Displaying publications 1 - 20 of 362 in total

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  1. Health in the tropics
    Malayan Medical Journal, 1932;7:132.
    Matched MeSH terms: Tropical Climate
  2. Fulltext A five-year survey of dematiaceous fungi in a tropical hospital reveals potential opportunistic species
    Yew SM, Chan CL, Lee KW, Na SL, Tan R, Hoh CC, et al.
    PLoS One, 2014;9(8):e104352.
    PMID: 25098697 DOI: 10.1371/journal.pone.0104352
    Dematiaceous fungi (black fungi) are a heterogeneous group of fungi present in diverse environments worldwide. Many species in this group are known to cause allergic reactions and potentially fatal diseases in humans and animals, especially in tropical and subtropical climates. This study represents the first survey of dematiaceous fungi in Malaysia and provides observations on their diversity as well as in vitro response to antifungal drugs. Seventy-five strains isolated from various clinical specimens were identified by morphology as well as an internal transcribed spacer (ITS)-based phylogenetic analysis. The combined molecular and conventional approach enabled the identification of three classes of the Ascomycota phylum and 16 genera, the most common being Cladosporium, Cochliobolus and Neoscytalidium. Several of the species identified have not been associated before with human infections. Among 8 antifungal agents tested, the azoles posaconazole (96%), voriconazole (90.7%), ketoconazole (86.7%) and itraconazole (85.3%) showed in vitro activity (MIC ≤ 1 µg/mL) to the largest number of strains, followed by anidulafungin (89.3%), caspofungin (74.7%) and amphotericin B (70.7%). Fluconazole appeared to be the least effective with only 10.7% of isolates showing in vitro susceptibility. Overall, almost half (45.3%) of the isolates showed reduced susceptibility (MIC >1 µg/mL) to at least one antifungal agent, and three strains (one Pyrenochaeta unguis-hominis and two Nigrospora oryzae) showed potential multidrug resistance.
    Matched MeSH terms: Tropical Climate*
  3. Fulltext Topography shapes the structure, composition and function of tropical forest landscapes
    Jucker T, Bongalov B, Burslem DFRP, Nilus R, Dalponte M, Lewis SL, et al.
    Ecol Lett, 2018 07;21(7):989-1000.
    PMID: 29659115 DOI: 10.1111/ele.12964
    Topography is a key driver of tropical forest structure and composition, as it constrains local nutrient and hydraulic conditions within which trees grow. Yet, we do not fully understand how changes in forest physiognomy driven by topography impact other emergent properties of forests, such as their aboveground carbon density (ACD). Working in Borneo - at a site where 70-m-tall forests in alluvial valleys rapidly transition to stunted heath forests on nutrient-depleted dip slopes - we combined field data with airborne laser scanning and hyperspectral imaging to characterise how topography shapes the vertical structure, wood density, diversity and ACD of nearly 15 km2 of old-growth forest. We found that subtle differences in elevation - which control soil chemistry and hydrology - profoundly influenced the structure, composition and diversity of the canopy. Capturing these processes was critical to explaining landscape-scale heterogeneity in ACD, highlighting how emerging remote sensing technologies can provide new insights into long-standing ecological questions.
    Matched MeSH terms: Tropical Climate*
  4. Decelerating growth in tropical forest trees
    Feeley KJ, Joseph Wright S, Nur Supardi MN, Kassim AR, Davies SJ
    Ecol Lett, 2007 Jun;10(6):461-9.
