Distribution patterns of tree species in a Malaysian tropical rain forest

Abstract. Spatial patterns of tree species were studied in a 50-ha tropical rain forest plot in the Pasoh forest, Malaysia. This forest is characterized by a high diversity and very high number of rare species. Out of the 745 species occurring with > five individuals, 80.4 % had an aggregated distribution, 19.5% were randomly distributed and one species had a regular distribution. The spatial patterns of rare vs. common species, juvenile vs. adult trees, and coarse vs. fine scales were compared. Rare species are generally less aggregated than common ones and most of the randomly distributed species are rare. Spatial patterns shift from high clumping to looser intensity or random distribution when moving from juveniles to adults for the same species. No adult tree species display a regular pattern, however. Regular distributions were rarely found; this is probably due to intraspecific competition at a local scale. There is a negative correlation between per capita death rate and population density. This study suggests that the Pasoh forest and its high diversity are subjected to multiple controlling factors, e.g., topography, spacing effect, density-dependent processes and species rarity. The importance of any factor changes across spatial and temporal scales.     

Variance and spatial scales in a tropical rain forest: changing the size of sampling units

The size of a sampling unit has a critical effect on our perception of ecological phenomena; it influences the variance and correlation structure estimates of the data. Classical statistical theory works well to predict the changes in variance when there is no autocorrelation structure, but it is not applicable when the data are spatially autocorrelated. Geostatistical theory, on the other hand, uses analytical relationships to predict the variance and autocorrelation structure that would be observed if a survey was conducted using sampling units of a different size. To test the geostatistical predictions, we used information about individual tree locations in the tropical rain forest of the Pasoh Reserve, Malaysia. This allowed us to simulate and compare various sampling designs. The original data were reorganised into three artificial data sets, computing tree densities (number of trees per square meter in each quadrat) corresponding to three quadrat sizes (5×5, 10×10 and 20×20 m⁽²⁾). Based upon the 5×5 m⁽²⁾ data set, the spatial structure was modelled using a random component (nugget effect) plus an exponential model for the spatially structured component. Using the within-quadrat variances inferred from the variogram model, the change of support relationships predicted the spatial autocorrelation structure and new variances corresponding to 10×10 m⁽²⁾ and 20×20 m⁽²⁾ quadrats. The theoretical and empirical results agreed closely, while the classical approach would have largely underestimated the variance. As quadrat size increases, the range of the autocorrelation model increases, while the variance and proportion of noise in the data decrease. Large quadrats filter out the spatial variation occurring at scales smaller than the size of their sampling units, thus increasing the proportion of spatially structured component with range larger than the size of the sampling units.     

Scale-dependent spatial patterns of species diversity in the tropical montane rain forest in Jianfengling,Hainan Island,China

Aims Spatial distribution patterns and formation mechanisms of species diversity are fundamental issues in community ecology. The objectives of this study are to assess the species diversity patterns at the different spatial scales in Jianfengling, Hainan Island, China.
Methods Based on the dataset from the 60 hm² plot in the tropical montane rain forest in Jianfengling, Hainan Island, the spatial distribution patterns of species richness, species abundance, Shannon-Wiener, Simpson and Pielou’s evenness indices were analyzed at six spatial scales, including 5 m × 5 m, 10 m × 10 m, 20 m × 20 m, 40 m × 40 m, 100 m × 100 m, and 200 m × 200 m, respectively.Important findings
Results showed that spatial distribution patterns of species richness, species abundance and Shannon-Wiener index were much more obviously changed with the spatial scales than Simpson and Pielou’s evenness indices. Change of variance of the species richness with the increase of spatial scales was unimodal, which had the maximum value at the 20 m × 20 m scale. Variance of the species abundance showed a linear relationship with the increase of spatial scales. The positive relationship between species richness and abundance gradually decreased and even disappeared with the increase of sampling scales, which may be correlated with the increase of habitat heterogeneity. The effects of spatial scales on Shannon-Wiener, Simpson, and Pielou’s evenness indices may be also correlated with the composition of rare species in the plot.     

