Maliau Basin Research Articles

Vertebrate Assemblage at a Fruiting Fig (Ficus caulocarpa) in Maliau Basin, Malaysia

We analyzed the species composition and abundance of birds and mammals at a fruiting hemi-epiphytic fig ( Ficus caulocarpa) in Maliau Basin, Sabah, Malaysia. Observations were conducted for 32 hours over five days. Forty-four species of birds and three mammal species were recorded. Of these, 28 birds and 2 mammals fed on the figs. In addition, nine species of insectivorous or omnivorous birds that did not feed on the figs were observed foraging in the tree, presumably on the large quantities of fig wasps produced. Inter- and intra-specific aggression was also observed among the species foraging in the tree. Overall the assemblage of large birds, such as hornbills, and mammals was poor, which seems to be due to the small size of the figs (<6 mm diameter) rather than a scarcity of these animals in the area. In contrast, the diversity of smaller bird species, especially the Pycnonotidae (Bulbuls) which comprised 13 species and 68% of visits, was high. Our results suggest fig-frugivore interactions may be more finely structured than reports from other, less pristine sites in Asia have indicated. Moreover, 34% of the birds observed are threatened or more severely endangered. We suggest that planting of hemi-epiphytic fig seedlings could be used to enhance the conservation value of small reserves and degraded forests, and that observations at fruiting figs could be used as an efficient method for assessing how well reserves are protected.

Ground-dwelling ant diversity in Maliau Basin, Borneo: Evaluation of hand-sorting methods to estimate ant diversity

The ground-dwelling ant fauna in tropical forests remains the “final frontier” in the study of Formicidae biodiversity. This is mainly due to a lack of convenient sampling methods for the inventory of ants in soil. In the present study, employing the hand-sorting of small soil cores, we carried out the first survey of ground-dwelling ants in Maliau Basin Conservation Area, in Sabah, Borneo, to compare disturbed and undisturbed forest ant communities and to evaluate the sampling method’s performance in assessing species richness and characterizing community structure of the ant fauna. For this purpose we set a 5 m long and 1 m wide transect, consisting of five 1-m2 sections, in disturbed and undisturbed forest plots in the area, and compared the sampling results of hand-sorting between the two plots. A total of 50 ant species, in 28 genera and eight subfamilies, were collected in the two plots, of which 32 species in 20 genera were collected from the undisturbed plot and 24 species in 18 genera from the disturbed plot. According to estimates of expected species richness, the hand-sorting of soil cores allowed for the collection of 66.7 to 80.0% of the ant species expected in the undisturbed plot, and 83.3 to 88.9% in the disturbed plot. Besides lower species richness, the ant community in the disturbed plot had lower species evenness and a different species composition in comparison to undisturbed plot, which may be related with environmental changes in the plot, due to open canopy. These results indicate that hand-sorting of small soil cores is a method that could provide reliable information, not only to estimate species richness at a site, but also to evaluate differences in community structure between sites.

A pristine environment and water quality in perspective: Maliau Basin, Borneo's mysterious world

AbstractThe chemical characteristics of the surface water of Eucalyptus River, in Maliau Basin, were studied based on its major ion chemistry and its suitability for drinking, domestic use and irrigation. Water samples from the river were collected and analysed for pH, temperature, dissolved oxygen (DO), electrical conductivity (EC), total dissolved solids (TDS), turbidity, Cl, SO4, Ca, Mg, Na and K. Besides major elements, Cu, Zn, Ni, Co, Fe, Mn, Cr, Bi, Cd, Ba, Pb, As, Al, V, Se, Ag, Sr and Li were also determined in this study. The results show that the river water of the area reflects natural factors and is regarded as fresh water and suitable for drinking and domestic use. The calculated values of sodium adsorption ratio (SAR), Mg hazard and salinity hazard indicate that the river water is of high quality and suitable for agricultural and irrigation purposes. This study contributes baseline data for a pristine, forested environment for future reference.

Hydrocarbon generation potential of the coals and shales around the Eucalyptus Campsite area, Maliau Basin, Sabah

Six shales and four coals of the Kapilit Formation (Early to Middle Miocene) from the adjacent area of Eucalyptus campsite, Maliau Basin, Sabah were analysed using organic petrological and organic geochemical methods to determine their hydrocarbon generating potential, maturity and depositional environment. The organic richness of the shale samples is generally good to very good, whilst for the coals, as usual, show very good organic carbon richness. The shale samples also show good to very good hydrocarbon generating potential (S2 values from 5.0 to 37.3 mg HC/g rock), except for two samples which possess poor hydrocarbon generating potential (S2 5.0) ratio, odd-over-even n-alkane distributions, presence of oleananes and dominance of C29 sterane homologs. Tricyclic terpanes and C30 steranes which are derived mainly from algae organic matter are present in very low relative abundance or are virtually absent. The depositional environment for the shales and coals is probably in a coastal plain or deltaic setting under oxic condition.

