Displaying publications 1 - 20 of 70 in total

Abstract:
Sort:
  1. A coastal vegetation survey of Pahang, Malaysia
    Rozainah M
    Sains Malaysiana, 2006;35:55-62.
    A survey on coastal vegetation of Pahang in some localities from Sg. Balok in Kuantan southwards to Kuala Endau in Rompin was conducted from middle 2004 to early 2005. A total of 88 species of plants were recorded and identified mostly to the generic or species level. The usual vegetation types were sand and mudflat beach vegetations like Pandanus odoratissimus, Ipomoea pes capre and Casuarina equisetifolia and mangrove vegetation like Sonneratia caseolaris, Rhizophora mucronata and Avicennia marina. This paper also reports some unique heath-type forest vegetation like Hopea spp. in Menchali area.
    Matched MeSH terms: Dipterocarpaceae
  2. A new species of Tenothrips pollinating Dipterocarpus sublamellatus in Malaysia
    Ng YF, Ain N, Lau KH
    Zootaxa, 2019 Nov 11;4695(4):zootaxa.4695.4.9.
    PMID: 31719347 DOI: 10.11646/zootaxa.4695.4.9
    Tenothrips keruing sp. n. is described from Malaysia. This new species was taken from the flowers of Dipterocarpus sublamellatus (local name Keruing kerut) during the recent mass-flowering. The male of this species has a pair of stout setae on abdominal tergite IX, and there are no sternal pore plates. A key to species of Tenothrips from Indomalaysia is provided.
    Matched MeSH terms: Dipterocarpaceae*
  3. A new symmetrical tetramer oligostilbenoid containing tetrahydrofuran ring from the stem bark of Dryobalanops lanceolata
    Ahmat N, Wibowo A, Mohamad SA, Low AL, Sufian AS, Yusof MI, et al.
    J Asian Nat Prod Res, 2014;16(11):1099-107.
    PMID: 25034352 DOI: 10.1080/10286020.2014.938059
    A new tetramer oligostilbenoid possessing tetrahydrofuran ring, malaysianol C (1), was isolated from the acetone extract of the stem bark of Dryobalanops lanceolata, together with four known oligostilbenoids nepalensinol E (2), ϵ-viniferin (3), laevifonol (4), and ampelopsin F (5). The structures of isolated compounds were elucidated on the basis of spectral evidence. The antibacterial activity of the isolated compounds was evaluated using resazurin microtitre-plate assay, whereas the cytotoxic activity was tested using MTT assay. The plausible biogenetic routes of the isolated compounds are also discussed.
    Matched MeSH terms: Dipterocarpaceae/chemistry*
  4. A palynological investigation of Vatica L. (Dipterocarpaceae) in Peninsular Malaysia
    Houssein M.A. El-Taguri, Latiff A
    Sains Malaysiana, 2014;43:1283-1293.
    Pollen morphology of 24 species of Vatica L. had been investigated using light and scanning electron microscopes. Vatica is a stenopalynous genus, the pollens are radially symmetrical, isopolar, subprolate to suboblate sometimes prolate rarely oblate, all tricolpate. Exine ornamentation varies from thin to medium reticulate. On the basis of pollen shape two groups of Vatica have been recognized. Within the genus pollen diversity is valuable for identification and delimiting species.
    Matched MeSH terms: Dipterocarpaceae
  5. A review of Megalogomphus sumatranus (Krüger, 1899) and its allies in Sundaland with a description of a new species from Borneo (Odonata: Anisoptera: Gomphidae)
    Dow RA, Price BW
    Zootaxa, 2020 Sep 04;4845(4):zootaxa.4845.4.2.
