Bornean Tropical Rainforest Research Articles

ボルネオ熱帯雨林での強乾燥が流出・土壌水分に与える影響:-マレーシア・ランビルヒルズ国立公園における観測-

ボルネオ熱帯雨林での強乾燥が流出・土壌水分に与える影響:-マレーシア・ランビルヒルズ国立公園における観測-

Distribution of phosphorus in an above-to-below-ground profile in a Bornean tropical rain forest

Abstract:Ecosystem pool of phosphorus (P) was determined as the sum of above-ground vegetation, roots, necromass and soils to 1 m deep in a tropical rain forest in Sabah, Malaysia. Relationships among soil P fractions, acid phosphatase activity and fine-root biomass across soil horizons were also determined to understand P availability. Ecosystem pools of P, and of simultaneously quantified nitrogen (N) and carbon (C) were 3.4, 12 and 370 Mg ha−1, respectively. Only 2.6% of the total ecosystem P was in the above-ground vegetation, contrasting to C (60%) and N (16%). Canopy foliage of dominant tree species showed an extremely high N to P ratio of 31.5, which implied the excessively short supply of P compared with ample N. Soil P primarily consisted of recalcitrant occluded fractions (78–91%) and only 4% was labile. Approximately three-quarters of labile soil P was an organic fraction (Po). The concentration of labile Po did not differ between soil horizons, while both phosphatase activity and fine-root density were the greatest in the topsoil (top 5 cm) and dramatically decreased with depth. This suggests that trees depend on the acquisition of P from the labile Po in the topsoil, despite a greater amount of labile P in the subsoil. Trees with a high foliar N/P ratio may invest N to acquire P from the topsoil by secreting phosphatase that consists of proteins, rather than investing C to extending roots to scavenge P in the subsoil.

Effect of forest structure on the spatial variation in soil respiration in a Bornean tropical rainforest

This study was undertaken to identify critical and practical factors explaining spatial variations in soil respiration and to estimate stand-scale soil respiration in an aseasonal tropical rainforest on Borneo Island. To this aim, we conducted soil respiration measurements at 25 points in a 40 m × 40 m subplot of a 4 ha study plot between 2002 and 2006, and examined the spatial variation in soil respiration averaged over the 4 years in relation to soil, root, and forest structural factors. In addition, we examined the spatial representativeness of soil respiration measured in the subplot using a specific scaling procedure. Consequently, we found significant positive correlation between the soil respiration and forest structural parameters such as the mean diameter at breast height (DBH), total basal area, and maximum DBH within 6 m of the measurement points. The most important factor was the mean DBH within 6 m of the measurement points, which had a significant linear relationship with soil respiration. Using the derived linear regression and an inventory dataset, we estimated the 4 ha plot-scale soil respiration. The 4 ha plot-scale estimation (6.0 μmol m −2 s −1) was nearly identical to the subplot-scale measurements (5.7 μmol m −2 s −1), which were roughly comparable to the nocturnal CO 2 fluxes calculated using the eddy covariance technique. In addition, we discuss characteristics of the stand-scale soil respiration at this site by comparing with those of other forests reported in previous literature in terms of the soil C balance. Soil respiration at our site was noticeably greater, relative to the incident litterfall amount, than soil respiration in other tropical and temperate forests probably owing to the larger total belowground C allocation by emergent trees. Overall, this study suggests the arrangement of emergent trees with larger DBH and their belowground C allocation could be primary factors controlling spatial variations in soil respiration in the tropical rainforest.

Plurality of tree species responses to drought perturbation in Bornean tropical rain forest

