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Symbiotic nitrogen (N)-fixing trees can provide large quantities of new N to ecosystems, but only if they are sufficiently abundant. The overall abundance and latitudinal abundance distributions of N-fixing trees are well characterised in the Americas, but less well outside the Americas. Here, we characterised the abundance of N-fixing trees in a network of forest plots spanning five continents, ~5,000 tree species and ~4 million trees. The majority of the plots (86%) were in America or Asia. In addition, we examined whether the observed pattern of abundance of N-fixing trees was correlated with mean annual temperature and precipitation. Outside the tropics, N-fixing trees were consistently rare in the forest plots we examined. Within the tropics, N-fixing trees were abundant in American but not Asian forest plots (~7% versus ~1% of basal area and stems). This disparity was not explained by mean annual temperature or precipitation. Our finding of low N-fixing tree abundance in the Asian tropics casts some doubt on recent high estimates of N fixation rates in this region, which do not account for disparities in N-fixing tree abundance between the Asian and American tropics. Synthesis. Inputs of nitrogen to forests depend on symbiotic nitrogen fixation, which is constrained by the abundance of N-fixing trees. By analysing a large dataset of ~4 million trees, we found that N-fixing trees were consistently rare in the Asian tropics as well as across higher latitudes in Asia, America and Europe. The rarity of N-fixing trees in the Asian tropics compared with the American tropics might stem from lower intrinsic N limitation in Asian tropical forests, although direct support for any mechanism is lacking. The paucity of N-fixing trees throughout Asian forests suggests that N inputs to the Asian tropics might be lower than previously thought.

ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimensions, censusing of all stems ≥1 cm in diameter, inclusion of tropical, temperate and boreal forests, and investigation of additional biotic (e.g., arthropods) and abiotic (e.g., soils) drivers, which together provide a holistic view of forest functioning. The 71 FDPs in 27 countries include approximately 7.33 million living trees and about 12,000 species, representing 20% of the world's known tree diversity. With >1300 published papers, ForestGEO researchers have made significant contributions in two fundamental areas: species coexistence and diversity, and ecosystem functioning. Specifically, defining the major biotic and abiotic controls on the distribution and coexistence of species and functional types and on variation in species' demography has led to improved understanding of how the multiple dimensions of forest diversity are structured across space and time and how this diversity relates to the processes controlling the role of forests in the Earth system. Nevertheless, knowledge gaps remain that impede our ability to predict how forest diversity and function will respond to climate change and other stressors. Meeting these global research challenges requires major advances in standardizing taxonomy of tropical species, resolving the main drivers of forest dynamics, and integrating plot-based ground and remote sensing observations to scale up estimates of forest diversity and function, coupled with improved predictive models. However, they cannot be met without greater financial commitment to sustain the long-term research of ForestGEO and other forest plot networks, greatly expanded scientific capacity across the world's forested nations, and increased collaboration and integration among research networks and disciplines addressing forest science.

Air temperature and light intensity in the tropical rainforest of Brunei Darussalam was recorded at a 20-minute interval from 2011 to 2017. Five units of the HOBO Pendant® data loggers were attached to tree trunks within a circle of 5 m radius at 2 m above the ground. Approximately once a year, data were downloaded, and the sensors serviced. The test site is in a peat swamp forest classified as a mixed dipterocarp forest. The redundancy of the sensors allows for the assessment of the relative precision of the datasets. The root means squared error (RMSE) for the temperature is 0.37°C, below the manufacturer's precision statement (0.53°C). The RMSE for the light intensity data was 569.5 lux. There was no detection of systematic errors in the data. The sensors were calibrated before deployment. The data sets were captured in 2017. Ancillary data were collected in 2018, consisting of RGB orthoimagery and Light Detection And Ranging (LiDAR) data collected from an airborne platform. The data is a unique source of information on the diurnal, intraannual periodic effects, as well as random weather-related and phenology-related phenomenons. Multiannual datasets in the same ecosystem will be published in the future, allowing for a multidisciplinary analysis of the data in the context of climate change and the impact on the tropical rainforest ecosystems. The raw and auxiliary datasets are hosted in the Mendeley repository [1] .

