Furthermore, with respect to elemental is controlled by plants (Kovalevsky, 1987). In trace uptake by plants, it has been demonstrated (Kovalevsky, element analysis this factor (non-essentiality) usually re- 1987) that some plants are more informative (non- sults in negative biogeochemical anomalies (Odhiambo, barrier) while others are not (barrier type), as illustrated 1988). Availability of the trace elements to plants has in Figure 2. been observed to result in physiological and/or At every pre-selected sample point, plants should be morphological changes in plants due to their toxicity (Cannon, 1960; Malyuga, 1964; Brooks, 1972; Rose et al., 1979).

In plant samples, statistical analyses of the trace element concentrations show typical negative skewness which is characteristic of geochemical data (Siegel, 1974; Al Ajely, 1984). The data can therefore be subjected to standard statistical treatment, in order to establish whether or not the concentration values obtained are true geochemical anomalies within the geochemical environment. Using all the concentration values obtained for each element assayed in a study, statistical threshold levels are calculated to determine the mean element concentration, local background concentration value, and local threshold concentration value for all the elements. The local background value Figure 2: Types of biogeochemical samples (LBV) is determined as the mean element concentration plus one standard deviation, while the local threshold sampled after a careful scrutiny of all the plants at that value (LTV) is the mean concentration plus two standard location in order to observe any visible signs of deviations. Concentration values higher than the local morphological anomalies. Each plant sample should threshold value are considered to be anomalous, as consist of the apical leaves of the plant. In the case of recommended originally by Marmo (1958), Sayala tree species, leaves are collected from several locations (1979), and Rose et al. (1979). Once these thresholds are (limbs or branches) around the canopy. These are then ascertained, concentration plots can be constructed using mixed to make one sample of approximately 10 to 15g in the biogeochemical data (Odhiambo, 1993). Results from weight. This recommendation is based on the result of a study around the chromite deposits in Kenya showed several studies which have shown that the elemental that smoothing biogeochemical data rids it of some content of leaves can vary greatly from one side of a spurious concentration values. Further, known sites of plant to another, depending on the location of the mineral chromite mineralization are clearly depicted and the deposit. There seems to be a longitudinal passage of serpentinite host rock is also clearly depicted by the inorganic material from the roots of one side of a plant to chromium, nickel and manganese anomalies. the limbs on the same side (Cannon, 1964; Singhroy, pers. comm., Feb., 1993). The synthesis of the element concentration plots performed by Odhiambo (1993) using the standard During the second field season, geobotanical smoothing technique shows that, even though the sampling and spectral measurements should be technique rids the data of some spurious concentration undertaken simultaneously. Plants found in proximity to values, it is still fairly accurate in locating the known a mineralized site during reconnaissance and are also in sites of the chromite/nickel deposits, especially when the non-mineralized sites should be sampled. In this case results are compared to those obtained by the sampling can then be focused on the two or three experimental plots. dominant species (as recommended by Malyuga, 1964, and Brooks, 1972) that were found by analyses from first It is concluded that concentrations of the chromite season data to respond well to the mineralization. pathfinder elements in geobotanical samples causes

34 B.D. Odhiambo measurable spectral shifts at the red spectral edge of mineralization shifts the red edge of the associated plants associated vegetation. The spectral response of plants to towards shorter wavelengths. element concentration is species specific since, a given Following from the conclusions presented above, five plant species responds uniquely to mineralization when recommendations made below arise mainly from the compared to another plant species. This observation studies undertaken in Kenya and from observations made concurs with observations made in the works of Masuo- over the years in publications on geobotanical appli- ka (1981), Labovitz et al., (1983) and Singhroy (1989). cations. Secondly, the spectral response of plants is element The first recommendation concerns the lack of specific. In this case, the effects of one element on the standard reference material for use in geobotanical independent spectral parameters were observed to be studies. There are two issues; first is the lack of any unique from those of another element. The chromite adequate reference standards. Secondly there are also no mineralization shifts the red edge of the associated plants towards shorter wavelengths. reference standard samples against which the spectra of different plants and their derived independent spectral Summary reflectance parameters can be compared. The second issue necessitates the identification of an appropriate The importance of selecting pathfinder elements for plant as a reference standard. analysis, together with the need to use high resolution The second recommendation stems from the spectroradiometers for analysis of the spectral reflec- availability of chromium (and other elements) in the tance characteristics of plants for mineral concentration biogeochemical environment. It is evident that the in the subsurface has been underscored (Odhiambo, chromite-tolerant plant species are associated with the 2008). The chromite indicator species were identified on mineralization. Therefore, the general lack of awareness the basis of high accumulations of the pathfinder among exploration geologists and environmentalists, as elements, coupled with their persistent occurrence in to the power of geobotanical research in mineral proximity to the chromite mineral deposits. Results from exploration, and the niche it occupies in environmental West Pokot District of Kenya case study demonstrate biogeochemistry and geoepidemiology raises the need to how chromite deposits can influence the associated carry out further studies. The effectiveness of the vegetation. technique in mineral exploration should be assessed, in The following conclusions are made from the study exploration programs. undertaken in West Pokot District of Kenya. First is the The third recommendation concerns measurement of concern of lack of standard reference material in pH and conductivity (Eh) conditions of associated soils. geobotanical studies. These are essential to ensure the These conditions are not usually presented in the results quality of the biogeochemical data. The second of similar studies. They are essential in understanding conclusion concerns the use of remote sensing since geochemical availability of an element around a mineral mineralized geobotanical unit are unique with respect to deposit. These parameters should always be measured. their spectral reflectance characteristics. It is evident that Similarly, sample preparation technique used should the delineation of geobotanical units is of particular always be clearly presented. This is because, for importance for geobotanical remote sensing studies. The anomalous concentrations of chromium were example, ashing of plant material preconcentrates the found in Satureja abyssinica, Leucas tomentosa, and in elements present in the sample as compared to plant Protea kilimandischarica. In these plants, the amount of material that is simply digested and then analysed. Such chromium does not exceed 500 ppm. These concen- an approach would facilitate comparisons of the trations are much lower than the chromium concentration concentration ranges of chromium (or other elements of values obtained by Wild (1974) from the serpentine interest) in similar geobotanical studies from different endemics around the Noro Chromite Mine area in regions. Zimbabwe. However, they are similar to the values Lastly, spectral geobotanical datasets are usually very obtained by Brooks (1972; 1987) and Brooks and Yang large and should therefore be archived in a "central (1984). Therefore, for purposes of prospective geobo- spectral data bank". This would facilitate quick tanical mineral exploration, the need to identify non- referencing of the spectral reflectance parameters of barrier plants like Protea kilimandischarica, Faurea plant samples from different geographical regions of the saligna and Satureja abyssinica seems critical. world. It is concluded that concentrations of the chromite pathfinder elements in geobotanical samples causes References measurable spectral shifts at the red spectral edge of Agricola, G., 1556: De Re Metallica, (Translated from the first associated vegetation. The spectral response of plants to Latin Edition of 1556) Dover Publications Inc., New York, element concentration is species specific since, a given 1950, 79p. plant species responds uniquely to mineralization when Al Ajely, K.O., Andrews, M.J., and Fuge, R., 1984: Biogeo- compared to another plant species. This observation chemical dispersion patterns associated with mineralized concurs with observations made in the works of porphyrystyle mineralization in the Coed y Brenin forest, Masuoka (1981), Labovitz et al., (1983) and Singhroy North Wales; in Prospecting in areas of glaciated terrain, The (1989). Secondly, the spectral response of plants is Institute of Mining and Metallugy, pp.1-10. element specific. In this case, the effects of one element Aranoff, S., Goodfellow, W., Bonham-Carter, G.F., and Ells- on the independent spectral parameters were observed to wood, D.J., 1986: Integration of surficial geochemistry and be unique from those of another element. The chromite Landsat imagery to discover skarn tungsten deposits using image analysis techniques; Proc. of IGARSS’ Symp., Zurich, Switzerland, ESA SP 254, pp.513-520.