    PMID: 33056753 DOI: 10.11646/zootaxa.4845.4.2
    Megalogomphus sumatranus (Krüger, 1899) and its allies in Sundaland are reviewed. The accessory genitalia of the males of this genus, hardly considered previously, are found to be taxonomically informative. The taxon from Borneo previously treated as M. sumatranus is described from both sexes as M. buddi sp. nov. (holotype ♂ Sungai Datai, Nanga Bloh, Lanjak Entimau Wildlife Sanctuary, Kapit Division, Sarawak, Malaysia, 22 viii 2013, leg. J. anak Awan M. anak Adau; deposited at the Naturalis Biodiversity Center, Leiden, the Netherlands). Megalogomphus borneensis (Laidlaw, 1914), described as a subspecies of M. icterops (Martin, 1903) and subsequently relegated to the synonymy of that species, is considered to be a distinct species. Megalogomphus icterops is however considered to be a junior synonym of M. sumatranus. A re-description of the holotype of Megalogomphus borneensis is provided as is the first description of the female. Descriptive notes with illustrations of Megalogomphus sumatranus are given.
    Matched MeSH terms: Dipterocarpaceae*
  6. Acid blue 25 adsorption on base treated Shorea dasyphylla sawdust: kinetic, isotherm, thermodynamic and spectroscopic analysis
    Hanafiah MA, Ngah WS, Zolkafly SH, Teong LC, Majid ZA
    J Environ Sci (China), 2012;24(2):261-8.
    PMID: 22655386
    The potential of base treated Shorea dasyphylla (BTSD) sawdust for Acid Blue 25 (AB 25) adsorption was investigated in a batch adsorption process. Various physiochemical parameters such as pH, stirring rate, dosage, concentration, contact time and temperature were studied. The adsorbent was characterized with Fourier transform infrared spectrophotometer, scanning electron microscope and Brunauer, Emmett and Teller analysis. The optimum conditions for AB 25 adsorption were pH 2, stirring rate 500 r/min, adsorbent dosage 0.10 g and contact time 60 min. The pseudo second-order model showed the best conformity to the kinetic data. The equilibrium adsorption of AB 25 was described by Freundlich and Langmuir, with the latter found to agree well with the isotherm model. The maximum monolayer adsorption capacity of BTSD was 24.39 mg/g at 300 K, estimated from the Langmuir model. Thermodynamic parameters such as Gibbs free energy, enthalpy and entropy were determined. It was found that AB 25 adsorption was spontaneous and exothermic.
    Matched MeSH terms: Dipterocarpaceae/chemistry*
  7. Fulltext Acuminatol and other antioxidative resveratrol oligomers from the stem bark of Shorea acuminata
    Muhammad N, Din LB, Sahidin I, Hashim SF, Ibrahim N, Zakaria Z, et al.
    Molecules, 2012 Jul 30;17(8):9043-55.
    PMID: 22847143 DOI: 10.3390/molecules17089043
    A new resveratrol dimer, acuminatol (1), was isolated along with five known compounds from the acetone extract of the stem bark of Shorea acuminata. Their structures and stereochemistry were determined by spectroscopic methods, which included the extensive use of 2D NMR techniques. All isolated compounds were evaluated for their antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (RSA) and the β-carotene-linoleic acid (BCLA) assays, and compared with those of the standards of ascorbic acid (AscA) and butylated hydroxytoluene (BHT). All compounds tested exhibited good to moderate antioxidant activity in the DPPH assay (IC₅₀s 0.84 to 10.06 mM) and displayed strong inhibition of β-carotene oxidation (IC₅₀s 0.10 to 0.22 mM). The isolated compounds were evaluated on the Vero cell line and were found to be non-cytotoxic with LC₅₀ values between 161 to 830 µM.
    Matched MeSH terms: Dipterocarpaceae/chemistry*
  8. Fulltext Ampelopsin E Reduces the Invasiveness of the Triple Negative Breast Cancer Cell Line, MDA-MB-231
    Tieng FYF, Latifah SY, Md Hashim NF, Khaza'ai H, Ahmat N, Gopalsamy B, et al.
    Molecules, 2019 Jul 18;24(14).
