Freshwater swamp forest in Singapore, with particular reference to that found around the Nee Soon Firing Ranges

29 Pages·1996·8 MB·English

by  I M Turner

Freshwater Swamp Forest in Singapore, with Particular
Reference to That Found Around the Nee Soon Firing Ranges
I.M. Turner1 Boo Chih Min1 Wong Yew Kwan2 Chew Ping Ting3 and
, , ,
Ali bin Ibrahim3
1 SchoolofBiologicalSciences.National UniversityofSingapore,Singapore 119260
2 89SooChowGardenRoad,Singapore575526
3 NationalParksBoard.SingaporeBotanicGardens.Singapore259569
Abstract
The freshwaterswampforestfoundaroundthe firing rangesatNee Soon isthe lastremaining areaofthis
forestformationinSingapore.ThevascularplantfloraoffreshwaterswampforestinSingaporeisreviewed,with
particular reference to the Nee Soon forest. Some preliminary soil, waterand foliar analyses indicate that the
swampforestatNeeSoonmayhaveconsiderablyhigheramountsofphosphorusavailabletothevegetationthan
thedrylandforestofBukitTimahNatureReserve. Nitrogenandpotassiumavailabilitiesappeartobesimilarat
thetwosites.TheNeeSoonswampforestisanextremelyimportantsiteforSingapore'snativebiotaandshould
receivethehighestpriorityforconservation.
Introduction
One of the least well-known of the forest formations of West Malaysia is
freshwater swamp forest. So named to distinguish it from the saltwater mangrove
swamps, itisaforesttypeofwet,oftenseasonallyflooded, lowlandareas(Whitmore
1975).Theonlyworkofanynote specificallyconcerningfreshwaterswampinthis
region is Corner's (1978) account of his studies, which were mostly floristic in
nature, of these forests in southeast Johore and Singapore. Corlett (1991) has
estimated that approximately 5% of Singapore was covered in freshwater swamp
before the major forest clearance of the nineteenth century began. The only
remaining area ofswamp forest in Singapore today is to be found around the Nee
Soon Firing Ranges in the Central Catchment Nature Reserve (Fig. 1). The fauna
of the Nee Soon forest and surrounding areas has been outlined by Ng and Lim
(1992). Botanically, thisareahas neverbeen studiedclosely, andit seems timelyto
consolidate our current knowledge ofthe forest into one publication.
The Nee Soon SwampForest
Swamp forest occurs in low-lying areas where slow-flowing streams drain
shallow valleys. The ground becomes saturated with the water table close to the
soil surfaceandthereareoftenperiodsofflooding. Suchswampsprobablyoccurred
historically inthe upperreachesofall theriversin Singapore(Corlett 1991).Corner
(1978) made detailed studies ofthe flora and forest structure ofthe swamp forest
nearMandai Road, which is now submergedbeneath Upper SeletarReservoir, and
in Jurong. Industrial and housing development have totally destroyed the Jurong
swamps.Thisleavesthe NeeSoonswampasthelastremnantoftheforestformation
in Singapore. It has probably survived because of the Firing Ranges, which lack
130
baffling walls or banks, making the surrounding area dangerous to the public and
unsuitable for any form of development. The approximate extent of the swamp
forest is shown in Figure 1. This has been delineated from data collected by a
number of field researchers, particularly D.H. Murphy who has mapped many of
the main streams ofthe area. It is estimated that the swamp forest covers about 87
ha, though much of this has been disturbed quite heavily at various times in the
past. There is concern that changes in the drainage regime of the forest may be
causing excessive soil erosion along some ofthe streams and causing the death of
the larger trees in certain areas (D.H. Murphy pers. comm.).
Figure1. Mapshowingthelocationofthe NeeSoonFreshwaterSwampForest, Singapore.Thestippledarea
indicatestheapproximateextentoftheswampforest.
Floristics
Appendix 1 gives alistofvascularplant species recorded from swamp forestin
Singapore. It is compiled from the list given by Corner (1978) for his plots at
Jurong and Mandai Road, specimens in the herbarium of the Singapore Botanic
Gardens (SING) where Nee Soon or Chan Chu Kang are given as collecting
localities,recentcollectionsfromtheNatureReservesmostlyasoutlinedbyTurner
etal. (1994) and the results ofthe forest survey ofWong etal. (1994). Clearly, the
floraofthe swampforest is rich, with more than 700 species havingbeen recorded
from this vegetation type in Singapore.
