Journal of Tropical Forest Science 8 (1): 59 - 70 (1995) 59

EFFECT OF HERBIVORY ON SEEDLING ESTABLISHMENT OF () UNDER PLANTATION FOREST IN PENINSULAR MALAYSIA

Naoki Kachi*, Toshinori Okuda

National Institute for Environmental Studies, Tsukuba, Ibaraki, 305 Japan

&

YaKheonn pSo g

Forest Research Institute of Malaysia, Kepong, 52109 Kuala Lumpur, Malaysia

Received February 1994______

KACHI, N., OKUDA, T. & YAP, S.K. 1995. Effect of herbivory on seedling establish- men Dryobalanopsf to aromatica (Dipterocarpaceae) under plantation fores Peninn ti - sular Malaysia. Post-dispersal surviva f kapulo r (Dryobalanops aromatica) monitores wa d i 60-year-olna d kapur plantatio mixed-speciea d nan s plantatio Kepongt na , Peninsular Malaysia. Kapur seeds showe dormanco dn germinatiod yan n started withi day3 n1- s after being placeforese th n td o floor n botI . h plantations, seed cotyledond an s - stage seedlings were consumed by vertebrates such as rodents and wild pigs. On average, less than 1 % of the seeds survived to the four-leaf seedling stage. After reachin four-leae gth f stage, predation appeare reducede b o dt t seedlinbu , g mortality probably cause watey db r stress and/or pathogens increased. Seedling e sixth -n si leaf stage had low mortality, allowing the establishment of a sapling bank under the canopy e resultTh . s indicate that natural regeneratio f kapuno plantationn i r y sma expectee b d when sufficient seeds produced during mast years compensate th r fo e high mortality durin seee earld gth d an y seedling stage.

Key words: Dipterocar p- Dryobalanops aromatica - herbivor y- kapu - predatior - n seeds - seedlings - survival

KACHI, N., OKUDA, T. & YAP, S.K. 1995. Kesan herbivori ke atas penubuhan anak benih Dryobalanops aromatica (Dipterokarpa) di bawah hutan ladang di Semenanjung Malaysia. Kemandirian selepas-penyerakan kapur (Dryobalanops aromatica) telah didapat i sebuad i h ladang kapur berusi i sebua d tahu0 6 an nhda ladang spesies campura i Kepongnd , Semenanjung Malaysia. Biji benih kapur menunjukkan tiada kedormana percambahan nda n bermula dalam mas har3 a1- i selepas ditempatkai nd lantai hutan i dalaD . m kedua-dua ladang, biji beni anan hda k beni i peringkahd t kotiledon dimakan oleh vertibrata seperti rode babn nda i hutan. Secara purata, kurang dari 1 % daripada biji benih adalah mandiri pada peringkat anak benih empat- daun. Selepas mencapai peringkat empat-daun, pemangsaan didapati berkurangan tetapi kematian anak benih mungkin disebabkan oleh tekana r dan/atanai u per- tambahan patogen. Anak benih-anak benih pada peringkat enam-daun mempunyai kadar kematian yang rendah, membolehkan penubuhan betau anak pokok di bawah sudur. Keputusan menunjukkan bahawa pemulihan semulajadi kapur di ladang-

*Present address: Department of Biology, Faculty of Science, Tokyo Metropolitan University, Hachioji, Tokyo, 192-03 Japan 60 Journal of Tropical Forest Science 8 (1): 59 - 70 (1995)

ladang mungkin dijangkakan bila biji benih-biji benih yang mencukupi dihasilkan pada tahun-tahun kematangannya bagi menggantikan pokok-pokok yang mati dengan banyaknya pada peringkat biji beni peringkan hda t awal anak benih.

