Cahiers scientifiques de l'océan Indien occidental 4, 2013 : 15-20. 15 Flora diversity of Mount Bar Le Duc Volcanic Crater (Ripailles Hill), Nouvelle Découverte, Mauritius. KERSLEY PYNEE¹, JEAN-YVES DUBUISSON² AND SABINE HENNEQUIN² 1- Mauritius Sugarcane Industry Research Institute, Mauritius Cane Industry Authority, Réduit, Mauritius. Current address: The Mauritius Herbarium, Agricultural Services, Ministry of Agro-Industry and Food Security, Réduit, Mauritius. kpynee@mail.gov.mu 2- Université Pierre et Marie Curie, UMR 7207 CNRS-MNHN-UPMC Centre de Recherches en Paléobiodiversité et Paléoenvironnements, 57 rue Cuvier, CP48, 75005 Paris, France. E-mail: jdubuiss@snv.jussieu.fr; shennequ@snv.jussieu.fr Reçu le 25/01/2013, accepté le 19/05/2013 ABSTRACT: The Mount Bar Le Duc volcanic crater is a remnant of 0.7 ha of native vegetation found within a larger disturbed and fragmented area of nearly 300 ha. A checklist of both native and alien plants was compiled for this study area. Botanical surveys carried out from 2011-2012 at this volcanic crater showed a total of 68 species of native plants from 42 families distributed on 62 genera. Of this, 48 species were angiosperms (30 families, 45 genera) and 20 were pteridophytes (12 families, 17 genera). The most species-rich families were Rubiaceae, Myrtaceae and Orchidaceae; and for the ferns, it was Hymenophyllaceae. For alien species, 28 species of 22 families and 26 genera were recorded. RÉSUMÉ : Le cratère volcanique du Mont Bar Le Duc est une zone vestige de 0,7 ha de végétation indigène dans une plus grande zone perturbée et fragmentée de près de 300 ha. Une liste de plantes indigènes et exotiques a été compilée pour cette zone d'étude. Les relevés botaniques effectués depuis 2011-2012 sur le Mont Bar Le Duc ont révélé un total de 68 espèces de plantes indigènes pour 42 familles et 62 genres : 48 espèces d'angiospermes (30 familles, 45 genres) et 20 espèces de ptéridophytes (12 familles, 17 genres). Parmi les angiospermes, les familles les plus riches en espèces sont les Rubiacées, les Myrtacées et les Orchidacées. Parmi les fougères, les Hymenophyllacées. Pour les espèces exotiques, 28 espèces, avec 22 familles et 26 genres, ont été enregistrées. KEYWORDS: habitat fragmentation, native species, Mascarenes, conservation. MOTS CLÉS : morcellement de l'habitat, espèces indigènes, Mascareignes, conservation. INTRODUCTION Mauritius (20.25 S, 57.5 E), a volcanic island, is one of the Mascarene islands together with Rodrigues and Réunion, located in the south west of the Indian Ocean (CHEKE & HUME, 2008). It is nearly 60 km long by 40 km wide, representing an area of 1865 km². Through three phases of volcanic activity, the emergence from the sea floor and other extensions of the island s area gave rise to primary craters, still recognizable from the Black River Mountain Ranges with the highest peak at 828 m, to the Moka Range and to some isolated peaks nearby (SADDUL, 1995). Globally, volcanic craters are known for their importance in the maintenance of biodiversity or to act as lakes and natural water reservoirs (DUKER & BORRE, 2001). In Mauritius, 36 craters have been identified, including eight which are well preserved, 14 less conserved but still easily recognisable, nine partially flooded but highly degraded and five are probable sites of old craters
16 Flora diversity of a volcanic crater, Mauritius K. PYNEE, J.