A taxonomic description of all castes of Colobopsisexplodens Laciny & Zettel, sp. n. from Borneo, Thailand, and Malaysia is provided, which serves as a model species for biological studies on “exploding ants” in Southeast Asia. The new species is a member of the Colobopsiscylindrica (COCY) group and falls into a species complex that has been repeatedly summarized under the name Colobopsissaundersi (Emery, 1889) (formerly Camponotussaundersi). The COCY species group is known under its vernacular name “exploding ants” for a unique behaviour: during territorial combat, workers of some species sacrifice themselves by rupturing their gaster and releasing sticky and irritant contents of their hypertrophied mandibular gland reservoirs to kill or repel rivals. This study includes first illustrations and morphometric characterizations of males of the COCY group: Colobopsisexplodens Laciny & Zettel, sp. n. and Colobopsisbadia (Smith, 1857). Characters of male genitalia and external morphology are compared with other selected taxa of Camponotini. Preliminary notes on the biology of C.explodens Laciny & Zettel, sp. n. are provided. To fix the species identity of the closely related C.badia, a lectotype from Singapore is designated. The following taxonomic changes within the C.saundersi complex are proposed: Colobopsissolenobia (Menozzi, 1926), syn. n. and Colobopsistrieterica (Menozzi, 1926), syn. n. are synonymized with Colobopsiscorallina Roger, 1863, a common endemic species of the Philippines. Colobopsissaginata Stitz, 1925, stat. n., hitherto a subspecies of C.badia, is raised to species level.

Phytochemical investigation on a crude methanolic bark extract of Goniothalamus velutinus resulted in the isolation of four compounds, aristolactam I ( 1 ), aristolactam BII ( 2 ), aristolactam AII ( 3 ) and velutinam ( 4 ). Compounds ( 1 ) and ( 2 ) have previously been isolated from the bark of G. velutinus but this is the first report on isolation of compounds ( 3 ) and ( 4 ) from this specie. Antibacterial activities of these compounds were tested against Gram-positive bacteria ( Bacillus subtilis , Bacillus spizizenii and Staphylococcus aureus ) but none of them showed any antibacterial activity under the tested concentrations. These compounds were also tested for anti-biofilm activity against Klebsiella pneumoniae , S. aureus , Streptococcus mutans and Proteus mirabilis and among the four compounds only velutinam ( 4 ) (70 µg/mL) inhibited biofilm formation of both S. mutans and P. mirabilis up to 41.3 and 78.9%, respectively. Whereas, the compounds aristolactam BII ( 2 ) (90 µg/mL) and aristolactam AII ( 3 ) (140 µg/mL) were active against S. mutans and inhibited their biofilm formation to 72.8% and 89.9%, correspondingly. In addition aristolactam I ( 1 ) did not show any inhibition of biofilm against the microorganism used in this study. The anticancer activity of velutinam ( 4 ) was evaluated against various cell lines including Human lung adenocarcinoma epithelial cells (A549), human embryonic kidney cells (HEK 293) and epidermoid cervical carcinoma cells (CaSki). The MTT antiproliferative assay resulted in IC 50 values of 21.57 µg/mL, 13.28 µg/mL and 10.97 µg/mL for A549, HEK 293 and CaSki, respectively. Although anticancer activity of velutinam ( 4 ) has been reported on HeLa and L1210 cell lines, it has never been reported for the cell lines under this study. To our knowledge, this is the first report on anticancer activity of velutinam ( 4 ) on these cell lines.

Tropical forests play a critical role in mitigating climate change because they account for large amount of terrestrial carbon storage and productivity. However, there are many uncertainties associated with the estimation of carbon dynamics. We estimated forest structure and carbon dynamics along a slope (17.3°–42.8°) and to assess the relations between forest structures, carbon dynamics, and slopes in an intact lowland mixed dipterocarp forest, in Kuala Belalong, Brunei Darussalam. Living biomass, basal area, stand density, crown properties, and tree family composition were measured for forest structure. Growth rate, litter production, and litter decomposition rates were also measured for carbon dynamics. The crown form index and the crown position index were used to assess crown properties, which we categorized into five stages, from very poor to perfect. The living biomass, basal area and stand density were 261.5–940.7 Mg ha−1, 43.6–63.6 m2 ha−1 and 6,675–8400 tree ha−1, respectively. The average crown form and position index were 4, which means that the crown are mostly symmetrical and sufficiently exposed for photosynthesis. The mean biomass growth rate, litter production, litter decomposition rate were estimated as 11.9, 11.6 Mg ha−1 a−1, and 7.2 g a−1, respectively. Biomass growth rate was significantly correlated with living biomass, basal area, and crown form. Crown form appeared to strongly influence living biomass, basal area and biomass growth rate in terms of light acquisition. However, basal area, stand density, crown properties, and biomass growth rate did not vary by slope or tree family composition. The results indicate that carbon accumulation by tree growth in an intact lowland mixed dipterocarp forest depends on crown properties. Absence of any effect of tree family composition on carbon accumulation suggests that the main driver of biomass accumulation in old-growth forests of Borneo is not species-specific characteristics of tree species.