Introduction

In many species, plantstage th en si from germinatio seedlino nt g establish- men e mosar t t vulnerabl mortalito et thein yi r life histories (Harper 1977)n I . tropical forests, seeds and seedlings are eaten or trampled by vertebrate animals (Coley 1983, Becke Wonr& g 1985, Schupp 1988, Clar Clark& k 1989, Howe 1990, Osunkjoy . 1992)al t e a , infeste insecty db s (Clar Clark& k 1985, Kha Tripathn& i 1991), attacked by fungi and other microorganisms (Augspurger 1983), buried under forest litter (Molofsky& Augspurger 1992,Vazquez-Yanes&Orozco-Zegovia 1992), washed away by rain, and suppressed by lack of light (Sasaki & Mori 1981, Augspurger 1984), water (Augspurger 1979 minerad )an l nutrients (Janzen 1974). In tropical forests, seedlings of several plant species suffer high mortality at vicinite th theif yo r conspecific adul abundancn a to t tree e s du naturaf eo l enemies (Janzen 1970). Thus, the probability of seedlings to survive in an artificially- established mono-specific dominant forest would be lower than that in areas with mixed-species typical of lowland tropical forests. However, evidence reported from neotropical forests suggested that this situation is not always true (Clark & Clark 1984 littld an )e evidenc bees eha n reported from Southeast Asia (Becker & Wong 1985). Dryobalanops aromatica (local name: kapur) is a canopy tree species (Symington 1943; see also a review by Appanah &Weinland 1993) with its natural distribution Malae inth y Peninsula, Sumatr Borned aan o (Foxworthy 1932) altitudinae Th . l range is between 70 and 400 m above sea level (Wyatt-Smith 1963). It is common well-drainen o d fine sandy soils (Symington 1943, Won 1987). al t ge . Unlike many other canopy tree specie lowlann si d tropical forests, kapu verys ri abundant locally. In natural conditions, kapu totae r morro th producelf % eo volum 60 - 0 f es4 o timber in the forests, although it is always accompanied by numerous other tree species (Foxworthy 1932, Vincent 1961) Peninsulan I . r Malaysiae , th mos f o t natural kapur forests occur in scattered patches along the east coast, stretching fro e southermth n par Terengganf o t u sout Johoro ht , wher e raineth y season extends from November to January (Foxworthy 1932, Wyatt-Smith 1963). A small natural stan kapuf do alss ri o founRanchine th n di g Forest Reserv wese th t n coasteo , althoug origis hit unknows ni n (Wyatt-Smith 1963). In laboratory conditions, freshly fallen and sound seeds of kapur germinate within a week with over 80% viability at 30 °C (Yap 1981), but the viability is quickly lost within three weeks mainly due to attacks by fungi and microorganisms (Jensen 1971) mosn i s tA . member Dipterocarpaceaef so seede ,th recalcitran e sar t regeneratiod an n depends largelpresence th n saplinya o f eo gforese banth n tko floor. e purposTh f thieo s stud investigato t s yi e post-dispersal surviva f kapuo l n i r kapur and mixed species plantations to determine if the monoculture kapur plantation regeneratn sca e naturally. 1 6 Journal of Tropical Forest Science (19950 8(1)7 - 9 :5 )

Methods

The site

Within the grounds of the Forest Reserve of Forest Research Institute of Malaysia (FRIM) in Kepong, Peninsular Malaysia (101°37'E, 3°13'N), a plantation of kapur was established durin late gth e 1920' earld san y 1930's canope Th . dominates yi d by kapur with height distanct aboum A f aroun0 so . 20 tm e0 dfro4 kapue mth r plantation, there is a mixed species plantation of similar age, where Shorea bracteolata, Dipterocarpus baudii, . semivestitusD e Dipterocarpaceae) th (al n i l , Gymnacranthera forbesii (Myristicaceae), Scorodocarpus borneensis (Olacaceae) d Paraserianthusan , falcataria (Leguminosae) are codominant, and kapur trees are absent. The canopy height is 30 - 35 m and the density of canopy trees is comparable to that of the kapur plantatio r individualn fo (17-2 a h r 5pe s with diameter t breasa s t height more than 10 cm).

