A distinctive white sediment in the caves of Mulu, Sarawak, Borneo is a well-preserved tephra, representing a fluvially transported surface air-fall deposit, re-deposited inside the caves. We show that the tephra is not the Younger Toba Tephra, formerly considered as most likely. The shards are rod-shaped with elongate tubular vesicles; the largest grains ~ 170 μm in length; of rhyolitic composition; and 87Sr/86Sr ratio of 0.70426 ± 0.00001. U–Th dating of associated calcites suggest that the tephra was deposited before 125 ± 4 ka, and probably before 156 ± 2 ka. Grain size and distance from closest potential source suggests an eruption of VEI 7. Prevailing winds, grain size, thickness of deposit, location of potential sources, and Sr isotopic ratio limit the source to the Philippines. Comparisons with the literature give the best match geochemically with layer 1822 from Ku et al. (2009a), dated by ocean core stratigraphy to 189 ka. This tephra represents a rare terrestrial repository indicating a very substantial Plinian/Ultra-Plinian eruption that covered the Mulu region of Borneo with ash, a region that rarely receives tephra from even the largest known eruptions in the vicinity. It likely will be a valuable chronostratigraphic marker for sedimentary, palaeontological and archaeological studies.

The magnitude and sustainability of incidental catches of marine mammals in fisheries was investigated in Sabah and Sarawak, East Malaysia, using a combination of interview surveys and observer trips on fishing boats. These fisheries involve around 15,000 registered fishing boats and generate annual landings of around 350,000 tonnes. Between March 1997 and December 2004, we interviewed fishermen working on 753 and 358 boats in Sabah and Sarawak, respectively, who were employing trawl nets, purse seines, gillnets and fish stakes. They were asked questions about sightings of marine mammals and interactions with fishing. We also followed 36 trawl and 10 purse seine fishing trips in Sabah between June 2003 and December 2004. Fishing was conducted in coastal waters and total annual catches by each method and region were estimated. Incidental catches of marine mammals were reported by fishermen from 310 (41%) and 99 (28%) fishing boats in Sabah and Sarawak, respectively. Gill-netters, trawlers and fish stakes were reported to catch cetaceans and dugongs, while purse seiners caught only cetaceans. The Irrawaddy dolphin, bottlenose dolphin, spinner dolphin, pantropical spotted dolphin, Indo-Pacific humpback dolphin and finless porpoise are the cetacean species known to be taken. Overall, the magnitude of incidental catches of marine mammals is greatest in gillnets. No marine mammal catches were seen during observer trips. Interview results suggest annual by-catches of 306 (95% CI = 250–369) cetaceans and 479 (95% CI = 434–528) dugongs in Sabah. Estimates for Sarawak were 221 (95% CI = 189–258) cetaceans per year and 14 (95% CI = 2–30) dugongs. These results suggest that by-catch rates, particularly in gillnets, may be unsustainably high. A dedicated monitoring and educational programme, together with the establishment of Marine Protected Areas, is urgently needed to minimize the threat.

The El Niño-Southern Oscillation (ENSO) phenomenon occurs irregularly and supra-annually at intervals of 2–7 y (Hughen et al. 1999, McPhaden et al. 2006), and is the strongest source of supra-annual climate fluctuation (Hughen et al. 1999, Philander 1990). During ENSO, the interior of the South-East Asian tropics, which is characterized by constant high temperature and no distinct dry season, experiences severe drought (Walsh 1996).

The physical and chemical seed characteristics of 11 dipterocarp species (four Dipterocarpus, two Dryobalanops and five Shorea species) were quantified to examine variations among species. We measured dry weight, pericarp thickness and concentrations of nitrogen, total phenol, condensed tannin, lignin, lipid, starch and total sugar. Although there was low intraspecific variation among parent trees, each species had unique characteristics. We found significant correlations between chemical defensive compounds (i.e. lignin and total phenol) and nitrogen concentration. However, these relationships were no longer significant when an outlier was removed. Fruiting frequency was not significantly correlated with any chemical compound. Seeds of Shorea species had a higher concentration of lipid than seeds of Dipterocarpus. The implications of variation in the physical and chemical characteristics of dipterocarp seeds are discussed.

Rainfall fluctuation influences the physiology and leaf production of the trees in tropical rain forests (Burslem et al. 1996, Condit et al. 1995, Reekie & Wayne 1992, Reich 1995), and consequently it may have an impact on the community of herbivores that depend on forest trees for their food resources (Aide 1988, 1992; Basset 1991, Coley 1998, Lowman 1985, van Schaik et al. 1993).

