Scientia Bruneiana

Effects of Acacia invasion on leaf litter nutrient and soil properties of coastal Kerangas forests in Brunei Darussalam

Aiman Yusoff — 2019-06-30

Exotic Acacia were introduced to Brunei Darussalam in the 1990s for plantation forestry and land rehabilitation but are now regarded as invasive. We assessed the effects of Acacia on litter nutrient composition and soil physicochemical properties of Brunei’s coastal Kerangas (heath) forests. Soil and litter samples were collected from ten 20 x 20 m plots in Acacia-invaded Kerangas forests (IKF) and ten uninvaded (UKF) plots. Soil samples were analyzed for pH, gravimetric water content and nutrient concentrations whereas litter samples were analyzed for total nutrients only. We recorded significantly higher concentrations of litter total N and P in the IKF than the UKF plots. In contrast, no significant differences were detected in soil properties, except for topsoil available P and subsoil exchangeable Ca which were both lower in the IKF plots. A significant positive correlation was detected between litter N and topsoil N in the IKF plots. We suggest that the fairly recent timescale of Acacia invasion (< 25 years) of the IKF sites resulted in the lack of significant increase of soil nutrients. In conclusion, Acacia invasion into Brunei’s forests can potentially alter both leaf litter and soil physicochemical properties of Kerangas forests, in particular affecting nutrient availability. This alteration of ecosystem may further enhance the invasion success of Acacia, making restoration attempts more challenging.

Amphibian species diversity in the proposed extension of the Bukit Teraja Protection Forest, Brunei Darussalam

Hanyrol H. Ahmad Sah — 2019-11-29

Amphibian species diversity was investigated within the lowland mixed-dipterocarp forest of the proposed extension of the Bukit Teraja Protection Forest (BTPF), Brunei Darussalam in north-west Borneo. A combination of both visual encounter and acoustic sampling techniques were conducted opportunistically as well as in six selected stream transects, each containing five 5x10m plots. A total of 39 species of frogs from seven families (Bufonidae, Ceratobatrachidae, Dicroglossidae, Megophryidae, Microhylidae, Ranidae, and Rhacophoridae) were identified from the BTPF. Most notably, four new records for Brunei were discovered: Hylarana nicobariensis, Kaloula baleata, Limnonectes malesianus, and Microhyla perparva. This brings the total number of amphibian species in Brunei Darussalam to 84. Canonical correspondence analysis showed that out of 13 measured environmental variables maximum stream depth and % soil/sand of ground cover were significantly correlated with anuran assemblage composition. Species overlap between the proposed extension of the Bukit Teraja Protection Forest and the Ulu Temburong National Park (UTNP) determined by the coefficient of biogeographic resemblance (CBR) showed low species complementarity between these two regions. This emphasizes the need to upgrade the proposed extension of the BTPF to a protection forest to ensure the conservation of regional amphibian biodiversity.

215 new seed plant species recorded for Brunei Darussalam

Siti Nur Amalina — 2019-11-29

We provide a checklist of new seed plant species (Angiosperms and Gymnosperms) in Brunei Darussalam with detailed information. The plant database for Brunei, extracted from the Global Biodiversity Information Facility (GBIF) was compared with the existing plant checklist for Brunei and plant holdings of the UBD herbarium (UBDH). 215 species of seed plants, belonging to 59 families, were found in the GBIF list that were absent in both the Brunei checklist and UBDH collections. The plant family that recorded the highest number of new plant species was Orchidaceae, but overall, tree species dominate the list. Only 8% of the new species were IUCN Red-List evaluated. Most new species collections came from Tutong district, but the highest number of new species was from Temburong district. Almost all new species collections came from areas with easy access such as near roads and around the Kuala Belalong Field Study Centre. As much of the Brunei rainforest remains unexplored, new discoveries are likely to occur.

Oleanane- and ursane- type triterpenoids from Eugenia grandis

Manoharan Karuppiah Pillai — 2019-11-29

Arjunolic acid (an oleanane-type triterpenoid) and asiatic acid (an ursane-type triterpenoid) were obtained as an inseparable mixture from a chloroform extract of stem-bark of Eugenia grandis (Myrtaceae). They were characterised mainly by analysis of their spectral data. Arjunolic acid and asiatic acid are reported to have a variety of biological and pharmacological activities, which include antibacterial, anti-inflammatory, antioxidant, antidiabetic, antihyperlipidemic, cardiacprotective, antitumor, anticancer and hepatoprotective activities. Arjunolic acid has been used as a cardio-protective phytotonic in traditional Ayurvedic medicine for centuries.