Since the 1970s Southeast Asian peat swamp forests have been increasingly threatened by anthropogenic disturbance. Peat swamps act as refuge for many endangered species, and they may turn into a net producer of CO2 and greatly contribute to climate change if cleared and drained. As one of the main invertebrate decomposers in the tropics, termites are likely to play a major role in peat forests. In this paper, we used a grid-based sampling plot protocol to sample termites in Brunei. We sampled termite communities in pristine and selectively logged peat swamp forests, that we compared with termite communities sampled in heath and dipterocarp forests. More precisely, we determined: (i) termite species diversity in peat swamp forests, and (ii) how termites respond to peat swamp logging. We found that species richness was the highest in the mixed dipterocarp forest. Selective logging had limited impact on species richness in peat swamp forest, suggesting that termite communities are resilient to limited amount of perturbations. Further data are needed to better understand the impact peat swamp clearance has on termite populations and their contribution to climate change.

The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (-9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth's climate., Our plot monitoring networks havebeen supported by multiple grants from a large number of funding bodies: European Research Council; Natural Environment Research Council; European Union’s Fifth, Sixth, and Seventh Framework Programme; Royal Society, Leverhulme Trust; Gordon and Betty Moore Foundation; David and Lucile Packard Foundation; State of São Paulo Research Foundation (FAPESP); National Council for Science and Technology Development of Brazil (CNPq); Agence Nationale de la Recherche; Conservation International; Missouri Botanical Garden; Smithsonian Institution; Wildlife Conservation Society; National Geographic Society; Centre for International Forestry; and Gabon’s National Park Agency.

Forty-five volatile organic compounds (VOCs) were identified or annotated in the mandibular gland reservoir content (MGRC) of the Southeast Asian ant Colobopsis explodens Laciny and Zettel, 2018 (Hymenoptera: Formicidae), using headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS) and liquid extraction combined with GC-MS. In extension of previous reports on VOCs of C. explodens, members of different compound classes, such as alkanes, aliphatic and aromatic carboxylic acids, and phenolics, were detected. The ketone 2-heptanone and the biochemically related phenolics benzene-1,3,5-triol (phloroglucinol, PG), 1-(2,4,6-trihydroxyphenyl)ethanone (monoacetylphloroglucinol, MAPG), 5,7-dihydroxy-2-methylchromen-4-one (noreugenin), and 1-(3-Acetyl-2,4,6-trihydroxyphenyl)ethanone (2,4-diacetylphloroglucinol, DAPG) dominated the GC-MS chromatograms. The identities of the main phenolics MAPG and noreugenin were further verified by liquid chromatography-high resolution-tandem mass spectrometry (LC-HRMS/MS). A comparative study of MGRC samples originating from three distinct field expeditions revealed differences in the VOC profiles, but the presence and relative abundances of the dominating constituents were largely consistent in all samples. Our study considerably extends the knowledge about the number and type of VOCs occurring in the MGRC of C. explodens. Based on the type of the detected compounds, we propose that the likely irritant and antibiotic phenolic constituents play a role in defense against arthropod opponents or in protection against microbial pathogens.