Drought perturbation driven by the El Nino Southern Oscillation (ENSO) is a principal stochastic variable determining the dynamics of lowland rain forest in S.E. Asia. Mortality, recruitment and stem growth rates at Danum in Sabah (Malaysian Borneo) were recorded in two 4-ha plots (trees ≥ 10 cm gbh) for two periods, 1986–1996 and 1996–2001. Mortality and growth were also recorded in a sample of subplots for small trees (10 to <50 cm gbh) in two sub-periods, 1996–1999 and 1999–2001. Dynamics variables were employed to build indices of drought response for each of the 34 most abundant plot-level species (22 at the subplot level), these being interval-weighted percentage changes between periods and sub-periods. A significant yet complex effect of the strong 1997/1998 drought at the forest community level was shown by randomization procedures followed by multiple hypothesis testing. Despite a general resistance of the forest to drought, large and significant differences in short-term responses were apparent for several species. Using a diagrammatic form of stability analysis, different species showed immediate or lagged effects, high or low degrees of resilience or even oscillatory dynamics. In the context of the local topographic gradient, species’ responses define the newly termed perturbation response niche. The largest responses, particularly for recruitment and growth, were among the small trees, many of which are members of understorey taxa. The results bring with them a novel approach to understanding community dynamics: the kaleidoscopic complexity of idiosyncratic responses to stochastic perturbations suggests that plurality, rather than neutrality, of responses may be essential to understanding these tropical forests. The basis to the various responses lies with the mechanisms of tree-soil water relations which are physiologically predictable: the timing and intensity of the next drought, however, is not. To date, environmental stochasticity has been insufficiently incorporated into models of tropical forest dynamics, a step that might considerably improve the reality of theories about these globally important ecosystems.

Less than 20-min time lags between transpiration and stem sap flow in emergent trees in a Bornean tropical rainforest

Sap flow velocities in stems (Sf s) were measured in four 50-m tall emergent trees in a Bornean tropical rainforest. Cross-correlation analysis was used to estimate time lags between diurnal patterns of Sf s and canopy-scale transpiration (Tr) calculated from a big-leaf model validated by water-vapor flux measurements at this site. The time lags between Sf s and Tr were found to be less than 20 min in these trees in both wet and medium dry conditions. In addition, the time lags between Sf s and sap flow velocities measured in a branch at the top of an emergent tree were also less than 20 min. These results are in contrast to those of previous studies conducted in a neo-tropical forest ecosystem, which reported significant time lags of 40–120 min between transpiration and stem sap flow in emergent trees. The results of this study suggest that hydraulic resistance along the conductive pathway and internal water storage between tree crown and stem are insignificant for this forest. Our results also suggest that sap flow measurements conducted at accessible points can be used to estimate canopy transpiration on a diurnal time scale without accounting for the time lags between canopy transpiration and stem sap flows, despite the 50-m tall forest canopy at our site.

Estimation of canopy water storage capacity from sap flow measurements in a Bornean tropical rainforest

Summary Canopy water storage capacity (Sc) is a key parameter for estimations of rainfall interception using a big-leaf model (BLM). This study proposes a simple method for estimating Sc. The crucial factor in this method is the canopy drying time (or wet canopy duration) after rainfall. The time can be estimated from sap flow measurements in accordance with an earlier study of ours in a Bornean tropical rainforest. By using the estimated canopy drying time to calibrate a BLM for rainfall interception, we derived Sc. This method could also provide aerodynamic resistance (Ra). To validate our estimations, the derived parameters Sc and Ra were compared to Sc and Ra determined independently by a method based on net rainfall measurements on an event basis and on wind profile measurements, respectively. The parameters in our method (Sc = 0.7 mm, Ra = 14 s m−1) were shown to correspond well to the values determined by independent methods. Furthermore, the method proposed in this study is applicable to tropical forests where short canopy drying times can be expected after rainfall; that is, if the cloudy weather after rainfall becomes sunny within 250 min.

Estimation of vertical profiles of leaf drying times after daytime rainfall within a Bornean tropical rainforest

AbstractSouth‐east Asian Bornean tropical rainforests have large and complex canopy structures. To clarify how forest structure affects wet‐canopy evaporation, it is necessary to consider wet‐canopy evaporation processes within the forest canopy, such as vertical profiles of canopy drying time. In a previous study a method was proposed that utilizes sap flow measurements to estimate canopy drying time after rainfall (CDTobs) during daytime. In this present study, the method was applied to estimations of the vertical variations in CDTobs in 11 individual trees of various heights, ranging from 2·7 m to 53 m. The study derived vertical profiles and showed that the lengths of CDTobs in lower canopy trees were 2–4 h longer than those in the upper canopy trees. The new method for CDTobs profiles presented in this study, which is available for validation of multi‐layer biosphere‐atmospheric models, is a useful illustration for clarifying wet‐canopy evaporation processes in tropical rainforests. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Seasonal and daily use of natural licks by sambar deer (Cervus unicolor) in a Bornean tropical rain forest