    PMID: 31323836 DOI: 10.3390/molecules24142619
    Breast cancer is the most common and the second leading cause of cancer-related deaths in women. It has two distinctive hallmarks: rapid abnormal growth and the ability to invade and metastasize. During metastasis, cancer cells are thought to form actin-rich protrusions, called invadopodia, which degrade the extracellular matrix. Current breast cancer treatments, particularly chemotherapy, comes with adverse effects like immunosuppression, resistance development and secondary tumour formation. Hence, naturally-occurring molecules claimed to be less toxic are being studied as new drug candidates. Ampelopsin E, a natural oligostilbene extracted from Dryobalanops species, has exhibited various pharmacological properties, including anticancer and anti-inflammatory activities. However, there is yet no scientific evidence of the effects of ampelopsin E towards metastasis. Scratch assay, transwell migration and invasion assays, invadopodia and gelatin degradation assays, and ELISA were used to determine the effects of ampelopsin E towards the invasiveness of MDA-MB-231 cells. Strikingly in this study, ampelopsin E was able to halt migration, transmigration and invasion in MDA-MB-231 cells by reducing formation of invadopodia and its degradation capability through significant reduction (p < 0.05) in expression levels of PDGF, MMP2, MMP9 and MMP14. In conclusion, ampelopsin E reduced the invasiveness of MDA-MB-231 cells and was proven to be a potential alternative in treating TNBC.
    Matched MeSH terms: Dipterocarpaceae/chemistry
  9. Archaeological resinous samples from Asian wrecks: Taxonomic characterization by GC-MS
    Burger P, Charrié-Duhaut A, Connan J, Flecker M, Albrecht P
    Anal Chim Acta, 2009 Aug 19;648(1):85-97.
    PMID: 19616693 DOI: 10.1016/j.aca.2009.06.022
    Plant resins, and particularly dammars from the Dipterocarpaceae family, were widely used in the past, notably as part of caulking material. The organic composition of resins, already complicated, is not always preserved over time and can be considerably affected by ageing. Hence, their occurrence in archaeological items leads to the necessity to identify them taxonomically with precision. Resinous organic materials collected near and/or on wrecks discovered in South China Sea, supposed to contain dammar resins because of their geographical excavation context, were investigated by gas chromatography-mass spectrometry (GC-MS), together with freshly collected dammars, to establish taxonomic and alteration parameters allowing to identify dammar even in very altered samples or in mixtures together with other organic materials. This study specially focuses on three samples collected within or close to the M1J wreck, a Portuguese wreck lost in the Straight of Malacca during the 16th century. Our analyses establish that all three are made of dammar, two of them in association with pitch and bitumen. In addition, biodegradation biomarkers were detected in all these three samples, indicating that they were submitted to microbial degradation processes during their ageing.
    Matched MeSH terms: Dipterocarpaceae/classification; Dipterocarpaceae/genetics; Dipterocarpaceae/chemistry*
  10. Beetle pollination of Shorea parvifolia (section Mutica, Dipterocarpaceae) in a general flowering period in Sarawak, Malaysia
    Sakai S, Momose K, Yumoto T, Kato M, Inoue T
    Am J Bot, 1999 Jan;86(1):62-9.
    PMID: 21680346
    Pollination ecology of an emergent tree species, Shorea (section Mutica) parvifolia (Dipterocarpaceae), was studied using the canopy observation system in a lowland dipterocarp forest in Sarawak, Malaysia, during a general flowering period in 1996. Although the species has been reported to be pollinated by thrips in Peninsular Malaysia, our observations of flower visitors and pollination experiments indicated that beetles (Chrysomelidae and Curculionidae, Coleoptera) contributed to pollination of S. parvifolia in Sarawak. Beetles accounted for 74% of the flower visitors collected by net-sweeping, and 30% of the beetles carried pollen, while thrips accounted for 16% of the visitors, and 12% of the thrips carried pollen. The apical parts of the petals and pollen served as a reward for the beetles. Thrips stayed inside the flower almost continuously after arrival, and movements among flowers were rare. Fruit set was significantly increased by introduction of beetles to bagged flowers, but not by introduction of thrips. Hand-pollination experiments and comparison of fruit set in untreated, bagged, and open flowers suggested that S. parvifolia was mainly outbreeding.
    Matched MeSH terms: Dipterocarpaceae
  11. Bioactive oligostilbenoids from Shorea maxwelliana King and their chemotaxonomic significance
    Zawawi NK, Ahmat N, Mazatulikhma MZ, Shafiq RM, Wahid NH, Sufian AS
    Nat Prod Res, 2013;27(17):1589-93.