Seed-sowing

A serie f experimentso s were conducte determino dt e survivorshieth d pan cause f mortalito s y following seed falf kapuro l Marcn I . h 1991, many trees flowered in the kapur plantation and mature fruits fell during June and August in the same year. Fallen fruits were collected from the kapur plantation during August 1991 frui e wingea s Th i .t t witdnu h fiv lon em 1.5-d c lobegan 8 m 2- c s(7 wide). The size of the nut (hereafter described as seed) is 2.5-3.5 cm long and 1.2 - 2.0 cm wide and the fresh weight is 5-10g. Natural density of fruits in the kapur plantatio variabls nwa e dependin topographe th n go localitd yan fruitinf yo g trees, ranging from 0 to 10 per m . In all experiments only visually undamaged 2 seeds were used, more othaf% whicn95 h germinate preliminara dn i y germination test. The seeds were immediately sown in the kapur and mixed-species plantations on 16 August 1991. Two plots (1 X 1 m) were established in each plantation and 72 seeds were sown in each plot. Seed survival and causes of mortality were monitored day2 1 sd aftean 6 r , sowing2 n o . Isolated seed havy ma se higher probabilit survivaf yo l than seeds occurringn i groups, as they are less likely to be discovered by predators (Boucher 1981). To assess whether isolation affects seed mortality, another experimen carries twa d out. Twelve canopy trees were arbitrarily chosen in the kapur and mixed-species plantation seedo tw sd wersan e place eacn di h compass directio from e m1 th t na bas eacf eo h tree seed tota6 A .9 f lso were left amon tree2 1 eacn e si gth h plantation Augus3 2 n o t 1991 determino T . longevite eth individuaf yo l seeds, surviva thesf lo e seeds was monitored for 76 days from the date of sowing until all but one seedling died or disappeared. 62 Journal of Tropical Forest Science 8 (1): 59 - 70 (1995)

Transplanting of seedlings

Three sets of transplant experiments were conducted to assess seedling survival starting from cotyledon, four-leaf six-lead an , f stages. After removin wingse gth , kapur seeds were sown in a black polyethylene bags, 10 cm in diameter, containing B-layer soil (5-3 deep)m 0c fro kapue mth r plantatio growd nan n outdoora n si nursery until transplanting photoe Th . n flux densities relativ open thao a et t nta site was ca. 3-4%. The light measurement was made on a overscattered cloudy day using a photon sensor (LI-COR Model LI-190SA). For the transplanting trials the following numbers of quadrats ( 1 x 1 m) and seedlings were used:

seedlings/quadraf o No. quadratf o .No s t Cotyledon stage 6 6 0 1 Four-lea 6 f stage 0 1 2 Six-leaf stage

same Th e set-ups were establishe botdn i h kapu mixed-specied ran s plantations. All plots were randomly distributed in an area of ca. 100 X 100 m. The respective experiments were started on 4 September, 11 October and 3 December 1991.

Protective cage experiment

determino T mortalite eth seedf y o seedling d san predatioo t e sdu smaly nb l mammals, an experiment using protecdve cages was conducted in the two planta- Augus9 tions2 n O t. 1991 matur0 1 , e kapur seeds were placeforese th n td o floor covered an d wit mesha cageho cagTw s . ewer witt mm ese h 5 opening8. X 8 1 f so in each plantation. Control plots were also set adjacent to the caged plots. The cages were remove Septembe9 1 n do r 199 day1 1(2 s after sowingcensue th d san ) was continued unti Novembe4 1 l rdays 7 1997 r .1fo

Size distribution of kapur

In the kapur plantation, a 550m2 plot divided into 5 X5m grids was established in March 1992 individual Al . l kapur trees including seedlings were markee th d dan diameters were measured r plantFo . s les highsm c tha 0 , 3 ndiameter s were measure abov stem e c grounde th m 0 higt eth d1 m a base c t h a 0 plantr 6 ,fo ,- 0 s3 plantr highfo m d c s hig 0 an ,mor m 3 c fot ha hig0 r em thosc t 20 tha ha - 0 0 ne20 6 . cm 0 10