-Y. DUBUISSON & S. HENNEQUIN (WILLAIME, 1984). Recently, a study at Kanaka Crater through peat coring and pollen analysis, reveals the island s environmental and climatic changes of the last 38,000 years (VAN DER PLAS et al., 2012). From the botanical point of view, and considering the only six voucher specimens from the Bar Le Duc crater harbored at The Mauritius Herbarium collected from 1992-2003, boosted me up to start updating our collection for this locality. Moreover, the purpose of such a survey was to obtain more detailed information and knowledge on the floral diversity of the said crater. MATERIALS AND METHODS STUDY AREA The Mount Bar Le Duc (Ripailles Hill) is a non-active volcanic crater located in the district of Quartier Militaire, next to Nouvelle Découverte, in the centre of Mauritius (WILLAIME, 1984) (Fig. 1a). It is an area composed of approximately 0.7 ha, situated between coordinates 20 12 39 S and 57 36 53 E and at an elevation ranging from 421 to 596 m above sea level. Its climate is relatively warm to humid, with a mean annual temperature of 25ºC, and annual rainfall between 2600 and 2800 mm (WILLAIME, loc. cit.). The studied area is a remnant of 0.7 ha of native vegetation found within a larger disturbed and fragmented area of nearly 300 ha. The fragmented area is a privately owned reserve and used for deer ranching (Cervus timorensis Blainville, 1822) and is surrounded by pastures, sugar cane fields, vegetables, pinus and eucalyptus plantations, and with very few native individuals of Ficus mauritiana (Moraceae) dispersed around. Figure 1. 1a) Photo showing volcanic crater of Mount Bar Le Duc ; 1b) flower of Roussea simplex (Rousseaceae)
Cahiers scientifiques de l'océan Indien occidental 4, 2013 : 15-20. 17 BOTANICAL SURVEY Qualitative vegetation survey through random sampling, comprising six days of fieldwork, were carried out in 2011 and 2012. The identification of species was done using mainly the Flore des Mascareignes (BOSSER et al., 1976 onwards) and Les Graminées des Paturages et des Cultures à Madagascar (BOSSER, 1969) and also by comparison with herbarium specimens. Voucher specimens of each species are deposited at The Mauritius Herbarium. Undetermined species are also included in the list. RESULTS AND DISCUSSION For the native plants, 68 species (42 families, 62 genera) including three undetermined species and one cryptogenic species were collected and accessed (Table 1 and 2). This botanical survey gave rise to 28% species endemic to Mauritius, 18% endemic to Mauritius and Réunion Island, 47% indigenous, two percent cryptogenic and four percent undetermined. Among the native angiosperms, 48 species (30 families, 45 genera), the most species-rich families were Rubiaceae, Myrtaceae and Orchidaceae (five species each), followed by Euphorbiaceae (four species), Poaceae (three species) and Urticaceae (two species) (Table 1). The richest genera were Angraecum (three species), Eugenia and Syzygium (two species each). In the case of the 20 native pteridophytes (12 families, 17 genera), the richest families were Hymenophyllaceae (four species), followed by Pteridaceae and Thelypteridaceae (three species each), and Lomariopsidaceae (two species) (Table 2). The richest genera were Cyclosorus (three species), and Nephrolepis (two species). The alien species (28) recorded in the surveyed area belong to 22 different families (Table 3). CONCLUSION The botanical survey carried out at Mount Bar Le Duc crater has increased the herbarium collections as well as our knowledge of the crater s vegetation. Some new records, comprising very rare native species (e.g. Roussea simplex, Fig. 1b) which are considered as Endangered according to the International Union for the Conservation of Nature criteria (IUCN 2001) are also collected and recorded. Further similar surveys in other craters of Mauritius should also be envisaged, which in turn, will provide valuable information, regarding future conservation measures for these habitats. ACKNOWLEDGEMENTS Special thanks to Drs Salem Saumtally and Asha Dookun-Saumtally for their support to KP. Dr Claudia Baider provided suggestions for improving the manuscript. We are also grateful to the owner, Director and staff at Bar Le Duc, especially to Mr Jean-Patrick Lesur, for their usual collaboration and permission to access the site. I sincerely appreciate the help of Messrs Cedric Soutif, Darmanand Sooklall, Isoop Damry and Ms Karen Martial during fieldworks.