The Place of Geobotany in Geology 35

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International Journal of Geobotanical Research, Vol. nº 6. 2016. pp. 37-55

Plant biodiversity, phytosociology and latitudinal ranges in Sahara meridional and Sahelian regions

(1) (2) (3) (1) (4) Manuel COSTA , Arnoldo SANTOS , Lleonard LLORENS , Pilar SORIANO & Herminio BOIRA

(1) Jardin Botánico. Universitat de València. Spain (2) Jardin Aclimatacion de la Orotava. Tenerife. Spain (3) Universitat Illes Balears. Spain (4) Instituto Agroforestal Mediterráneo. Universidad Politécnica. Valencia. Spain

Abstract: Phytosociological aspects and latitudinal distribution of the main species of Southern and Western Sahara are analysed. From the statistical analysis of the matrix of 98 vegetation samples, five new associations for W. and S. Sahara are proposed. Differential ecological characteristics and distribution areas are reported. Ass.Tetraenetum gaetulae include subhalophilous species in coastal areas and dunes of the W Sahara (Mauritanie). Launaeo nudicaulis-Pergularietum tomentosae include characteristic species of the ergs in W Sahara; Boscio salicifoliae-Combretum micranthi constitute a transit community from the savannah to the desert with an irregular belt in the Sahelian-Sudanian area; associations Salvadoro persicae-Leptadenietum pyrotechnicae and Fagonio olivieri-Aervetum javanicae are typical plant communities in the ergs, regs and general plain sand areas of the meridional Sahara. A relation of the species and communities with latitudinal ranges, climatic data and soil characteristics has been established. A new phytosociological class, Panico turgidi-Acacietea raddianae, and order, Panico turgidi–Acacietalia raddianae, are proposed by grouping the last four associations. The differential values of the taxonomic biodiversity index and biotypes among the Sahelian, Saharan-Sudanian and hyperdesertic Saharan-Sudanian regions are also reported. Ethnobotanical aspects, such as plant use, nutritional, medicinal and domestic resources, are cited. Keywords: Sahara, erg, regs, phytosociology, corology, biodiversity.

Introduction Previous works into plant geography, particularly of sandy dunes and regs, have led to floristic catalogues Studies about Saharan vegetation (Quézel, 1958, 1965, 1969) emphasise that no flora has been defined to different with synthetic assays for interpretation purposes. biogeographical regions, nor clear bioclimatic differen- As pointed out in several studies (Quézel & Simon- tiation. Extreme dry conditions allow certain bioindicator neau, 1962; Killian, 1960), the proposal of one phytoso- species to colonise on sandy dunes, soil (ergs), rocky ciological scheme from floristic affinities of vegetation sandbanks (regs, desert area covered with coarse gravel samples and published floristic catalogues presents great and small stones) and mountain slopes. difficulty. The numerous studies conducted on meridional Saha- The principal biogeographic delimitation of desert ran vegetation have focused principally on areas of high zones has been established from the mean values of mountains, their valleys, and formations about isolated annual precipitations of around 200 mm. When consi- wet areas. The best known flora and communities corres- dering the immense domain of the Saharan Arabian de- pond to the massifs of Tibesti (Marie & Monod, 1950), sert and other factors that determine water balance, the L’ Air (Bruneau de Mire et Guillet, H., 1956); L’ Enedi limits can also be defined by 100-mm isohyets (Ozenda, (Guillet, H., 1968) W. Sahara (Guinochet, M. et Quézel, 1983). These limits do not presuppose any exact corres- 1954; P. Quézel, P. et Simonneau, P. 1960, 1962). pondence with the chorology of certain plant species, Nevertheless, phytosociological studies done in big and other ecological factors, like soil properties or geo- sandy areas (ergs, regs, oueds, etc.) have considered a morphology, can determine their extension and form. relatively small sampling area, and have been limited to Numerous studies have been done on the bioclimatic isolated proposals of communities without the floristic and floristic Saharan domain, and many have defined its relations that allow phytosociological relations and northern area (Barry et Celles1973; Barry et Faurel 1974; syntaxonomical unities to be established. Rossetti 1963; Monod 1957).

Corresponding author: Herminio Boira. Instituto. Agroforestal Mediterráneo. CPI. Universidad Politécnica de Valencia. Cno. Vera 14, 46022 . Valencia. (Spain). email: [email protected].. ISSN: 22536302 (print)/ISSN: 22536515 (on line) ©Editaefa DOI: 10.5616/ijgr 160004 38 M. Costa, A. Santos, L. Llorens, P. Soriano & H. Boira

Presence of the Atlas mountain range, especially its (Capot-Rey 1952). Bioclimatic islands appear exceptio- southern faces, determines that Saharan conditions settle nally in the mountains of central Sahara (Aïr, Adrar Ifo- abruptly along the whole Morocco-Algerian slope. To ghas, Ennedi, etc.) the south of Djelfa (Algeria), the high reliefs (1600 m) Absence of mountains along the whole frontier with maintain moderate precipitation and temperature condi- tropical forest determines a progressive change towards tions, and permit presence of aleppo pine (P. halepensis) typical Saharan vegetation over a wide area of the tran- and typical Mediterranean health (garriga) sition Sahelian-Sudanian region in which man tropical However at a short distance and at lower latitudes, savannah species, such as Acacia sp., plant grasses and climatic variables begin to define a desert climate. In La- palms (Capot-Rey 1952) are frequent, and sometimes ghouat (N. Sahara, Algeria), annual precipitation values dominant. Fewer studies have been conducted in this area are 150 mm and temperatures reach an average mean of than those done on the northern limit. However, we intend around 25ºC, while the mean precipitation value in Lar- to establish a limit by following the dispersion areas of geau (N. Chad) does not reach 20 mm. species like Cornulaca monacantha (S limit) and Cenchrus When applying the xerothermicity index (Bagnouls ciliaris (N limit) and, if applicable, they coincide consi- and Gaussen, 1953) to this fringe, the limit of the Sahara derably with the 150 -m isohyet. on its northern slope can be determined by the index curve 300, and comes very close to previous limits. Ho- This work aims to establish the principal plant asso- wever, we consider that new bioclimatic indices should ciations of S and W Sahara regions, bioclimatic typifica- be applied as they would establish a better relationship of tion and their phytosociological relationships with their species and vegetation with temperature, precipitation floristic and biogeographic data. and seasonality. Study area From the chorological view point, several authors (Ozenda 1983; Capot-Rey 1952; Le Houérou 1968) have Floristic and biogeographic data were obtained from proposed the fringe at which esparto grass (Stipa tena- eight itineraries (N–S) across Western and Southern Sa- cissima) disappears, or that at which fructification of hara through four expeditions between 1996 and 2005 date palms (Phoenix dactylifera) is not complete at the (Fig. 1), including the Sahelian-Sudanian and Saharan- northern limit of the Sahara. These references possess a Arabian regions of Niger, Mauritania, Mali, N. Burkina relative value due to both the biological plasticity of Faso and Chad (African subkingdom, Good, 1964; Ri- other species and the irregularity of the physical environ- vas-Martínez & al., 1999). The characteristic taxa of the mental. Sudanian-Sahelian and Saharan-Arabian units were de- The semiarid southern border of the Sahara in wes- termined and data on their latitudinal limits are reported. tern and central Africa has more imprecise limits. From Use of biodiversity, evaluated in the floristic and the bioclimatic viewpoint, enough consent has been biological data, is the object of the ethnobotanical refe- reached to admit the 200-mm isohyet as a boundary line rence.

Figure 1. Study transects across the Sahelian-Sudanian and Saharan- Arabian regions of Mauritania, Mali, Burkina Faso, Niger and Chad.

Plant biodiversity, phytosociology and latitudinal ranges in Sahara meridional and Sahelian regions 39

Material and methods Nouadhibou, (Mauritania), Faya-Largeau (Chad) using a 30-year record period. The areas of both vegetation samples (Fig. 1) and the Floristic α-biodiversity (Shannon & Weaver, 1949) main bioindicator taxa were recorded by GPS devices in was calculated from the abundance values of species UTM units. Data were processed to establish latitudinal (Raunkaier, 1937). dispersion ranges, the extreme values for each species The references of the plant resources used for popu- and the delimitation of the associations area. Plant names lation and indigenous tribes were based on both the bi- in text follow The Plant List. Vegetation samples were bliography and the observed or directly obtained data. collected by the Sigmatistic method (Braun-Blanquet, 1964). In spite of the difficulty of applying this method Results to Saharan vegetation (Ozenda, 1983), a syntaxonomical The study, which was carried out in two biogeogra- outline based on numerical data processing and the com- phic regions, was related to the ?bioclimatic characteris- munity proposed in previous works was obtained. The tics according to the thermicity index (It= 813), and also phytosociological analysis was carried out with specific to the general ombrothermic (Io= 0.05-3.28) and ombro- osftware (Pc.-Ord V. 6, Twinspan, 2011) after elimina- thermic dry period (Iod = 0.0-0.06) (Rivas-Martínez & ting all the inventories of poorly present species, which 2 al., 1999). The Saharan-Sudanian region has a bioclimate did not contribute significant information, and after that is tropical xeric, infratropical semiarid (Fig. 2), with applying euclidean distances and Ward´s method for the loose forest, thorny tree and shrubs (savannah, Sahel). linkage groups of relevés. The Saharan-Arabian region has a Mediterranean hyper- The edaphohygrophilous communities of “gueltas” desertic (Mehd), inframediterrannean (ime) macroclima- and plains were also excluded as mountain vegetation. te, and also a bioclimate between hyperarid (har) and ul- Vegetation areas were characterised by bioclimatic trahyperarid (uha). In this bioclimate, vegetation corres- indicator indices, such as thermicity (It) and ombro- ponds to infratropical hyperarid desert with sparse vege- thermic (Io, Iod ) (Rivas-Martínez 2008). The values of 2 tation (S and W Sahara) or perennial halophytic steppes the bioclimatic indices were calculated from the climatic in littoral areas of the W Sahara (Rivas-Martínez 2008). data that corresponded to eight localities in the studied Samples of vegetation have been reported in 160 areas (Agadez, Bilma and Niamey (Niger), Uagadugu inventories, including 140 species. (Burkina), Bamako (Mali), Tinduf (Argelia), Atar and

