Dipterocarp Forest In Peninsular Malaysia Research Articles

Effects of vegetation structure on avian biodiversity in a selectively logged hill dipterocarp forest

Southeast Asian tropical rainforests are shrinking at an alarming rate largely due to anthropogenic activities such as logging and agricultural expansion. The loss of tropical rainforests from human exploitations caused devastating and irreversible impacts on avian biodiversity. The establishment of protected areas is an effective tool to mitigate further forest biodiversity loss. However, the ability of degraded rainforest to support avian biodiversity is still remain little known. Here, we assessed bird assemblages in a hill dipterocarp forest in Peninsular Malaysia which was selectively logged almost three decades ago. We examined the effects of site-level attributes, particularly vegetation structure on bird community composition, species richness and abundance of selected feeding guild groups (i.e. insectivorous, carnivorous, and frugivorous). Generally, we found that a selectively logged hill dipterocarp forest can still support a large proportion of forest birds, including those species with high conservation values. Our data also revealed that avian biodiversity was positively related to the number of fallen snags, number of standing snags, number of shrubs, number of trees with DBH < 5 cm, and elevation. In contrast, avian biodiversity was negatively linked to canopy cover percentage, number of palms, and number of trees with DBH 30–50 cm. Our findings suggest the importance of post-harvest site-level attributes management in order to improve avian biodiversity in logged hill dipterocarp forests. Above all, urgent actions are needed to incorporate hill dipterocarp forests, including those already disturbed by logging into protected area networks in Peninsular Malaysia to mitigate forest biodiversity loss.

Diversity and ecology of araceae in the water catchment area of Ulu Sat, Kelantan, Peninsular Malaysia

Araceae or aroid is familiarly known as keladi to the locals. The purpose of this study is to assess the diversity and ecology of Araceae in the Water Catchment Area of Ulu Sat, Kelantan, Peninsular Malaysia. The random sampling method was applied. A total of 26 species from 13 genera of Araceae were recorded from the water catchment area of Ulu Sat, Machang, Kelantan, Peninsular Malaysia. This represents about 18.6% out of an estimated 140 species and 46.2% of the 28 genera of Araceae reported for Peninsular Malaysia. The result also shows that 24 species or 92.3% of the collection are the common Araceae species found in lowland dipterocarp forest in Peninsular Malaysia. However, the collection include the species recently recorded, Aglaonema cochinchinense Engl. and the endemic species, Alocasia puber (Hassk.) Schott for Peninsular Malaysia. The paper will also discuss the distribution and ecology of some important Araceae collected from this area.

Spatial variations of soil silicon availability and biogenic silicon flux in a lowland tropical forest in Malaysia

AbstractTropical tree species differ widely in their silicon (Si) accumulation patterns, but the implications of such species differences for ecosystem Si flux remain unexplored. We analyzed how biogenic Si flux via leaf litter and soil Si availability in the upper soil vary spatially within a 2 ha area in a lowland Dipterocarp forest in Peninsular Malaysia. Silicon concentration per unit leaf dry mass of 86 dominant tree species in this plot ranged from 0.4 to 126 mg/g. Soil Si availability at 100 sampling points and Si flux via leaf litter at 66 litter traps showed large variations up to 3.3‐ and 17.9‐folds, respectively. However, they correlated neither with each other nor with the expected Si flux from tree species composition in the neighborhood. When we classified tree species to four groups by their leaf Si concentrations (negligible, low, moderate and high), tree species with moderate leaf Si concentrations were significantly more abundant on Si‐rich soils. In contrast, the other three groups did not show any significant spatial relationships with soil Si availability. These results indicate that soil Si availability, Si accumulation by vegetation and Si flux via leaf litter show wide spatial variations in a lowland tropical forest, without a simple relationship with each other.

Evapotranspiration and water source of a tropical rainforest in peninsular Malaysia.