海南尖峰岭热带山地雨林物种多样性空间分布格局的尺度效应

物种多样性的空间分布格局和维持机制是群落生态学的基本问题。为了探讨海南尖峰岭地区物种多样性空间分布格局的尺度效应, 以海南尖峰岭热带山地雨林60 hm²样地为研究对象, 分析了物种丰富度、物种多度、Shannon-Wiener指数、Simpson指数以及Pielou均匀度指数随6个空间取样尺度(5 m × 5 m、10 m × 10 m、20 m × 20 m、40 m × 40 m、100 m ×100 m、200 m × 200 m)的变化。结果表明: 相比Simpson指数和Pielou均匀度指数, 物种丰富度、多度以及Shannon-Wiener指数具有更为明显的空间尺度效应; 物种丰富度的方差随取样尺度增加呈现单峰分布特征, 并且在20 m × 20 m尺度上达到最大值, 而物种多度的方差随取样尺度的增加而增大; 物种丰富度和多度的正相关性随着取样尺度的增加逐渐减小甚至消失, 这可能与随取样尺度增加生境异质性增加有关; 取样尺度对3个物种多样性指数空间分布的影响可能与研究区域内稀有种的组成有关。     

Liana habitat associations and community structure in a Bornean lowland tropical forest

Lianas (woody vines) contribute substantially to the diversity and structure of most tropical forests, yet little is known about the importance of habitat specialization in maintaining tropical liana diversity and the causes of variation among forests in liana abundance and species composition. We examined habitat associations, species diversity, species composition, and community structure of lianas at Sepilok Forest Reserve, Sabah, Malaysia in northeastern Borneo among three soil types that give rise to three distinct forest types of lowland tropical rain forest: alluvial, sandstone hill, and kerangas (heath) forest. Alluvial soils are more nutrient rich and have higher soil moisture than sandstone soils, whereas kerangas soils are the most nutrient poor and drought prone. Lianas ≥0.5-cm in diameter were measured, tagged, and identified to species in three square 0.25-ha plots in each forest type. The number of lianas ≥0.5 cm did not differ significantly among forest types and averaged 1348 lianas ha⁻¹, but mean liana stem diameter, basal area, estimated biomass, species richness, and Fisher’s diversity index were all greater for plots in alluvial than sandstone or kerangas forests. Liana species composition also differed greatly among the three habitats, with 71% of species showing significant positive or negative habitat associations. Sandstone forests were intermediate to alluvial and kerangas forests in most aspects of liana community structure and composition, and fewer species showed significant habitat associations with this forest type. Ranking of forest types with respect to liana density, biomass, and diversity matches the ranking in soil fertility and water availability (alluvial > sandstone hill > kerangas). These results suggest that edaphic factors play an important role in maintaining liana species diversity and structuring liana communities.     

Identifying spatial patterns in the tropical rain forest structure using hemispherical photographs

This work emphasises the usefulness of hemispherical photography for identifying spatial patterns in the tropical rain forest structure. Structural variability was investigated at a local (intra-site) scale, in relation to the forest mosaic, and at a regional (inter-sites) scale, for its implication in forest typology. Four primary forest sites, from 0.6 to 1 ha, were investigated in Central Sumatra, Indonesia.In a first instance, a qualitative analysis of the forest 3-D structure was found to be very helpful in the interpretation of quantitative results related to forest dynamics. The quantitative analysis was undertaken through the assessment of three structural characteristics: (1) the canopy openness (CO), or visible sky as seen from all directions of the hemisphere, (2) the spherical variance (SV), which quantifies the spatial dispersion of gaps and, (3) the plant area index (L_p), defined as half the surface area of canopy elements per unit ground area. At the local scale, maps of the CO values gave an indication about disturbance location and extent, providing an interesting document for studies on forest dynamics. At the regional scale, between-sites comparisons of CO, SV and L_p values added new information on forest structural differences when compared to dendrometric measurements. These results emphasised the fact that rain forest may exhibit high structural variability, even within a same bioclimatic region and a narrow altitude range. Hemispherical photographs could be a quick means of further investigating this spatial variability and it's relation to physical environment, thus providing information that is crucial for the refining of forest typology in the area.     