Figure 2. Characteristic bioclimograms of the studied areas in the Saheliana-Sudaniana (Tropical xeric, Niamey) and meridional Saharan-Arabian (Tropical hyperxeric, Bilma) regions

Biogeographical trends glutinosum, Guiera senegalensis and Anogeissus leiocarpa often present together with other elements also The mean values and range of species’ latitudinal dis- from the savannah, like Hyparrhenia hirta and Eleusine tribution (e.s.) was calculated from the GPS-recorded indica, among others. A more restricted distribution of coordinates in the inventories (Fig. 3). Commiphora pedunculata and Caralluma dalzielii can The most significant taxa in the Shaelian-Sudanian be found in areas of central and western Sahel. region (13º-16ºLN) belong to the driest facies of the sa- Species, such as Acacia seyal, Boscia senegalensis vannah forest: Cenchrus biflorus, Faidherbia albida, and Capparis decidua, surpass 16ºLN. in spite of their Leptadenia lancifolia, Hyphaene thebaica, Acacia nilo- optimum sahelian, around which the northern limit tica, Boscia octandra and Bauhinia reticulata. They are seems to be established. This is because they grow pre- accompanied in transition areas by characteristic species ferably in the centre-oriental areas of the studied territory of the tropical savannah, with species of the family (Mali, Chad), where the Sahelian-Sudanian domain Combretaceae (Combretum micranthum, Combretum

40 M. Costa, A. Santos, L. Llorens, P. Soriano & H. Boira northwardly draws a lobe, which reaches 18º LN, exclu- lanatus, Leptadenia pyrotechnica and Stipagrostis plu- ding the massif of Ennedi. These chorological conside- mosa). rations reaffirmed the limits shown on the vegetation The Saharan-Arabian region, as a synthesis of clima- map of southern Sahara (Quézel et al. 1964). te, flora and vegetation, is characterised by the domain of The transition from the Sahelian-Sudanian region to species with a wide latitudinal spectrum. Nevertheless, the Saharan-Arabian one (Fig. 2) is gradual and, except the optimal area lies between 16º and 20ºLN. Further the western area of Mauritania, characteristic savannah north, species become poor and flora is represented by species do not surpass 16ºLN. limited taxa with a marked hyperxeric character (Salsola In the vegetation samples and records of this region, vermiculata, Nucularia perrinii, Cornulaca monacantha frequent pan-Saharan species are strongly present when and Fagonia olivieri) which, according to our records, latitudes surpass 16ºLN. (Acacia tortilis, Balanites reach 22.5ºLN in the areas surroundings Taudemi (Mali). aegyptiaca, Maerua crassifolia Acacia flava, Citrullus

Figure 3. Latitudinal ranges of principal species of the Sahelian and Saharan meridional vegetation. (*) Characteristic species of sintaxonomic unities

Figure 4. Biotypes ranges (a) and floristic biodiversity (b) in Saharan and Sahelian vegetation. MF, macrophanerophytes; F, phanerophytes; NF, nanophanerophytes; Ch, chamephytes; H, hemicriptophytes; T, terophytes

Plant biodiversity, phytosociology and latitudinal ranges in Sahara meridional and Sahelian regions 41

The typical species of the Saharan area are Ziziphus cially Panicum turgidum and Acacia tortilis subsp. lotus, Chrozophora brocchiana, Salvadora persica, raddiana. These plants are tolerant to different xeric bio- Aristida caerulescens, Stipagrostis pungens, Calotropis climates and possess a high capacity as nitrogen-fixing procera and Indigofera stenophylla. agents and improve degraded soil (E. Le Floch, M. Grou- In the western regions of the Sahara (Mauritania), the zis, 2003). transition from the savannah to desert areas occurs with With very little floristic affinity to the previous four less presence of differential species, according to the flo- associations, the community with Tetraena gaetula, Ta- ristic records obtained. The oceanic influence stresses the marix amplexicaulis and Nitraria retusa, along the coas- dryness conditions and allows the presence of Saharo- tal dunes of Mauritania, is characteristic of sandy and Macaronesian and Mediterranean species. Unlike central saline habitats. regions, three biogeographical unities range from north The vegetation of NW Sahara (Mauritanie) shows to south: a) Saharo-Mediterranean, with characteristic major floristic differences with previous ones, among species like Ziziphus jujuba, Lycium intricatum, Ziziphus which Launaea nudicaulis and Pergularia tomentosa are lotus, Launaea nudicaulis and Caylusea hexagyna. highlighted. Unlike previous reports (Monod, 1944; Barry & al., 1987), From the results based on floristic distances, five new these regions in the present study reached southern limits associations are proposed: Tetraenetum gaetulae, Lau- at around 20ºLN, close to the coast; b) Saharan-Arabian naeo nudicaulis-Pergularietum tomentosae Boscio Sali- regions (18ºLN - 20ºLN.); c) the Sahelian-Sudanian re- cifoliae-Combretum micranthi, Salvadoro persicae-Lep- gion, between Mauritania and Senegal, which extends tadenietum pyrotechnicae and Fagonio olivieri-Aervetum along more regular limits (up to 15ºLN). javaniae The last four are included in the Ord. Panico turgidi-Acacietalia raddianae (nova), Cl. Panico turgidi- Chorology and Biodiversity Acacietea raddianae (nova). Despite the extreme environmental conditions, floris- I. SARCOCORNIETEA FRUTICOSAE Br.-Bl. &Tüxen ex A. & tic Saharan-Arabian biodiversity (Fig. 4) reached values O. Bolòs 1950 of 2.01, and 2.11 for Sahelian-Sudanian biodiversity. The principal difference between these two Ia. Salsoleto-Nitrarietalia P. Quézel 1965 biogeographical sectors was due more to biological Ia.1 Limoniastreto-Zigophyllyllion P. Quézel 1965. forms than to number of species. Under more extreme Ia.1.1 Tetraenetum gaetulae associatio nova hoc loco. conditions, the floristic biodiversity of the hyperdesertic Type releve (holotypus): Table 1, releve nº 2; subass. Saharan region was markedly insobra una ferior (Ibf euphorbietosum balsamiferae nova, holotypusTable =1.49). 1, rel.14; subass. frankenietosum hirsutae nova, The biodiversity of biotypes expressed more outstan- holotypusTable 1, rel. 16. dingly the changes noted among the studied floristic regions (Fig. 4a). Loss of biodiversity (Fig. 4b) became A subhalophilous plant community in the ergs that more patent between the Sahelian (Ibf = 1.55) and Sa- border the sabkhas and steppic habitats around the oueds haran (Ibf = 1.12) regions and drastically fell to lower depressions along the west Sahara. The association presents certain floristic analogies with formerly studied values in the hyperdesertic areas (Ibf = 0.86). Phanero- communities in the NW region of the Sahara (Maire, phytes (s.l.) were generally dominant in the sahelian 1957; Quézel, 1965). region, while chamephytes and therophytes dominated in Taking into account previous observations about the desert regions. phytosociological groups for the halophyle vegetation of Plant communities the Sahara, we include the association in the Salsolo- Nitrarietalia order, with a broader floristic and ecolo- Desertic plant associations have decisive ecological gical spectrum than that of Juncetalia maritimi for factors in the topographical characteristics of the terrain Sahara W., and in the Al. Limoniastreto-Zigophyllyllion, and soil properties. Lack of biotic relationships and cli- to which it has the best floristic affinity (Tetraena sp, matic severity does not allow any type of succession and Zigophyllum sp. Suaeda vermiculata, Tamarix amplexi- dynamism (Rivas Martínez 2008). caulis etc., Table 1). Independently of the hierarchical treatment that can Characteristic species (Salsola vermiculata, Nitraria be attributed, it is necessary to point out the difficulties retusa and Tetraena gaetula subs. waterlotii) colonise of distinguishing associations, such as syntaxonomical soils of variable salinity (1.2-2.5% of soluble salts). unities, in spaces in where it is hard to find phanero- Accordingly this factor proposes two sub-associations: phytes and other perennial species with indicative values. euphorbietosum balsamiferae, (Type relevé (holotypus): The phytosociological studies conducted in the Algerian Table 1, relevé no. 14), typical of maritime sands with subhalophylous species (Tetraena simplex, Tamarix Sahara (Girgis, 1970; Barry et Faurel, 1974) have shown amplexicaulis) and frankenietosum hirsutae (Type relevé the low floristic consistency of communities, where cha- (holotypus); Table 1, relevé no. 16) in sublittoral areas racteristic species have a low probability (p ≤ 0.1) of with markedly halophyte species (Frankenia hirsuta and being found in all the relevés. In our study, the synthetic Suaeda vermiculata). table (Tab. 6) indicates a relatively high presence for These communities cover the wadis of valleys with characteristics species (above 75%). lower salinity than their beds (with Arthrocnemum sp., The phytosociological unities, which are the result of Salicornia sp., etc.). This association extends by coastal a statistical process using a matrix of presence-abundan- sand dunes and valleys near the Mauritania littoral, from ce values, provided us with four interrelated groups for Nouadhibou (N) to Tiouilit, Nouakchott and Tiguent (S) Saharan species with a wide chorological range, espe- (Fig. 5 A).