To evaluate water use and the supporting water source of a tropical rainforest, a 4‐year assessment of evapotranspiration (ET) was conducted in Pasoh Forest Reserve, a lowland dipterocarp forest in Peninsular Malaysia. The eddy covariance method and isotope signals of rain, plant, soil, and stream waters were used to determine forest water sources under different moisture conditions. Four sampling events were conducted to collect soil and plant twig samples in wet, moderate, dry, and very dry conditions for the identification of isotopic signals. Annual ET from 2012 to 2015 was quite stable with an average of 1,182 ± 26 mm, and a substantial daily ET was observed even during drought periods, although some decline was observed, corresponding with volumetric soil water content. During the wet period, water for ET was supplied from the surface soil layer between 0 and 0.5 m, whereas in the dry period, approximately 50% to 90% was supplied from the deeper soil layer below 0.5‐m depth, originating from water precipitated several months previously at this forest. Isotope signatures demonstrated that the water sources of the plants, soil, and stream were all different. Water in plants was often different from soil water, probably because plant water came from a different source than water that was strongly bound to the soil particles. Plants showed no preference for soil depth with their size, whereas the existence of storage water in the xylem was suggested. The evapotranspiration at this forest is balanced and maintained using most of the available water sources except for a proportion of rapid response run‐off.

Occurrence of stomatal patchiness and its spatial scale in leaves from various sizes of trees distributed in a South-east Asian tropical rainforest in Peninsular Malaysia.

In this study, we demonstrated the occurrence of stomatal patchiness and its spatial scale in leaves from various sizes of trees grown in a lowland dipterocarp forest in Peninsular Malaysia. To evaluate the patterns of stomatal behavior, we used three techniques simultaneously to analyze heterobaric or homobaric leaves from five tree species ranging from 0.6 to 31 m in height: (i) diurnal changes in chlorophyll fluorescence imaging, (ii) observation and simulation of leaf gas-exchange rates and (iii) a pressure-infiltration method. Measurements were performed in situ with 1000 or 500 μmol m(-2) s(-1) photosynthetic photon flux density. Diurnal patterns in the spatial distribution of photosynthetic electron transport rate (J) mapped from chlorophyll fluorescence images, a comparison of observed and simulated leaf gas-exchange rates, and the spatial distribution of stomatal apertures obtained from the acid-fuchsin-infiltrated area showed that patchy stomatal closure coupled with severe midday depression of photosynthesis occurred in Neobalanocarpus heimii (King) Ashton, a higher canopy tree with heterobaric leaves due to the higher leaf temperature and vapor pressure deficit. However, subcanopy or understory trees showed uniform stomatal behavior throughout the day, although they also have heterobaric leaves. These results suggest that the occurrence of stomatal patchiness is determined by tree size and/or environmental conditions. The analysis of spatial scale by chlorophyll fluorescence imaging showed that several adjacent anatomical patches (lamina areas bounded by bundle-sheath extensions within the lamina) may co-operate for the distributed patterns of J and stomatal apertures.

Estimation of light-use efficiency through a combinational use of the photochemical reflectance index and vapor pressure deficit in an evergreen tropical rainforest at Pasoh, Peninsular Malaysia

In the search for a better method of estimating the light-use efficiency (LUE) of evergreen tropical rainforests, we employed remotely sensed spectral vegetation indices (VIs) to monitor both CO2 flux and canopy spectral reflectance over 3years in a lowland dipterocarp forest in Peninsular Malaysia. We investigated the sensitivity of five VIs calculated from spectral reflectance: the photochemical reflectance index (PRI), the canopy chlorophyll index (CCI), the normalized difference vegetation index (NDVI), the enhanced vegetation index (EVI) and the water index (WI).During the monitoring period, clear seasonal variations were not found in LUE, the observed VIs or the phenological timing (particularly new leaf flush) of dominant dipterocarp trees. Although leaf phenology tended to correlate with variations in the CCI, the highest correlation coefficient among the relationships between LUE and the VIs was observed in PRI (R=0.341, n=699). Among the relationships between LUE and meteorological factors, the strongest correlation was found between LUE and vapor pressure deficit (VPD; R=−0.580). These results suggest that unseasonal variation in LUE would be more affected by water conditions than leaf phenology or green leaf mass, and that the PRI has lower sensitivity for direct estimation of LUE compared to VPD in this evergreen tropical rainforest.To improve the accuracy in estimating LUE, we examined the potential of combinational use of VIs and meteorological factors. Variable selection by stepwise multiple regression showed that the best variable combination for LUE estimation was the PRI and VPD (R=0.612). The relative root mean square error (rRMSE) in the simple regression models using PRI, VPD and PRI×VPD, and the multiple regression model using PRI and VPD, was 22.5%, 19.4%, 19.0% and 18.7%, respectively. Based on these results, we concluded that (1) the estimation method solely based on the PRI as in the case of other temperate deciduous forests is not suitable in the tropical evergreen rainforest, and (2) the combinational use of the PRI and VPD offers one of the better models for estimating LUE in tropical evergreen rainforests.