    PMID: 17498145
    The impacts of global change on tropical forests remain poorly understood. We examined changes in tree growth rates over the past two decades for all species occurring in large (50-ha) forest dynamics plots in Panama and Malaysia. Stem growth rates declined significantly at both forests regardless of initial size or organizational level (species, community or stand). Decreasing growth rates were widespread, occurring in 24-71% of species at Barro Colorado Island, Panama (BCI) and in 58-95% of species at Pasoh, Malaysia (depending on the sizes of stems included). Changes in growth were not consistently associated with initial growth rate, adult stature, or wood density. Changes in growth were significantly associated with regional climate changes: at both sites growth was negatively correlated with annual mean daily minimum temperatures, and at BCI growth was positively correlated with annual precipitation and number of rainfree days (a measure of relative insolation). While the underlying cause(s) of decelerating growth is still unresolved, these patterns strongly contradict the hypothesized pantropical increase in tree growth rates caused by carbon fertilization. Decelerating tree growth will have important economic and environmental implications.
    Matched MeSH terms: Tropical Climate*
  5. Re-evaluation of individual diameter : height allometric models to improve biomass estimation of tropical trees
    Ledo A, Cornulier T, Illian JB, Iida Y, Kassim AR, Burslem DF
    Ecol Appl, 2016 Dec;26(8):2374-2380.
    PMID: 27907254 DOI: 10.1002/eap.1450
    Accurate estimation of tree biomass is necessary to provide realistic values of the carbon stored in the terrestrial biosphere. A recognized source of errors in tree aboveground biomass (AGB) estimation is introduced when individual tree height values (H) are not directly measured but estimated from diameter at breast height (DBH) using allometric equations. In this paper, we evaluate the performance of 12 alternative DBH : H equations and compare their effects on AGB estimation for three tropical forests that occur in contrasting climatic and altitudinal zones. We found that fitting a three-parameter Weibull function using data collected locally generated the lowest errors and bias in H estimation, and that equations fitted to these data were more accurate than equations with parameters derived from the literature. For computing AGB, the introduced error values differed notably among DBH : H allometric equations, and in most cases showed a clear bias that resulted in either over- or under-estimation of AGB. Fitting the three-parameter Weibull function minimized errors in AGB estimates in our study and we recommend its widespread adoption for carbon stock estimation. We conclude that many previous studies are likely to present biased estimates of AGB due to the method of H estimation.
    Matched MeSH terms: Tropical Climate*
  6. The interspecific growth-mortality trade-off is not a general framework for tropical forest community structure
    Russo SE, McMahon SM, Detto M, Ledder G, Wright SJ, Condit RS, et al.
    Nat Ecol Evol, 2021 Feb;5(2):174-183.
    PMID: 33199870 DOI: 10.1038/s41559-020-01340-9
    Resource allocation within trees is a zero-sum game. Unavoidable trade-offs dictate that allocation to growth-promoting functions curtails other functions, generating a gradient of investment in growth versus survival along which tree species align, known as the interspecific growth-mortality trade-off. This paradigm is widely accepted but not well established. Using demographic data for 1,111 tree species across ten tropical forests, we tested the generality of the growth-mortality trade-off and evaluated its underlying drivers using two species-specific parameters describing resource allocation strategies: tolerance of resource limitation and responsiveness of allocation to resource access. Globally, a canonical growth-mortality trade-off emerged, but the trade-off was strongly observed only in less disturbance-prone forests, which contained diverse resource allocation strategies. Only half of disturbance-prone forests, which lacked tolerant species, exhibited the trade-off. Supported by a theoretical model, our findings raise questions about whether the growth-mortality trade-off is a universally applicable organizing framework for understanding tropical forest community structure.
    Matched MeSH terms: Tropical Climate*
  7. Damage to living trees contributes to almost half of the biomass losses in tropical forests
    Zuleta D, Arellano G, McMahon SM, Aguilar S, Bunyavejchewin S, Castaño N, et al.
    Glob Chang Biol, 2023 Jun;29(12):3409-3420.