131
VegetationStructure and Physiognomy
The forestatNee Soonhas an appearance similartothatoutlinedforfreshwater
swampforestinotherlocalitiesbyCorner(1978).Thegroundissaturatedwithfrequent
smallstreamsandpoolsofwater.Manyofthetreesexhibittheprolificdevelopment
oflarge stilt roots and/or abundant pneumatophores ofvarious descriptions, that
Corner illustrates profusely in his book. In apparently primary areas, the trees can
m
reach large size, withheights of40 ormorebeingrecorded(Hill 1977).
During a survey of the forest communities of the Central Catchment Nature
Reserve(Wongetal. 1994)three0.2haplotswereenumeratedintheswampforest.
The location ofplots 26, 27 and 28 are given inFigure 1. The floristic composition
for trees of greater than 30 cm girth at breast height (1.3 m) in the three plots is
given in Table 1. The composition ofthe three plots was different from the plots
surveyed in the primary forest on dryland sites (Turner et al. 1996b). Important
speciesintermsofbasalareawerePometiapinnata, Palaquiumxanthochymum,
Mangifera griffithii, Glutei wallichii and Strombosia ceylanica. Corner (1978)
reportedthesetobeabundantinhisMandaiRoadplots, indicatingastrongsimilarity
in the forestbetween the two sites, which is not surprising given theirpropinquity.
Table1
Composition ofthe forest community (> 30 cm gbh) in three 0.2 ha plots in the Nee Soon swamp
forest,n=numberofindividualsofeachspecies,ba=totalbasalarea(cm2).Speciesareindescending
orderoftotal basalareasummedforthethreeplots. Someindividualscouldnotbe identifiedandare
referredtoby code numbers.
plot
26 27 28
species n ba n ba n ba
Pometiapinnata 6 10599 5 10357 2 6531
PaJaquiianxanthochymum 5 17983 2 1866 2 7128
Mangiferagriffithii 5 8853 7 4649 6 6160
Glutawallichii 5 6466 3 3082 5 6362
Strombosiaceylanica 10 8104 3 1017 11 5295
Z 19 1 13440
Pentacetriptera 3 7322
Z03 6237
1
Palaquiumrostratum 2 3107 1 2114
Santiriarubiginosa 5 4955
Mussaendopsisbeccariana 4 1406 5 1514 4 1912
Gonystylusmaingayi 2 4494
Polyalthiaglauca 5 1635 6 2521
Campnospermaauriculatutn 1 3677
Bhesapaniculata 2 1571 1 1559 4 484
Lophopetalummultinerviian 1 232 4 2982
Calophyllumteysmannii 2 3199
U 11 1 3182
Xanthophyllumellipticum 2 2750
Gymnacrantherafarquhariana 4 1656 1 447 2 604
132
plot
26 27 28
Vaticaridleyana 3 735 2 1758
Ganuamotleyana 3 2060 I 215
Ochanostachysamentacea 2192
1
Sandoricumbeccarianum 2166
1
Myristicacinnamomea 3 2027
Myristicaelliptica 1 72 1 588 2 1353
Xanthophylliimaffine 3 758 6 1174
Caralliabrachiata 2 1422 1 207 1 199
Macarangaconifera 2 1811
Alstoniaangustiloba 1790
1
Horsfieldiapolysphenda 2 558 1209
Triommamalaccensis 376 1 1283
Scaphiummacropodum 1 1559
Artocarpuskemando 1515
1
Xylopiamalayana 733 2 736
1
Eugeniacerina 1 1450