Results

Survivorship at seed stage

Seed kapuf so r showe dormanco dn majorite th d sounyf an y o d seeds germinated within thre efielde dayth n .si Seeds kapu e sowth n i r plantatio mortalit% 93 d nyha Journal of Tropical Forest Science 8(1): 59 - 70 (1995) 63 after 12 days. The majority of them were consumed by predators within two days after sowing (Figure 1). In contrast, seeds in the mixed-species plantation had relatively low mortality compared with those in the kapur plantation (p<0.001,Chi- square test base datn do respectivn ao e sampling days).

4 6 8 10 12 14 Days after seed sowing

Figur . e1 Survivorshi f seedpo f Dryobalanopso s aromatica (kapur) transplante n duplicati d e plots in the Forest Research Institute of Malaysia. (Vertical bars indicate the range of 95% confidence limits; open circle: in the mixed-species plantation; closed circle: in the kapur plantation).

In the other experiment when isolated seeds were placed around individual trees 97% of germinating seeds were lost or dead by the 5th day in the kapur plantation. Seeds similarly placemixed-speciee th n di s plantation suffere% d92 mortality afte day4 3 r s (Figuraverage Th . e2) e longevite day6 th seed f y2. n o s i s swa kapur plantatio 14.d n an 1 mixed-speciee dayth n si s plantatio difference th d nan e between the highls mwa y significan 0.001< p ( t , Mann-Whitney U-test). Most of the seeds protected by cages germinated without predation and these seedlings survived until the cages were removed. After removing the cages, the seedlings were eate mammaly nb s (characterise leftovey db r seed coat halfd san - eaten seeds) resultin higa n gi h mortalit whee 21sy yth e da (Figurtnn th O . e3) cages were removed in the experimental plots, 41 % of the seedlings in the uncaged control plots situate kapue th n di r plantation were surviving, whil wer% ee53 still present in the mixed-species plantation (Figure 3). By the 77th day all but two seedlings were dead. 64 Journal of Tropical Forest Science 8(1): 59 - 70 (1995)

Figur . e2 Survivorshi f seedpo f Dryobalanopso s aromatica (kapur) place n isolatiodi n around canopa yForese treth n ei t Research Institut f Malaysiaeo . (Each averagpoine th s i t e over 12 tree plots; vertical bars indicate: the range of 95 % confidence limits; open circle: in the mixed-species plantation; closed circle: in the kapur plantation).

Figure 3. Effects of protective cages on survivorship of seeds and seedlings of Dryobalanops aromatica (kapur) transplanted in plantations in the Forest Research Institute of Malaysia. (Vertical bars indicat confidenc % e rang95 th e f o e e limits; circles: protecte cagesy db ; triangle; control; closed symbols e kaputh n i :r plantation; open symbols e mixed-specieth n i : s plantation arroe Th .w indicate time sth e whe protective nth e cages were removed). Journal of Tropical Forest Science 8 (1): 59 - 70 (1995) 65

Survivorship at cotyledon stage

Mortality-during the early seedling stage, while the cotyledons were still at- tached, was also high. The probability of cotyledon-stage seedlings to survive to the four-lea botn i h% 2 sites mai. fe stagca Th .s n ecauswa mortalitf eo predatios ywa n by mammals. Some insect damag leaveo et alss oswa observed. Thre cenr en pe (i t the kapur plantation) and 7% (in the mixed species plantation) of seedlings failed to produce any leaves, when their shoot apexes were damaged by insects and/or microbial pathogens. In the kapur and mixed-species plantations, the survival of cotyledon stage seedling s approximatelwa s y linea semi-logarithmia n ri c plot (Figur . There4) e wa significano sn t difference regressione th n si specifif so c mortality rates between kapur and mixed-species plantations (p > 0.05, t-test for comparisons of two regression slopes and intercepts). The mortality rate after pooling all data was 6% per day.