    PMID: 23035830 DOI: 10.1080/14786419.2012.730047
    Phytochemical investigation on the stem bark of Shorea maxwelliana yielded five oligostilbenoids identified as α-viniferin (1), maximol A (2), vaticanol A (3), suffruticosol A (4) and vaticanol G (5). Chemotaxonomy of isolated compounds was discussed briefly. Major compounds were tested for neurotoxic and cytotoxic activities. Neurotoxicity for all tested compounds did not pose any toxic effect against cultured cell (cell viability range ±100-94%). Compounds 2-5 possessed active cyctotoxic activity against HL60 cell line with IC50 values range of 2.7-78 µg mL(-1).
    Matched MeSH terms: Dipterocarpaceae/chemistry*
  12. Fulltext Cadmium-109 Radioisotope Adsorption onto Polypyrrole Coated Sawdust of Dryobalanops aromatic: Kinetics and Adsorption Isotherms Modelling
    Olatunji MA, Khandaker MU, Amin YM, Mahmud HN
    PLoS One, 2016;11(10):e0164119.
    PMID: 27706232 DOI: 10.1371/journal.pone.0164119
    A radiotracer study was conducted to investigate the removal characteristics of cadmium (109Cd) from aqueous solution by polypyrrole/ sawdust composite. Several factors such as solution pH, sorbent dosage, initial concentration, contact time, temperature and interfering metal ions were found to have influence on the adsorption process. The kinetics of adsorption was relatively fast, reaching equilibrium within 3 hours. A lowering of the solution pH reduced the removal efficiency from 99.3 to ~ 46.7% and an ambient temperature of 25°C was found to be optimum for maximum adsorption. The presence of sodium and potassium ions inhibited 109Cd removal from its aqueous solution. The experimental data for 109Cd adsorption showed a very good agreement with the Langmuir isotherm and a pseudo-first order kinetic model. The surface condition of the adsorbent before and after cadmium loading was investigated using BET, FESEM and FTIR. Considering the low cost of the precursor's materials and the toxicity of 109Cd radioactive metal, polypyrrole synthesized on the sawdust of Dryobalanops aromatic could be used as an efficient adsorbent for the removal of 109Cd radioisotope from radionuclide-containing effluents.
    Matched MeSH terms: Dipterocarpaceae
  13. Fulltext Carbon stocks and fluxes in tropical lowland dipterocarp rainforests in Sabah, Malaysian Borneo
    Saner P, Loh YY, Ong RC, Hector A
    PLoS One, 2012;7(1):e29642.
    PMID: 22235319 DOI: 10.1371/journal.pone.0029642
    Deforestation in the tropics is an important source of carbon C release to the atmosphere. To provide a sound scientific base for efforts taken to reduce emissions from deforestation and degradation (REDD+) good estimates of C stocks and fluxes are important. We present components of the C balance for selectively logged lowland tropical dipterocarp rainforest in the Malua Forest Reserve of Sabah, Malaysian Borneo. Total organic C in this area was 167.9 Mg C ha⁻¹±3.8 (SD), including: Total aboveground (TAGC: 55%; 91.9 Mg C ha⁻¹±2.9 SEM) and belowground carbon in trees (TBGC: 10%; 16.5 Mg C ha⁻¹±0.5 SEM), deadwood (8%; 13.2 Mg C ha⁻¹±3.5 SEM) and soil organic matter (SOM: 24%; 39.6 Mg C ha⁻¹±0.9 SEM), understory vegetation (3%; 5.1 Mg C ha⁻¹±1.7 SEM), standing litter (<1%; 0.7 Mg C ha⁻¹±0.1 SEM) and fine root biomass (<1%; 0.9 Mg C ha⁻¹±0.1 SEM). Fluxes included litterfall, a proxy for leaf net primary productivity (4.9 Mg C ha⁻¹ yr⁻¹±0.1 SEM), and soil respiration, a measure for heterotrophic ecosystem respiration (28.6 Mg C ha⁻¹ yr⁻¹±1.2 SEM). The missing estimates necessary to close the C balance are wood net primary productivity and autotrophic respiration.Twenty-two years after logging TAGC stocks were 28% lower compared to unlogged forest (128 Mg C ha⁻¹±13.4 SEM); a combined weighted average mean reduction due to selective logging of -57.8 Mg C ha⁻¹ (with 95% CI -75.5 to -40.2). Based on the findings we conclude that selective logging decreased the dipterocarp stock by 55-66%. Silvicultural treatments may have the potential to accelerate the recovery of dipterocarp C stocks to pre-logging levels.