Diospyrosmaingayi 1 718 2 692
Jackiopsisornata 1 1386
Lithocarpusbennettii 2 1384
Sterculiamacrophylla 1 1263
Alseodaphnebancana 1 828 2 382
Sterculiacordata 1 1191
Magnoliacandollii 1 241 3 740 2 194
Z09 1 1146
Campnospermasquamatum 2 263 3 832
Aquilariamalaccensis 1052
1
Tristaniopsismerguensis 1 1016
Archidendronellipticum 1 998
Horsfieldiasucosa 2 993
Aglaiarubiginosa 2 985
Z 17 2 926
Blumeodendrontokbrai 3 1165
Pellacalyxaxillaris 2 409 1 447
Horsfieldiacrassifolia 1 796
Xylopiafusca 1 796
Alangiumnobile 1 115 1 616
Xanthophylliimobscuntm 1 688
Knemacommunis 1 509 1 176
Osmeliaphilippinensis 3 471 1 127 1 72
Litseaerectinervia 2 320 2 328
Memecylonedule 1 644
Knemacurtisii 1 644
Lophopetalumwightianum 602 4 2982
1
Garciniaparvifolia 1 140 2 454
Kibataliamaingayi 1 575
Knemaconferta 1 535
Mastixiatrichotoma 2 509
Cryptocaryaferrea 1 97 3 366
MYRISTICACEAE 460
1 1
Beilschmiediakunstleri 1 447
Castanopsisnephelioides 436
1
:
26 27 28
Z12 1 215 1 215
Knemalaurina 1 412
U12 1 412
Macarangatriloba 1 72 2 159 1 140
Lasearobusta 361
Myrisacalowiana 1 357
Prunuspohsiachya 1 347
Parishianudngayi 1 336
Dysoxyiumdensiflorum 1 316
Shoreaplmycarpa i 306
Baccaureaminor 1 296
Knemahookeriana i 286
Caiophyllumdtspar i 277
Kibaracoriacea 1 277
Knemalatericia 2 264
Baccaureaparvifoua i 258
Diospyroslanceifoba i 249
Phoebegrandis 1 241
Mangiferafoeada i 232
Zll 1 232
Asia:jr>:a:r.;j;. i 225
Baccaurearacemosa 1 215
Z14 i 215
Gnesumgnemon i 215
Garciniaeugenafoha 1 215
Aglaiaodoraassima i 207
PtemandracoeruJescens i 207
PimeiodendrongriJJuhh i 199
Garciniaforbesii i 199
Z10 191
Z 18 1 191
Baccaureahookeri 1 183
Shoreamacropiera i 183
Xeosconechiniakingii 1 176
Aporusapenangensis I 176
Myrisacainers i 176
Cyamocahxramutiflorus j 168
Shoreamalis i 154
Sarcothecagriffnhii 1 154
DiospyrospUosanshera 153
Meianochylacaesia 72 i 81
Knemamalayana i 147
Z15 1 140
Caiophyllumtetrapterum 1 134
Eugeniapapillosa i 134
Gynooochesaxillaris 1 134
Garcinianervosa 115
Horsf.eldiawaUichii 1 109
Z13 i 103
Lmimmmkntw\tkam i 103
Pyrenanaacuminata i 103
134
plot
26 27 28
Buchananiasessilifolia 1 97
Z 16 97
1
Elaeocarpuspetiolatus 92
1
Lithocarpussundaicus 1 92
Euryaacuminata 1 92
Sterculiantbiginosa 1 87
Gymnacrantherabancana 87
1
Microcosblattifolia 1 81
Bhesarobiista 1 81
Stemonoponisscorpioides 1 81
Memecylonlilacinum 1 81
Diplosporamalaccensis 1 81
Dysoxylumexcelsum 72
1
Ardisiacolorata 72
1
Symplocosfasciculatus 1 72
XanthophyllumviteUinwn 1 72
TOTAL(bainm2 108 9.18 107 6.64 121 8.20
)
The terrestrial herbs have been surveyed also in these three plots (Turner etal.
1996a) .Twentyspecieswererecorded(Table2),withonlyAglaonemanebulosum
and Labisia pumila being found in all three plots. The Araceae proved to be
particularly diverse.
