Rain Forest in the City: Bukit Timah Nature Reserve Singapore CONTENTS Chapter 1 Introduction ................................................................................... 1 Richard T. Corlett Chapter 2 History ............................................................................................ 7 Richard T. Corlett Chapter 3 Flowering Plants ......................................................................... 11 Richard T. Corlett Chapter 4 Rubiaceae ..................................................................................... 29 Hugh T. W. Tan, K.S. Chua & Ian M. Turner Chapter 5 Pteridophytes ............................................................................... 61 Y.C. Wee Chapter 6 Bryophytes ................................................................................... 71 Y.C. Wee & Haji Mohamed Chapter 7 Algae ............................................................................................. 77 Y.C. Wee Chapter 8 Vesicular-Arbuscular Mycorrhizae .......................................... 81 I. Louis Chapter 9 Mammals ..................................................................................... 93 Richard T. Corlett & Peter W. Lucas Chapter 10 Long-Tailed Macaques ............................................................. 105 Peter W. Lucas Chapter 11 Birds ........................................................................................... 121 N. Kang & Christopher J. Hails Chapter 12 Amphibians and Reptiles ......................................................... 145 L.M. Chou Chapter 13 Freshwater Decapod Crustaceans ........................................... 151 Peter K.L. Ng Chapter 14 Fishes .......................................................................................... 159 Kelvin K.P. Lim Chapter 15 The Future ................................................................................. 165 Richard T. Corlett Chapter 1 Introduction Department of Ecology & Biodiversity The University of Hong Kong Hong Kong Bukit Timah Nature Reserve consists of 81 hectares, mostly covered in forest, on the slopes and summit of Singapore's highest hill, Bukit Timah (162.5m) (figs. 1 & 2; fig. 1, chap. 11). This small reserve supports an incredible diversity of plants and animals which cannot survive outside the forest, yet it is only 8 kilometres from the city centre and a few minutes' walk from several crowded shopping arcades. It is visited daily by hundreds of people - walkers, joggers, nature lovers, school groups and tourists. It provides a research area for many Singapore-based and visiting scientists, and has featured in numerous scientific publications: Bukit Timah may well be the best studied forest area in Southeast Asia. It is also probably the oldest rain forest reserve in the region, if not the world. Bukit Timah Nature Reserve is an island on an island. The forest on Bukit Timah hill has been isolated from other forest areas since at least 1860, if not considerably earlier. Today it is surrounded by roads, buildings, ex-quarries, and other open areas, and cut off from the more extensive, mostly secondary, forest in the Central Catchment Nature Reserve to the east by the 8-lane Bukit Timah Expressway (fig.1, chap. 11). Access to the Reserve is along Hindhede Drive, at .the end of which is a car park and the excellent new Visitor Centre. (fig.2). A metalled road serves the Telecoms Tower and the summit within the Reserve but is closed to private vehicles. A network of well-marked footpaths penetrates the forest and there are huts for rest and shelters at various points. For Singaporeans, Bukit Timah Nature Reserve is a public park with a difference. In place of close-mown grass with neatly-arranged trees and shrubs, there is the full exuberance of untamed tropical nature. Bright sun is replaced by cool shade, the hum of traffic is almost obscured by the sounds of unseen insects and birds. Many people come just to climb Singapore's highest hill but, for an increasing number, it is the forest and its inhabitants which are the main attraction. School trips, extensive media coverage, and the efforts of the Nature Society (Singapore) have served to raise Singaporeans' awareness of nature to an extent which is probably unique in an Asian city. For Singapore, Bukit Timah is also an historical monument: a substantial and accessible remnant of the forest which covered the whole island less than two centuries ago. Unlike many older capitals, Singapore has no great old buildings Figure 1. Map of Singapore showing Forest Reserves in 1897 (hatched) and Nature Reserves in 1994 (dotted). Inset map of the central part of the island showing the water catchment area and Bukit Tirnah Nature Reserve (BT). or spectacular ruins, but what other