    PMID: 36938951 DOI: 10.1111/gcb.16687
    Accurate estimates of forest biomass stocks and fluxes are needed to quantify global carbon budgets and assess the response of forests to climate change. However, most forest inventories consider tree mortality as the only aboveground biomass (AGB) loss without accounting for losses via damage to living trees: branchfall, trunk breakage, and wood decay. Here, we use ~151,000 annual records of tree survival and structural completeness to compare AGB loss via damage to living trees to total AGB loss (mortality + damage) in seven tropical forests widely distributed across environmental conditions. We find that 42% (3.62 Mg ha-1  year-1 ; 95% confidence interval [CI] 2.36-5.25) of total AGB loss (8.72 Mg ha-1  year-1 ; CI 5.57-12.86) is due to damage to living trees. Total AGB loss was highly variable among forests, but these differences were mainly caused by site variability in damage-related AGB losses rather than by mortality-related AGB losses. We show that conventional forest inventories overestimate stand-level AGB stocks by 4% (1%-17% range across forests) because assume structurally complete trees, underestimate total AGB loss by 29% (6%-57% range across forests) due to overlooked damage-related AGB losses, and overestimate AGB loss via mortality by 22% (7%-80% range across forests) because of the assumption that trees are undamaged before dying. Our results indicate that forest carbon fluxes are higher than previously thought. Damage on living trees is an underappreciated component of the forest carbon cycle that is likely to become even more important as the frequency and severity of forest disturbances increase.
    Matched MeSH terms: Tropical Climate*
  8. Fulltext The road to recovery: a synthesis of outcomes from ecosystem restoration in tropical and sub-tropical Asian forests
    Banin LF, Raine EH, Rowland LM, Chazdon RL, Smith SW, Rahman NEB, et al.
    Philos Trans R Soc Lond B Biol Sci, 2023 Jan 02;378(1867):20210090.
    PMID: 36373930 DOI: 10.1098/rstb.2021.0090
    Current policy is driving renewed impetus to restore forests to return ecological function, protect species, sequester carbon and secure livelihoods. Here we assess the contribution of tree planting to ecosystem restoration in tropical and sub-tropical Asia; we synthesize evidence on mortality and growth of planted trees at 176 sites and assess structural and biodiversity recovery of co-located actively restored and naturally regenerating forest plots. Mean mortality of planted trees was 18% 1 year after planting, increasing to 44% after 5 years. Mortality varied strongly by site and was typically ca 20% higher in open areas than degraded forest, with height at planting positively affecting survival. Size-standardized growth rates were negatively related to species-level wood density in degraded forest and plantations enrichment settings. Based on community-level data from 11 landscapes, active restoration resulted in faster accumulation of tree basal area and structural properties were closer to old-growth reference sites, relative to natural regeneration, but tree species richness did not differ. High variability in outcomes across sites indicates that planting for restoration is potentially rewarding but risky and context-dependent. Restoration projects must prepare for and manage commonly occurring challenges and align with efforts to protect and reconnect remaining forest areas. The abstract of this article is available in Bahasa Indonesia in the electronic supplementary material. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.
    Matched MeSH terms: Tropical Climate*
  9. Fulltext Consistent patterns of common species across tropical tree communities
    Cooper DLM, Lewis SL, Sullivan MJP, Prado PI, Ter Steege H, Barbier N, et al.
    Nature, 2024 Jan;625(7996):728-734.
    PMID: 38200314 DOI: 10.1038/s41586-023-06820-z
    Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1-6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.
    Matched MeSH terms: Tropical Climate*
  10. Dynamics of the forest communities at Pasoh and Barro Colorado: comparing two 50-ha plots
    Condit R, Ashton PS, Manokaran N, LaFrankie JV, Hubbell SP, Foster RB
    Philos Trans R Soc Lond B Biol Sci, 1999 Nov 29;354(1391):1739-48.