Table 1.- Tetraenetum gaetulae ass. nova hoc loco subass. euphorbietosum balsamiferae nova hoc loco (rel. 9-14). ; subass. frankenietosum hirsutae nova hoc loco (rel. 15-18). (Limoniastreto-Zigophyllion, Salsoleto-Nitrarietalia, Sarcocornietea fruticosae) Altitude (m.a.s.l) 265 514 285 332 325 270 448 190 306 260 450 260 245 95 110 190 270 265

Area m2 100 200 200 100 100 200 100 200 200 200 100 200 100 200 100 200 100 100

Cover (%) 60 70 75 55 40 40 30 75 65 50 50 50 50 60 45 20 60 50

Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Ip Characteristics species:

Tetraena gaetula subsp. waterlotii 4 1 + 4 3 3 3 1 3 1 3 2 1 3 + 3 3 3 V Charac. All., Ord and Cl.: Tamarix amplexicaulis - 1 4 - - 1 - 4 3 3 1 ------III Nitraria retusa - 4 2 - - + - 2 - - - - 1 1 - - - - III Calotropis procera - + + - - - - + 1 + + + ------III Charac. subassociation euphorbietosum balsamiferae

Euphorbia balsamifera ------1 1 2 3 3 3 - - - - III

Tetraena simplex ------2 1 - 1 2 1 - - - - III Cenchrus biflorus ------1 2 - 1 - + - - - - II Stipagrostis plumosa ------1 1 - 1 ------II Farsetia stylosa ------1 1 - - - 1 - - - - II Salvadora persica ------+ - - 1 1 - - - - - II Charac. subassociation frankenitosum hirsutae

Frankenia hirsuta ------1 2 - 1 II Suaeda vermiculata ------1 2 1 II Atriplex glauca ------3 1 - 1 II Bassia tomentosa ------1 1 1 II

Other species: Cistanche tubulosa 1 in 2; Salsola vermiculata + in 8; Launaea nudicaulis 1, Heliotropium bacciferum 1 in 9; Maerua crassifolia + in 12; Lycium intricatum + in 13; Panicum turgidum 1 in 14; Lotus glinoides + in 15. Localities.- Mauritania. 1: 20º46'20''N 17º02'44''W; 2: 26º39'32''N 09º0'51''W; 3: 18º37'22''N 15º38'19''W; 4: 18º37'22''N 15º38'19''W; 5: 18º51'54''N 16º09'20''W; 6: 26º36'05''N 09º06'11''W; 7: 27º21'01''N 08º14'54''W; 8: 17º36'02''N 16-01'10''W; 9: 17º41'42''N 15º59'58''W; 10: 20º55'46''N 13º11'23''W; 11: 22º40'52''N 13º11'18''W; 12: 23º27'50''N 12º45'40''W; 13: 18º37'22''N 15º38'19''W; 14: 17º-12'-17''N 16º04'41''W; 15: 20º55'46''N 13º11'23''W; 16: 19º08'27''N 14º59'41''W; 17: 19º40'18''N 14º17'17''W; 18: 20º05'44''N 13º44'59''W. M. Costa, A. Santos, L. Llorens, P. Soriano & H. Boira H. & P. Soriano Llorens, L. Santos, M. A. Costa,

Plant biodiversity, phytosociology and latitudinal ranges in Sahara meridional and Sahelian regions 43

Photo 1.- Halophilous post littoral comunnity (Tetraenetum gaetulae) with Frankenia hirsuta, Suaeda vermiculata, Launaea nuducaulis and Pergularia tomentosa as dominant species. Nouakchot, Mauritania

Photo 2.- Community with Acacia tortilis subsp. raddiana, Panicum turgidum, Launaea nudicaulis, Lycium intricatum (foreground) and Pergularia tomentosa, as characteristic species. Typical of the ergs and W. Sahara dunes, Mauritania. (Ass. Launaeo nudicauli-Pergularietum tomentosae).

II. PANICO TURGIDI-ACACIETEA RADDIANAe classis nova progressive presence of Sahelian characteristic tree hoc loco. species, such as Ceiba pentandra, Adansonia digitata, Typus nominis: Panico turgidi-Acacietalia raddianae. Acacia nilotica and Combretum sp. Northwardly, hyperarid conditions determine low diversity with the charac- II.1. Panico turgidi-Acacietalia raddianae ordo novus teristic presence of Fagonia olivieri, Aerva javanica and hoc loco. Stipagrostis pungens as the best indicators. Typus nominis: Panico turgidi–Maeruion crassifo- The classic characteristic species are: Panicum turgi- liae. dum, Acacia tortilis subsp. raddiana, Stipagrostis plumo- II.1.1. Panico turgidi–Maeruion crassifoliae alliance sa, Schouwia purpurea, Maerua crassifolia, Heliotro- nova hoc loco. pium bacciferum, Lycium intricatum, Gymnocarpos These classes show a widespread distribution, princi- sclerocephalus, Asteriscus graveolens, Combretum sp. pally throughout the Saharo-Arabic (Saharan-Arabian) and Calotropis procera. region, from a Saharo-Mediterrannean hyperdesertic to a Sahelian xeric and hyperxeric bioclimate. II.1.1a. Launaeo nudicaulis-Pergularietum tomentosae They represent the characteristic vegetation of ergs, associatio nova hoc loco regs and sand soils. They are present in areas of central Most characteristic species are scattered in Western and southern Sahara, where some communities mark the and Central Sahara, but some (Andrachne telephioides, border with the Sahel (Boscio salicifoliae–Combretum Pergularia tomentosa, Launaea nudicaulis, etc.) have a micranthi). The transition to southern areas shows the distribution restricted to the erg plains of Mauritania

Table 2.- Launaeo nudicaulis- Pergularietum tomentosae ass. nova hoc loco (Panico turgidi–Maeruion crassifoliae, Panico turgidi–Acacietalia raddianae, Panico turgidi-Acacietea raddianae) Altitude (m.a.s.l.) 445 224 315 223 220 270 327 430 432 395 420 426 460 420 315 264 112 295 295 295 285 304

Area (m2) 400 200 400 400 600 400 600 400 200 200 400 200 200 400 400 600 200 200 200 400 400 200

Cover (%) 80 55 90 80 85 40 70 40 20 20 85 55 65 85 80 85 95 90 60 90 95 90

Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Ip Characteristics species:

Launaea nudicaulis + + + 1 1 1 1 2 1 . 2 2 2 1 1 2 . . . 1 . . IV Pergularia tomentosa . . 1 + . 1 1 1 1 1 1 . . . + 1 . 2 2 . 1 1 IV Characteristics of All. and Ord.:

Asteriscus graveolens 1 1 1 1 2 1 + . . 1 1 ...... III Echium humile . . 2 1 1 1 ...... + . . . . 1 . . . III Asphodelus tenuifolius 1 . 3 . 1 2 . . . + . . . . . 1 ...... III Lycium intricatum ...... 1 . . 1 . . 2 3 1 ...... II Cullen plicatum . . . 4 . 1 . . . . 2 ...... 1 + II Gymnocarpos sclerocephalus . . . 1 1 1 ...... 1 . . . 1 . . . . II Characteristics of ord. and class:

Panicum turgidum . 1 3 2 2 . 3 . . . 2 1 2 2 1 3 4 3 + 3 3 2 V

Acacia tortilis subsp. raddiana + . 3 + 1 + 2 1 2 2 3 . + 1 2 1 . . . 3 2 + V Heliotropium bacciferum . 2 . . 1 1 2 . . 1 . . . 1 . 1 1 . . 1 . 1 III Salvia aegyptiaca . . 1 . 1 1 2 ...... + . . . 1 . . . III & H. Boira H. &

Anvillea garcinii subsp. radiata . . 1 . . . . . 1 . + . 1 + . + ...... III Maerua crassifolia ...... + . . 1 . . . . . 2 2 II Citrullus lanatus ...... 1 . . . + . . . . . + . . . . + II Stipagrostis plumosa . + ...... 1 . . . . 3 II Schouwia purpurea . . . 1 3 + ...... II Companion:

Haloxylon salicornicum ...... 1 + 1 3 ...... II Nucularia perrinii ...... 1 1 2 . . 3 2 . . II Salsola vermiculata 2 ...... 2 1 1 ...... II Farsetia stylosa ...... + . 1 . . 2 3 . 1 . . II Tetraena gaetula subsp. waterlotii 2 3 ...... + . 1 ...... II

M. Costa, A. Santos, L. Llorens, P. Soriano Llorens, L. Santos, M. A. Costa, Andrachne telephioides . . + . 1 1 . . . + ...... II