0 15 0 10 0 5 Days after transplanting

Figure 4. Survivorship of cotyledon stage seedlings (top figure) and four-leaf stage seedlings (bottom figure) of Dryobalanops aromatica (kapur) transplanted in plantation e Foresth n si t Research Institut Malaysif eo a. (Close d circld ean solid line: in the kapur plantation: open circle and broken line: in the mixed- species plantation). 66 Journal of Tropical Forest Science (19950 8(1)7 - 9 5 ):

Survivorship at four-leaf stage

When seedlings at the four-leaf stage were transplanted in the kapur and mixed- species plantations, they were also eate mammalsy nb mortalite Th . y rates, however, were reduced to 2.2% per day (in the kapur plantation) and 1.3% per day (in the mixed-species plantation) respectively (Figur . These4) e values were about one- fourtmortalite th f ho y rate obtaine cotyledoe th r dfo n stage seedlings specifie Th . c mortality highes e ratkaputh wa e n i rr plantatio ne mixed-specie th tha n i n s plantatio 0.05< p n( , Mestfor comparison regressioo tw f so n slopes).

Survivorship after six-leaf stage

Kapur seedlings reaching the six-leaf stage exhibited low mortality when com- pared with those obtained for the cotyledon and four-leaf stages. By the 7th month after transplanting plant0 ,2 onlf o s y2 wer e kapu e death n di r plantatiol al d nan survived in the mixed-species plantation.

Possible causes of mortality

Figur showe5 s relative importanc differenf eo t mortality factorcotyledoe th t a s n and four-leaf stages. Mammalian predation accounted for 92% (in kapur planta- mixed-speciee th n (i % 95 tion d s plantation)an mortalite th f )o y among cotyledon stage seedlings; 65% (in the kapur plantation) and 93% (in the mixed-species plantation mortalite th f o ) y amon four-leafe gth stage seedlings kapue th n rI . plantation, 35% of plants at the four-leaf stage were dead due to wilting probably caused by water stress. A part of the mortality may have been attributable to an induced damage of the root system during transplanting.

n-96 n-96 i.oo 1.00

c 0.80 C0.80 o 6 0.60 §• |0.60 £ o,40 &-0.40

0.20 0.20

0.00 0.00 Kapur Mixed-species Kapur Mixed-species plantation plantation plantation plantation

Figur . e5 Proportio survivaf no mortalitd lan y factors during cotyledon (left figure fourd an ) - leaf stage of seedlings (right figure) of Dryobalanops aromatica (kapur) in plantations in the Forest Research Institute of Malaysia. (Closed area: eaten by mammals; shaded area: wilted and dead; hatched area: the main stem or apical shoot was damaged and dead; open area: surviving plants). (Right hand side is the results from the mixed-species plantation and left hand side is those from the kapur plantation). Journal of Tropical Forest Science 8(1)(19950 7 - 9 :5 ) 67

Size distribution of kapur

Figure 6 shows frequency distribution of stem diameters of all individuals of kapuplantatione th n ri size classifies eTh .i logarithmia n do c scale individuall Al . s with diameters more than 40 cm are canopy trees belonging to the first generation. majorite Th individualf yo s wer sizn ei e constitutin, classecm 3 s1- sapline gth g bank. There were vercurrenw yfe t year seedlings whic includee har smallese th n di t size class, reflecting high mortalitie see e seedlind th dan n si g stages.

100

0.16 0.4 1.0 2.5 6.3 16.040.0 100.0 Diameter class (cm scaleg ,lo )

Figure 6. Frequency distribution of stem diameters of Dryobalanops aromatica (kapur) individuals including seedling a kapu n i s r plantatio Forese th n i t Research Institute of Malaysia. (Number of samples is 326).