Seasonal and daily use of natural licks by sambar deer (Cervus unicolor) was examined with camera traps in the Deramakot Forest Reserve, Sabah, Malaysian Borneo. The visitation frequency by females was significantly higher in the wet season (October to March) than in the dry season (April to September) (0.277/day and 0.120/day, respectively), while that by males was not significantly different between seasons (0.190/day and 0.138/day, respectively). Our results imply that the increased female visitation frequency in the wet season reflects the peak of their physical demands (e.g., lactation). The visitation frequency in the dark period (1800 h - 0600 h) was significantly higher than that in the light period (0600 h - 1800 h) (85% and 15%, respectively). Sambar deer are generally assumed to forage at night, and the utilisation of natural licks corresponded to their foraging habits. This study suggests that, for sambar deer, natural licks are among the most important habitats not only for daily sustenance but also for reproductive support.

Differences in the dry‐mass cost of sapling vertical growth among 56 woody species co‐occurring in a Bornean tropical rain forest

Summary 1Above-ground structure was analysed in saplings of 56 sympatric species in a Bornean rain forest with consideration of the phylogenetic background to elucidate interspecific variation in the dry-mass cost and its ecological consequences. 2The extension cost (total above-ground mass) in 1·5-m tall saplings varied eightfold among the 56 species. However, no significant differences in extension cost were observed among saplings of three crown types (branched, monoaxial simple-leaved, and monoaxial compound-leaved), although the monoaxial crown type has been considered an adaptation for achieving rapid height growth. The lack of differences arose because the advantages of monoaxial saplings in structural cost for displaying a given leaf area were unexpectedly small. 3Understory species had a significantly higher extension cost than canopy species because of their thicker, and consequently, heavier trunks. This trend was common to the three crown types; thus, the higher extension cost was not caused by the prevalence of a specific crown type in understory species. 4For all 56 species combined, the trade-off between height growth efficiency and light-interception-enhancing morphology was prominent. This structural trade-off, which makes efficient vertical growth incompatible with survival in the understory, potentially enables the stable coexistence of these species in a temporally heterogeneous light environment.

Modeling CO2 exchange over a Bornean tropical rain forest using measured vertical and horizontal variations in leaf‐level physiological parameters and leaf area densities

Southeast Asian tropical rain forests are among the world's most important biomes in terms of global carbon cycling; nevertheless, the impact of environmental factors on the ecosystem CO2 flux remains poorly understood. One‐dimensional multilayer biosphere‐atmosphere models such as soil‐vegetation‐atmosphere transfer (SVAT) models are promising tools for understanding how interactions between environmental factors and leaf‐level physiological parameters might impact canopy‐level CO2 exchange. To examine application of the SVAT model in tropical rain forests, which is expected to be difficult partly because of the complex canopy structure and large number of tree species, we measured vertical and horizontal variations in leaf‐level physiological parameters and leaf area densities together with eddy covariance measurements using a canopy crane in a tropical rain forest in Sarawak, Malaysia. Despite differences in species and canopy positions, leaf nitrogen per unit area (Na) within the canopy could be one‐dimensionally described as a linear function of height. Na also clearly explained the other leaf‐level physiological parameters across species and canopy positions. Even though the leaf area density profile likely varies in this tropical forest, the SVAT model satisfactorily reproduced the eddy covariance measurements. Furthermore, the CO2 flux calculated on the assumption that Na measured in the upper canopy was distributed evenly throughout was almost the same as that taking the vertical gradient into consideration. These findings suggest that when reproducing the CO2 flux in tropical rain forests using the SVAT model, the leaf area density profile obtained from the leaf area index (LAI) measured at one point and leaf‐level physiological properties measured across species in the upper canopy are sufficient.

