In a I-ha plot all ground herb species were recorded. Within the plot selected properties were investigated in three 20 m × 20 m subplots. The number of ground herb species and individuals in the subplots were lowest near to a local hilltop and they increased towards the lowest part of the plot. There was no significant difference in canopy openness, or in thickness of leaf litter layer, between the upper and lower subplots. In the upper subplot the soil layer was thin and the weathered bedrock was close to the surface. In the lower subplot the soil was much deeper. The pH and concentrations of Mg were significantly lower and %loss-on-ignition, total P and total N concentrations were significantly higher in the upper subplot. Elevation and soil moisture were significantly correlated in the upper 10 cm of soil. It is not possible to select any one abiotic property as being the critical determinant of the gradient of ground herbs. However, it is suspected that the availability of water in the topsoil, particularly after droughts, may be more important than the soil nutrients in limiting herb distribution.

Bat 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.

Mistnets were set at ground level and 11–30 m above ground in lowland rainforest at Kuala Lompat in peninsular Malaysia, and Sepilok in Sabah, to compare the abundance of fruit bats in the subcanopy and at ground level. Capture rates in the subcanopy were up to 100 times greater than at ground level, averaging 3–7 bats per net-night. Species diversity was higher in the subcanopy than forest understorey. Two species that were frequently captured in the subcanopy, Megaerops wetmorei and Dyacopterus spadiceus, were previously thought to be rare. The abundance of Old World fruit bats in the subcanopy indicates that their roles in pollination and seed dispersal of Malaysian forest trees may be greater than previously recognized. Further research on foraging ranges, food selection and roosting habits is required to determine the overall importance of fruit bats in forest regeneration through seed dispersal, and the adequacy of existing reserves for their conservation.

The germination of 43 tree species native to the lowland forests of Malaysia was monitored on forest soil in trays placed in closed-canopy forest, an artificial forest gap, and a large clearing. Germination varied significantly among habitats, with only seven species germinating well in all three sites. Seed germination of most species demonstrated clear patterns of shade tolerance or intolerance identical to those long recognized for tree seedlings. Favoured locations for germination were similar to known distributional patterns of adult individuals in mature and secondary forests. Most forest canopy species germinated in the gap, but germination in the large clearing was dramatically reduced or nil; the regeneration of these species in large clearings will be severely retarded even when seeds are present. Canopy-induced inhibition of germination was apparent in several pioneer species; seeds moved from the forest into the gap or clearing germinated rapidly. Results indicate that natural treefall gaps do not inhibit the germination of most species, but do allow pioneer species to germinate, and therefore regenerate. Although germination occurred in all three locations, the level of germination for particular species varied greatly among habitats. We conclude that germination requirements play a very important role in controlling the species composition of regeneration in forest understorey, gap, and large clearing habitats.

Discrete humus layers are common on podzols under temperate coniferous and tropical heath forests, and patchy layers also occur under some temperate broadleaved forests on non-podzolic soils. We used multiple data sets to test the reported association of humus with oligotrophic but non-podzolic soils under non-heath dipterocarp forest at Lambir, Sarawak. We examined the distribution, morphology and nutrient dynamics of necromass on soils derived from sandstone and shale. Concentrations of the main mineral nutrients were lower in fresh litter on the very oligotrophic sandstone soils than on shale. The rates of litterfall were similar, so that annual litterfall fluxes of all nutrients were lower on sandstone. The lower nutrient concentrations and fluxes in the litter on sandstone resulted in slower decomposition, longer residence times and larger standing crops of forest-floor necromass, with lower concentrations of nutrients. The necromass on sandstone sequestered significantly more N, K and Mg but less Ca and Mn than on shale, with no significant difference for P. The variations in necromass nutrient dynamics were associated with morphological differences. There were mats of densely rooted humus under the litter on sandstone, whereas litter lay directly over the mineral topsoil on shale. Spatial associations with soil nutrients were weak for necromass thickness, but clear for humus. The proportions of nutrients in the litterfall and necromass reflected the stoichiometric profiles of the soils. We attribute the differences in necromass nutrient dynamics and their association with soil reserve nutrients to lower rates of nutrient replenishment from the weathering of sandstone than from shale. Necromass characteristics are robust field indicators of multivariate edaphic differences in these and other tropical forests on Acrisols/Ultisols derived from Tertiary clastic sediments.

For analysing field data as well as for modelling purposes it is useful to classify tree species into a few functional types. In this paper a new aggregation of tree species of the dipterocarp rain forests in Sabah (Borneo), Malaysia, is developed. The aggregation is based on the two criteria successional status and potential maximum height. Three classes of successional status (early, mid and late successional species) and five classes of potential maximum heights (≥ 5 m, 5–15, 15–25, 25–36, > 36 m) lead to a combination of 15 functional types. The criteria of the developed classification are chosen to suit for applications with process-based models, such as FORMIX3 and FORMIND, which are based on photosynthesis production as the main process determining tree growth. The concept is universal and can easily be applied to other areas. With this new method of grouping a more realistic parametrization of process-based rain forest growth models seems to be possible.

Reproductive phenology of 117 individuals from a total of 20 ginger species (Costaceae and Zingiberaceae) was monitored for up to 21 mo in a lowland mixed dipterocarp forest in the Lambir Hills National Park, Sarawak. Of these 20 species of iteroparous perennials, pollinated by either spiderhunters (Nectariniidae), medium-sized Amegilla bees (Anthophoridae), or small halictid bees (Halictidae), many reproduced more than once a year, or flowered continuously with short interruptions. Significant but weak synchronization in flowering events among conspecific individuals was detected for only two species out of the five examined (Etlingera aff. metriocheilos and Amomum somniculosum). The low synchronization within the population, the overlapping flowering among species sharing common pollinators, and the high flowering frequency for each species, contrast markedly with the reproductive phenology of hummingbird-pollinated and large bee-pollinated plants of related taxa in the Neotropics. Although the plants studied do not include all members of each pollination guild, at least one species within a guild was flowering at any time except in the spiderhunter-pollinated guild. Some bee-pollinated gingers may serve as keystone species for survival of the traplining bees living on floral nectar and pollen.