Functional effects of ants in rainforest canopies depend on difficult to characterize ant diets. In Bornean dipterocarp forests, certain diurnal, arboreal, territorial, and ecologically dominant ‘COCY’ ant species (Colobopsis cylindrica clade) grazed epiphytic biofilms on adaxial leaf surfaces, as well as on tree trunks and branches. Microscopic examination of worker buccal pellets revealed numerous (mainly ascomycete) fungal spores, together with insect appendages and cuticle. Direct observations, video-imaging, and δ15N isotope data rule out feeding by predation, but isotopes cannot separate fungi from plant and insect exudates as principal nitrogen sources. Lipid-rich products, extracted from pellets in situ, are hypothesized sources of essential sterols. Also present in pellets were colorful mandibular gland (MG) compounds unique to this ant clade and deployed, as a derived character state, in suicidal defense of foraging territories. Mildly antimicrobial and highly adhesive MG products also occur basally in the clade and may have first evolved for roles in microbial sterilization and food-gathering and processing. Proteomic studies of YG COCY ants detected 2% proteins in hypertrophied, product-filled MG reservoirs, but SDS-PAGE qualitative analysis revealed mostly low-molecular mass proteins and peptides (8–15 kDa), too small for enzymes but consistent with membrane-binding proteins and/or antimicrobial peptides. Breakdown of chitin and chitosan in pellets may occur with enzymes derived from molting fluids in insect cuticle (proteases and chitinases) and/or fungi and bacteria. To the extent that COCY workers collect and consume pathogenic and/or beneficial phyllosphere microbes, ant effects on plants may be mediated by these activities. Abstrak Sejauh mana terdapat kesan fungsi semut di kanopi hutan hujan berasaskan kesukaran mengkaji pemakanan semut tersebut. Di dalam hutan dipterokarp Borneo spesies tertentu dari klad Camponotus (Colobopsis) cylindricus (spesies ‘COCY’) yang giat pada siang, tinggal di pokok, mempertahankan kawasan dan berekologi dominan didapati memakan lapisan nipis (biofilem) hidupan epifit pada permukaan daun dan juga batang dan dahan pokok. Pemerhatian pelet yang masih dalam mulut pekerja semut yang belum lagi tukar kepada produk yang berlipid tinggi mendedahkan banyak spora kulat (kebanyakannya ‘ascomycete’) yang tercampur dengan bahagian badan dan kutikal serangga. Pemerhatian dan data isotop δ15N menunjukkan ketiadaan predasi tetapi tidak dapat menunjukkan bahawa kulat dan cecair dari tumbuhan merupakan punca nitrogen utama. Pelet juga mengandungi kompaun glanda mandibular (MG) yang unik kepada klad semut tersebut yang digunakan oleh spesies-spesies yang tertentu dalam pertahanan kawasan pemakanan sehingga mati, iaitu satu ciri yang kemudian muncul. Produk MG yang kuat melekat mungkin muncul untuk memainkan peranan dalam pemungutan bahan makanan dan mungkin juga merendahkan kesan mikrob semasa pemerosesan makanan untuk dapat N dan/atau lipid (misalnya sterol sejati). Kajian proteomik dapat mengesani protin sebanyak 2 peratus yang terkandung di dalam takungan MG yang diisikan dengan produk, juga penganalisis kualitatif SDS-PAGE menunjukkan protin dan peptid yang bermolekular rendah (8-15 kDa) yang terlalu halus bagi enzim tetapi boleh jadi protin pengikatan membran atau peptid antimikrob. Penghancuran kitin dan kitosan dalam bahan pelet mungkin berlaku berkesan dari enzim yang berpunca dari kutikal serangga (yang mengandungi kitinas) dan/atau kulat dan bakteria. Kesan semut ke atas tumbuh-tumbuhan kemungkinan dipengaruhi aktiviti tersebut sejauh mana pekerja COCY memungut dan makan mikrob filoplan yang patogenik dan/atau berguna.

The aim of this manuscript is to present a protocol describing the metabolomic analysis of Bornean 'exploding ants' belonging to the Colobopsis cylindrica (COCY) group. For this purpose, the model species C. explodens is used. Ants belonging to the minor worker caste possess distinctive hypertrophied mandibular glands (MGs). In territorial combat, they use the viscous contents of their enlarged mandibular gland reservoirs (MGRs) to kill rival arthropods in characteristic suicidal 'explosions' by voluntary rupture of the gastral integument (autothysis). We show the dissection of worker ants of this species for the isolation of the gastral portion of the wax-like MGR contents as well as listing the necessary steps required for solvent-extraction of the therein contained volatile compounds with subsequent gas chromatography-mass spectrometry (GC-MS) analysis and putative identification of metabolites contained in the extract. The dissection procedure is performed under cooled conditions and without the use of any dissection buffer solution to minimize the changes in the chemical composition of the MGR contents. After solvent-based extraction of volatile metabolites contained therein, the necessary steps for analyzing the samples via liquid-injection-GC-MS are presented. Lastly, data processing and putative metabolite identification with the use of the open-source software MetaboliteDetector is shown. With this approach, the profiling and identification of volatile metabolites in MGRs of ants belonging to the COCY group via GC-MS and the MetaboliteDetector software become possible.