18 Flora diversity of a volcanic crater, Mauritius K. PYNEE, J.-Y. DUBUISSON & S. HENNEQUIN Table 1. List of native angiosperms from Mount Bar Le Duc Crater. Status: (C) Common (individuals > 50), (O) Occasional (50 < individuals >10), (R) Rare (5< individulas < 10) and (VR) Very Rare (individuals < 5). Origin: Cryptogenic (C), Indigenous (I), Endemic to Mauritius (MAU), Endemic to Mauritius and Réunion (MAU, REU), Mascarenes (MAS) and Undetermined (U). IUCN criteria: Critically Endangered (CR), Endangered (EN), Vunerable (VU), Near Threatened (NT),, Data Deficient (DD) and Not Evaluated (NE). Barecode no. Family Taxa Life form Statut at Mt B. le Duc Origin MAU 0009247 Achariaceae Erythrospermum monticolum Thouars var. pyrifolium (Lam. ex Poiret) Sleumer S R MAU NT MAU 0009128 Aphloiaceae Aphloia theiformis (Vahl) Benn. S VR I LC MAU 0009237 Apocynaceae Tabernaemontana persicariifolia Jacq. S VR MAU, REU EN MAU 0009129 Asteraceae Faujasiopsis flexuosa (Lam.) C. Jeffrey subsp. flexuosa S VR MAU LC MAU 0009106 Bignoniaceae Colea colei (Bojer ex Hooks) M. L. Green S VR MAU EN MAU 0009271 Connaraceae Cnestis glabra Lam. L R I LC MAU 0009093 Elaeocarpaceae Elaeocarpus integrifolius Lam. T VR MAU CR MAU 0009110 Erythroxylaceae Erythroxylum macrocarpum O. E. Schulz S VR MAU LC MAU 0009092 Euphorbiaceae Orfilea neraudiana (Baillon) Webster T VR MAU - MAU 0009238 Euphorbiaceae Hancea integrifolia (Willd.) S. E. C. Sierra, Kulju & Welzen S VR MAU, REU EN MAU 0009245 Euphorbiaceae Acalypha integrifolia Willd. subsp. marginata (Poiret) Coode var. marginata (Poiret) Coode S VR MAU EN MAU 0009269 Euphorbiaceae Macaranga mauritiana Bojer ex Baill. T VR MAU EN MAU 0009232 Hypoxidaceae Hypoxis angustifolia Lam. var. angustifolia H O C NE MAU 0009136 Lauraceae Ocotea aff. mascarena (Buchoz) Kostern S VR MAU EN MAU 0009118 Laxmanniaceae Cordyline mauritiana (Lam.) Macbride S VR MAU, REU EN MAU 0009131 Loganiaceae Geniostoma pedunculatum Bojer ex DC. S VR MAU, REU MAU 0011112 Melastomataceae Memecylon sp S VR MAU MAU 0009117 Moraceae Ficus mauritiana Lam. T R MAU, REU EN MAU 0009339 Myrtaceae Eugenia pyxidata (J.Guého & A.J.Scott) N.Snow S VR MAU MAU 0009341 Myrtaceae Eugenia psidioidea (J.Guého & A.J.Scott) N.Snow S VR MAU MAU 0009126 Myrtaceae Psiloxylon mauritianum (Bouton ex Hook. f.) Baillon T VR MAU, REU EN MAU 0009342 Myrtaceae Syzygium contractum (Poir.) J.Guého & A.J.Scott T VR MAU MAU 0009111 Myrtaceae Syzygium mauritianum Guého et A.J.Scott T VR MAU MAU 0009114 Ochnaceae Ochna mauritiana Lam. S VR MAU LC MAU 0009103 Orchidaceae Angraecum calceolus Thouars H R I NE MAU 0009135 Orchidaceae Angraecum pectinatum Thouars H R I NE MAU 0009249 Orchidaceae Polystachya concreta (Jacq.) Garay & H. R. Sweet H R I NE MAU 0009252 Orchidaceae Disperis oppositifolia Sm. H R I NE MAU 0009264 Orchidaceae Angraecum mauritianum Frapp. H R I NE MAU 0009133 Phyllanthaceae Phyllanthus phillyreifolius Poiret var. commersonii Muell. Arg. S VR MAU R MAU 0011115 Pittosporaceae Pittosporum senacia Putt. subsp. senacia S VR I LC MAU 0009246 Poaceae Isachne mauritiana Kunth. H R NE MAU 0009267 Poaceae Oplismenus hirtellus Beauv. H O I NE MAU 0009261 Poaceae Brachiaria umbellata H C I NE MAU 0009242 Ranunculaceae Clematis mauritiana Lam. L VR I LC MAU 0009098 Rhamnaceae Scutia myrtina (Burm. f.) Kurz L R I LC MAU 0009115 Rousseaceae Roussea simplex Sm. L VR MAU CR MAU 0009113 Rubiaceae Danais fragrans (Lam.) Pers. L VR MAU, REU LC MAU 0009123 Rubiaceae Mussaenda arcuata Poiret L VR I VU MAU 0009132 Rubiaceae Antirhea borbonica J. Gmelin S VR MAU, REU EN MAU 0009235 Rubiaceae Bremeria landia (Poir.) Razafimandimbison & Alejandro T VR MAU, REU EN MAU 0009253 Rubiaceae Ixora vaughanii (Verdc.) Mouly & B. Bremer S VR MAU CR MAU 0009265 Sapindaceae Doratoxylon apetalum (Poir.) Radlk. var. diphyllum (Cordem.) Friedmann S R I LC MAU 0009239 Smilacaceae Smilax anceps Willd. L VR I LC MAU 0009109 Stilbaceae Nuxia verticillata Lam. T R MAU, REU LC MAU 0009257 Urticaceae Elatostema fagifolium (Poiret) Brongn. H R MAU, REU LC MAU 0009259 Urticaceae Pilea sp H R MAU 0009134 Xanthorrhoeaceae Dianella ensifolia (L.) DC. S R I LC criteriaiucn