    Matched MeSH terms: Dipterocarpaceae/chemistry*
  14. Characterization and effect on skin hydration of engkabang-based emulsions
    Abd Gani SS, Basri M, Rahman MB, Kassim A, Abd Rahman RN, Salleh AB, et al.
    Biosci Biotechnol Biochem, 2010;74(6):1188-93.
    PMID: 20530909
    Formulations containing engkabang fat and engkabang fat esters, F10 and E15 respectively were prepared using a high-shear homogenizer, followed by a high-pressure homogenizer. Both formulations were stable at room temperature, at 45 degrees C, and after undergoing freeze-thaw cycles. The particle sizes of F10 and E15 after high pressure were 115.75 nm and 148.41 nm respectively. The zeta potentials of F10 and E15 were -36.4 mV and -48.8 mV respectively, while, the pH values of F10 and E15 were 5.59 and 5.81 respectively. The rheology of F10 and E15 showed thixotropy and pseudoplastic behavior respectively. There were no bacteria or fungal growths in the samples. The short-term moisturizing effect on 20 subjects analyzed by analysis of variance (ANOVA), gave p-values of 7.35 x 10(-12) and 2.77 x 10(-15) for F10 and E15 respectively. The hydration of the skins increased after application of F10 and E15 with p-value below 0.05.
    Matched MeSH terms: Dipterocarpaceae/chemistry*
  15. Fulltext Complete plastome sequence of Vatica mangachapoi (Dipterocarpaceae): a vulnerable (VU) plant species in Southeast Asia
    Wang JH, Zhao KK, Zhu ZX, Wang HF
    Mitochondrial DNA B Resour, 2018 Oct 03;3(2):1145-1146.
    PMID: 33490565 DOI: 10.1080/23802359.2018.1522977
    Vatica mangachapoi is a tree up to 20 m tall with white resinous. It is distributed in China (Hainan province), Indonesia, Malaysia (N Borneo), Philippines, Thailand, and Vietnam. It grows in forests on hills and mountain slopes below 700 metres. Its durable wood is used for making boats and building bridges and houses. It has been ranked as a VU (Vulnerable) species in China. Here we report and characterize the complete plastid genome sequence of V. mangachapoi in an effort to provide genomic resources useful for promoting its conservation and phylogenetic research. The complete plastome is 151,538 bp in length and contains the typical structure and gene content of angiosperm plastome, including two Inverted Repeat (IR) regions of 23,921 bp, a Large Single-Copy (LSC) region of 83,587 bp and a Small Single-Copy (SSC) region of 20,109 bp. The plastome contains 114 genes, consisting of 80 unique protein-coding genes, 30 unique tRNA gene, and 4 unique rRNA genes. The overall A/T content in the plastome of V. mangachapoi is 62.80%. The phylogenetic analysis indicated that V. mangachapoi and V. odorata is closely related and as an independent branch in Malvales in our study. The complete plastome sequence of V. mangachapoi will provide a useful resource for the conservation genetics of this species and for the phylogenetic studies for Vatica.
    Matched MeSH terms: Dipterocarpaceae
  16. Complex pollination of a tropical Asian rainforest canopy tree by flower-feeding thrips and thrips-feeding predators
    Kondo T, Nishimura S, Tani N, Ng KK, Lee SL, Muhammad N, et al.
    Am J Bot, 2016 Nov;103(11):1912-1920.
    PMID: 27797714
    PREMISE OF THE STUDY: In tropical rainforests of Southeast Asia, a highly fecund thrips (Thrips spp.) responds rapidly to the mass flowering at multiple-year intervals characteristic of certain species such as the canopy tree studied here, Shorea acuminata, by feeding on flower resources. However, past DNA analyses of pollen adherent to thrips bodies revealed that the thrips promoted a very high level of self-pollination. Here, we identified the pollinator that contributes to cross-pollination and discuss ways that the pollination system has adapted to mass flowering.