Discussion

Mortality factors of seeds

Weevils (alcidode nanophyesd san majoe knowe th e )ar r b pesto nt seef so d crops of dipterocarps including kapur (Singh 1974). They attack kapur seeds at an early stag seef eo d development. Other insect species also attack kapur seeds mortalit% causin80 - 0 gy4 before ripening (Kobayashi 1974) recenA . t study seede recordeth f so thabeed % ha tdn 90 infeste larvay db e of various insects before dispersa Tsubaki. (Y l Takamur. K , . IntachatJ a& , unpublished). After dropping onto the ground, kapur seeds are often heavily attacked by predators (Singh 1974). Wild pigs (Sus scrofa) could have partly contributee th o dt mortality of seeds, as their tracks were observed in and around the plots. When kapur seeds were protected by cages, most of them germinated without predation protectivthe (Figur As e2). cag effectivewas e against only small mammalsis it , 68 Journal of Tropical Forest Science 8 (1): 59 - 70 (1995)

most likely tha maie tth n predators were rodents whicf ,o h murid sciuridd san e sar dominant in the plantations (Nor Azman Hussein, personal communication). Seed predation by mammals tended to be higher in the kapur plantation than in the mixed-species plantation (Figures 1& 2). Higher predation pressure in the kapur plantatio expectede b n nca , because befor durind ean experimente gth s seed-fall was continuing in the kapur plantation, which must have attracted predators. timine Th intensitd gan predatiof yo n varied among mixed-specie plote th n si s plantation. Seed somn si e plots were discovere consumed dan mammaly db s within a day after being placed on the ground, while in the other plots they remained undisturbe morr dfo e tha weeko e ratn tw predatio f eTh so . (Figure2) d n nan ca s 1 be variable depending on the density of predators. When the density is low asexpected mixed-speciee inth s plantation, som equickle seedb y syma discovere predatory db s while others may not.

Mortality factors of seedlings

Mammalian predatio importann a s ni t componen f mortalitto y during seed seedlind an g stage f severaso l tropical tree species (Sork 1987, Schupp 1988, Molofsk Fishey& r 1993). Thi alsd soha been observe kapurdn i , where cotyledons newld an y developing shoots were bitten ofanimaly fb s (Foxworthy 1932)r ou n I . experiment, when seedling e cotyledoth t a s n stage were transplantee th n di plantations, they were frequently eaten by animals, most likely rodents and wild pigs, although there wer direco en t observations. Insect feedin leaven g o apicad san l meristem occasionalls swa y observed during the experiment, but insect herbivory usually does not kill the seedlings. Foxworthy (1932) recorded that young twig kapuf so r were often attacke scolytiy db d beetles belongin genue th go st Cryphalus, attace th t caust k bu deatno alse e ed th th o di f ho whole plant. The low predation of kapur seedlings after reaching the six-leaf stage could be attributed to several factors. It could be that the plants at this stage are no longer attractive to mammalian predators thus reducing predators' activities. Although ther bees eevidencha o nn far o palatabilitee s ,th plante havth y f yo se ma changed during the development of seedlings possibly due to production of secondary substances like phenolics in plant tissues as observed by Freeland and Janzen (1974).

Regeneration of kapur

Kapur forests often show copious natural regeneration. A census of trees 17cm girt t breasha t height (GBH naturad ovea )an n i r l kapur fores t Bukia t t Bauk Forest Reserv Terenggann ei u alon ease gth t coas Peninsulaf to r Malaysia showed that the kapur trees had a continuous size distribution (Wyatt-Smith 1963). A large number of seedlings and saplings were also found in the same forest. Persistent occurrenc sapline th f o eg kapu e banth n ki forest indicates tha forese a th t s i t Journal of Tropical Forest Science 8 (1): 59 - 70 (1995) 69 self-replacing climax forest rather than a forest in an intermediate stage of plant succession. In our census on the size distribution in the kapur plantation, a considerable number of saplings with diameters 1-3 cm (ca. 50 individuals per 100 m2) were found under the canopy. Therefore, a sapling bank for natural regeneration can be established even in plantation conditions. However, the numbe f seedo r s produce particulae th dn i r observatior yeaou t havf o rno ey nma been high enough to increase the level of the sapling bank, because very few current-year seedlings were observe fiele th dn di (Figur . e6) The results of our transplant experiment showed a high survival rate after reachin six-leae gth f stag contrasn ei hige th ho t mortalit precedine th n yi g stages. These findings suggest tha hig e spitn ti th hf epredatioo n pressure during seed dan early seedling stages heava , y seed flusmasa n i ht year coul t somdle e seedo st germinat establisd ean h after escaping fro predatione mth cohorA . seedlingf to s could then reac six-leae hth f stag produco et saplinea g bank unde canopye rth . Natural regeneration of kapur plantation will be from these seedlings and can be accelerated when appropriate canopy gaps are created. Recent observation on the kapur fores Ranchinn ti Abdy gb . Rahman (1993. etal ) also demonstrate abilite dth y of kapu regenerato rt e unde densra e canopy plantatioa s A . n practice alss i t oi , recommended that nursery-grown seedlings should be transplanted at or after the six-leaf stage.