Unlike most other fungi, molds of the genus Trichoderma (Hypocreales, Ascomycota) are aggressive parasites of other fungi and efficient decomposers of plant biomass. Although nutritional shifts are common among hypocrealean fungi, there are no examples of such broad substrate versatility as that observed in Trichoderma. A phylogenomic analysis of 23 hypocrealean fungi (including nine Trichoderma spp. and the related Escovopsis weberi) revealed that the genus Trichoderma has evolved from an ancestor with limited cellulolytic capability that fed on either fungi or arthropods. The evolutionary analysis of Trichoderma genes encoding plant cell wall-degrading carbohydrate-active enzymes and auxiliary proteins (pcwdCAZome, 122 gene families) based on a gene tree / species tree reconciliation demonstrated that the formation of the genus was accompanied by an unprecedented extent of lateral gene transfer (LGT). Nearly one-half of the genes in Trichoderma pcwdCAZome (41%) were obtained via LGT from plant-associated filamentous fungi belonging to different classes of Ascomycota, while no LGT was observed from other potential donors. In addition to the ability to feed on unrelated fungi (such as Basidiomycota), we also showed that Trichoderma is capable of endoparasitism on a broad range of Ascomycota, including extant LGT donors. This phenomenon was not observed in E. weberi and rarely in other mycoparasitic hypocrealean fungi. Thus, our study suggests that LGT is linked to the ability of Trichoderma to parasitize taxonomically related fungi (up to adelphoparasitism in strict sense). This may have allowed primarily mycotrophic Trichoderma fungi to evolve into decomposers of plant biomass., Author summary Individual fungi rely on particular host organisms or substrates for their nutrition. Therefore, the genomes of fungi feeding on plant biomass necessarily contain genes encoding plant cell wall-degrading enzymes, while animal parasites may depend on proteolytic activity. Molds in the genus Trichoderma (Ascomycota) display a unique nutritional versatility. They can feed on other fungi, attack animals, and degrade plant debris. The later property is so efficient that one species (T. reesei) is commercially used for the production of cellulolytic enzymes required for making biofuels and other industry. In this work, we have investigated the evolution of proteins required for plant cell wall degradation in nine Trichoderma genomes and found an unprecedented number of lateral gene transfer (LGT) events for genes encoding these enzymes. Interestingly, the transfers specifically occurred from Ascomycota molds that feed on plants. We detected no cases of LGT from other fungi (e.g., mushrooms or wood-rotting fungi from Basidiomycota) that are frequent hosts of Trichoderma. Therefore, we propose that LGT may be linked to the ability of Trichoderma to parasitize on related organisms. This is a characteristic ecological trait that distinguishes Trichoderma from other mycoparasitic fungi. In this report, we demonstrate that the lateral transfer of genes may result in a profound nutritional expansion and contribute to the emergence of a generalist capable of feeding on organic matter of any origin.

A supra-annual, community-level synchronous flowering prevails in several parts of the tropical forests of Southeast Asia and its evolution has been hypothesized to be linked to pollinator shifts. The aseasonal Southeast Asian lowland rainforests are dominated by Dipterocarpaceae, which exhibit great floral diversity, a range of pollination syndromes and include species with annual and supra-annual gregarious flowering. Phylogenetic relationships within this family are still unclear, especially in the tribe Shoreeae. Here, we develop a pipeline to maximize recovery of genome-wide SNPs from restriction-site associated DNA sequencing (RADseq) in non-model organisms across wide phylogenetic scales. We then infer phylogenomic relationships in the tribe Shoreeae using both traditional and coalescent analyses. The phylogenetic trees obtained with these methods are congruent to each other and highly resolved. They allow reconstructing the evolutionary patterns of floral traits (number of stamens, anther structure and anther/appendage size) in the group. Our inferences indicate that species with many stamens, but smaller, globose anthers and longer appendages and have evolved multiple times from species with fewer stamens, but larger, oblong anthers and shorter appendages. This could have happened in parallel to iterative shifts in pollinators across the uncovered phylogeny from larger, longer generation to smaller, shorter-generation insects that can quickly build up the necessary population sizes during mass flowering episodes.

