The morphology and exine ornamentation of fresh pollen from four dipterocarp species in Sabah

Peer reviewedPublisher PD

Polyosma maliauensis

Polyosma maliauensis is a small tree recorded only once from the Maliau Basin Conservation Area in Central Sabah. The estimated area of occupancy (AOO) and extent of occurrence (EOO) are both 4 km2 and are not in decline. The area is a Totally Protected Area (TPA). The potential threat is climate change which may push the species towards a higher threat category or Extinct in the near future, as a warming climate will degrade the habitat of the species and potentially cause drought. Hence, it is assessed as Vulnerable. Polyosma maliauensis is endemic to Sabah, Malaysia. It is known only from the lower montane forest of the Maliau Basin Conservation Area, Sabah (Saw 2004)

Comparative vessel traits of Macaranga gigantea and Vatica dulitensis from Malaysian Borneo

Trade-offs in wood anatomical characteristics reflect different strategies used by trees to deal with water transport in response to variation in environmental conditions. To study vascular strategies for Bornean rainforest trees, we compared water transport-related anatomical characteristics in branch wood between the common tree species Vatica dulitensis (Dipterocarpaceae) from old-growth forest and the common pioneer tree species Macaranga gigantea (Euphorbiaceae) from selectively logged forest. We hypothesised that the vessel traits of the pioneer species would reflect the need to capture and transport resources to support its fast growth rate (resource-acquisitive strategy), while the species of the old-growth forest would display more conservative vessel traits (resource-conservative strategy). We found that M. gigantea had significantly greater vessel area, hydraulically weighted diameter, vessel area to number ratio, and potential hydraulic conductivity than V. dulitensis. These results suggest that vessel traits of the common old-growth species would ensure high hydraulic safety during occasional drought when soil moisture is limited, while the common species of selectively logged forest possesses an efficient water transport system but its vessels would confer lower hydraulic safety during drought conditions. These contrasting vascular strategies highlight the potential for divergent responses of species of Bornean forest trees to future climatic extremes

Polyalthia lasioclada

Polyalthia lasioclada is restricted to the montane area in Kinabalu Park and Mensalong Forest Reserve, Sabah. The estimated area of occupancy (AOO) and extent of occurrence (EOO) are 16 km2 and 29 km2, respectively. Due to land use change, estimated past loss of the species' AOO and EOO has been about 20% and 22%, respectively. Decline has now ceased as the species is protected in situ in at least two Totally Protected Areas. However, the species is at risk from potential threats such as climate change and forest fire which if they occur could drastically change its conservation status to Critically Endangered or Extinct. Hence, it is assessed as Vulnerable. Polyalthia lasioclada is endemic to Sabah, Malaysia. It is only known from Mount Kinabalu and vicinity. It is estimated that at least 20% of the species' area of occupancy (AOO) and 22% of its extent of occurrence (EOO) has been lost (based on GeoCAT reduction analysis). However as the remaining individuals are in protected areas decline is not continuing. The species has a small remaining AOO and EOO of 16 km2 and 29 km2, respectively

Polyalthia montis-silam

Polyalthia montis-silam is restricted to Mount Silam area and Madai Hill in Lahad Datu district. The estimated area of occupancy (AOO) and extent of occurrence are 16 km2 and 47 km2, respectively. Due to land-use changes there has been an estimated decline of 20% in AOO. Fire is a potential threat that could drive this species to Critically Endangered or Extinct in the near future. Hence, it is assessed as Vulnerable. Polyalthia-montis-silam is endemic to Sabah, Malaysia. It was recorded from Lahad Datu district

Schefflera serpentinicola

Schefflera serpentinicola is only known from Wuluh river, Kinabalu Park. The estimated area of occupancy (AOO) and extent of occurrence (EOO) are both 4 km2. The most plausible threat that could affect this species is climate change, in the form of temperature extremes and droughts. If this was to occur it could rapidly drive the species towards Critically Endangered or Extinct within a short space of time. Hence it is assessed as Vulnerable. Schefflera serpentinicola is endemic to Sabah, Malaysia. It is only known from Wuluh river, Kinabalu Park

Polyscias havilandii

Polyscias havilandii is a tree known from Mount Kinabalu and vicinity. The estimated extent of occurrence (EOO) and area of occupancy (AOO) are both 8 km2. Due to land use changes, a decline of at least 60% is inferred due to reductions in EOO and AOO over the past three generations (90 years). The remaining known individuals are within protected area (Kinabalu Park). Thus, it is assessed as Endangered. Polyscias havilandii is endemic to Sabah, Malaysia. This species is restricted to Kinabalu Park (Totally Protected Area)

Timonius tambuyukonensis

Timonius kinabaluensis is only known from Ranau district, Sabah. The estimated area of occupancy (AOO) and extent of occurrence (EOO) are both 8 km2. The species is threatened by forest fire (Bukit hampuan forest reserve) with recurring fires occurring especially in the dry season. If these were to occur it could drive the species towards Critically Endangered or Extinct in the near future. Hence, it is assessed as Vulnerable. Timonius kinabaluensis is endemic to Sabah, Malaysia. It is restricted to the western and southern part of Kinabalu Park

Borneodendron aenigmaticum

The species is endemic to Sabah. It is found growing in primary forest that occurs on ultramafic substrates. The estimated area of occupancy (AOO) and extent of occurrence (EOO) are 56 km2 and 8,777.8 km2 respectively. Although the AOO is calculated from known existing records, it is considered that the actual AOO may be considerably larger than this due to under sampling. There are no records of habitat decline for the species as ultramific areas are protected in Sabah. Therefore, the species occurs in nine Totally Protected Areas and no direct threats impact the species. Hence, it is assessed as Least Concerned. The species is endemic to Sabah, it is known to occur on ultramafic substrates

Timonius kinabaluensis

Timonius kinabaluensis is only known from Ranau district, Sabah. The estimated area of occupancy (AOO) and extent of occurrence (EOO) are both 8 km2. The species is threatened by forest fire (Bukit hampuan forest reserve) with recurring fires occurring especially in the dry season. If these were to occur it could drive the species towards Critically Endangered or Extinct in the near future. Hence, it is assessed as Vulnerable. Timonius kinabaluensis is endemic to Sabah, Malaysia. It is restricted to the western and southern part of Kinabalu Park