Acknowledgements

We thank Nor Affandy Othman, Mohd Abudullah Ihsham Ibrahim and Shufian Mohame their dfo r fiel d. Appanaadvics S assistance hi Lia d o r ean fo tBo hm Li , for commenting on an earlier draft of the paper. The present study is part of a joint research project betwee Forese nth t Research Institut Malaysif e o th d aan National Institute for Environmental Studies of Japan (Global Environment Re- search Programme grante Japay db n Environment Agency, Gran . E-2)tNo .

References

ABD. RAHMAN , SHAHRULZAMANK. , WEINLAND& . I , . 1993G , . Growth performancea f o s naturally regenerated stan kapuf do r (Dryobalanops aromatica Gaertn. year7 3 ) f s afte heava r y low thinning treatment. P. 94 in Abstracts of the International Conference on Tropical Rainforest Research: Current Issues. Universiti Brunei Darussalam. APPANAH WEINLAND& . S , . 1993G , . Planting Quality Timber Trees Peninsularn i Malaysia Review.A - Malayan Forest Record . Fores38 . tsNo Research Institut Malaysiaf eo , Kuala Lumpur. AUGSPURGER . 1979K . C ., Irregular rai e germinationth cued an s seedlind nan g survivaa f o l Panamanian shrub (Hybanthus prunifolius). Oecologia 44:53-59. AUGSPURGER 1983. K . ,C . Seed dispersa tropicae th y lb l tree, Platypodium elegans,escape th d f eo an its seedlings from fungal pathogens. Journal of Ecology 71 : 759 - 771. AUGSPURGER, C.K. 1984. Light requirements of neotropical tree seedlings: a comparative study of growt survivald han . Journal 795- o7 f .Ecology77 : 2 7 BECKER, P. & WONG, M. 1985. Seed dispersal, seed predation, and juvenile mortality of Aglaia sp. (Meliaceae lowlann i ) d dipterocarp rainforest. Biotropica 17:230-237. BOUCHER, D. H. 1981. Seed predation by mammals and forest dominance by Quercus eoides, a tropical lowland oak .414 - Oecologia9 . 40 : 9 4 70 Journal of Tropical Forest Science 8 (1): 59 - 70 (1995)