Goniothalamus velutinus Airy Shaw belongs to the family Annonaceae which is known to have anticancer, antitumor and many other bioactivities. Natives of Sabah and Sarawak use root decoction of G. velutinus for the treatment of headache and food poisoning while the bark was used as a mosquito repellent. Bark and leaf extracts of this plant, obtained from Brunei Darussalam, were tested for phytochemical and antioxidant activities. Phytochemical screening of plant extracts revealed the presence of alkaloids, steroids, terpenoids and cardiac glycosides. Quantitative determination of total phenolics, total flavonoids, and various in vitro antioxidant activities (DPPH, ABTS and FRAP) of methanolic extract was carried out using colorimetric methods. The total phenolic content, expressed as mg of gallic acid equivalent (GAE) per gram of extract, was found to be 68 mg GAE/g and 78 mg GAE/g for bark and leaves respectively. The radical scavenging activity measurement, expressed in terms of EC 50 (effective concentration of extract in μg/mL that reduces DPPH absorbance to 50% as compared to negative control), for leaf and bark extracts was found to be 155 μg/mL and 204 μg/mL respectively. Standards trolox and ascorbic acid show EC 50 value of 5 μg/mL and 4 μg/mL respectively. Trolox equivalent antioxidant capacity (TEAC) was measured using the ABTS and FRAP method. Result for bark and leaf extracts was 79 mg and 106 mg trolox equivalent (TE)/g respectively for the ABTS method. For FRAP assay, results for bark and leaf extracts were 80 and 89 mg TE/g respectively.

본 연구는 항공 LiDAR 자료를 이용하여 열대원시림인 브루나이 지역의 지상부 생체량을 정량화하기 위하여 수행되었다. 25ha 크기의 연구대상지에 0.09ha ( $30m{\times}30m$ ) 크기의 24개의 표본구 내에서 조사된 각 표본점 내 개체목의 흉고직경 및 위치자료를 활용하였다. 또한, 항공 LiDAR 자료를 이용하여 수치표면모델(Digital Surface Model), 수치지형모델(Digital Terrain Model), 수고모델(Canopy Height Model)을 구축하였다. 수고모델을 표본구단위로 분할하고 총 12개의 LiDAR 높이변수를 구축하였다. 표본구별로 상대생장식을 이용하여 계산된 생체량과 LiDAR 자료로부터 추출된 변수간의 다중회귀분석을 통해 LiDAR 자료로부터 생체량을 추정할 수 있는 식을 도출하였다. 표본구의 생체량은 평균 366.48 Mg/ha였으며, 155.81 Mg/ha부터 597.21 Mg/ha까지 분포하였다. LiDAR로부터 생체량을 추정하는 식의 검증 결과, 결정계수 값은 0.84로 나타났다. 【This study aims to quantify the stand-level above ground biomass in intact tropical rain forest of Brunei using airborne LiDAR data. Twenty four sub-plots with the size of 0.09ha ( $30m{\times}30m$ ) were located in the 25ha study area along the altitudinal gradients. Field investigated data (Diameter at Breast Height (DBH) and individual tree position data) in sub-plots were used. Digital Surface Model (DSM), Digital Terrain Model (DTM) and Canopy Height Model (CHM) were constructed using airborne LiDAR data. CHM was divided into 24 sub-plots and 12 LiDAR height metrics were built. Multiple regression equation between the variables extracted from the LiDAR data and biomass calculated by using a allometric equation was derived. Stand-level biomass estimated from LiDAR data were distributed from 155.81 Mg/ha to 597.21 Mg/ha with the mean value of 366.48 Mg/ha. R-square value of the verification analysis was 0.84.】

Singapore. National Research Foundation (Singapore-MIT Alliance for Research and Technology)