    METHODS: By comparing the patterns of floral visitation and levels of genetic diversity in adherent pollen loads among floral visitors, we evaluated the contribution of each flower visitor to pollination.

    KEY RESULTS: The big-eyed bug, Geocoris sp., a major thrips predator, was an inadvertent pollinator, and importantly contributed to cross-pollination. The total outcross pollen adhering to thrips was approximately 30% that on the big-eyed bugs. Similarly, 63% of alleles examined in S. acuminata seeds and seedlings occurred in pollen adhering to big-eyed bugs; about 30% was shared with pollen from thrips.

    CONCLUSIONS: During mass flowering, big-eyed bugs likely travel among flowering S. acuminata trees, attracted by the abundant thrips. Floral visitation patterns of big-eyed bugs vs. other insects suggest that these bugs can maintain their population size between flowering by preying upon another thrips (Haplothrips sp.) that inhabits stipules of S. acuminata throughout the year and quickly respond to mass flowering. Thus, thrips and big-eyed bugs are essential components in the pollination of S. acuminata.

    Matched MeSH terms: Dipterocarpaceae/genetics; Dipterocarpaceae/parasitology; Dipterocarpaceae/physiology*
  17. Conservation gap analysis of dipterocarp hotspots in Sarawak using GIS, remote sensing and herbarium data
    Stephen P. Teo, Paul P.K. Chai, Mui-How Phua
    Sains Malaysiana, 2013;42:1237-1246.
    Dipterocarpaceae is the dominant tree family in the tropical rain forests of Southeast Asia. Borneo is the centre of diversity for the dipterocarps. Identification of hotspots is important for forest and biodiversity conservation efforts. Species Occurrence Models (SOMs) were generated for all 247 species of dipterocarps recorded in Sarawak using herbarium occurrence data and based on the best model selected. The species occurrence density map for each genus and category (endemic and non endemic) was generated by overlaying the SOMs of all species in each genus or category. The species occurrence density maps were analyzed with land cover map from Landsat 7-EMT+ images and protected forest areas for identifying hotspots for conservation in Sarawak. Overlaying the SOM maps revealed that areas in central Sarawak and the southwest region (northwest Borneo around Kuching) are the main hotspots of dipterocarp diversity in Sarawak while the coastal lowland areas in the lower Rejang and Baram River which are mainly peat swamp forest are poorer in species occurrence density. In terms of endemism, as with dipterocarp diversity, the mixed diptercarp forest of central Sarawak is also the most important hotspot. Gap analysis revealed that most protected forest areas are in southwest Sarawak (Bako, Kubah, Tanjung Datu and Gunung Gading National Parks) and in the northern part of Sarawak (Niah, Lambir Hills and Mt Mulu National Parks). This leaves the hotspot in the central part of Sarawak least protected. Protected areas only cover between 2 and 4% of the total areas for the different hotspots (75% species density) while majority of the hotspots that are still forested are outside the protected areas.
    Matched MeSH terms: Dipterocarpaceae
  18. Defaunation and habitat disturbance interact synergistically to alter seedling recruitment
    Granados A, Brodie JF, Bernard H, O'Brien MJ
    Ecol Appl, 2017 10;27(7):2092-2101.
