Proceedings of the Nature Reserves Survey Seminm: Gardens' Bulletin Singapore 49 (1997) 161-223. Checklist of Vascular Plants in the Nature Reserves of Singapore P.T. CHEW, SAIFUDDIN SURAN AND ALI IBRAHIM Singapore Botanic Gardens, 1 Ouny Road, Singapore 259569 Abstract This vascular plant checklist of the Nature Reserves of Singapore is a compilation of historical records (herbarium specimens, published and unpublished checklists) as well as recent field observations and studies. A total of 1634 species of vascular plants have been recorded in the Nature Reserves since the last century, of which 443 (or 29% of the indigenous species) have not been seen during the last 10 years. Introduction The current Nature Reserves of Singapore consist of the Bukit Timah Nature Reserve (BTNR) and the Central Catchment Nature Reserve (CCNR). Floristic inventory and research in the past were mostly concentrated at BTNR, the Bukit Timah Reserve as it was formerly known. It was one of the first Forest Reserves to be established in Singapore in 1883. In 1951, the Nature Reserves Ordinance was enacted and the Central Catchment Area, now known as the Central Catchment Nature Reserve, was included as one of the five Forest Reserves. In 1990, the newly gazetted National Parks Act established a National Parks Board, which acts as a trustee for the current Nature Reserves. , The objectives of the Nature Reserves are, as stated in Part II of the National Parks Act 1990: (a) the propagation, protection and preservation of the plants (flora) and animals (fauna) of Singapore; (b) the study, research and preservation of objects and places of aesthetic, historical or scientific interest; (c) the study, research and dissemination of knowledge in botany, · horticulture, biotechnology and natural and local history; 162 Card. Btt/1. Singapore 49(2) (1 997) and the following was added as Part VII in the National Parks Act 1996: (d) recreational and educational use by the public. In 1991, a six-year Nature Reserves Survey (NRS) project was initiated by the National Parks Board (NParks), primarily to inventory the physical and biological components of the Nature Reserves, particularly, that of the lesser known CCNR. Materials The documentation of Singapore's flora started in the late nineteenth century. A literature and herbarium search at the Singapore Botanic Gardens H erbarium (SING) yielded a long list of historical flora records of the Nature Reserves of Singapore. These include Report on the Forests of the Straits Settlements (Cantley, 1884), Flora of Singapore (Ridley, 1900), Freshwater Swamp-forest of South lahore and Singapore (Corner, 1978); and specimen records by H.N. Ridley, I.H. Burkill, R.E. Holttum, E.J.H. Corner, and more recently, J. Sinclair in the 1950s-1960s. After a lapse of about 30 years, interest in biodiversity revived when field collections were carried out at Lower Peirce (within the CCNR) under an independently commissioned survey for a separate project proposal in 1990. This was followed by the NRS project, of which floristic inventory was the primary component during the period 1991 to 1994. Field surveys of the CCNR flora were conducted by NParks staff and consultants (Wong et al., 1994; Ali et at., 1997), and researchers and student assistants from the National University of Singapore (Turner et al., 1994, 1996a, 1996b, 1996c, 1997). Besides these recent compilations of Singapore fl ora, checklists (Turner et al. , 1990, Turner,1993, 1995; Wee & Ng, 1994; Ng & Wee, 1994; Chin et al. , 1995; Tan, 1995) and selected flora inventory research carried out in the Nature Reserves in the last decade (Wong, 1987; Swan, 1988; Corlett, 1990, 1991; Sim et at. , 1992; Tan et al. , 1995; LaFrankie et at., 1996; Chua et al., 1996) are available. In addition, the flora in a two-hectare plot in the BTNR is under a long-term population dynamic study carried out by the National Institute of Education, Nanyang Technological University, in conjunction with the Center for Tropical Forest Science (CTFS). Check/is / of vascular plams 163 Methods The compiled list of indigenous vascular plant species (Appendix 1) that are or were probably fo und growing in the Nature Reserves since the last century is derived from the various publications listed above, herbarium records in the Singapore Botanic Gardens Herbarium, and the unpublished checklists noted below. Naturalised