    PMID: 11605618
    Dynamics of the Pasoh forest in Peninsular Malaysia were assessed by drawing a comparison with a forest in Panama, Central America, whose dynamics have been thoroughly described. Census plots of 50 ha were established at both sites using standard methods. Tree mortality at Pasoh over an eight-year interval was 1.46% yr(-1) for all stems > or = 10 mm diameter at breast height (dbh), and 1.48% yr(-1) for stems > or = 100 mm dbh. Comparable figures at the Barro Colorado Island site in Panama (BCI) were 2.55% and 2.03%. Growth and recruitment rates were likewise considerably higher at BCI than at Pasoh. For example, in all trees 500-700 mm in dbh, mean BCI growth over the period 1985-1995 was 6 mm yr(-1), whereas mean Pasoh growth was about 3.5 mm yr(-1). Examining growth and mortality rates for individual species showed that the difference between the forests can be attributed to a few light-demanding pioneer species at BCI, which have very high growth and mortality; Pasoh is essentially lacking this guild. The bulk of the species in the two forests are shade-tolerant and have very similar mortality, growth and recruitment. The Pasoh forest is more stable than BCI's in another way as well: few of its tree populations changed much over the eight-year census interval. In contrast, at BCI, over 10% of the species had populations increasing or decreasing at a rate of >0.05 yr(-1) compared to just 2% of the species at Pasoh). The faster species turnover at BCI can probably be attributed to severe droughts that have plagued the forest periodically over the past 30 years; Pasoh has not suffered such extreme events recently. The dearth of pioneer species at Pasoh is associated with low-nutrient soil and slow litter breakdown, but the exact mechanisms behind this association remain poorly understood.
    Matched MeSH terms: Tropical Climate
  11. TroCCAP recommendations for the diagnosis, prevention and treatment of parasitic infections in dogs and cats in the tropics
    Dantas-Torres F, Ketzis J, Mihalca AD, Baneth G, Otranto D, Tort GP, et al.
    Vet Parasitol, 2020 Jul;283:109167.
    PMID: 32580071 DOI: 10.1016/j.vetpar.2020.109167
    The Tropical Council for Companion Animal Parasites Ltd. (TroCCAP) is a not-for-profit organisation whose mission is to independently inform, guide and make best-practice recommendations for the diagnosis, treatment and control of companion animal parasites in the tropics and sub-tropics, with the aim of protecting animal and human health. In line with this primary mission, TroCCAP recently developed guidelines for the diagnosis, treatment and control of feline and canine parasites in the tropics. The development of these guidelines required unique and complex considerations to be addressed, often inapplicable to developed nations. Much of the tropics encompass middle-to-low income countries in which poor standards of environmental hygiene and large populations of stray dogs and cats coexist. In these regions, a range of parasites pose a high risk to companion animals, which ultimately may place their owners at risk of acquiring parasitic zoonoses. These considerations led to the development of unique recommendations with regard, for example, to deworming and endoparasite testing intervals for the control of both global and 'region-specific' parasites in the tropics. Moreover, the 'off-' or 'extra'-label use of drugs for the treatment and control of parasitic infections is common practice in many tropical countries and many generic products lack manufacturers' information on efficacy, safety, and quality control. Recommendations and advice concerning the use of such drugs and protocols are also addressed in these guidelines. The formation of these guidelines is an important first step towards improving the education of veterinarians specifically regarding best-practice for the diagnosis, treatment and control of canine and feline parasites in the tropics.
    Matched MeSH terms: Tropical Climate
  12. The clinical features of hand-arm vibration syndrome in a warm environment--a review of the literature
    Su AT, Darus A, Bulgiba A, Maeda S, Miyashita K
    J Occup Health, 2012;54(5):349-60.
    PMID: 22863899
    The internationally accepted limit values and the health effects of hand-transmitted vibration exposure have been described extensively in the literature from temperate climate countries but not from a tropical climate environment.

    OBJECTIVES: We conducted a systematic review of the health effects of hand-transmitted vibration exposure in tropical countries to determine the characteristics of hand-arm vibration syndrome in a warm environment and compared the findings with the results of the systematic reviews published by the US NIOSH.