Table2
Terrestrial herbaceous species recorded fromthe three0.2 haplots enumerated inNee Soon swamp
forest. + indicatespresence.
species plot plot plot
26 27 28
Aglaonemanebulosum + + +
Aglaonemanitidum + +
Alocasiadenudata +
Amischotolypegracilis + +
Cryptocorynegriffithii + +
Cyrtospermamerkusii +
Homalomenasp. 1 +
Homalomenasp.2 +
Labisiapumila + + +
Lecanorchismalaccensis +
Leptaspisurceolata +
Lindsaeadoryophora +
Mapaniacuspidata +
Mapaniasquamata +
Ophiorrhizasingaporensis +
Peliosanthestelassp.humilis +
Plocoglottisjavanica +
Schismatoglottiswallichii +
Syngrammaalismifolia + +
Trichomanesobscurum +
Totalnumberofspecies 6 12 10
135
Soil
The soil in freshwater swamp forest is generally rich in organic matter,
presumably because the anaerobic nature of the waterlogged conditions reduces
the rate of decomposition. However, this process has not proceeded far enough
to develop soils of high enough organic matter content to be considered peats
(generally >90% loss-on-ignition by mass). Some preliminary analyses for soil
samples from Nee Soon (Table 3) showed the soil surface to have high loss-on-
ignition, averaging nearly 80% and approaching 90% in places, though the values
dropped rapidly below 5 cm depth to generally less than 50% loss-on-ignition.
Some pH measurements showed that stream water and soil water lay in the range
4.6-5.5, with soil pH at 5 cm depth to be lower, 4.0-4.5. The concentrations of
the major plant nutrients, nitrogen, phosphorus and potassium, were measured in
the litter, soil and some foliar samples (shade leaves) gathered at Nee Soon (Table
4 and 5). Surprisingly, the littergenerally had lowerconcentrations ofthe important
elements than the top 5 cm layer ofthe soil. Possibly this represents the flushing
of nutrients down through the soil.
The nutrient concentration data can be compared with values obtained for the
coastal hill dipterocarp forest at BukitTimah (Grubb etal. 1994). The comparison
of the soil values between the two sites is difficult given the very different soil
bulk densities because ofthe high organic mattercontent ofthe soils at Nee Soon.
BukitTimah has more acidic soil (3.7-4.0 versus 4.0-4.5) and slightly higher litter
concentrations of N (12.9-14.5 versus 9.4 mg g 1), lower concentrations of P
(0.21-0.23 versus 0.47 mg g ') and higherconcentrations ofK (2.0-5.9 versus 0.48
mg g '). The foliage samples show a similar pattern with higher mean P in the
leaves at Nee Soon (1.72 versus 0.68 mg g '), but lower N (13.2 versus 17.1 mg
g 1) and K (8.3 versus 10.5 mg g 1) concentrations. It would appearthat Nee Soon
probably has more phosphorus available for plant growth than Bukit Timah, but
possibly slightly less nitrogen and potassium. Phosphorus appears to be the nutrient
limiting the growth of non-mycorrhizal plants on Bukit Timah soil (Burslem et
al. 1994), though mycorrhizal plants seem not to be responsive to P fertilization
(Burslem etal. 1995). Nee Soon may, therefore, present a potentially more fertile
site for plant growth, but of course the water-logged conditions are highly
unfavourable to many species. This relatively high nutrient availability may be
what prevents peat formation from occurring.
136
Table3 Table4
AnalysesofsoilandleaflitterfromNeeSoonSwamp FoliaranalysesforshadeleavesfromtreesatNeeSoon
Forest,Singapore. SwampForest,Singapore.
loss-on- totalN totalP total species totalN total P total
ignition (mgg-') (mgg1) (mg; (mgg') (mgg1) (mg;
(%) Archidendronsp. 18.9 1.28 8.9
leaflitter Calophyllumsp. 7.7 0.55 5.7
sample 1 9.88 0.52 0.52 Desmosdasymaschala 16.2 2.86 11.0
sample2 8.50 0.42 0.48 Diospyrossp. 10.6 1.88 7.5
sample3 9.83 0.49 0.43 Litsearidleyi 9.7 2.41 12.3
mean 9.40 0.47 0.48 Nepheliumsp. 14.2 1.95 7.1
Pternandraechinata 12.4 1.22 5.8
soil(0-5cm) Strombosiaceylanica 14.3 1.16 8.3
sample 1 88.7 22.2 0.87 0.51 sp.indet. 14.8 2.17 7.9
sample2 60.8 12.8 0.70 0.52 mean 13.2 1.72 8.3
sample3 89.6 17.5 0.87 0.64
mean 79.7 17.5 0.81 0.56
soil(5-10cm)
sample 1 54.8 9.53 0.84 0.72
sample2 34.8 6.25 0.45 0.69
sample3 47.5 7.41 0.54 1.16
mean 45.7 7.73 0.61 0.86
Conservation
Nee Soon is now Singapore's last fragment of freshwater swamp remaining.