Less than half of anthropogenic carbon dioxide emissions remain in the atmosphere. While carbon balance models imply large carbon uptake in tropical forests, direct on-the-ground observations are still lacking in Southeast Asia. Here, using long-term plot monitoring records of up to half a century, we find that intact forests in Borneo gained 0.43 Mg C ha−1 per year (95% CI 0.14–0.72, mean period 1988–2010) in above-ground live biomass carbon. These results closely match those from African and Amazonian plot networks, suggesting that the world’s remaining intact tropical forests are now en masse out-of-equilibrium. Although both pan-tropical and long-term, the sink in remaining intact forests appears vulnerable to climate and land use changes. Across Borneo the 1997–1998 El Niño drought temporarily halted the carbon sink by increasing tree mortality, while fragmentation persistently offset the sink and turned many edge-affected forests into a carbon source to the atmosphere., The existence of a pan-tropical forest carbon sink remains uncertain due to the lack of data from Asia. Here, using direct on-the-ground observations, the authors confirm remaining intact forests in Borneo have provided a long-term carbon sink, but carbon net gains are vulnerable to drought and edge effects.

Tropical peatlands now emit hundreds of megatons of carbon dioxide per year because of human disruption of the feedbacks that link peat accumulation and groundwater hydrology. However, no quantitative theory has existed for how patterns of carbon storage and release accompanying growth and subsidence of tropical peatlands are affected by climate and disturbance. Using comprehensive data from a pristine peatland in Brunei Darussalam, we show how rainfall and groundwater flow determine a shape parameter (the Laplacian of the peat surface elevation) that specifies, under a given rainfall regime, the ultimate, stable morphology, and hence carbon storage, of a tropical peatland within a network of rivers or canals. We find that peatlands reach their ultimate shape first at the edges of peat domes where they are bounded by rivers, so that the rate of carbon uptake accompanying their growth is proportional to the area of the still-growing dome interior. We use this model to study how tropical peatland carbon storage and fluxes are controlled by changes in climate, sea level, and drainage networks. We find that fluctuations in net precipitation on timescales from hours to years can reduce long-term peat accumulation. Our mathematical and numerical models can be used to predict long-term effects of changes in temporal rainfall patterns and drainage networks on tropical peatland geomorphology and carbon storage.

Tropical forests are global centres of biodiversity and carbon storage. Many tropical countries aspire to protect forest to fulfil biodiversity and climate mitigation policy targets, but the conservation strategies needed to achieve these two functions depend critically on the tropical forest tree diversity-carbon storage relationship. Assessing this relationship is challenging due to the scarcity of inventories where carbon stocks in aboveground biomass and species identifications have been simultaneously and robustly quantified. Here, we compile a unique pan-Tropical dataset of 360 plots located in structurally intact old-growth closed-canopy forest, surveyed using standardised methods, allowing a multi-scale evaluation of diversity-carbon relationships in tropical forests. Diversity-carbon relationships among all plots at 1 ha scale across the tropics are absent, and within continents are either weak (Asia) or absent (Amazonia, Africa). A weak positive relationship is detectable within 1 ha plots, indicating that diversity effects in tropical forests may be scale dependent. The absence of clear diversity-carbon relationships at scales relevant to conservation planning means that carbon-centred conservation strategies will inevitably miss many high diversity ecosystems. As tropical forests can have any combination of tree diversity and carbon stocks both require explicit consideration when optimising policies to manage tropical carbon and biodiversity., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

This study investigated the contribution of termites to mass loss of dead wood ( Macaranga bancana , Elateriospermum tapos , and Dillenia beccariana ) in a lowland tropical rainforest, Brunei Darussalam. Mesh bag method was used to exclude termites, and the mass remaining was monitored after 3, 7, 13, and 23 months. C/N ratio of the samples was analyzed after 13 and 23 months. Initial wood density was 0.63, 0.92, and 1.02 g/cm 3 for M. bancana , E. tapos , and D. beccariana , respectively, and the termite contribution to mass loss was an average (range) of 13.05±5.68 (4.17-29.59%), 3.48±1.13 (2.20-6.49), and 3.40±1.92% (0.74-10.78), respectively. Until 7 months, termites contributed highly to mass loss, given the low initial wood density, and interaction effect of species and treatment was significant. After 7 months, the contribution decreased in M. bancana and E. tapos , whereas it increased consistently in D. beccariana . The interaction effect was not significant, whereas differences in C/N ratio among the species were significant, with a lower C/N ratio in M. bancana and E. tapos than in D. beccariana . After 23 months, the differences in C/N ratio were not significant, and ants were present at 40% of control samples in M. bancana and E. tapos . Our results suggest that the contribution of termites to mass loss varies by dead wood species and is temporally variable. Initial wood traits could affect the termite feeding in the beginning, however, termites thereafter could forage in response to the varying C/N ratio among species and predators.