Habitat associations of Sterculiaceae trees in a Bornean rain forest plot

Abstract.Questions: 1. Are trees in a Bornean tropical rain forest associated with a particular habitat? 2. Does the strength of habitat association with the species‐specific optimal habitat increase with tree size?Location: A 52‐ha plot in a mixed dipterocarp forest in a heterogeneous landscape at the Lambir Hills National Park, Sarawak, East Malaysia.Methods: Ten species from the Sterculiaceae were chosen as representative of all species in the plot, on the assumption that competition among closely related species is more stringent than that among more distantly related taxa. Their habitat associations were tested using data from a 52‐ha plot by a torus‐translation test.Results: The torus‐translation test showed that eight out of the ten species examined had significant association with at least one habitat. We could not find negative species‐habitat associations for rare species, probably due to their small sample sizes. Among four species small trees were less strongly associated with habitat than large trees, implying competitive exclusion of trees in suboptimal habitats. The other four species showed the opposite pattern, possibly owing to the smaller sample size of large trees. A habitat had a maximum of three species with which it was significantly positively associated.Conclusions: For a species to survive in population equilibrium in a landscape, habitats in which ‘source’ subpopulations can be sustained without subsidy from adjacent habitats are essential. Competition is most severe among related species whose source subpopulations share the same habitat. On the evidence of source subpopulations identified by positive species‐habitat association, species‐habitat association reduces the number of confamilial competitors. Our results therefore indicate that edaphic niche specialization contributes to coexistence of species of Sterculiaceae in the plot, consistent with the expectations of equilibrium hypotheses.

Habitat associations of Sterculiaceae trees in a Bornean rain forest plot

Abstract Questions: 1. Are trees in a Bornean tropical rain forest associated with a particular habitat? 2. Does the strength of habitat association with the species-specific optimal habitat increase with tree size? Location: A 52-ha plot in a mixed dipterocarp forest in a heterogeneous landscape at the Lambir Hills National Park, Sarawak, East Malaysia. Methods: Ten species from the Sterculiaceae were chosen as representative of all species in the plot, on the assumption that competition among closely related species is more stringent than that among more distantly related taxa. Their habitat associations were tested using data from a 52-ha plot by a torus-translation test. Results: The torus-translation test showed that eight out of the ten species examined had significant association with at least one habitat. We could not find negative species-habitat associations for rare species, probably due to their small sample sizes. Among four species small trees were less strongly associated with habitat than ...

Carbon Dioxide Exchange over a Bornean Tropical Rainforest

Carbon Dioxide Exchange over a Bornean Tropical Rainforest

Carbon and water cycling in a Bornean tropical rainforest under current and future climate scenarios

We examined how the projected increase in atmospheric CO 2 and concomitant shifts in air temperature and precipitation affect water and carbon fluxes in an Asian tropical rainforest, using a combination of field measurements, simplified hydrological and carbon models, and Global Climate Model (GCM) projections. The model links the canopy photosynthetic flux with transpiration via a bulk canopy conductance and semi-empirical models of intercellular CO 2 concentration, with the transpiration rate determined from a hydrologic balance model. The primary forcing to the hydrologic model are current and projected rainfall statistics. A main novelty in this analysis is that the effect of increased air temperature on vapor pressure deficit ( D) and the effects of shifts in precipitation statistics on net radiation are explicitly considered. The model is validated against field measurements conducted in a tropical rainforest in Sarawak, Malaysia under current climate conditions. On the basis of this model and projected shifts in climatic statistics by GCM, we compute the probability distribution of soil moisture and other hydrologic fluxes. Regardless of projected and computed shifts in soil moisture, radiation and mean air temperature, transpiration was not appreciably altered. Despite increases in atmospheric CO 2 concentration ( C a) and unchanged transpiration, canopy photosynthesis does not significantly increase if C i/ C a is assumed constant independent of D (where C i is the bulk canopy intercellular CO 2 concentration). However, photosynthesis increased by a factor of 1.5 if C i/ C a decreased linearly with D as derived from Leuning stomatal conductance formulation [R. Leuning. Plant Cell Environ 1995;18:339–55]. How elevated atmospheric CO 2 alters the relationship between C i/ C a and D needs to be further investigated under elevated atmospheric CO 2 given its consequence on photosynthesis (and concomitant carbon sink) projections.

Annual water balance and seasonality of evapotranspiration in a Bornean tropical rainforest