Aboveground biomass of tropical rain forest stands in Indonesian Borneo

Aboveground plant biomass was examined in a tall virgin tropical lowland evergreen rain forest dominated by Dipterocarpaceae in Sebulu, East Kalimantan, Indonesia, with special reference to the gap-, building- and mature phases of the forest growth cycle. From the records of dimensions of sample trees examined by the stratified clip technique and DBH inventory data of trees in a study plot, the biomass of larger trees (DBH 4.5 cm) was estimated by the allometric correlation method. The biomass of smaller plants (DBH < 4.5 cm) was estimated by harvesting the plants in small quadrat plots. Although large differences were found between aboveground-biomass-estimates in different patches of different growth stages, the aboveground biomass in a 1.0 ha plot was 509 t/ha, and the one-sided LAI was 7.3 ha/ha. These values seem to result from the tall forest architecture with huge emergent trees (over 70 m high) and a moderate packing of plant mass indicated by the basal area value of 38.8 m²/ha for trees with DBH 4.5 cm.This study was financed through a grant to H. Ogawa from the Overseas Scientific Research Funds of the Ministry of Education, Science, and Culture, Tokyo. Sponsorship from the Lembaga Ilumu Pengetahuan Indonesia (LIPI), Jakarta, the Lembaga Biologi National (LBN), Bogor, and the Herbarium Bogoriense, Bogor is gratefully acknowledged. We are also grateful to Drs Soetiyati, M. Rifai, K. Kartawinata, and the staffs of P. T. Kutai Timber Indonesia for their kind support, Dr K. Ogino for his advice and cooperation in field work, and Dr H. Kataoka for providing us with the geological map of Samarinda Province.     

Reproductive patterns of selected understorey trees in the Malaysian rain forest: the sexual species

HA, C. O., SANDS, V. E., SOEPADMO, E. & JONG, K., 1988. Reproductive patterns of selected understorey trees in the Malaysian rain forest: the sexual species. Investigations were carried out on the floral, fruit and seed biology, and the embryology of representatives of the Sapindaceae and Bombacaceae which occur in the lower canopy of the lowland rain forest of Peninsular Malaysia. Pollination studies indicated cross-compatibility and outbreeding in all species examined, associated with self-compatibility in the polygamous monecious Pometia pinnata and Allophylus cobbe and, to a limited extent, in the effectively dioecious Xerospermum intermedium . In these sapindaceous species, together with the self-incompatible androdioecious Nephelium lappaceum , the structurally hermaphrodite flowers were determined embryologically to be functionally female with no anther dehiscence. The self-incompatible Durio griffithii of the Bombacaceae, and X. intermedium, N. lappaceum and P. pinnata were shown by embryological studies to form a sexual zygote. The observations on these outcrossing species are considered in relation to their potential for gene exchange and their contribution to the maintenance of species diversity in the lowland rain forest.     

Reproductive patterns of selected understorey trees in the Malaysian rain forest: the apomictic species

HA, C. O., SANDS, V. E., SOEPADMO, E. & JONG, K., 1988. Reproductive patterns of selected understorey trees in the Malaysian raia forest: the apomictic species. Garcinia is the predominant representative of the Clusiaceae in the understorey of the lowland rain forest of Peninsular Malaysia. In Pasoh Forest Reserve the dioecious species G. paruifolia was investigated since no male trees, but only trees with structurally hermaphodite flowers which later set fruit, were found there. Pollination and embryological studies indicated a condition of non-pseudogamous agamospermy, with no viable pollen grains being formed in the staminodes, and the unfertilized egg cell giving rise to the embryo. Supportive studies were made of microspore development in G. forbesi , and of embryogenesis and seed development in G. malaccensis and G. scortechinii which also appear to be agamospermous. The role of either facultative or obligate apomixis in gene fixation in these dioecious species is discussed, and the possible adaptive significance of reproductive versatility among certain rain forest trees is examined.     

