The Decline and Conservation Management of the Threatened Endemic Palms of the Mascarene Islands
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Oryx Vol 36 No 1 January 2002 The decline and conservation management of the threatened endemic palms of the Mascarene Islands Mike Maunder, Wayne Page, John Mauremootoo, Richard Payendee, Yousoof Mungroo, Aleks Maljkovic, Christian Vericel and Ben Lyte Abstract The conservation status of the five genera population fragmentation, invasive plants and animals, and 11 species of palm endemic to the Mascarene Islands and high levels of seed predation that prevent natural (Mauritius, La Re´union and Rodriques) are reviewed. regeneration. The advantages of in situ management for All species are threatened with extinction; nine taxa the recovery of these palm populations are discussed. are classified as Critically Endangered and four as Without a long-term conservation programme, utilising Endangered on the 2000 IUCN Red List. Two taxa both in situ and ex situ management, extinction of wild survive as single wild specimens (Hyophorbe amaricaulis populations will occur. and Dictyosperma album var. conjugatum); an additional seven taxa have wild populations of 100 or fewer. Keywords Acanthophoenix, Dictyosperma, ex situ, Although the historical phase of large-scale forest clear- Hyophorbe, in situ, Latania, Mascarene Islands, palms, ance has passed, the remaining palm populations in Tectiphiala. the Mascarenes are under threat from the eCects of of the challenges in managing threatened island plants, Introduction and the endemic species include some of the most widely The Mascarene Islands are situated to the east of cultivated commercial and ornamental palm species in Madagascar in the south-west Indian Ocean (Fig. 1). the world (Maunder et al., 2001). They consist of three main islands: Mauritius and The palm family Arecaceae is represented in the Rodrigues, comprising The Republic of Mauritius, and Mascarenes by 11 species in five endemic genera (Moore La Re´union, a French Overseas Department. The islands &Gue´ho, 1984) (Table 1). Three tribes belonging to three are recognised as part of the Madagascar biodiversity sub-families are represented in the Mascarenes, the hot spot (sensu Myers et al., 2000) and as an IUCN Coryphoideae (Latania in Borasseae), Ceroxyloideae (Hyophorbe Centre of Plant Diversity (CPD Site 102) (Strahm, 1994). in Hyophorbeae)andtheArecoideae (Acanthophoenix, The importance of conserving the Mascarene palm flora Tectiphiala and Dictyosperma in the Areceae)(Uhl& was recognised by Cadet (1977), Moore (1977) and the Dransfield, 1987). The genus Hyophorbe has a remarkable IUCN/SSC Palm Action Plan (Strahm, 1996a). The con- distribution, with its closest allies in the Ceroxylidaeae servation needs of the Mascarene palms illustrate many restricted to northern South America, Central America and the Caribbean (Uhl & Dransfield, 1987; Uhl et al., 1995). The highest palm diversity occurs on the oldest Mike Maunder (Corresponding author) Conservation Projects Development Unit, Royal Botanic Gardens, Kew, Richmond, Surrey, UK. island, Mauritius, with seven species and eight taxa, six Present address: Conservation Department, The National Tropical of which are endemic. La Re´union has four species, of Botanical Garden, 3530 Papalina Road, Kalaheo, Kauai, Hawaii 96741, which two taxa are endemic; and Rodrigues has three USA. E-mail: [email protected] species of which three taxa are endemic (Table 1). The Ben Lyte Conservation Projects Development Unit, Royal Botanic genera Dictyosperma, Hyophorbe and Latania are found Gardens, Kew, Richmond, Surrey, UK. on all three islands. Acanthophoenix occurs on both Wayne Page, John Mauremootoo, Richard Payendee and Aleks Mauritius and La Re´union and Tectiphiala is endemic Maljkovic Mauritius Wildlife Foundation, Ken Lee Building, Edith Cavell only to Mauritius. Two of the endemic genera, Tectiphiala Street, Port Louis, Mauritius. and Acanthophoenix, are monospecific. Christian Vericel Conservatoire Botanique National de Mascarin, Domaine The original distribution and ecology of the Mascarene de Colimac¸ ons, F-97436 Saint Leu, La Re´ union. palms is diBcult to assess because the major period of Yousoof Mungroo Director, National Parks and Conservation Service, habitat destruction preceded any formal botanical or Government of Mauritius, Reduit, Mauritius. ecological studies (Cheke, 1987). For instance, the coastal Received 5 September 2000. Revision requested 24 April 2001. woodlands of Mauritius were subject to heavy exploitation Accepted 20 September 2001. of ebony (Diospyros spp.) in the mid seventeenth century 56 © 2002 FFI, Oryx, 36(1), 56–65 DOI: 10.1017/S0030605301000011 Printed in the United