city can boast a fragment of history as old and complex as the rain forest on Bukit Timah? As this volume shows, Bukit Timah is a major research site for local scientists and for foreign researchers working in Singapore. Research at Bukit Timah is not just of local importance. For research projects which do not require the presence of the complete original rain forest biota, Bukit Timah offers an unrivalled proximity of primary dipterocarp forest and laboratory facilities equiped to the highest international standards. This permits studies requiring frequent monitoring or delicate equipment which would be difficult or impossible at more remote locations. Perhaps the most important international role that Bukit Timah plays, however, is as an experiment - unplanned and incompletely documented - on the effects of fragmentation and isolation on a species-rich rain forest biota. Studies of extinction at Bukit Timah are hampered, however, by the variable quality of nineteenth century records and a major role of this volume is to act as a new "base line" against which future changes can be measured. The worldwide acceleration of tropical deforestation over the past decades has made an understanding of species survival in the forest fragments which remain an urgent task. Nature recreation, education, and research, however impohant, are not the primary functions of a nature reserve. Bukit Timah Nature Reserve is, first and foremost, a store of biodiversity for future generations. We do not know the total number of species the reserve supports since many groups of organisms, including most of the invertebrates, are virtually unstudied, but the diversity of plants alone (chap. 3-7) justifies the reserve status. Bukit Timah has few known endemic species (species found nowhere else) but this number may rise as more invertebrates groups are studied in detail. Sadly, the number of endemic species will probably also rise as the increasing deforestation of southern Malaysia reduces the ranges of forest specialists. Morever, for plant and animal species with wide geographical ranges, Bukit Timah is often at the southern limit of distribution, so the local populations are likely to be genetically distinct from populations of the same species to the north. The organisation of this volume is straightforward. After an account of the history of the reserve (chap. 2), there are separate chapters on those major groups for which we could find authors: in practice, the plants and the vertebrates. The flowering plants (Angiosperms: chap. 3), with at least 840 species, are the largest plant group at Bukit Timah. The ferns and their allies (Pteridophytes : chap. 5) have more recorded species (107) than the Bryophytes (53 species: chap. 6) and the Algae (19 specie$: chap. 7), but the latter two groups have been little studied at Bukit Timah and the totals given are undoubtedly underestimates. The birds are by far the most species-rich vertebrate group (c. 110 species: chap. 1I), followed by the amphibia and reptiles (at least 37 species: chap. 12), the mammals BUKIT TIMAH NATURE RESERVE (c. 15 species, excluding bats: chapter 9), and the fishes (10-12 spp.: chap. 14). Note the unfortunate absence of a chapter on by far the most species-rich group of organisms at Bukit Timah, the insects (30-50,000 species?). In addition, there are chapters on some smaller or less conspicuous groups on which detailed studies have been made: the mycorrhizal fungi (chap. 8), the freshwater decapod crustaceans (chap. 13), the Rubiaceae (the largest family of flowering plants at Bukit Timah: chapter 4), and the macaques (chap. 10). To a large extent, the unevenness of coverage reflects unevenness in our knowledge of the Reserve, in turn a result of unequal research effort. We hope that this volume will spur efforts to fill some of the gaps. Obvious gaps include the bats (omitted from the mammal chapter because of inadequate data), the butterflies (for which there is fairly good historical information), and every other terrestrial invertebrate group. Moreover, for the great majority of species mentioned in this volume, the only information we have is the name and general habitat: detailed ecological studies of individual species (with the exception of the Long- tailed Macaque) have still to be carried out. Bukit Timah is not the only rain forest reserve on the outskirts of a major city. In Brazil, several important remnants of the threatened Atlantic Rain Forest are near urban areas, including the 7900 ha Serra de Cantareira State Park, 12 km from the centre of Sao Paulo, a megapolis of over 15 million people, and Tijuca National Park, a secondary forest reserve on the margins of Rio de Janeiro (Por, 1992). These reserves suffer from similar problems to Bukit Timah,