Caylusea hexagyna . . 1 . 1 1 ...... 1 ...... II 44

Euphorbia calyptrata . 1 1 1 1 ...... 1 . . . 1 . . . . III Tetraena simplex . . 1 . . . 1 ...... 1 ...... II Ziziphus lotus ...... 3 ...... + . 3 3 II Lotus glinoides 1 1 1 . . . . + . . . . . 1 ...... II Gymnocarpos decander ...... 1 ...... 1 1 ...... II biodiversity,Plant phytosociology and latitudinal inranges Sahara meridional and regions Sahelian Cotula cinereum 2 1 . . . + ...... + ...... II Trichodesma africanum ...... + . . 1 . . . . 1 . . . II Atractylis aristata . . 1 . . 1 ...... + + . . II Cleome paradoxa ...... 1 . . . . + II Searsia tripartita ...... 2 . . . . . 2 2 ...... II Anastatica hierochuntica 3 . . . 1 + ...... II Atriplex halimus ...... 1 1 1 ...... II Ephedra alata ...... 1 1 1 ...... II Paronychia arabica . . 1 . . 1 ...... 1 ...... II Asparagus altissimus ...... 1 . . . . . 1 + ...... II Convolvulus trabutianus ...... + + ...... II Fagonia arabica . . . . . + ...... 2 . . . . . II Nitraria retusa ...... 1 . . . . . 1 ...... II Piptadenia flava ...... + . . 1 II

Other species: Pulicaria undulata 1, Aristida caerulescens 1, in 3; Euphorbia balsamifera 1, Indigofera colutea 1, en 18; Neurada procumbens, 1 in 21; Fagonia oliveri 1, Senna italica +, in 23. Localities.- Mauritania. 1: 26º36'05''N 9º06'11''W; 2: 24º10'51''N 11º51'18''W; 3: 25º04'45''N 11º28'26''W; 4: 24º10'51''N 11º51'18''W; 5: 24º10'51''N 11º51'18''W; 6: 26º09'47''N 10º35'16''W; 7: 22º52'41''N 12º49'06''W; 8: 26º39'32''N 09º00'51''W; 9: 26º39'32''N 09º00'51''W; 10: 26º19'50''N 09º37'28''W; 11: 26º19'50''N 09º37'28''W; 12: 26º19'50''N 09º37'28''W; 13: 26º9'28''N 10º33'21''W; 14: 26º09'47''N 10º35'16''W; 15: 26º09'47''N 10º35'16''W; 16: 22º52'41''N 12º49'06''W; 17: 20º05'44''N 14º44'59''W; 18: 22º11'01''N 13º08'24''W; 19: 22º11'01''N 13º08'24''W; 20: 26º08'47''N 11º51'18''W; 21: 22º11'01''N 13º08'24''W; 22: 20º57'13''N 13º10'58''W.

46 M. Costa, A. Santos, L. Llorens, P. Soriano & H. Boira

Table 3. Boscio salicifoliae-Combretum micranthi Panico turgidi–Maeruion crassifoliae, Panico turgidi–Acacietalia raddianae, Panicoturgidi-Acacietea raddianae. Altitude (m.a.s.l.) 310 315 290 285 270 265 275 280 290 375 390 450 2 Area m 200 300 300 350 400 300 300 400 300 400 200 400 Cover (%) 45 60 45 40 60 35 55 50 45 55 20 70 Number 1 2 3 4 5 6 7 8 9 10 11 12 Ip Characteristics species: Combretum micranthum 1 1 1 1 1 1 1 1 1 1 . 1 V Boscia salicifolia 1 . . 1 1 1 1 1 1 1 1 . V Adansonia digitata 1 1 . . . . . 1 1 1 + . IV Combretum glutinosum . 1 . 1 1 1 1 1 1 1 . . III Ceiba pentandra ...... 1 1 . + . III Anogeissus leiocarpa 1 ...... 1 1 . . III Commiphora pedunculata 1 . 1 ...... 1 . 3 III Eleusine indica . 1 1 . . . 1 . . . . . III Ficus cordata . . . . 1 1 1 . . . . . III Bauhinia reticulata . 1 . . . . . 1 . . . . II Hyparrhenia hirta . . 1 . 1 . 1 . . 1 . . III Heteropogon contortus 1 . 1 ...... II Characteristics All. and Ord.: Balanites aegyptiaca 1 1 1 1 1 . 1 . 1 1 2 1 V Faidherbia albida . . . . . 1 . 1 . . . . II Indigofera colutea . . . . 1 1 ...... II Calotropis procera . . 1 1 ...... 2 2 III Acacia nilotica . 1 . 1 1 1 ...... III Guiera senegalensis 1 1 . . . . . 1 . 1 . . III Ziziphus jujuba . 1 . 1 . 1 1 . 1 1 . 1 IV Characteristics of Class: Acacia tortilis subsp. raddiana . 1 1 1 . 1 1 1 1 1 1 1 V Maerua crassifolia . 1 1 . . . . 1 1 1 . 1 IV Companion: ...... Euphorbia balsamifera . 1 1 1 1 . . 1 1 . . . IV Acacia seyal 1 1 . . 1 . . . . . + 2 III Leptadenia lancifolia . . . 1 . . 1 1 . 1 . . III Cenchrus biflorus . 1 1 . . . 1 . . 1 . . III Leptadenia pyrotechnica . . . 1 1 ...... II Piptadenia flava . . . . 1 . . . 1 . . . II Aristida caerulescens . . . . 1 . 1 . . . . . II Other species: Panicum turgidum 1 in 2; Chrozophora brocchiana 1 in 3; Boscia senegalensis 2 in 12. Localities.- Mali: 1: 12º 56' 07'' N, 01º 04' 42'' W; 2: 13º23'59''N 1º00'23''W; 3: 13º33'16''N 0º17'27''W; 4: 17º39'40''N 3º9'37''W; 5: 17º53'11''N 3º16'43''W; 6: 17º8'26''N 3º11'17''W; 7: 16º35'29''N 2º58'06''W; 8: 16º8'33''N 2º52'30''W; 9: 15º55'2''N 2º33'34''W; 10: 15º41'28''N 2º31'56''W. Tchad: 11: 13º40'11.6''N 16º24'27.4''E. Niger: 12: 15º58'06''N 06º58'16''E

Photo 3.- Vegetation of the big sandy areas (erg, regs, oueds and sand plains around the mountains) with nanophanerophytes as Salvadora persica, Balanites aegyptiaca and grasses as Leptadenia pyrotechnica and Panicum turgidum (Ass. Salvadoro persicae-Leptadenietum pyrotechnicae). Erg of Iferouane, Niger.

Plant biodiversity, phytosociology and latitudinal ranges in Sahara meridional and Sahelian regions 47