In the first 3 mo of 1998, an aseasonal tropical rain forest at Lambir Hills National Park on the north-west coast of Borneo suffered an unusually severe drought. Extreme climatic events such as this one are expected to influence tree population structure and community dynamics through differential effects on growth and mortality. The demographics of seedlings of seven shade-tolerant tree species, including two dipterocarps, during this severe drought were contrasted with baseline demographic data from two earlier census intervals, one of which included a slight drought, and one of which included no drought. Hemispherical photographs were used to document an opening of the canopy that resulted from the dieback and mortality of large trees during the severe 1998 drought. Seedlings that experienced an increase in canopy openness were less likely to die than other seedlings. Rates of mortality and height loss were significantly increased in association with drought. The overall mortality rates during the severe drought and slight drought census intervals were 8.2% y-1 and 7.3% y-1 respectively, compared with 4.9% y-1 for the non-drought census interval. The incidence of height loss during the severe drought census interval was 27.5%, compared with rates of 11.7% and 20.1% for earlier census intervals. Dipterocarp species were less affected than some non-dipterocarp species, and the smallest seedlings suffered the greatest impact. If droughts in this region continue to increase in intensity and severity, they may ultimately cause a change in the species population densities and stand structure of the understorey seedling community of this rain forest.

This paper completes an account of the subfamily Alpinioideae (Zingiberaceae) of Lambir Hills National Park, Sarawak, Malaysia, started in the first paper of this series (Sakai & Nagamasu, 1998), which lists 12 Amomum species from the park. Twenty-two species in the genera Alpinia, Elettaria, Elettariopsis, Etlingera, Hornstedtia and Plagiostachys (Zingiberaceae) are reported from Lambir Hills, Sarawak, with systematic and ecological notes. Four species, Etlingera baramensis, E. inundata, E. newmanii and Plagiostachys glandulosa, are described as new to science, and Hornstedtia leonurus is reported from Borneo for the first time. In Etlingera inundata floral dimorphism is reported. The informal grouping of Etlingera proposed by Smith (1986b) is re-examined. Synonymies of Etlingera coccinea, Hornstedtia minor, H. affinis and H. phaeochoana and the generic position and synonymies of H. sarawacensis and H. conica are discussed. Lectotypes of Achasma brevilabrum (=Etlingera brevilabrum), Alpinia ligulata, Elettaria coccinea (=Etlingera coccinea), Elettaria speciosa (=Etlingera elatior) and Hornstedtia alliacea (=H. conica) are designated. Keys are also provided to all Bornean genera and species of Alpinioideae.

The population dynamics of 8500 shade-tolerant tree seedlings of 13 tree species were followed for 10 years at rain forests in Lambir Hills National Park and Bako National Park, Malaysian Borneo. Since these dipterocarp forests have lower rates of canopy gap formation than do rain forests elsewhere, tree seedling biology was predicted to differ. Approximately 50% of seedlings present in 1986 were still alive in 1996. Seven out of thirteen had seedling populations composed predominantly of individuals that were at least 10 years old. These seedlings can undergo alternating periods of relatively rapid and slow growth. Many seedlings that grew rapidly in the first census interval survived through a period of suppression in the second census interval, and conversely many seedlings with a history of suppression had exceptionally high growth in the final census interval. Seedlings of South-East Asian forest tree species are long-lived and appear to be adapted to long periods of suppression in the understorey.

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.

A new monotypic genus, Tamijia (Zingiberaceae), and its species T. flagellaris are described from Sarawak, Borneo. T. flagellaris is quite unique with the lateral staminodes connate to the labellum, the plane of distichy of the leaf shoot transverse to the rhizome, long trailing inflorescences and ovary unilocular with parietal placentation. Although the species is placed in Alpineae based on the plane of distichy, it is quite distinctive from most of the species in the tribe in some other characters, and is important in considering the current system of tribes and genera of the family.

Elettaria (Zingiberaceae) of Sarawak are studied, and eight species are recognised including four new species: E. linearicrista, E. longipilosa, E. brachycalyx and E. kapitensis. Elettaria surculosa and E. stolonifera, which have previously been included in E. multiflora, are treated as independent species. Examination of recent collections reveal that characters such as anther dehiscence patterns, form of the labellum and anther crest are taxonomically important. A key to all species of Bornean Elettaria is provided.

Two new species of Aeschynanthus from Borneo, A. argentii Mendum and A. pseudohybridus Mendum, and one from Palawan (Philippines), A. batakiorum Mendum & Madulid, are described and illustrated.

Zingiber kelabitianum from Sarawak, Borneo is described. This new species belongs to section Zingiber, having radical, erect inflorescences. It is related to Z. pachysiphon B.L. Burtt & R.M. Sm. in the large size of the plant and the robust, cylindrical inflorescences with deflexed bracts. It differs in the dense, yellow-brown indumentum of the leaf sheath and ligules, the bright red bracts, the longer bracteole and the free, well-developed lateral lobes of the labellum. The traditional uses of the plant by the indigenous people, the Kelabits, are described.

Amomum roseisquamosum (Zingiberaceae) is described from Sarawak, Borneo. This new species is related to A. borneense and A. epiphyticum of Smith's (1989) Group V for Bornean species, sharing an epiphytic habit, crested anther-thecae and flattened fruits, but differs in having white flowers, a shorter corolla tube equal to the calyx tube, and lateral petals connate to the labellum. The systematic position is discussed.