CLARK, D. B. & CLARK, D. A. 1984. Spacing dynamics of a tropical rain forest tree: evaluation of the Janzen-Connel model. American 788- 9 Naturalist.76 : 4 12 CLARK CLARK& . . 1985B A . . D ,D , . Seedling dynamic tropicaa f so l tree: impact herbivorf so d yan meristem damage. Ecology 1884: 6 6 - 1892. CLAR CLAR& . 1989. B A rol. e . KK D physicaD f . eTh o l damag seedline th n ei g mortality regimf eo a neotropical rain forest. Oikos 55 : 225 - 230. COLEY, P.D. 1983. Herbivory and defensive characteristics of tree species in a lowland tropical forest. Ecological Monograph 53 : 209-233. FOXWORTHY . 1932W . F , . Dipterocarpaceae Malay e oth f Peninsula. Malayan Forest Record. 10 . sNo Federated Malay States Government. pp 9 28 . FREELAND . &JANZENJ . W , . 1974H . D , . Strategie herbivorn si mammalsy yb role f :th plan eo t secondary compounds. American Naturalist 108:269-289. HARPER . 1977L . ,J . Population Biology of Plants. Academic Press, London. HOWE.H.F. 1990. Surviva growtd an l juvenilf ho e Viroia surinamensis Panaman i : effect herbivorf so y and canopy closure. Journal of Tropical Ecology 6: 259-280. JANZEN.D.H. 1970. Herbivores and the number of tree species in tropical forests. American Naturalist 104:501-528. JANZEN . 1974H . D , . Tropical blackwater river, animals masd ,an t fruitin Dipterocarpaceaee th y gb . Biotopica : 69-1036 . JENSEN . 1971A . L , . Observatio viabilite th n no Bornef yo o camphor Dryobalanops aromatica Gaertn. Proceedings of the International Seed Testing Association 36 : 141-146. TRIPATHIKHAN& . L . . 1991M , S . R , . Seedling surviva growtd an l earlf h o latd yan e successional tree species as affected by insect herbivory and pathogen attack in sub-tropical humid forest stands of north-east India. Acta Oecologia 12 : 569 - 579. KOBAYASHI 1974K , . Ecological stud seen yo d productio f kapuno keladand ran . Nettai Ringyo (Tropical Forestry) 34 : 16 - 20. MOLOFSKY,J. &AUGSPURGER,C.K1992 effece leaTh f . o t f litte earln ro y seedling establishment i ntropicaa l forest. 77 - . 8 Ecology6 : 3 7 MOLOFSKYJ. & FISHER, B. L. 1993. Habitat and predation effects on seedling survival and growth in shade-tolerant tropical trees 265- .1 Ecology.26 : 4 7 OSUNKJOYA, O. O., ASH, J. E., HOPKINS, M. S. & GRAHAM, A. W. 1992. Factors affecting survival of tree seedlings in North Queensland rainforest. Oecologia 91: 569 - 578. SASAKI MORI& . S , . 1981T , . Growth response dipterocarf so p seedling lighto st . Malaysian Forester 23:319-345. SCHUPP . 1988W . E ,. See earld dan y seedling predatio forese th n ti understor treefald yan l gaps. Oikos 51:71-78. SINGH 1974K . D , . Seed pesl somf so e dipterocarps. Malaysian. 36 - Forester24 : 7 3 SORK, V. L. 1987. Effects of predation and light on seedling establishment in Gustavia superba. Ecology 134: 8 6 11350- . SYMINGTON . 1943F . ,C . Forester's Manual of Dipterocarps. Malayan Forest Record . (reprinte16 . sNo d in 1974 by Penerbit Universiti Malaya, Kuala Lumpur) VAZQUEZ-YANES, C. & OROZCO-ZEGOVIA, A. 1992. Effects of litter from a tropical rainforest on tree seed germinatio d establishmenan n t under controlled conditions. Tree Physiology: 11 391-400. VINCENT, A. J. 1961. A Survey of the Kapur (Dryobalanops aromatica Gaertn f): Silvicultural Treatment Research Plots Naturallyn i Artificiallyd an Regenerated Forest, Malaya. Forest Research Institute Research Pamphle . Fores36 . tNo tDepartment . Federatio Malayaf no . WONG, K. M., SAW, L. G. & KOCHUMMEN, K M. 1987. A survey of the forests of the Endau-Rompin area, Peninsular Malaysia: principal forest types and floristic notes. Malaysian Heritage & Scientific Expedition: Endau-Rompin. Malaysian Nature Journal 41:125-144. WYATT-SMITH.J. 1963. Manual of Malaysian Silviculture for Inland Forests. Malayan Forest Records No. 23. Forestry Department, Peninsular Malaysia. YAP1981K . S , . Collection, germinatio d storagan n f dipterocaro e p seeds. Malaysian Forester: 44 281-300.