Cahiers scientifiques de l'océan Indien occidental 4, 2013 : 15-20. 19 Table 2. List of native and undetermined pteridophytes from Mount Bar Le Duc Crater. Status: (C) Common (individuals > 50), (O) Occasional (50 < individuals >10), (R) Rare (5< individulas < 10) and (VR) Very Rare (individuals < 5). Origin: Cryptogenic (C), Indigenous (I), Endemic to Mauritius (MAU), Endemic to Mauritius and Réunion (MAU, REU), Mascarenes (MAS) and Undetermined (U) Barecod e no. Family Taxa formlife Statut at Mt B. le Duc Origin MAU 0009105 Blechnaceae Blechnum attenuatum (Sw.) Mett. var attenuatum H O I MAU 0009137 Cyatheaceae Cyathea borbonica Desv. var. latifolia (Hook.) Bonap. H VR MAU MAU 0009102 Davalliaceae Davallia repens (L.f.) Diels H R I MAU 0009091 Dryopteridaceae Ctenitis pauciflora (Kaulf.) Holttum H O MAU MAU 0009100 Hymenophyllaceae Crepidomanes bipunctatum (Poir.) Copel. H R I MAU 0009261 Hymenophyllaceae Abrodictyum sp H VR MAU 0009343 Hymenophyllaceae Didymoglossum cuspidatum Ebihara & Dubuisson H C I MAU 0009345 Hymenophyllaceae Hymenophyllum inaequale (Poir.) Desv. H C I MAU 0009097 Lomariopsidaceae Nephrolepis cordifolia (L.) C. Presl. var cordifolia H C I MAU 0009121 Lomariopsidaceae Nephrolepis biserrata (Sw.) Schott H O I MAU 0009240 Marattiaceae Marattia fraxinea Sm. H R I MAU 0009108 Polypodiaceae Belvisia spicata (L.f.) Mirbel H R I MAU 0009234 Psilotaceae Psilotum nudum (L.) P. Beauv. H R I MAU 0009120 Pteridaceae Adiantum hispidulum Sw. H R I MAU 0009233 Pteridaceae Antrophyum immersum (Bory ex. Willd) Matt. H R I MAU 0009244 Pteridaceae Ochropteris pallens (Sw.) Sm. H VR I MAU 0009099 Selaginellaceae Selaginella fruticulosa (Bory ex Willd.) Spring H O MAU, REU MAU 0009096 Thelypteridaceae Cyclosorus unitus (L.) Holttum H C I MAU 0009101 Thelypteridaceae Cyclosorus pulcher (Bory ex Willd.) Holttum H R I MAU 0009130 Thelypteridaceae Cyclosorus hispidulus (Decne.) Ching H R I Table 3. List of alien species from Mount Bar Le Duc Crater Family Taxa Anacardiaceae Schinus terebinthifolius Raddi Arecaceae Livistona chinensis (Jacq.) R. Br ex Mart. Asteraceae Ageratum conyzoides L. Asteraceae Mikania micrantha Kunth Boraginaceae Cordia curassavica (Jacq.) Roem. et Schult. Bromeliaceae Ananas bracteatus (Lindl.) Schultes Cyatheaceae Cyathea cooperi (F. Muell.) Domin Cyperaceae Killinga bulbosa P. Beauv. Lamiaceae Lantana camara L. Lauraceae Litsea monopetala (Roxb.) Pers. Lygodiaceae Lygodium microphyllum Malpighiaceae Hiptage benghalensis (L.) Kurz Melastomataceae Clidemia hirta D. Don. Melastomataceae Ossaea marginata (Desr.) Triana Myrtaceae Psidium cattleianum Sabine Myrtaceae Syzygium jambos (L.) Alston. Myrtaceae Eucalyptus robusta J.E. Smith Oleaceae Ligustrum robustum Blume var. walkeri (Decaisne) Mansf. Orchidaceae Phaius tankervillae Blume Pinaceae Pinus elliotti Engelm. Poaceae Paspalum paniculatum L. Primulaceae Ardisia elliptica Thunb. Primulaceae Ardisia crenata Sims Primulaceae Ardisia aff. solanacea Roxb. Rhamnaceae Rhamnus nepalensis (Wall.) Laws Rubiaceae Oldenlandia corymbosa L. var. caespitosa (Benth.) Verdc. Strelitziaceae Ravenala madagascariensis Sonnerat Theaceae Camellia sinensis (L.) O. Kuntze
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