    METHODS: We searched major medical databases including MEDLINE, PubMed, Embase, CINAHL, Ovid and Cochrane based on the terms "hand arm vibration syndrome," "hand transmitted vibration," "vibration white finger" and "Raynaud" up to January 2011. Only studies conducted in a tropical or subtropical environment were selected for the review. The quality of the selected papers was assessed independently by two investigators using predefined criteria. A standard set of information was abstracted from the papers for review.

    RESULTS: Only six papers from tropical countries and three papers from subtropical countries were available in the literature. No vibration white finger was reported in the tropical countries. Neurological symptoms were prevalent in the vibration-exposed workers. Finger coldness seems to be an important surrogate for vascular disorder in a tropical environment. Meta-analysis could not be performed due to inadequacy of the information reported in these papers.

    CONCLUSIONS: The current dose-response relationship in ISO5349-1 for hand-transmitted vibration exposure is not applicable to a tropical environment. Further studies on hand-arm vibration syndromes in tropical countries are needed.

    Matched MeSH terms: Tropical Climate*
  13. Phylogenetic turnover along local environmental gradients in tropical forest communities
    Baldeck CA, Kembel SW, Harms KE, Yavitt JB, John R, Turner BL, et al.
    Oecologia, 2016 10;182(2):547-57.
    PMID: 27337965 DOI: 10.1007/s00442-016-3686-2
    While the importance of local-scale habitat niches in shaping tree species turnover along environmental gradients in tropical forests is well appreciated, relatively little is known about the influence of phylogenetic signal in species' habitat niches in shaping local community structure. We used detailed maps of the soil resource and topographic variation within eight 24-50 ha tropical forest plots combined with species phylogenies created from the APG III phylogeny to examine how phylogenetic beta diversity (indicating the degree of phylogenetic similarity of two communities) was related to environmental gradients within tropical tree communities. Using distance-based redundancy analysis we found that phylogenetic beta diversity, expressed as either nearest neighbor distance or mean pairwise distance, was significantly related to both soil and topographic variation in all study sites. In general, more phylogenetic beta diversity within a forest plot was explained by environmental variables this was expressed as nearest neighbor distance versus mean pairwise distance (3.0-10.3 % and 0.4-8.8 % of variation explained among plots, respectively), and more variation was explained by soil resource variables than topographic variables using either phylogenetic beta diversity metric. We also found that patterns of phylogenetic beta diversity expressed as nearest neighbor distance were consistent with previously observed patterns of niche similarity among congeneric species pairs in these plots. These results indicate the importance of phylogenetic signal in local habitat niches in shaping the phylogenetic structure of tropical tree communities, especially at the level of close phylogenetic neighbors, where similarity in habitat niches is most strongly preserved.
    Matched MeSH terms: Tropical Climate*
  14. Fulltext Whole-ecosystem experimental manipulations of tropical forests
    Fayle TM, Turner EC, Basset Y, Ewers RM, Reynolds G, Novotny V
    Trends Ecol Evol, 2015 Jun;30(6):334-46.
    PMID: 25896491 DOI: 10.1016/j.tree.2015.03.010
    Tropical forests are highly diverse systems involving extraordinary numbers of interactions between species, with each species responding in a different way to the abiotic environment. Understanding how these systems function and predicting how they respond to anthropogenic global change is extremely challenging. We argue for the necessity of 'whole-ecosystem' experimental manipulations, in which the entire ecosystem is targeted, either to reveal the functioning of the system in its natural state or to understand responses to anthropogenic impacts. We survey the current range of whole-ecosystem manipulations, which include those targeting weather and climate, nutrients, biotic interactions, human impacts, and habitat restoration. Finally we describe the unique challenges and opportunities presented by such projects and suggest directions for future experiments.
    Matched MeSH terms: Tropical Climate*
  15. Degradation of two acetanilide herbicides in a tropical soil
    Sahid IB, Wei CC
    Bull Environ Contam Toxicol, 1993 Jan;50(1):24-8.