Structural geology of the Neogene Maliau Basin, Sabah

The Maliau Basin (Maliau outlier) is made up of about 7,500 metres thick sandstone and mudstone layers deposited in a deltaic-coastal environment, assigned the Kapilit Formation. The layers at the base of the basin consist mainly of mudstones reaching up to 2,000 metres thick. Near the rim of the basin, thick sandstone layers and coal seams occur. Towards the centre of the basin a series of sandstone-dominated and mudstone-dominated sequences of various thicknesses occur. The deposition took slight unconformity place during the Middle Miocene (10-15 million years ago). The basin sits with slight unconformity on older sedimentary rocks (Tanjong Formation), also comprising of thick layers of sandstone and mudstone. The orientation of bedding generally follows the semi-circular shape of the basin. The dip of bedding varies from 5-10 degrees at the centre to 45-50 degrees at the rim. Sub­ vertical to vertical fractures shows four main fracture orientations, NW-SE, NE-SW, NNW-SSE and WNW-ESE. Faulting is quite rare inside the basin. However, outside the basin, minor normal faults occur trending E-W and NE-SW. A sheared zone occurs at the southeastern part of the basin, possibly due to a major fault, the Lonod Fault. Based on regional and local structures the Maliau Basin is interpreted to have. developed initially in an extensional regime, whereby an enormous amount of sediments were deposited in a subsiding basin and later subjected to compression (inversion).

On the knowledge of the clearwing moth (Lepidoptera, Sesiidae) of the Maliau Basin, Sabah, Borneo

On the knowledge of the clearwing moth (Lepidoptera, Sesiidae) of the Maliau Basin, Sabah, Borneo

Termite assemblages in two distinct montane forest types at 1000 m elevation in the Maliau Basin, Sabah

Termites were surveyed at an altitude of 1000 m in Maliau Basin, Sabah (Borneo), in two primary forest habitats: lower montane forest and stunted facies of upper montane forest. Soil, wood, litter, termite nests, and arboreal microhabitats up to a height of 2 m above ground were sampled using a belt transect protocol. Two transects were run in each forest type. The upper montane forest transects collected 11 and 13 species, compared with 15 and 19 in the lower montane forest transects. With the addition of species records from casual sampling (conducted with roughly equal effort in each forest type), totals of 18 species were found in the upper montane forest, and 34 species in the lower montane forest. Similar species richness and relative abundance of wood-feeding termites were found in both forest types. However, the lower montane forest had greater richness and relative abundance of species that feed on soil and extremely decayed soil-like wood. This difference is attributed mainly to (i) the well developed, organic-rich soils of the lower montane forest being more suitable for soil-dwelling and mound-building termites compared with the upper montane forest which has sandy soils with a thick covering of peat, and (ii) the low-stature and open canopy of the upper montane forest creates microclimatic conditions which are adverse for soil-feeding termites compared with the high, closed canopy in the lower montane forest. As expected, comparisons with similar studies in lowland forests in Southeast Asia confirmed that the upland forests are relatively depauperate.

Decapods of the Maliau Basin, Sabah, Malaysia, with Description of a New Species of Thelphusula (Brachyura: Gecarcinucidae)

Three species of decapod crustaceans belonging to three families are recorded from the Maliau Basin, Sabah, Malaysia. A new gecarcinucid crab, Thelphusula hulu, new species, is described. The palaemonid prawn Macrobrachium sabanus and the parathelphusid crab Parathelphusa valida are recorded for the first time from such a high altitude (490 m a.s.l.).

DECAPODS OF THE MALIAU BASIN, SABAH, MALAYSIA, WITH DESCRIPTION OF A NEW SPECIES OF THELPHUSULA (BRACHYURA: GECARCINUCIDAE)

ABSTRACT Three species of decapod crustaceans belonging to three families are recorded from the Maliau Basin, Sabah, Malaysia. A new gecarcinucid crab, Thelphusula hulu, new species, is described. The palaemonid prawn Macrobrachium sabanus and the parathelphusid crab Parathelphusa valida are recorded for the first time from such a high altitude (490 m a.s.l.).

The Maliau Basin, Sabah: Geology and tectonic setting

A field survey of the eastern half of the Maliau Basin established the presence of several good quality coal seams in the dominant mudstone sequence of the Early to Middle Miocene Tanjung Formation. Although volumetrically minor, the several metres thick sublitharenite beds dominate the landscape forming high waterfalls, concen­ tric cuesta and other ridges with dipslopes inclined into the basin. Sandstone channel fills are common. Sedimentary current indicators including current ripple marks, tabular and trough cross beds, and lineation of carbonised plant fragments indicate that the Il).ajority of currents was towards northeast. The presence of coal, dominant mudstone, marine body and trace fossils suggest that the Tanjung Formation developed in low-energy environ­ ment, probably in wide tidal flats. Except for one locality exposing open folds, the beds dip uniformly and gently inward forming an eccentric basinal structure associated with normal faulting. These phenomena could have only been caused by gravitational subsi­ dence without tectonic compression. The northern boundary strike ridge intercepts internal strike ridges at oblique angles. This pattern and the off-centre position of the youngest beds suggest that the Maliau Basin during the deposition of the Tanjung Formation became progressively narrower while its depocentre migrated towards the south rim. The structural basins contairiingthe Tanjung Formation and time-equivalent Kapilit Formation are arranged in northeast and southeast rows; the Maliau basin occupying the junction of these two directions. Geologically the Maliau Basin is the landward extension of the Tarakan Trough and is at least partially floored by melange rocks of the Kinabalu Suture Zone. Subsidence ofthis basin and other early-middle Miocene basins of east Sabah began when the East Sabah Terrane stopped drifting south and isostatic readjustment sank the denser ophiolitic basement of the suture zone.