Kingdom Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.234, on 28 Sep 2021 at 19:38:12, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605302000091 Conservation of Mascarene palms 57 50°E60°E and clearance for sugar cane plantations after 1709. The 10°S original composition of the lowland Mauritian forests is hinted at in a Dutch manuscript of 1677 that illustrates Madagascar large numbers of palms (both pinnate and fan leaved) in the forest (Algeneen Staatsarchief, reproduced in Indian Ocean Grove, 1995). It is possible that species or populations became extinct prior to the initial botanical surveys of Mauritius Rodrigues 20°S the eighteenth and early nineteenth centuries. For instance, La Ré union it is diBcult to reconcile some early descriptions of Islands palms on Rodrigues by Leguat (1708) with extant species Mascarene (Strahm, 1989). Following the extinction of endemic bird and reptile species, and decline in fruit bat populations, it is likely that pollination and fruit dispersal ecologies 500 0 500 km have been modified (Vaughan & Wiehe, 1937; Witmer, 1991). Observations on Round Island suggest that endemic Round Island reptiles play at least a peripheral role in the pollination Flat Island of palms; individuals of the endemic day gecko Phelsuma Gunners Quoin guentheri have been observed dusted with pollen and moving between inflorescences on adjacent trees of both Latania and Hyophorbe whilst hunting insects (M. Maunder, Mauritius pers. obs.). Early human colonists of the Mascarenes utilised the palms for construction, as a valuable source Pamplemousse of edible palm heart (‘palmiste’ or ‘cabbage’), and some Pieter Both palms, probably Latania, were tapped for their ‘wine’ (Leguat, 1708; Brouard, 1963). The area of original habitat in the Mascarenes has Curepipe been dramatically reduced; in Mauritius less than 5% s Mts bou C Bam survives (Sa ord, 1997). Today Mauritian lowland palm Ile aux Aigrettes woodland survives, albeit in a degraded form, only on Mt Cocotte S Round Island, where three palm taxa occur: Latania outh ern Upl ands loddigesii, Hyophorbe lagenicaulis and Dictyosperma album var. conjugatum.OnLaRe´union the coastal palm forest 20 020 20 km has been cleared for coCee and sugar plantations, and these areas are now covered by fire-influenced savannahs (The´baud & Strasberg, 1997). In the east and south of St Denis La Ré union La Re´union some lowland wet forest survives, although this is still subject to some illegal clearance and the impact of invasive plants. Leguat (1708) described Mafate Rodrigues as ‘‘richly spread with great and tall trees. The rivers that we saw run from them water’d valleys, Les Palmistes Ravine de Takamaka whose fertility we could not doubt’’. As a result of St Leu extensive forest clearance, fire, grazing and invasive weeds Rodrigues has lost all indigenous forest except for a few small fragments at Gran Montagne and Anse Le Tampon Quittor (Strahm, 1983). Grand Anse St Philippe Populations of all the Mauritius upland palm species occur as isolated sub-populations in areas where Mar Longue Reserve 20 020 20 km forest is fragmented by stands of exotic weeds, forestry plantations or agricultural areas. Mountains in the north, east and south-west of Mauritius, previously linked by Fig. 1 The location of the Mascarene Islands of La Re´union C (a French Overseas Department), and Mauritius and Rodriques contiguous forest, are now e ectively isolated by housing, (together the Republic of Mauritius) to the east of Madagascar in industrial development and agriculture. In contrast, the south-east Indian Ocean, and Mauritius and La Re´union with La Re´union still supports extensive areas of upland locations and islands mentioned in the text. forest. © 2002 FFI, Oryx, 36(1), 56–65 Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.234, on 28 Sep 2021 at 19:38:12, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605302000091 58 M. Maunder et al. Table 1 The names, occurrence, IUCN Red List category (Oldfield et al., 1998; Hilton-Taylor, 2000) and criteria (see IUCN, 1994 for explanations of criteria), and estimated wild populations of the Mascarene endemic palms. Red List category Estimated wild Taxon Vernacular name Mauritius La Re´union Rodrigues (criteria) population Acanthophoenix rubra (Bory) palmiste X X CR (B1+2c) c. 1300 H. Wendl. Dictyosperma album (Bory) princess palm, white X X CR (D) c. 30 H. Wendl. & Drude ex ScheC. hurricane palm var. album Dictyosperma album var. aureum golden hurricane palm X CR (D) <10 Balf. F. Dictyosperma album var. conjugatum hurricane palm X CR (D) 1 H. E. Moore & L. J. Gue´ho Hyophorbe amaricaulis Mart. lonely palm X CR (B1+2abde, 1 C1+2b, D) Hyophorbe indica Gaertn. poison palm X EN (D) c. 500 Hyophorbe lagenicaulis (L. H.