This study presents the results of 2 years combined field measurements of water vapor exchange with the atmosphere and simplified model calculations at Lambir Hills National Park, Sarawak, Malaysia (4°12′N, 114°02′E). The study site was located in a lowland mixed dipterocarp forest, a major type of Bornean tropical rainforest, where there is no clear seasonality in environmental factors such as radiation, temperature, vapor pressure deficits and precipitation; instead, unpredictable dry spells often occur throughout the year. Modified [Priestley, C.H.B., Taylor, R.J. (1972). On the assessment of surface heat flux and evaporation using large-scale parameters, Mon. Weather Rev. 100, pp. 81–92] and equilibrium evaporation expressions enabled us to understand further the environmental control of water vapor exchanges with the atmosphere and to produce a complete gap-filled data set of the hydrologic fluxes within this environment. The equilibrium evaporation from a well-watered surface sufficiently reproduced the transpiration rate ( T r ); any discrepancies between the equilibrium and actual evaporation rates were caused by unpredictable intra-annual dry spells, which reduced transpiration. There were some discrepancies during the study period because of exceptional dry sequences, but in normal years the annual transpiration rate can be obtained from the equilibrium evaporation expression. The estimated annual T r (1193.1 mm) and evapotranspiration (1545.0 mm) rates were nearly identical to the highest values reported for some humid tropical forests. Although, there were exceptional dry sequences during the study period, the annual average fraction of available energy dissipated by T r at this site (0.69) was almost the same as the medium value between the dry and wet seasons in Amazonian tropical forests. This implies that the annual dynamics of the latent heat flux for this tropical rainforest are under more humid conditions than those of other tropical rainforests.

Water cycling in a Bornean tropical rain forest under current and projected precipitation scenarios

Southeastern Asian tropical rain forests are among the most important biomes in terms of annual productivity and water cycling. How their hydrologic budgets are altered by projected shifts in precipitation is examined using a combination of field measurements, global climate model (GCM) simulation output, and a simplified hydrologic model. The simplified hydrologic model is developed with its primary forcing term being rainfall statistics. A main novelty in this analysis is that the effects of increased (or decreased) precipitation on increased (or decreased) cloud cover and hence evapotranspiration is explicitly considered. The model is validated against field measurements conducted in a tropical rain forest in Sarawak, Malaysia. It is demonstrated that the model reproduces the probability density function of soil moisture content (s), transpiration (Tr), interception (Ic), and leakage loss (Q). On the basis of this model and projected shifts in precipitation statistics by GCM the probability distribution of Ic, Q and, to a lesser extent, s varied appreciably at seasonal timescales. The probability distribution of Tr was least impacted by projected shifts in precipitation.

Tree biodiversity in protected and logged Bornean tropical rain forests and its measurement by satellite remote sensing

AbstractAim Conservation activities have increasingly focused on issues at the level of the landscape but are constrained by limited data and knowledge relating to biodiversity at this scale. Satellite remote sensing has considerable, but under‐exploited, potential as a source of information on biodiversity at the landscape level. Remote sensing has generally been used to assess biodiversity indirectly, using approaches that often fail to fully exploit the information content of the imagery and typically only with regard to the species richness component of biodiversity. The aim of this paper was to assess the potential of remote sensing as a source of information on the richness, evenness and composition of tree species in a tropical rain forest.Location The test site was a c. 225 km2 region centred on the Danum Valley Field Centre, Borneo. This test site contained regions of undisturbed and differentially logged rain forest.Methods Data on tree biodiversity had been acquired for fifty‐two sample plots by standard field survey methods and were used to derive summary indices of biodiversity for seedlings, saplings and mature trees. Differences between logged and unlogged sites were evaluated by comparison of the indices and species accumulation curves. A Landsat Thematic Mapper (TM) image of the site acquired close to the date of the field survey was obtained and rigorously pre‐processed. Feedforward neural networks were used to derive predictions of biodiversity indices from the imagery. A Kohonen self organizing map neural network was used to ordinate the field data to derive classes of forest defined by relative similarity in species composition. The separability of the defined classes in the Landsat TM image was evaluated with a discriminant analysis.Results Analyses of the field data revealed considerable variation in the biodiversity of seedlings, saplings and trees at the site, associated, in part, with differences in logging activities. This variation in biodiversity was manifest in the remotely sensed data. The analyses indicated an ability to (1) predict biodiversity indices, with the highest correlation between predicted and actual index observed for evenness described by Shannon entropy (r = 0.546), but especially to (2) classify nine forest classes defined on the basis of similarity in tree species composition (accuracy 95.8%).Main conclusions Logging activities impacted on biodiversity and the resulting variation in biodiversity was reflected in the remotely sensed imagery. Using methods that exploit more fully the information content of the imagery than those used in other previous studies, a richer representation of biodiversity may be derived. This representation includes estimates of key summary indices of biodiversity, notably richness and evenness, as well as information on species composition. The results indicate that remotely sensed data may be used as a source of information on biodiversity at the landscape scale that may be used to inform conservation science and management.