Vertical variation in leaf gas exchange parameters for a Southeast Asian tropical rainforest in Peninsular Malaysia

Vertical variation in leaf gas exchange characteristics of trees grown in a lowland dipterocarp forest in Peninsular Malaysia was investigated. Maximum net photosynthetic rate, stomatal conductance, and electron transport rate of leaves at the upper canopy, lower canopy, and forest floor were studied in situ with saturated condition photosynthetic photon flux density. The dark respiration rate of leaves at the various heights was also studied. Relationships among gas exchange characteristics, and also with nitrogen content per unit leaf area and leaf dry matter per area were clearly detected, forming general equations representing the vertical profile of several important parameters related to gas exchange. Numerical analysis revealed that the vertical distribution of gas exchange parameters was well determined showing both larger carbon gain for the whole canopy and at the same time positive carbon gain for the leaves of the lowest layer. For correct estimation of gas exchange at both leaf and canopy scales using multi-layer models, it is essential to consider the vertical distribution of gas exchange parameters with proper scaling coefficients.

Water and heat fluxes above a lowland dipterocarp forest in Peninsular Malaysia

AbstractWe measured the fluxes of sensible and latent heat between a low‐land dipterocarp forest in Peninsular Malaysia and the atmosphere. No clear seasonal or interannual changes in latent heat flux were found from 2003 to 2005, while sensible heat flux sometimes fluctuated depending on the fluctuation of incoming radiation between wet and dry seasons. The evapotranspiration rates averaged for the period between 2003 and 2005 were 2·77 and 3·61 mm day−1 using eddy covariance data without and with an energy balance correction, respectively. Average precipitation was 4·74 mm day−1. Midday surface conductance decreased with an increasing atmospheric water vapour pressure deficit and thus restricted the excess water loss on sunny days in the dry season. However, the relationship between the surface conductance and vapour pressure deficit did not significantly decline with an increase in volumetric soil water content even during a period of extremely low rainfall. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Midday depression of leaf CO2 exchange within the crown of Dipterocarpus sublamellatus in a lowland dipterocarp forest in Peninsular Malaysia

We observed diurnal and seasonal patterns of leaf-scale gas exchange within the crown of a Dipterocarpus sublamellatus Foxw. tree growing in a lowland dipterocarp forest at Pasoh, Peninsular Malaysia. Observations were carried out nine times over 6 years, from September 2002 to December 2007. Observation periods included both wet and mild-dry periods, and natural and saturated photosynthetic photon flux density (PPFD) light conditions. In situ measurements of the diurnal change in net photosynthetic rate and in stomatal conductance were carried out on canopy leaves of a 40-m-tall D. sublamellatus tree, which was accessed from a canopy corridor. A diurnal change in electron transport rate was observed under saturated PPFD conditions. The maximum net assimilation rate was approximately 10 micromol m(-2) s(-1). There was a clear inhibition of the net assimilation rate coupled with stomatal closure after late morning and this inhibition occurred year-round. Although the electron transport rate decreased alongside this inhibition, it sometimes followed on. Numerical analysis showed that the main factor in the inhibition of the net assimilation rate was patchy bimodal stomatal closure, which occurred in both mild-dry and wet periods. The midday depression occurred year-round, though there are fluctuations in soil moisture during the mild-dry and wet periods. The magnitude of the inhibition was not related to soil water content but was related to vapor pressure deficit (VPD): that is, whether the days were sunny and hot or cloudy and cool. On cloudy, cool days in the wet period, the net photosynthesis was only moderately inhibited, but it still decreased in the afternoon and was coupled with patchy stomatal closure, even in quite moderate VPD, leaf temperature and PPFD conditions. Our results suggest that patchy stomatal closure signaled by the increase in VPD, in transpiration and by circadian rhythms, was the key factor in constraining midday leaf gas exchange of the D. sublamellatus canopy leaves.