    PMID: 8418934
    Matched MeSH terms: Tropical Climate*
  16. Fulltext Tropical forests are thermally buffered despite intensive selective logging
    Senior RA, Hill JK, Benedick S, Edwards DP
    Glob Chang Biol, 2018 03;24(3):1267-1278.
    PMID: 29052295 DOI: 10.1111/gcb.13914
    Tropical rainforests are subject to extensive degradation by commercial selective logging. Despite pervasive changes to forest structure, selectively logged forests represent vital refugia for global biodiversity. The ability of these forests to buffer temperature-sensitive species from climate warming will be an important determinant of their future conservation value, although this topic remains largely unexplored. Thermal buffering potential is broadly determined by: (i) the difference between the "macroclimate" (climate at a local scale, m to ha) and the "microclimate" (climate at a fine-scale, mm to m, that is distinct from the macroclimate); (ii) thermal stability of microclimates (e.g. variation in daily temperatures); and (iii) the availability of microclimates to organisms. We compared these metrics in undisturbed primary forest and intensively logged forest on Borneo, using thermal images to capture cool microclimates on the surface of the forest floor, and information from dataloggers placed inside deadwood, tree holes and leaf litter. Although major differences in forest structure remained 9-12 years after repeated selective logging, we found that logging activity had very little effect on thermal buffering, in terms of macroclimate and microclimate temperatures, and the overall availability of microclimates. For 1°C warming in the macroclimate, temperature inside deadwood, tree holes and leaf litter warmed slightly more in primary forest than in logged forest, but the effect amounted to <0.1°C difference between forest types. We therefore conclude that selectively logged forests are similar to primary forests in their potential for thermal buffering, and subsequent ability to retain temperature-sensitive species under climate change. Selectively logged forests can play a crucial role in the long-term maintenance of global biodiversity.
    Matched MeSH terms: Tropical Climate*
  17. Fulltext Occurrence of oriental flies associated with indoor and outdoor human remains in the tropical climate of north Malaysia
    Kumara TK, Disney RH, Abu Hassan A, Flores M, Hwa TS, Mohamed Z, et al.
    J Vector Ecol, 2012 Jun;37(1):62-8.
    PMID: 22548537 DOI: 10.1111/j.1948-7134.2012.00200.x
    Flies attracted to human remains during death investigations were surveyed in north Peninsular Malaysia. Six families, eight genera, and 16 species were identified from human remains, with the greatest fly diversity occurring on remains recovered indoors. The total relative frequency of species was led by Chrysomya megacephala (Fabricius, 1794) (46%), followed by Chrysomya rufifacies (Macquart, 1842) (22%), Sarcophaga (Liopygia) ruficornis (Fabricius, 1974) (5%), Sarcophaga spp. (4%), Synthesiomyia nudiseta Wulp, 1883 (6%), Megaselia spp. (3%), Megaselia scalaris (Loew, 1866), (2%), Megaselia spiracularis Schmitz, 1938 (2%), and Chrysomya villeneuvi Patton, 1922 (2%). Hemipyrellia tagaliana (Bigot, 1877), Desmometopa sp., Megaselia curtineura (Brues, 1909), Hemipyrellia ligurriens Wiedemann 1830, Ophyra sp., Sarcophaga princeps Wiedemann 1830, Piophila casei (Linnaeus, 1758), and unidentified pupae each represented 1%, respectively.
    Matched MeSH terms: Tropical Climate*
  18. Fulltext Do epigeal termite mounds increase the diversity of plant habitats in a tropical rain forest in peninsular Malaysia?
    Beaudrot L, Du Y, Rahman Kassim A, Rejmánek M, Harrison RD
    PLoS One, 2011;6(5):e19777.