This syntaxon has a good floristic likeness to the ass. It is the characteristic formation of the big sandy Acacia raddiana, Panicum turgidum and Foleyola billo- areas of the ergs and regs of the Meridional Sahara in- tti proposed by Guinet and Sauvage (1954), and by cluding the oueds and lower sand areas around big Quezel (1961, 1965) for the NW Sahara (oueds and erg mountain massifs. of the hamadas, south Morocco). Moreover, the nume- Previously, Quezel (1961) proposed for the vegeta- rous presence of optimal tropical and sahelian species tion of sand plains (erg and regs of W Sahara, S. Argelie makes it difficult to establish a syntaxonomical scheme. and Central Sahara), and from the affinity of the invento- This association represents the characteristic vegeta- ries published by several authors, only one association tion of the ergs and sand dunes of the Western Sahara with Calligonum comosum and Stipagrostis pungens (J. and corresponds to the central and northern regions of Kyllian, 1961), included in the Ord. Aristidetalia Mauritania. (Guinochet et Quézel, 1954). The table of this associa- They are frequent species that come from the ergs tion includes only four inventories (20%) with Salvadora and slopes of the Saharan Atlas range (Ziziphus lotus), others from bedrocks near mountain formations (Searsia persica and Leptadenia pyrothecnica. It also shows a tripartita), or also, in the most southern ergs, elements low floristic correlation with all the other inventories, were widely distributed in the Central and South Sahara including those with differential species. on the limit with the Sahel (Foleyola billotii, Caylusea The proposed syntaxon include the species of the hexagyna etc.). As some of the characteristics species are major Saharan dispersion. Only some sahalian elements on the limit of its natural area, they show a low homo- are present, but scarcely. geneity and abundance index. Type relevé (holotypus) The most important vegetation samples were collec- Table 2, rel. 16. ted from Mali (Tilemsi Valley, Adrar of Tachdaït, The area of the association ranges from central Tigharghar, Tabrichat and Hamada El Haricha), Niger regions of Mauritania to Tindouf Sabkha (Ergs de (Ergs of the Aïr, Anakom, Iferouane, Tnerere and Bilma Iguidi, El Hammami, (N) and to Maqteir and Adrar (S) and Adrar Bous, Tenerere du Tafassasset), Chad (ergs (Fig. 5, B). and regs of the Barh El Gazel region, Erg Djourab and Enedi, the Biltine region) and S Mauritanie (Keur Macen II.1.1b. Boscio salicifoliae-Combretum micranthi asso- (Fig. 5 D). ciatio nova hoc loco II.1.1d. Fagonio olivieri-Aervetum javanicae associatio This association, which is typically Sahelian, extends nova hoc loco on the rocky wadis of the irregular limits across the Southern sector of the Sahara, and comes into contact to The group formed by Fagonia olivieri, Aerva java- the South with the Savannah forest. nica and Cornulaca monacantha, together with other The characteristic species of this association are some Saharan species of a wide distribution, constitute the typical phanerophytes of the savannah, e.g., Combretum dispersed populations that are found under hyperxero- micranthum, Combretum glutinosum, Adansonia digita- phytic conditions, which extend between 21-23ºC LN. ta, Ceiba pentandra and other xerophyte species. (Fig. 2) throughout Central Sahara (Fig. 1, Mali, Chad It is one of the characteristic communities of Sahel, and Niger). Type relevé (holotypus): Table 5, rel. 7. within general Saharan vegetation, due to the constant It is the characteristic association of the regions with presence of xerophyte and hyperxerophyte species of the a high aridity index. Its irregular area of distribution is central and southern Sahara; e.g., Acacia tortilis, Eleu- included between 15ºN and 22ºN, with no exceptions in NW Mauritania and C. Chad (Fig. 5E). sine indica, Maerua crassifolia, Balanites aegyptiaca, Euphorbia balsamifera, etc. Type relevé (holotypus): Other xerophyte species are frequent, like Citrullus Table 3, rel. 10. lanatus, Stipagrostis pungens and S. plumosa. The study area includes NE Burkina (regions of The group formed by Fagonia olivieri, Aerva Mansha, Dori and Markoy), C.S Mali (areas of Azaouad javanica and Cornulaca monacantha, together with other and Gourma) and Niger (the Ader region) (Fig. 5 C). Saharan species of a wide distribution, constitute the Due to the frequent presence of plants with a high dispersed populations that are found under hyperxero- and food forage value (Acacia sp., Maerua crassifolia, phytic conditions, which extend between 21-23ºC LN. Combretum sp., Hyparrhenia hirta, Heteropogon sp. (Fig. 2) throughout Central Sahara (Fig. 1, Mali, Chad etc), this is the plant community that endures the and Niger). Type relevé (holotypus): Table 5, rel. 7. strongest human and animal impacts. It is the characteristic association of the regions with a high aridity index. Its irregular area of distribution is II.1.1c. Salvadoro persicae-Leptadenietum pyrotechni- included between 15ºN and 22ºN, with no exceptions in cae associatio nova hoc loco NW Mauritania and C. Chad (Fig. 5E). This association contains several species with a Other xerophyte species are frequent, like Citrullus strong presence in all the inventories. The characteristic lanatus, Stipagrostis pungens and S. plumosa. species of this association, Salvadora persica and Lep- Syntaxonomical scheme tadenia pyrothecnica, show greater fidelity that others of major ecological and chorological amplitudes (Acacia SARCOCORNIETEA FRUTICOSAE Br.-Bl. &Tüxen ex tortilis, Panicum turgidum and Balanites aegyptiaca). A. & O. Bolòs 1950 Type relevé (holotypus): Table 4, rel. 14. ● SALSOLETO-NITRARIETALIA P. Quézel 1965 ♦ All. Limoniastreto-Zigophyllyllion P. Quézel 1965

48 M. Costa, A. Santos, L. Llorens, P. Soriano & H. Boira

Tetraenetum gaetulae ass. nova hoc loco Salvadoro persicae-Leptadinietum pyrotechnicae associatio nova hoc loco. PANICO TURGIDI–ACACIETEA RADDIANAE classis nova Fagonio olivieri-Aervetum javanicae associatio nova hoc loco (Pergularieto-Pulicarietea P. Quezel, 1965) hoc loco. ● PANICO TURGIDI-ACACIETALIA RADDIANAE ordo novus Associations proposed for lower slopes of the Atlas hoc loco (Sahara W, C and S) in Saharan NW (Quezel, P., 1965, Quezel, P. et Simon- ♦ Panico turgidi-Maeruion crassifoliae alliance nova neau, P. 1962, Guinochet, M. et Quezel, P. 1954), has hoc loco few relations with the communities described. Only Ass. Launaeo nudicaulis-Pergularietum tomentosae asso- Acacia tortilis and Panicum turgidum (Ord. Pergulario- ciatio nova hoc loco. Pulicarietalia, Quezel 1965), without syntaxonomic Boscio salicifoliae-Combretum micranthi associatio typification, has close relations with the class described nova hoc loco. in the present study.

Figure 5. Distribution areas of the ass. Tetraenetum gaetulae (A), Launaeo nudicauli- Pergularietum tomentosae (B), Boscio salicifoliae-Combretum micranthi (C), Salvadoro persicae-Leptadinietum pyrotechnicae (D) and Fagonio olivieri-Aervetum javanicae (E).

Photo 4. Fagonia oliveri DC. (Zigophyllaceae) with Stipagrostis pungens. Characteristic species of the hyperxero- phytic communities (Ass. Fagonio olivieri-Aervetum javani), disperses along the Central Sahara (Enedi, Tchad).

Table 4.- Salvadoro persicae-Leptadenietum pyrotechnicae (Balanition aegyptiacae, Maeruetalia, Panico Acacietea raddianae) Altitude (m.a.s.l.) 272 271 310 320 207 299 286 281 282 278 289 288 559 345 275 286 227 25 12 459 450 455 1215 ## ##

Area (m2) 300 200 400 400 300 200 200 400 400 200 400 300 400 300 400 400 200 200 ## 200 200 400 300 ## ##

Cover (%) 40 20 45 40 20 20 15 30 30 20 70 40 65 60 70 40 60 30 20 30 45 80 60 50 60

biodiver Plant Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Ip Association characteristics

Salvadora persica 1 . 1 1 1 1 1 1 1 1 2 2 . 2 2 1 . 2 1 1 1 1 2 2 1 V Leptadenia pyrotechnica 1 1 1 1 . . 1 1 1 . . 1 1 1 . . 3 1 1 . . . . 1 1 IV

Characteristics of all. and ord. sity, phytosociology and latitudinal inranges Sahara meridional and regions Sahelian Balanites aegyptiaca 1 1 1 1 1 1 1 1 1 1 1 1 . 2 1 . 1 . 1 . 1 2 1 1 2 V Maerua crassifolia 1 . 1 1 1 1 . 1 . . 1 . 2 . 2 2 1 . . 2 1 1 3 . 1 IV Faidherbia albida ...... 1 1 1 . 1 . 1 . . . . . 1 . 2 1 2 1 III Calotropis procera 1 . 1 1 ...... + . . . 1 . . . . . 1 + + 1 . III Aerva javanica . . 1 1 1 . . 1 1 . . . 1 1 + . . . . . 1 2 . . 1 III Stipagrostis pungens . . . . 1 1 . 1 1 . + 1 . . . . 1 ...... III Cenchrus biflorus 1 ...... 1 ...... + . . 1 ...... II Boscia salicifolia 1 . 1 . . . . . 1 ...... II Boscia senegalensis ...... 2 2 ...... 1 II Characteristic class

Acacia tortilis subsp. raddiana 1 1 1 1 1 1 1 1 1 1 2 2 2 2 . 1 2 2 1 . 2 3 2 1 2 V Panicum turgidum 1 1 1 1 1 1 1 1 1 . 2 . 2 1 . 1 1 + . 1 1 2 . . 1 V Aristida caerulescens . . 1 ...... 1 ...... 1 . . . II Stipagrostis plumosa ...... + + . . . + ...... II Companions Ziziphus jujuba . . 1 1 ...... 1 ...... 1 . 1 + . . II Capparis decidua ...... 2 . 2 1 2 1 ...... II Hyphaene thebaica ...... 1 1 2 . . . 2 ...... II Acacia seyal 1 . 1 1 . . . . . 1 ...... II Schouwia purpurea . . 1 1 ...... 1 II Chrozophora brocchiana . . . . . 1 ...... 1 ...... I Leptadenia lancifolia ...... 1 ...... 1 . . . . I Andrachne telephioides ...... + . + . . . I Guiera senegalensis 1 ...... 1 ...... I Other species: in 1, Euphorbia balsamifera 1; in 3, Piptadenia flava 1: in 10, Indigofera colutea 1; in 11, Hyparrhenia hirta 1; in 18, Senna italica 1; in 19, Salsola vermiculata +; Tetraena gaetula subsp. waterlotii, +; Nitraria retusa, 1; in 22, Fagonia arabica, 1; in 24, Trichodesma africanum, 1; in 26, Combretum micranthum 1; in 27, Citrullus lanatus, 1.