species sampled in the survey are recorded in Appendix 2. The record sources for the four columns, R, H, P and S, in Appendices 1 and 2 are as follows: R - records from field collections, published data from NRS, and published data during the period 1991 - 1997 from the "Additions to the Flora of Singapore" and "The Angiosperm Flora of Singapore" series published in the Gardens' Bulletin Singapore, 44- 49. H - herbarium specimens records in SING. P- publication records denoted as follows: C- Corlett (1990, 1991); F ­ Wee (1983, 1984); N - Corner (1978); T - Chua et al. (1996), Tan et al. (1995), Tan (1995, 1997); W- Wong (1987). S - unverified records denoted as follows: 1 - observations from NParks staff and NRS unpublished checklists, 2 - unpublished checklist of BTNR flora (Corlett, late 80s), 3 - collections from the Centre for Natural Product Research (CNPR) project and 4 - collections from the CTFS project. The records reported under S are non-exhaustive. Sources 1, 3 and 4 are complementary to R while source 2 is complementary to H, based on dates of collections. Of the new unverified records discovered from this survey that are not found in the Singapore checklist (Turner, 1993), those that have not been recorded as far south as Johore, the nearest state of Peninsula Malaysia, were left out. Observations The total vascular plant records for the Nature Reserves of Singapore is 1634 species, as listed in Appendices 1 and 2. Of these species, 1525 are indigenous (Appendix 1) and 109 (7%) are exotic (Appendix 2). For the NRS, 916 species (under R) were recorded with an additional 258 species (1 , 3 & 4 under S) noted during the period. 164 Card. Bull. Singapore 49(2) (1997) A total of 1190 vascular plant species are recorded for the Nature Reserves within the last 10 years, of which 341 species or 29% (excluding those listed in recent publications under P) are new records for the Nature Reserves. Of the 1267 old records (those older than 10 years) for the Nature Reserves, 443 (35%) species were not seen during this NRS project period. Some of these species may be extinct as a result of habitat loss (tidal freshwater swamp where the present U pper Seletar Reservoir resides) and forest fragmentation due to clearing and cultivation within the century. Others probably still survive in the Nature Reserves. Out of 1190 species recorded within the last ten years in the Nature Reserves, 90 (7 .5%) are exotic. In comparison, only 11 (0.8%) species out of 1297 species were exotic for records earlier than the last ten years, an eight fold increase in ten years. Discussion From the literature survey, it can be seen that in the last few decades there was an absence of field work in the CCNR. It is noteworthy that prior to the NRS, the Singapore flora checklist comprises mainly records more than 30 years old. Consequently, the NRS inventory sets an important milestone in the documentation of fl ora in Singapore in filling this gap. Records of lianas, herbaceous, climbing and creeping epiphytes, terrestrial ferns, sedges, grasses, and aquatic and semi-aquatic flora are also expected to be not as complete as that of the tree flora in the NRS, as these were randomly sampled rather than sampled intentionally as defined taxonomic groups. As noted above, exotics have been invading the Nature Reserves within the last few decades. The number of exotic species establishing in the Nature Reserves should be monitored in future surveys for management implications in the conservation of indigenous species. Acknowledgements We should like to thank Drs. R.T. Corlett, H.T.W. Tan, I.M. Turner, S.K.Y. Lum, J.V. LaFrankie and their students and assistants, and Mr Y.K. Wong, D .H. Murphy and E.S.K. Tang for providing published and unpublished fl ora checklists and records of the Singapore Nature Reserves. Check/is! of vascular plan Is 165 References Ali Ibrahim, P.T. Chew, Hj Sidek Kiah & J.T.K. Lai. 1997. New records of plant species from Singapore. Gardens' Bulletin Singapore. 49: 49-54. Cantley, N. 1884. Report on the Forests of the Straits Settlements. Singapore Printing Office, Singapore. Chin, S.C., R.T. Corlett, Y.C. Wee & S.Y. Geh (eds.). 1995. Rain forest in the city: Bukit Timah Nature Reserve Singapore. Gardens' Bulletin Singapore. Suppl. 3. Chua, K.S., B.C. Soong & H.T.W. Tan. 1996. The Bamboos of Singapore. 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