Mapping the biomass of Bornean tropical rain forest from remotely sensed data

AbstractThe biomass and biomass dynamics of forests are major uncertainties in our understanding of tropical environments. Remote sensing is often the only practical means of acquiring information on forest biomass but has not always been used successfully. Here the conventional approaches to the estimation of forest biomass from remotely sensed data were evaluated relative to techniques based on the application of artificial neural networks. Together these approaches were used to estimate and map the biomass of tropical forests in north‐eastern Borneo from Landsat TM data. The neural networks were found to be particularly suited to the application. A basic multi‐layer perceptron network, for example, provided estimates of biomass that were strongly correlated with those measured in the field (r = 0.80). Moreover, these estimates were more strongly correlated with biomass than those derived from 230 conventional vegetation indices, including the widely used normalized difference vegetation index (NDVI).

Forest fire smoke and a test of hemispherical photography for predicting understorey light in Bornean tropical rain forest

Hemispherical canopy photographs are now widely used to estimate the proportion of above canopy PPFD (photosynthetic photon flux density) that is transmitted to the forest understorey. Some studies have obtained good results, while others have found that predictions are not always independent of forest type or condition, and that errors are sometimes large beneath very dense canopies. Lack of repeatability can make it difficult to compare sites, studies, or photographs taken at different times. In this study the method for calibrating predictions from photographs was tested in logged and undisturbed tropical broadleaf forest in Borneo, during both the wet and dry seasons. During the dry season a regional smoke ‘haze’ caused by widespread forest fires provided very uniform diffuse conditions and thus a unique test of the calibration. Total transmission (the ‘global transmission factor’, T t) was modelled as the weighted average of direct and diffuse transmission, with the weighting on diffuse transmission ( f d′) determined as the value which maximised the correlation between T t and measured PPFD. f d′ is an indirect measure of f d, the actual proportion of above canopy PPFD that is diffuse. f d′ should increase with cloudiness or smoke haze. Accurate determination of f d′ is important for prediction of transmission over short time-scales, such as days or weeks. f d′ was modelled for each day and was correlated ( r 2 = 0.65) with daily shadow band measurements of the above canopy diffuse component during the wet season. During the dry season, f d′ initially decreased with the expected increase in sunshine hours, then the smoke haze halved above canopy PPFD and f d′ increased from less than 0.5 to 1.0, thus validating this method of calibration. After calibration, predictions of T t from photographs in logged forest were repeatable, accurate ( r 2 > 0.96) and linear for sites with PPFDs ranging from less than 5% of above canopy PPFD to sites with more than 50% of above canopy PPFD. f d′ modelled from monthly or longer averages of transmission factors and PPFD was within 0.12 of f d. Results were more variable ( r 2 = 0.68) if calibration was based on data from undisturbed forest only. Overall accuracy and repeatability between sites were attributed to increased digitised image resolution, the use of a spot meter with a narrow field of view to set photograph exposure times, and other improvements in methodology.

Diversity in specific gravity and water content of wood among Bornean tropical rainforest trees

Wood properties were measured for trees in lowland dipterocarp forests in West Kalimantan. In 1993 and 1994, 353 samples of 286 species were collected from trunk base of trees of approximately 5 cm in diameter, and the specific gravities (SG: oven dry weight/fresh volume) and water contents of wood including bark were measured. The SG of each species ranged from 0.21 to 0.84, and the mean ± SD was 0.53 ± 0.13. The wide range of SG suggests that the forest had a high diversity in wood properties. The most dominant and diversified genus in this area was Shorea, and the SG of 15 species varied from 0.21 to 0.71. The range covered SG of pioneer (six Macaranga, 0.29–0.43) and small trees in primary forests (nine Eugenia and 10 Xanthophyllum, 0.55–0.77). The SG average for tree species of secondary forests of 2–6 years old was 0.31. It was significantly smaller than that of primary forests (0.58). In a primary dipterocarp forest plot, light‐wood species grew faster in diameter than heavy‐wood species. Water content ranged from 0.26 to 0.76. Heavy wood had low water content. Among light‐wood species, some (Shorea, Artocarpus) had low water contents and others (Ficus) had high water contents. Some riverine trees also had high water contents. These wood properties appear strongly related to the life history of trees and successional stage.