WOS: 000373538000024, Essential oils from the leaves, aerial stems, basal stems, and rhizomes of Etlingera fimbriobracteata (K.Schum.) R.M.Sm. were analyzed using a gas chromatography-flame ionization detector (GC-FID) and by gas chromatography-mass spectrometry (GC-MS). beta-Pinene (67.8%) and 1,8-cineole (37.2%) were the main components of the oils from leaves and aerial stems, respectively, whereas decanal was the main component of basal stems and rhizomes (27.5% and 34.4%, respectively). The antioxidant activities of the oils were evaluated using several in vitro assays; the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging assays, the reducing power ability (RPA) assay, and the ferric reducing antioxidant power (FRAP) assay. In all the tests, essential oils from different plant parts showed very poor antioxidant activity compared with those of the reference standards, ascorbic acid (AA) and butylated hydroxytoluene (BHT). However, all the oils exhibited moderate to potent broad-spectrum antimicrobial activity against all tested strains except for Pseudomonas aeruginosa. In disc diffusion and broth microdilution assays, the inhibition zones and MIC values of the essential oils were in the range of 8-87.7mm and 2.4-625 mu g/mL, respectively. Because of their strong antimicrobial activity, the essential oils of E. fimbriobracteata could be a potential alternative to conventional antimicrobials in food, cosmetics, and pharmaceutical industries, Government of Brunei Darussalam, We thank the Government of Brunei Darussalam for providing the scholarship to Shahid-Ud-Daula and Universiti Brunei Darussalam for the use of facilities to perform this research. The authors also thank Noramalina Ismail, Rafizah Mat Serudin, and laboratory technicians of the Environmental and Life Sciences Program for their help with collecting plant samples and facilitating laboratory work.

Intact dipterocarp forests in Asia act as crucial carbon (C) reservoirs, and it is therefore important to investigate the C dynamics in these forests. We estimated C dynamics, together with net ecosystem production (NEP), in an intact tropical dipterocarp forest of Brunei Darussalam. Fifty-four simulation units (plots; 20 m � 20 m) were established and initial C stocks were determined via direct field measurement. The C dynamics were annually simulated with a regression model and the Forest Biomass and Dead organic matter Carbon (FBDC) model. The initial C stock (Mg C�ha-1) of biomass, litter, dead wood and mineral soil were 213.1 � 104.8, 2.0 � 0.8, 31.3 � 38.8, and 80.7 � 15.5, respectively. Their annual changes (Mg C�ha-1 year-1) were 3.2 � 1.1, 0.2 � 0.2, -3.7 � 6.1, and -0.3 � 1.1, respectively. NEP was -0.6 � 6.1 Mg C�ha-1 year-1, showing large heterogeneity among the plots. The initial C stocks of biomass and dead wood, biomass turnover rates and dead wood decay rates were elucidated as dominant factors determining NEP in a sensitivity analysis. Accordingly, investigation on those input data can constrain an uncertainty in determining NEP in the intact tropical forests. Scopus

The advancement of LiDAR technology has enabled more detailed evaluations of forest structures. The so-called "Volumetric pixel (voxel)" has emerged as a new comprehensive approach. The purpose of this study was to estimate plot-level above-ground biomass (AGB) in different plot sizes of 20 m x 20 m and 30 m x 30 m, and to develop a regression model for AGB prediction. Both point cloud-based (PCB) and voxel-based (VB) metrics were used to maximize the efficiency of low-density LiDAR data within a dense forest. Multiple regression model AGB prediction performance was found to be greatest in the 30 m x 30 m plots, with R-2, adjusted R-2, and standard deviation values of 0.92, 0.87, and 35.13 Mg.ha(-1), respectively. Five out of the eight selected independent variables were derived from VB metrics and the other three were derived from PCB metrics. Validation of accuracy yielded RMSE and NRMSE values of 27.8 Mg.ha(-1) and 9.2%, respectively, which is a reasonable estimate for this structurally complex intact forest that has shown high NRMSE values in previous studies. This voxel-based approach enables a greater understanding of complex forest structure and is expected to contribute to the advancement of forest carbon quantification techniques.