Role of environmental and spatial processes in structuring anuran communities across a tropical rain forest

This study aimed to evaluate if anuran species distributions in riparian and non‐riparian areas are influenced by environmental factors (i.e. niche) and/or by spatial factors (i.e. dispersal). The environmental variables analysed were altitude, distance from the stream and leaf litter depth. Spatial factors were represented by the eigenvectors extracted from geographical coordinates by eigenfunction analysis. The study was conducted in 24 km² of terra‐firme forest in Central Amazonia, Manaus – Amazonas, Brazil. Between November 2008 and May 2009, three samples were taken from 41 plots, 21 plots being placed at non‐riparian areas and another 20 placed in riparian areas. We submitted the assemblage dataset to a partial redundancy analysis to evaluate the contributions of environmental and spatial variables (selected with a forward selection procedure). In addition, we tested if communities differ from riparian and non‐riparian areas using a db‐MANOVA. Species richness and species composition differed between riparian and non‐riparian plots. Some species were restricted to riparian areas. Altitude was the only significant variable (P = 0.005) explaining 21% of the total variance. When analysing the data from all plots using the partial redundancy analysis, 27% of the variance was explained by spatial and environmental variables. The environmental variables explained exclusively 4% of the variance in assemblage composition, and 13% was explained by environmental variables that were also structured in space (i.e. the shared fraction), while 10% was explained exclusively by spatial variables. In conclusion, our results showed differences between the assemblages of riparian and non‐riparian areas which can be explained by the distribution of anuran species along environmental gradients altitude and distance to streams, with little evidence of dispersal limitation.     

长白山落叶阔叶混交林的物种多样性、种群空间分布格局及种间关联性研究

根据在吉林省蛟河实验管理局1 hm²落叶阔叶混交林样地调查结果,对落叶阔叶混交林的群落结构、物种多样性、主要树种的空间分布格局以及树木种群的种间关联进行了研究.结果表明,树木种群优势程度不明显;乔木、灌木、草本的均匀度指数、生态优势度指数都较低.对5个主要乔木种群的空间格局均呈现聚集分布;15个主要树种之间有14个种对存在着显著的种间关联,一个种独立;树种之间正关联的种对少,关联强度低,而负关联多且较高,群落结构组成不稳定,处于软阔叶林向硬阔叶林直至红松阔叶林过渡的阶段.     

Behaviour and ecology of birds in tropical rain forest canopies

The canopy of rain forests exhibits several distinct features that determine avian adaptations. Light intensity and colour, wind, and temperature are the most important components of the physical environment. Tree architecture poses many challenges for the evolution of avian morphological features, and resource availability varies greatly. The canopy is easily accessible for birds that are equipped to travel over considerable distances. Given these conditions, high behavioural flexibility, and adaptations in behaviour and morphology related to a nomadic life-style, should prevail among canopy birds. The easy access for certain groups of birds also has consequences for the historical processes that shape canopy bird communities. Birds may contribute greatly to forest dynamics and composition, mainly due to their role as seed dispersers. We elaborate on these points with behavioural, morphological, and ecological data collected at our Neotropical study site in southern Venezuela (Surumoni Canopy Crane Project). We discuss how behaviour and morphological features reflect the ecological demands in the canopy. We contrast the specific behavioural and ecological characteristics of canopy birds with those of species found in the other tiers of the rain forest. It is pointed out that much of our knowledge is biased towards the Neotropics, and that better knowledge of the larger canopy species is needed for conservation.     