Localities.- Burkina: 1: 14º35'26''N 00º02'21''W; 2: 14º43'38''N 00º03'11''W. Mali: 3: 15º02'33''N 00º55'06''W; 4: 15º21'32''N 00º57'54''W; 5: 22º33'58''N 04º00'43''W; 6: 21º28'20''N 03º56'13''W; 7: 19º57'44''N 03º43'00''W; 8: 18º17'47''N 03º23'06''W; 9: 18º13'35''N 03º23'27''W; 10: 17º53'11''N 03º16'43''W; Tchad: 11: 14º47'29.6''N 17º09'60''E; 12: 14º50'15''N 17º15'52''E; 13: 17º15'37.7''N 21º37'31''E; 14: 17º39'30.2''N 19º40'26.5''E; 15: 15º47'46''N 18º20'17.1''E; 16: 14º53'13''N 17º15'57''E. Mauritania: 17: 20º55'46''N 13º11'18''W; 18: 17º12'17''N 16º04'41''W; 19: 16º41'08''N 16º02'51''W. Niger: 20: 17º54'02''N 07º35'59''E; 21: 17º53'17''N 07º37'45''E; 22: 17º52'14''N 07º34'57''E; 23: 19º06'49''N 08º55'48''E; 24: 15º09'33''N 05º45'27''E; 25: 20º10'21''N 12º45'47''E. 49

Tab. 5.- Ass. Fagonio oliveri-Aervetum javanicae (Panico turgidi-Maeruion crassifoliae, Panico turgidi-Acacietalia raddianae, Panico turgidi-Acacietea raddianae) Altitude (m.a.s.l.) 240 230 274 410 300 292 295 315 560 280 204 320 318 360 320 720 1022 710 735 Area (m2) 200 200 200 200 200 200 200 200 200 100 400 400 200 200 100 200 200 100 100 Cover (%) 15 25 40 25 15 30 20 55 10 15 35 30 15 20 10 45 55 15 35 Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Ip Characteristics Ass. Fagonia olivieri 1 1 . 1 1 . 1 2 + 1 1 1 1 1 1 3 3 1 3 V Aerva javanica . . 2 + . . 1 . . 1 1 1 1 1 1 + + 1 1 IV Cornulaca monacantha . 1 . . 1 1 1 . 1 . 1 . 1 1 . . . . . III Characteristics of all. ord. and class. Panicum turgidum 1 1 2 + . 2 1 . 1 . 1 1 1 1 . + 1 . . IV Acacia tortilis subsp. raddiana . 1 . . . . . 1 1 . 1 1 . 1 . + . . . III Maerua crassifolia . . . + . . . 1 . 1 1 1 ...... III Stipagrostis pungens 1 1 1 1 . 1 1 . 1 ...... 1 . III Citrullus lanatus . . . + . . . . . 1 1 1 1 . . 1 1 . 1 III

Stipagrostis plumosa . . 1 2 1 + 1 3 ...... III Chrozophora brocchiana ...... 1 1 1 1 . . 1 2 . . III

& H. Boira H. & Piptadenia flava . 1 ...... 1 1 . 1 . . . . . II

Indigofera colutea . 1 . . + ...... II Aristida caerulescens . . + . . + + ...... II Schouwia purpurea ...... 1 1 ...... II Balanites aegyptiaca ...... 1 1 1 ...... II Farsetia stylosa . . . . 1 . . 1 ...... II Senna italica ...... 1 + II Others species: Cenchrus biflorus 2 in 4; Neurada procumbens 1 in 5; Capparis decidua 1 in 8; Acacia seyal 1 in 10; Calotropis procera 1 in 12; Heliotropium bacciferum 3 in 16, Convolvulus trabutianus +. in 18 Localities.- Mali. 1: 22º2'20''N 2º59'16''W; 2: 21º57'26''N 3º59'28''W; 10: 14º57'48'' N, 0º8'58''W; 11: 15º38'11''N, 1º2'49''W; 12: 15º56'39''N, 1º11'46''W; 13: 17º38'24''N, 0º1'29''E; 14: 19º48'31''N 1º8'30''W; 15: 17º38'24''N, 0º1'29''E; Tchad: 3: 15º17'46''N 17º54'51''E; 4: 15º47'40''N 20º02'27''E; 5: 14º00'46N 16º29'35''E; 6: 13º41'52''N 16º29'27''E; 7: 13º42'18''N 16º16'39''E; Mauritania: 8, 22º40'52''N 13º11'18''W; Niger: 9: 20º44'46''N 12º30'26''E; 16: 19º12'43''N 09º00'14''E; 17: 19º22'20''N 9º17'14''E; 18: 19º59'45''N 8º40'21''E; 19: 20º17'24''N 9º00'27''E. M. Costa, A. Santos, L. Llorens, P. Soriano Llorens, L. Santos, M. A. Costa,

50 2

Table 6.- Phytosociological synthesis of Saharan Arabian (W and S) & Sahelian Sudanian vegetation Associations

Launaeo Salvadoro Fagonio Boscio salicifoliae- Tetraenaetum nudicaulis- persicae- olivieri- Combretum gaetulae Pergularietum Leptadenietum Aervetum micranthi biodiversity,Plant phytosociology and latitu tomentosae pyrotechnicae javanicae Characterístics of association 1 2 3 4 5

Tetraena gaetula subsp. waterlotii (Maire) Beier & Thulin V 2,3

Tamarix amplexicaulis Ehrenb. III 2,4

Nitraria retusa (Forssk.) Asch. III 1,7

Calotropis procera (Aiton) Dryand. III 0,3

Atriplex glauca L. II 1,7

Bassia tomentosa (Lowe) Maire & Weiller II 1,0

Frankenia hirsuta L. II 1,3

Suaeda vermiculata Forssk. ex J.F.Gmel. II 1,3

Tetraena simplex (L.) Beier & Thulin. III 1,4 II 1,0

Launaea nudicaulis (L.) Hook.f. IV 1,2 dinal inranges Sahara meridional and regions Sahelian

Pergularia tomentosa L. IV 1,0

Heliotropium bacciferum Forssk. III 1,2

Nucularia perrinii Batt. II 1,8

Anastatica hierochuntica L. II 1,4

Asparagus altissimus Munby II 0,7

Asphodelus tenuifolius Cav. III 1,5

Asteriscus graveolens (Forssk.) Less. III 1,0

Atractylis aristata Batt.ylis prolifera Boiss. II 0,6

Atriplex halimus L. II 1,0

Caylusea hexagyna (Forssk.) M.L.Green II 1,0

Cleome paradoxa R.Br. II 0,6

Convolvulus trabutianus Schweinf. & Muschl. II 0,2

Cotula cinereum Delile II 0,9

Cullen plicatum (Delile) C.H.Stirt. II 1,6

Echium humile Desf. III 1,2

Ephedra alata Decne. II 1,0

Euphorbia calyptrata Coss. & Kralik III 1,0 51

Fagonia arabica L. II 1,6

Gymnocarpos decander Forssk. II 1,0

Gymnocarpos sclerocephalus (Decne.) Dahlgren & Thulin. II 1,0

Haloxylon salicornicum (Moq.) Bunge ex Boiss.. II 1,3

Lotus glinoides Delile II 0,8

Lycium intricatum Boiss. II 1,8

Paronychia arabica (L.) DC. II 1,0

Salsola vermiculata L. II 1,5

Salvia aegyptiaca L. III 1,0

Searsia tripartita (Ucria) Moffett II 2,0

Trichodesma africanum (L.) Sm. II 0,7

Ziziphus lotus (L.) Lam. II 2,3

Combretum micranthum G.Don V 1,0

Adansonia digitata L. IV 0,9

Combretum glutinosum Perr. ex DC. III 1,0

Ceiba pentandra (L.) Gaertn. III 0,7

Anogeissus leiocarpa (DC.) Guill. & Perr. III 1,0

Commiphora pedunculata (Kotschy & Peyr.) Engl. III 1,5

Eleusine indica (L.) Gaertn. III 1,0

1,0

& H. Boira H. & Ficus cordata Thunb. III

Bauhinia reticulata DC. II 1,0

Hyparrhenia hirta (L.) Stapf III 1,0

Heteropogon contortus (L.) P.Beauv. ex Roem. & Schult. II 1,0

Salvadora persica L. II 0,7 V 1,3

Leptadenia pyrotechnica (Forssk.) Decne. II 1,0 IV 1,1

Capparis decidua (Forssk.) Edgew. II 1,6

Boscia senegalensis Lam. II 1,7

Hyphaene thebaica (L.) Mart. II 1,5

Fagonia olivieri DC. V 1,4

Cornulaca monacantha Delile III 1,0

Aristida caerulescens Desf. II 0,4 M. Costa, A. Santos, L. Llorens, P. Soriano Llorens, L. Santos, M. A. Costa,

Characterístics of Class, Order and Aliance.