Relationship between Economic Value and Species Diversity of Timber Resources in a Hill Forest in Peninsular Malaysia

Timber resource is a major component of tropical forest and usually undervalued economically. This paper attempts to examine the relationship between economic value and species diversity of a hill dipterocarp forest in Peninsular Malaysia. The rank-abundance curve described a lognormal distribution pattern, indicating high diversity communities. The species diversity indices obtained were high: Fisher’s alpha diversity index ranged from 96.53 to 109.56, Shannon-Weiner index were 5.29 to 5.39, while values of Simpson Index ranged from 134.02 to 151.11. The estimated mean stumpage value per hectare was Malaysian Ringgit RM25 413 and the main contribution was from the family Dipterocarpaceae. The regression analysis showed that the relationship between stumpage value and species diversity was not significant at the 5% level (p>0.05). Timber volume, size of trees and the presence of high timber value have great influence on the stumpage value for a given forest area.

Effect of selective logging on canopy and stand structure and tree species composition in a lowland dipterocarp forest in peninsular Malaysia

The authors compared tropical rain forest canopy structure and tree species composition in two forests southeast of Kuala Lumpur, Malaysia: a primary forest and a regenerating forest that was selectively logged in 1958. For each of the forests, the study plots were set out and all trees of ≥1 cm in DBH (diameter at breast height) were mapped and measured. Canopy heights were measured in the two study plots based upon aerial triangulation using aerial photographs taken over the forests in 1997. Using this data, digital elevation models of the canopy were then constructed. The mean canopy height was greater in the primary forest (27.4 m versus 24.8 m), as was the variance in height and the number of emergent canopy trees >40 m height. The mean canopy surface area in the primary forest was nearly 1.5 times the value in the regenerating forest, and the mean crown size of canopy layer trees in the primary forest was more than twice that in the regenerating forest. The species diversity index (Fisher’s α) differed for the two forests, indicating that tree species diversity had been affected by the logging. Both forests had the same five families with the greatest stem density (stems ha −1), but the 50 most abundant species, in terms of both stem density and basal area, differed greatly between the two forests. Stem densities and basal areas were similar, but the number of stems per hectare and the basal areas of medium-sized trees (10–30 cm in DBH) were distinctly higher in the regenerating forest. These results suggest that average basal area and stem density in the regenerating forest that had been selectively logged 41 years earlier had recovered to levels similar to those in the primary forest; however, the regenerating forest had a more monotonic canopy structure comprised of medium-sized trees growing at high density. These findings also imply that structural development takes a long time to manifest in a regenerating forest as a result of the time taken for the development of emergent and canopy trees and the formation of gaps; structural development might also be delayed by the high density of medium-sized trees in the canopy layer.

Woodpecker abundance in a logged (40 years ago) vs. unlogged lowland dipterocarp forest in Peninsular Malaysia

Woodpeckers (Picidae) are a group of birds particularly sensitive to logging and deforestation because they nest in cavities located in large trees and often forage on large trunks or standing dead trees. The diverse woodpecker community of lowland dipterocarp forests in Peninsular Malaysia was investigated in a forest selectively logged 40 y ago and in adjacent primary forest at Pasoh Forest Reserve (PFR). Line transects were conducted at dawn and dusk in each forest type to document potential differences in the woodpecker communities in logged vs. unlogged forest. A total of 121 woodpeckers were recorded along transects, including 14 of the 15 species known to occur at PFR. Eleven species were encountered in logged forest, 12 species were encountered in primary forest, and nine species were found at both sites. A significant difference in the overall woodpecker community between the two forest types was found. Of the most common species, Meiglyptes tristis, Reinwardtipicus validus and Dryocopus javensis were significantly more common in primary forest. Only one species, Picus mentalis, was significantly more abundant in logged forest. Possible causes for the differences observed are discussed.