山西灵空山刺五加种群空间分布格局及种间空间关联性

以山西灵空山自然保护区刺五加(Acanthopanax senticosus(Rupr.Maxim.)Harms)种群为对象,采用空间点格局方法中的Ripley’s K函数,对刺五加种群不同龄级的空间分布格局及其与主要灌木物种间的空间关联性进行研究,并对种群空间分布格局进行可视化解析。结果显示,刺五加种群中幼年个体数量多,径级结构呈金字塔型,为增长型种群,能够实现持续更新;刺五加种群的径级Ⅰ在小尺度上呈聚集分布,随着尺度增大出现随机分布;径级Ⅱ、Ⅲ、Ⅳ在全尺度上呈聚集分布,径级Ⅴ、Ⅵ在小尺度上为聚集分布,随着龄级和空间尺度的增大,刺五加种群聚集强度渐弱,呈现随机分布;刺五加种内关联在全尺度上呈正相关,但与群落中主要灌木在小尺度上呈不相关或负相关,在大尺度上呈负相关。研究表明刺五加的生长条件较为适宜,并可以通过相互之间的庇护作用,减弱种内竞争,但与其他树种间存在强烈竞争,生存现状较差,在群落中处于劣势。     

Nutrient fluxes via litterfall and leaf litter decomposition vary across a gradient of soil nutrient supply in a lowland tropical rain forest

The extent to which plant communities are determined by resource availability is a central theme in ecosystem science, but patterns of small-scale variation in resource availability are poorly known. Studies of carbon (C) and nutrient cycling provide insights into factors limiting tree growth and forest productivity. To investigate rates of tropical forest litter production and decomposition in relation to nutrient availability and topography in the absence of confounding large-scale variation in climate and altitude we quantified nutrient fluxes via litterfall and leaf litter decomposition within three distinct floristic associations of tropical rain forest growing along a soil fertility gradient at the Sepilok Forest Reserve (SFR), Sabah, Malaysia. The quantity and nutrient content of small litter decreased along a gradient of soil nutrient availability from alluvial forest (most fertile) through sandstone forest to heath forest (least fertile). Temporal variation in litterfall was greatest in the sandstone forest, where the amount of litter was correlated negatively with rainfall in the previous month. Mass loss and N and P release were fastest from alluvial forest litter, and slowest from heath forest litter. All litter types decomposed most rapidly in the alluvial forest. Stand-level N and P use efficiencies (ratios of litter dry mass to nutrient content) were greatest for the heath forest followed by the sandstone ridge, sandstone valley and alluvial forests, respectively. We conclude that nutrient supply limits productivity most in the heath forest and least in the alluvial forest. Nutrient supply limited productivity in sandstone forest, especially on ridge and hill top sites where nutrient limitation may be exacerbated by reduced rates of litter decomposition during dry periods. The fluxes of N and P varied significantly between the different floristic communities at SFR and these differences may contribute to small-scale variation in species composition.     

Various population fluctuation patterns of light-attracted beetles in a tropical lowland dipterocarp forest in Sarawak

The population fluctuation pattern of light-attracted beetles was studied from August 1992 to September 1998 (for 73 months) using ultraviolet light-traps set at three vertical levels in a tropical lowland dipterocarp forest in Sarawak, Malaysia. During our study, a general flowering occurred from April to July in 1996, and flowering on a small scale in 1997 and 1998. We analyzed the data for eight scarabaeid and six meloid species, some of which were anthophilous species. Various fluctuation patterns were observed among the beetle species in aspects of both seasonality and correlation with the supraannual phenological pattern. Three large chafer species (Scarabaeidae, Melolonthini) showed a clear seasonal fluctuation pattern with a peak once from March to May every year, the peak monthly catch greatly fluctuating annually. Other scarabaeid beetles did not show such a clear seasonal population pattern and hardly fluctuated annually. Populations of an anthophilous scarabaeid species, Parastasia bimaculata, a specific pollinator of Homalomena propinqua (Araceae), hardly fluctuated, probably because of its response to the constant flowering of its floral hosts. Monthly catches of an anthophilous scarabaeid, Anomala sp., and meloid beetles showed clear supraannual patterns in response to the general flowering and were significantly correlated with the flowering intensity with or without a lag of a month. The fluctuation pattern of meloids suggests a supraannual population fluctuation pattern of their hosts, i.e., megachilid/anthophorid bees. Received: November 9, 1999 / Accepted: February 8, 2000