    PMID: 28660670 DOI: 10.1002/eap.1592
    Vertebrate granivores destroy plant seeds, but whether animal-induced seed mortality alters plant recruitment varies with habitat context, seed traits, and among granivore species. An incomplete understanding of seed predation makes it difficult to predict how widespread extirpations of vertebrate granivores in tropical forests might affect tree communities, especially in the face of habitat disturbance. Many tropical forests are simultaneously affected by animal loss as well as habitat disturbance, but the consequences of each for forest regeneration are often studied separately or additively, and usually on a single plant demographic stage. The combined impacts of these threats could affect plant recruitment in ways that are not apparent when studied in isolation. We used wire cages to exclude large (elephants), medium, (sambar deer, bearded pigs, muntjac deer), and small (porcupines, chevrotains) ground-dwelling mammalian granivores and herbivores in logged and unlogged forests in Malaysian Borneo. We assessed the interaction between habitat disturbance (selective logging) and experimental defaunation on seed survival, germination, and seedling establishment in five dominant dipterocarp tree species spanning a 21-fold gradient in seed size. Granivore-induced seed mortality was consistently higher in logged forest. Germination of unpredated seeds was reduced in logged forest and in the absence of small to large-bodied mammals. Experimental defaunation increased germination and reduced seed removal but had little effect on seed survival. Seedling recruitment however, was more likely where logging and animal loss occurred together. The interacting effects of logging and hunting could therefore, actually increase seedling establishment, suggesting that the loss of mammals in disturbed forest could have important consequences for forest regeneration and composition.
    Matched MeSH terms: Dipterocarpaceae/growth & development; Dipterocarpaceae/physiology*
  19. Distance- and density-dependent leaf dynamics of seedlings of a tropical rainforest tree
    Numata S, Kachi N, Okuda T, Manokaran N
    Oecologia, 2017 Oct;185(2):213-220.
    PMID: 28852866 DOI: 10.1007/s00442-017-3935-z
    Parental distance and plant density dependence of seedling leaf turnover and survival was examined to investigate predictions of the Janzen-Connell hypothesis. The focal study species, Shorea macroptera is a canopy tree species in a lowland rain forest in peninsular Malaysia. We found that the peak of the distribution of plants shifted from 3-6 m to 6-9 m during the course of the change from seedling to sapling stage. The leaf demography of the seedlings was influenced by their distance from the adult tree and also by the seedling density. Although significant density- and distance dependence in leaf production was not detected, seedling leaf loss decreased with distance from the parent tree and with seedling density. Similarly, leaf damage was not found to be distance- or density-dependent, but net leaf gain of seedlings increased with distance from the parent tree. Although no significant distance- or density-dependence was evident in terms of leaf damage, significant distance dependence of the net leaf gain was found. Thus, we concluded that positive distance dependence in the leaf turnover of seedlings may gradually contribute to a shift in the distribution pattern of the progeny through reductions in growth and survivorship.
    Matched MeSH terms: Dipterocarpaceae/growth & development; Dipterocarpaceae/physiology*
  20. Diurnal changes in leaf gas exchange characteristics in the uppermost canopy of a rain forest tree, Dryobalanops aromatica Gaertn. f
    Ishida A, Toma T, Matsumoto Y, Yap SK, Maruyama Y
    Tree Physiol, 1996 Sep;16(9):779-85.
    PMID: 14871685
    Dryobalanops aromatica Gaertn. f. is a major tropical canopy species in lowland tropical rain forests in Peninsular Malaysia. Diurnal changes in net photosynthetic rate (A) and stomatal conductance to water vapor (g(s)) were measured in fully expanded young and old leaves in the uppermost canopy (35 m above ground). Maximum A was 12 and 10 micro mol m(-2) s(-1) in young and old leaves, respectively; however, because of large variation in A among leaves, mean maximum A in young and old leaves was only 6.6 and 5.5 micro mol m(-2) s(-1), respectively. Both g(s) and A declined in young leaves when T(leaf) exceeded 34 degrees C and leaf-to-air vapor pressure deficit (DeltaW) exceeded 0.025, whereas in old leaves, g(s) and A did not start to decline until T(leaf) and DeltaW exceeded 36 degrees C and 0.035, respectively. Under saturating light conditions, A was linearly related to g(s). The coefficient of variation (CV) for the difference between the CO(2) concentrations of ambient air and the leaf intercellular air space (C(a) - C(i)) was smaller than the CV for A or g(s), suggesting that maximum g(s) was mainly controlled by mesophyll assimilation (A/C(i)). Minimum C(i)/C(a) ratios were relatively high (0.72-0.73), indicating a small drought-induced stomatal limitation to A and non-conservative water use in the uppermost canopy leaves.
    Matched MeSH terms: Dipterocarpaceae
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links