Is there stratification in diversity or preferred flight height of geometroid moths in Malaysian lowland tropical forest

Moths from the superfamily Geometroidea were collected using standard Rothamsted light-traps at three levels on a tower (i.e. 1, 15, and 30 m) concurrently monthly for thirteen months in a lowland dipterocarp forest in Peninsular Malaysia. There was no consistently significant difference in species richness, abundance and diversity (as measured by α from the log-series) for individual sampling months between the three levels although values tended to be lower at the highest level. The diversity for the canopy (high) level was significantly lower when all samples were pooled. Here plant diversity is lower and the forest architecture is less complex. The geometroid moths are uniformly distributed throughout the three levels, with indications of preference for canopy or ground-level flight for some higher taxa. Some groups, such as Geometrinae, show much narrower vertical flight patterns than do others, such as Boarmiini. No significant coincidence of flight preference levels within distinct strata was detected.

Trap design for monitoring moth biodiversity in tropical rainforests

AbstractExperimental comparisons were made between samples of moths obtained by Rothamsted tungsten-filament and Robinson mercury-vapour light-traps operating in a lowland dipterocarp forest in Peninsular Malaysia. The Rothamsted trap gave more uniform and consistent samples and performed better in the tropical conditions than the Robinson trap. There were no significant differences between the overall measurement of diversity for the group Geometroidea between the two trap designs although the Robinson trap was much more erratic from night to night. The total catch of non-Geometroidea moths was remarkably similar in the two trap types. The choice of appropriate light-trap designs for biodiversity studies in tropical rainforest is discussed.

Introduction of ecological studies in a hill dipterocarp forest in Peninsular Malaysia

Introduction of ecological studies in a hill dipterocarp forest in Peninsular Malaysia

Trophic structure of bat communities in the understorey of lowland dipterocarp rain forest in Malaysia

ABSTRACTBat communities in the understorey of primary lowland dipterocarp forest in peninsular Malaysia and Sabah were sampled with mist nets and harp traps to estimate their trophic structure. Overall, 4 of 26 species (15%) at one site, and 6 of 33 species (18%) at the other site were frugivores, while the remainder were insectivores. In terms of individuals, 7–12% of all captures were frugivores. However, the true proportion of frugivores at both sites was probably closer to 1%, because the sampling procedures were strongly biased towards frugivores. In contrast, previously published studies indicate that frugivores comprise 34–48% of species, and up to 80% of individuals in bat communities in the understorey of Neotropical forest. These results support the hypothesis, developed from studies of bird communities, that the under-storey of Malaysian dipterocarp forest supports relatively few obligate frugivores, at least in non-masting years. However, further data are required on bats in the canopy, and on the foraging ranges of bats to compare the absolute densities of bats in Malaysian and Neotropical forests.

Recruitment, growth and mortality of tree species in a lowland dipterocarp forest in Peninsular Malaysia

ABSTRACTChanges in the lowland dipterocarp forest structure and composition are described for a 34-year period between 1947 and 1981 in Sungei Menyala Forest Reserve, Peninsular Malaysia. Although tree density declined by about 10%, basal area changed little, averaging 32.4 m2 ha−1. Size class distributions in 1947 and 1981 were not significantly different. Mortality rates were independent of size class. Mortality exceeded recruitment during the first 16 years to 1963, but was thereafter almost exactly balanced by recruitment. Recruitment rate increased significantly for the latter part of the study.Mortality was greater than average for understorey species and lower for emergents. Pioneer and late seral species together showed significantly higher mortality rates. Amongst the commoner species, emergent, late-seral and pioneer species showed the highest annual diameter growth rates with species averages over all size classes exceeding 3 mm yr−1; rates for main-canopy species were between 1.5 and 2.5 mm yr−1, and understorey species generally less than 2 mm yr−1.Species richness was almost identical in 1947 and 1981 (243, 244 species), but a clear decline (to 229 species) between 1953 and 1971 was recovered by 1981. Most species showed little net change in density over the 34-year period, but eight of the 32 commoner species showed significant changes, all unidirectional. These changes in species composition are not negligible, but further analysis is needed to determine if, for example, they are related to disturbance of part of the plot in 1917.