Acacia tortilis subsp. raddiana (Savi) Brenan V 1,5 V 1,0 V 1,6 III 0,7

Panicum turgidum Forssk. V 2,2 I 1,0 V 1,2 IV 0,9

Maerua crassifolia Forssk. II 1,3 III 1,0 IV 1,4 III 0,8

Anvillea garcinii subsp. radiata (Coss. & Durieu) Anderb. III 0,6 II 1,0 II 1,0 biodiversity,Plant phytosociology and latitudinal inranges Sahara meridional and regions Sahelian

Balanites aegyptiaca (L.) Delile V 1,1 V 1,2 II 1,0

Schouwia purpurea (Forssk.) Schweinf. II 1,7 II 1,0 II 1,0

Farsetia stylosa R.Br. II 1,0 II 1,4 II 1,0

Cenchrus biflorus Roxb. II 1,1 III 1,0 II 0,8

Citrullus lanatus (Thunb.) Matsum. & Nakai II 0,4 III 0,9

Euphorbia balsamifera Aiton III 2,2 IV 1,0

Faidherbia albida (Delile) A.Chev. II 1,0 III 1,2

Indigofera colutea (Burm.f.) Merr. II 1,0 II 0,5

Piptadenia flava (DC.) Benth. II 0,6 II 1,0 II 1,0

Stipagrostis plumosa Munro ex T.Anderson II 1,0 II 1,4 II 0,2 III 1,3

Stipagrostis pungens (Desf.) De Winter III 0,9 III 1,0

Andrachne telephioides L. II 0,6 I 0,2

Nitraria retusa (Forssk.) Asch. II 1,0 I 0,6

Tetraena gaetula subsp. waterlotii (Maire) Beier & Thulin II 1,6 I 0,6

Calotropis procera (Aiton) Dryand. III 1,5 III 0,7

Boscia salicifolia Oliv. V 1,0 II 1,0

Ziziphus jujuba Mill. IV 1,0 II 0,9

Acacia nilotica (L.) Delile III 1,0 I 1,0

Acacia seyal Delile III 1,0 II 1,0

Guiera senegalensis J.F.Gmel. III 1,0 I 1,0

Leptadenia lancifolia (Schumach. & Thonn.) Decne. III 1,0 I 1,0

Aerva javanica (Burm.f.) Juss. ex Schult. III 1,1 IV 0,8

Chrozophora brocchiana (Vis.) Schweinf. I 1,0 III 1,2

Senna italica Mill. I 0,6 II 0,5

54 M. Costa, A. Santos, L. Llorens, P. Soriano & H. Boira

Human and Saharan plant resources. Capot- Rey, R. 1952. Les limites du Sahara français. Trav. Inst. Rech. Sah., t. 8. The use of natural resources in Saharan and sub- Capot-Rey, R. 1952. Les limites du Sahara Français. Trab. Inst. Saharan ethnics has been the object of numerous stu- Rech. Sahar. Univ. Argel. 8, 23-48. dies. Moving away from the Sahel, sorghum cultiva- Chini, C., Bilia, AR., Keita, A. and Morelli, C., (1992). Pro- tions and increasingly more different species of millet, toalkaloids from B. angustifolia. Planta Medica, 58, 476. and the use of natural plant resources becomes less evident and meet only domestic feeding, therapeutics Girgis, W.A. 1970. Phytosociological studies of the Vegetation of the Maryut area project U.A.R.J. Bot. t. XIII, 234-253. and medicinal necessities. The different Acacia species are used as rubber Good, R. 1964. The Geography of the Flowering Plants. 3 ed. Wiley, New York. 518 pp. sources and combustible material. Growing tourism and is extension are drastically reducing tree popula- Guillet, H. 1968. Le peuplement végétal du massif de l’ Enne- tions, which are scarcely found nowadays. di. C.R. Soc. Biogéog., nº 383-388, 95-106. In the Sahelian-Sudanian region, the common Guinet, Ph. et Sauvage, Ch. 1954. Les Hammada Sud maro- applications of Bombacaceae, species of the Combre- caines. Botanique. Trav. Inst. Sci. chérif., Sér. Gén. 2, pp. 75- taceae family, are used for medicinal purposes: the 167. Rabat. association of the desert bechic and emollient (Com- Guinochet, M. et Quézel, P. 1954. Reconnaissance phytoso- bretum micranthum and Guiera senegalensis), diuretic ciologique autour du Grad Erg occidental. Trav. Inst. Rech. Sah., t. XII, pp. 11- 27. and cholagogues (Combretum micranthum, Combre- tum glutinosum), vasoconstrictors, and also for diffe- Killian, J. 1960. Contribution a l´etude phytosociologique du rent injuries. In this region, the use of the natural plant Grand Erg Oriental. Terres et Eaux 37.) resources represents 25% of industrial or domestic, Le Floc´h E. et M. Grouzis. 2003. Acacia raddiana, un arbre 40% of therapeutic and 25% of feeding purposes. des zones arides á usages multiples. In: Un arbre au désert. Acacia raddiana. Grouzis, M. And Le Floch´h, E., Edit. In the Saharan-Arabian region, the progressive decrease in agriculture has led to a more widespread use Le Houerou H.N. 1968. La désertisation du Sahara septentrio- of natural resources for feeding, some of which have a nal et des steppes limitrophes (Libye, Tunisie). Ann. Algér. Géogr., nº 6. very high nutritious (Maerua crassifolia with 20% of proteins in dry leaves) value. The consumption of fruits Maire, 1952- 1968. Flore du l’ Afrique du Nord. Vol. I à XIV, (pulp and seeds of Balanites aegyptiaca, Capparis sp., Paris. Ziziphus sp.), and leaves of Salvadora persica and Marie, R. & Monod, Th. 1950. Etudes sur la flora et la ve- Balanites aegyptiaca is frequent. getation du Tibesti. Mem. Inst. Fr. Afr. Noire, 8. p. 140. The presence of toxic alkaloids in the leaves of Monod, Th. 1944. Tableau d’ ensemble des divisions adoptées Boscia salicifolia (Chini & al. 1992), allows chamae- et remarques sur l’esquisse phytogeographique de M. Murat. phyte to survive shepherding. However in times of Mem. of Nat. Antiacridien. 1: 13-14 et 26-31. shortage or famine, it is consumed by tribes prior to Monod, Th. 1957. Les grandes divisions chorologiques de l’ the maceration and denaturalisation of leaves. Afrique. Comm. For Tech. Cooperation in Afrika Scient. Council for Afrika, nº 24 The medicinal use of Salvadora persica is constant in all Saharan territories. Its young stems are em- Ozenda, P. 1983. Flore du Sahara. 2 Ed.. C.N.R.S. Paris. 602 ployee as tooth brushes for dental hygiene given their pp antibacterial properties. Pcord V.4.5 1999. MjM Software Design. Oregon. USA. Pressure on biodiversity is stronger due to the Quézel, P. 1954. Contribution a l’étude`de la flore et la vègè- previously indicated circumstances. Of all the species tation du Hoggar mentioned in the biogeographical and phytosociolo- Quézel, P. 1958. Mision Botanique au Tibesti. Inst. Rech. gical characterisation (Fig. 2), 47% are the object of Sahar. Alger, Mém., 4, 357 pp. nutritional use, 47% to medicinal use, and 31% to Quézel, P. 1961. Contribution a la flore du Sahara. Bull. Soc. industrial or other uses. Hist. Nat. Afr. N. 52. Pp. 225- 232. References Quézel, P. 1965. La Végétation du Sahara du Tchad á la Mau- ritanie. Gustav Fisher Verlag. Stuttgart. 333 pp Bagnouls, F. et Gaussen, H. 1963. Saison séche et índice xé- Quézel, P., Bruneau, Ph., et Gillet, H. 1964. Carte internatio- rothermique. Doc. Pour la carte des producctions végétales. nale du tapis végétal au 1/1.000.000, feuille Largeau (Tchad). Vol. I, art. 8, 47 pp. Tolouse. I.G.N. (France). Vincennes Barry, J.P. & al. 1987. L’ Adrar mauritanien entre Sahel et Quézel, P. & Simonneau, P. 1960. Note sur la vegetation halo- Sahara. Approches biogéographiques et geomorphologiques. phile du Sahara Occidental. Bull. Res. Council. of Israel. 8, D Ecologia Medit.: XII (1-2), 131-181. 1-4. pp. 253-262. Barry, J.P. et Celles J. Cl. 1973. Le problème des divisions Quézel, P. & Simonneau, P. 1962. Contribution a l’ etude phy- bioclimatiques et floristiques au Sahara algérien. Naturalia tosociologique du Sahara Occidental. L´ action des irrigations monspeliensia, sér. Bot. Fasc. 23-24. sur la végétation spontanée.- Ann. Agron. 13, pp. 221- 253. Barry, J.P. et Faurel, L. 1974. Carte de la végétation de l’Al- Quézel, P. 1969. Le Plateaux du Darfour nord- occidental et le gerie, feuille de Ghardaia au 1/500.000 . Mém. Soc. Hist. Nat. Jebel Gourgeil (Rep. du Soudan). Flore et végétation. Afr. du N., nº 11, 128 p. Dossiers de la Rech. Coopérative sur Programme nº 45, Braun–Blanquet, J., 1964. Pflanzensoziologie. 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