Demography_of_threatened_tree_species_in_Vietnam

Demography of threatened tree species in Vietnam P.D Chien Demography of threatened tree species in Vietnam ISBN-10: 90-393-4407-8 ISBN-13: 978-90-393-4407-1 NUR 904 @ 2006 P.D Chien Printed by: Print Partners Ipskamp, Enschede Cover design: Marjolein Kortbeek Photos: P.D Chien All rights reserved No part of this publication, apart from bibliographic data and brief quotations in critical reviews, may be reproduced, re-recorded or published in any form including photocopy, microfilm, electronic or electromagnetic record, without written permission Demography of threatened tree species in Vietnam Demografie van bedreigde boomsoorten in Vietnam (met een samenvatting in het Nederlands) ðộng thái quần thể lồi bị đe dọa Việt Nam (phần tóm tắt tiếng Việt Nam) Proefschrift ter verkrijging van de graad van doctor van de Universiteit Utrecht op gezag van de rector magnificus, prof.dr W.H Gispen, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op woensdag 29 november 2006 des middags te 12:45 uur door Pham Duc Chien geboren op 15 september 1967 te Thai Binh, Vietnam Promotor: Prof Dr M.J.A Werger, Utrecht University Prof Dr Nguyen Hoang Nghia, Forest Science Institute of Vietnam Co-promotor: Dr P.A Zuidema, Utrecht University The investigations reported in this thesis were carried out within the framework of the Tropenbos-Vietnam Programme and the Plant Ecology and Biodiversity Group at Utrecht University This study was financially supported by Tropenbos International and the Forest Science Institute of Vietnam To Ha and Duy Contents Chapter General introduction Chapter Vietnamese forestry, biodiversity and threatened tree species 19 With M.J.A Werger & N.H Nghia Chapter Conservation prospects for threatened Vietnamese tree species: results from a demographic study 57 With P.A Zuidema & N.H Nghia; submitted Chapter Population viability analysis of threatened tree species in Vietnam 83 with P.A Zuidema; submitted Chapter What dimension to use for matrix dimension of tree? recommendations based on a validation of age estimate by tree ring analysis 107 with P.A Zuidema; submitted Chapter General discussion and summary 125 Samenvatting (summary in Dutch) 137 Tóm tắt kết nghiên cứu (summary in Vietnamese) 145 Acknowledgements 155 Curriculum vitae 157 Chapter General introduction Forest status in the tropics Tropical forests are characterized by a very high plant diversity: covering less than 10% of the land areas, they posses more than 50% of all known plant species on earth (Wilson 1995, Mayaux et al 2005) In a single of these forests, as many as 300 tree species can coexist (Gentry 1998b), although a large difference may occur between continents and regions (Givnish 1999, ter Steege et al 2000) Yet, during the past decades, tropical forests have severely declined, with around million lost and more than million visibly degrading each year (Achard et al 2002) The main causes for the loss of tropical forests are agricultural expansion, over-harvesting, development of plantations, mining operation, industry, urbanization and road building (Geist & Lambin 2002) As a result, an unknown, but large number of species has become extinct, while many others run the risk of extinction (Frankham et al 2002, World Conservation Union ‘IUCN’ 2006) Among tropical areas, SouthEast Asia has the highest relative rate of deforestation (Achard et al 2002, Brook et al 2006), also is facing a serious problem of species extinction (Sodhi et al 2004, IUCN 2006) Tropical forests in Vietnam Three quarters of Vietnam is composed of hills and mountains, which was originally covered by tropical forests (Trung 1998) Being a venue of plant species emigrated from three flora areas: the Himalaya-Yunnam-Guizhou flora in the North-West, the India-Myanmar flora in the West, and the Malaysia-Indonesian flora in the South and South-East, Vietnam harbours a very high number of plant species (Trung 1998, Chan et al 1999, Lap 1999) (for details see Chapter 2) Nevertheless, due to many reasons, such as rapid changes in land use, over-harvesting and long wars, the forests of Vietnam have severely declined, both in quantity and quality (Dang et al 2001, for details see Chapter 2) Consequently, many species of Vietnam run the risk of extinction (Nghia 2005), of which around 150 are critically endangered and vulnerable (IUCN 2006) As threatened tree species often occur in small and isolated populations (Ministry of Science, Technology and Environment ‘MSTE’ 1996, cf Ouborg 1993), they are very vulnerable to local extinction due to demographic stochasticity or lack of genetic variation (Menges 1992; Lande 1993; Oostermeijer et al 2003) On the other hand, tropical trees are often slow-growing, long-lived species, Chapter taking a long time to reach the age of reproduction (Chambers et al 1998, Fichtler et al 2003, Laurance et al 2004), and this makes it difficult to determine whether the population is growing or declining in size (Kwit et al 2004) It is therefore necessary to carry out a demographic study for these species in order to decide on actions before they have declined below the critical level The context of this study In this dissertation, a demographic study of six threatened tree species was carried out in four protected areas in Vietnam: Annamocarya sinensis and Parashorea chinensis in Cuc Phuong National Park, Calocedrus macrolepis and Manglietia fordiana* in Ba Vi National Park, Dacrydium elatum in Bach Ma National Park, and Pinus kwangtungensis in Hang Kia – Pa Co Nature Reserve The status and distribution of the six species are presented in Chapter The four protected areas are briefly described below Figure Location of four protected areas in Vietnam: Hang Kia – Pa Co Nature Reserve (1), Ba Vi National Park (2), Cuc Phuong National Park (3), and Bach Ma National Park (4) Ba Vi National Park Ba Vi NP is located in Ha Tay province (21°N, 105°E, Fig.1), about 50 km northwest of Ha Noi Covering 12,023 ha, the Park includes low to middle high mountains, and is surrounded by plains The climate in the region is characterized by an average precipitation of 2600 mm y-1, an average annual temperature of 23°C and a pronounced cold and dry season from November to March (Forest Technique and Science Association of Vietnam ‘FTSA’ 2001) The natural forests occur at altitudes * : Some scientists call it Manglietia hainanensis, but we prefer the name Manglietia fordiana as Manglietia hainanensis is conspecific with Manglietia fordiana (Liang & Nooteboom 1993) 10