Many species ofplants and animals are now restricted to this area, hence making
Nee Soon ofgreat importance in terms ofthe biodiversity ofSingapore. The plant
list includesAeschynanthus wallichii, Bulbophyllum macranthum, Cystorchis
variegata, Kopsiasingapurensis, Luvunga crassifolia, Neoscortechinia kingiiand
Xylopiafiisca. Ng and Lim (1992) listmany animal species restricted, in Singapore,
to Nee Soon. Species found at Nee Soon are generally not found at Bukit Timah,
and vice versa, so the two are the twin pillars of biodiversity in Singapore and
require strict protection.
Acknowledgements
We are grateful to D.H. Murphy, H.T.W. Tan, K.S. Chua and Haji Sidek for
sharing their expertise and data concerning Nee Soon swamp forest. Jeanette Ong
provided valuable technical assistance in the laboratory, and Jean Yong helped in
preparing the figure.
References
&
Burslem, D.F.R.P., Turner, I.M. Grubb, P.J. (1994). Mineral nutrient status of
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Burslem.D.F.R.P..Turner. I.M. & Grubb. P.J. ( 19941. Responsestoelevatednutrient
supply and simulated drought among shade-tolerant tree seedlings of lowland
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138
APPENDIX
1
SPECIESLISTOFVASCULARPLANTSFORFRESHWATERSWAMPFORESTINSINGAPORE
Species marked with an asterisk are those recorded by Corner (1978) from freshwater swamp
forestinSingapore.Wheretaxonomicrevisionshavenecessitatednamechanges,orspecimenswere
misidentified, the name used by Corner is given in parentheses. Other species are those collected
recentlyorknownfromherbariumspecimenswhereNee Soon swampforestorChanChu Kang are
givenasthecollectinglocality. FormoreinformationregardingNRS seriescollectionsseeTurneret
al. (1994). Speciesrecorded fromthethree0.2haplots at Nee Soon (Wongetal. 1994)are marked
withadagger(t). Onlyforestspeciesareincluded.ThedeterminationofMangifera speciesfollows
Kostermans & Bompard (1993).
LYCOPODOPHYTA
Lycopodiaceae
Huperzianummulariifolia (Blume)Jermy - Ridley s.n. (Oct 1889)
* Huperziaphlegmaria (L.) Rothm. (Lycopodiumphlegmaria)- Ridley2420(1884)
* Huperziasquarrosa (G.Forst.)Trevisan {Lycopodiumsquarrosum)
Selaginellaceae
Selaginellaargentea(Wall.)Spr. - NRS1972
FILICINOPHYTA
Adiantaceae
t Syngrammaalismifolia(C. Presl)J. Sm. - NRS1610
* Taenitisblechnoides (Willd.) Sw.
Aspleniaceae
Asplenium batuenseAlderw. - NRS1185
AspleniummacrophyllumSw.-Goodenoughs.n.(1890)
* AspleniumnidusL.
* Aspleniu??i nitidum Sw.(Aspleniumglaucophyllum)
Blechnaceae
Blechnumfinlaysonianum Hook. &Grev. - Ridley6121 (1894)
* Blechnu???orientateL.
* Stenochlaenapalustris (Burm.) Bedd.- NRS1589
Cyatheaceae
* Cyatheaglabra(Blume)Copel. - NRS1526
* Cyathealatebrosa (Wall,exHook.) Copel.- NRS1508
Davalliaceae
DavalliaangustataWall,exHook.& Grev.- Ridley3599a (189?)
Dennstaedtiaceae
* Histiopterisincisa (Thunb.)J.Sm.