    PMID: 21625558 DOI: 10.1371/journal.pone.0019777
    The extent to which environmental heterogeneity can account for tree species coexistence in diverse ecosystems, such as tropical rainforests, is hotly debated, although the importance of spatial variability in contributing to species co-existence is well recognized. Termites contribute to the micro-topographical and nutrient spatial heterogeneity of tropical forests. We therefore investigated whether epigeal termite mounds could contribute to the coexistence of plant species within a 50 ha plot at Pasoh Forest Reserve, Malaysia. Overall, stem density was significantly higher on mounds than in their immediate surroundings, but tree species diversity was significantly lower. Canonical correspondence analysis showed that location on or off mounds significantly influenced species distribution when stems were characterized by basal area. Like studies of termite mounds in other ecosystems, our results suggest that epigeal termite mounds provide a specific microhabitat for the enhanced growth and survival of certain species in these species-rich tropical forests. However, the extent to which epigeal termite mounds facilitate species coexistence warrants further investigation.
    Matched MeSH terms: Tropical Climate*
  19. Growth strategies differentiate the spatial patterns of 11 dipterocarp species coexisting in a Malaysian tropical rain forest
    Suzuki RO, Numata S, Okuda T, Nur Supardi MN, Kachi N
    J Plant Res, 2009 Jan;122(1):81-93.
    PMID: 19037582 DOI: 10.1007/s10265-008-0198-0
    We examined relationships between mortality rate, relative growth rate (RGR), and spatial patterns of three growth stages (small, medium, and large trees) for 11 dipterocarp species in the Pasoh 50-ha plot. Mortality rates for these species tended to be positively correlated with RGRs, although the correlation was significant only at the small-tree stage. Seven species with high growth and mortality rates exhibited peaks in spatial aggregation at small distances (<100 m) in small trees, but this aggregation disappeared in medium and large trees. In contrast, the other four species with low growth and mortality rates aggregated at large distances (>200 m) throughout the three growth stages in all but one species. Negative associations between different growth stages were observed only for the high-mortality species, suggesting density-dependent mortality. The high-mortality species showed habitat associations with topography, soil type, and the forest regeneration phase after gap formation, whereas the three low-mortality species only had associations with the forest regeneration phase. A randomization procedure revealed that these habitat associations explained little of their spatial aggregation. Our results suggest that the growth strategy has a large effect on the structuring of the spatial distribution of tree species through mortality processes.
    Matched MeSH terms: Tropical Climate*
  20. Linking mesohabitat selection and ecological traits of a fish assemblage in a small tropical stream (Tinggi River, Pahang Basin) of the Malay Peninsula
    Kano Y, Miyazaki Y, Tomiyama Y, Mitsuyuki C, Nishida S, Rashid ZA
    Zoolog Sci, 2013 Mar;30(3):178-84.
    PMID: 23480377 DOI: 10.2108/zsj.30.178
    Mesohabitat selection in fluvial fishes was studied in a small tropical stream of the Malay Peninsula. A total of 681 individuals representing 24 species were sampled at 45 stations within heterogeneous stream (ca. 1 km in length), in which water depth, water velocity, substrate size, and riparian canopy cover were measured as environmental variables. A canonical correspondence analysis (CCA) yielded a diagram that shows a specific mesohabitat selection of the fish assemblage, in which the species were plotted widely on the CCA1-CCA2 biplot. Generalized linear model also revealed a significant pattern of the mesohabitat selection of several species. Water velocity and substrate size mainly separated on CCA1, indicating variation of pool (deep, slow-flow section) and riffle (shallow, fast-flow section) structures is a primary factor of mesohabitat selection in the fluvial fish assemblage. The mean body weight of species significantly correlated with CCA1; larger species tended to inhabit pools, while small ones occupied riffles. The riparian canopy cover separated on CCA2. The trophic level of species significantly correlated with CCA2; herbivorous species (low trophic level) selected open sites without riparian cover, whereas omnivorous/carnivorous (middle-high trophic level) species preferred highly covered sites. In conclusion, our results suggest that mesohabitat selection is closely related to the species feeding habit, which is consistent with the results of previous studies.
    Matched MeSH terms: Tropical Climate*
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