Peat Swamp Research Articles

Elevational variability in the fractal structure of the root system of Kobresia tibetica in alpine peat swamp

Root fractal structure is the result of the phenotypic plasticity of plant root conformation in response to environmental heterogeneity, which can reflect the adaptation strategy of plants to the external environment. Four altitudinal gradients of 3400 m, 3500 m, 3600 m, and 3700 m were selected as experimental sites in Gahai Wetland on the Ruoerge Plateau. Additionally, the Win-RHIZO root analyzer and the standardized major axis estimation (SMA) method were employed to examine the fractal structure of Kobresia tibetica root system at various elevations in the alpine peat swamp. The results showed that the height, density, aboveground biomass, soil water content of the wetland community, as well as the fractal dimension of Kobresia tibetica root system decreased gradually with the increase of altitude, whereas the fractal abundance of Kobresia tibetica root system gradually grew. Kobresia tibetica root fractal dimension and fractal abundance at the 3400 m and 3700 m sites are in a very significant negative correlation between the sample area (p < 0.01), in the land of 3500 m and 3600 m sample was a significantly negative correlation between (p < 0.05). Meanwhile, there is a “shift” between both trade-off relationships. There were elevational differences in the allometric growth relationship between root fractal dimension and root fractal abundance. At the 3400 m sample location, Kobresia tibetica root fractal structure’s regression equation’s SMA slope was <−1, suggesting that the root fractal dimension’s growth rate was greater than the fractal abundance’s growth rate. The SMA slope of the regression equation for the fractal structure of the root system at the 3700 m sample site was >−1, suggesting that the growth rate of Kobresia tibetica root system’s fractal dimension was slower than that of its fractal abundance. Furthermore, at the 3500 m and 3600 m sites, the development rates of fractal dimension and fractal abundance of Kobresia tibetica roots were similar. As the altitude rises, the root system of Kobresia tibetica changes from “dense” to “diffuse”, illustrating how populations of alpine peat swamp plants have ecologically adapted to habitat stress.

Complete genome sequences of Lactococcus lactis D1_2, a bacterium with antimicrobial properties isolated from peat soil.

Lactococcus lactis is a beneficial lactic acid bacterium commonly studied for its probiotic properties and role in dairy production. Here, we present a complete genome of Lactococcus lactis D1_2, isolated from peat swamp forests. To discover the potential antimicrobial properties, the complete genome of the strain was sequenced and analyzed.

Assessment of variability of peat physicochemical properties, subsidence and their interactions within Selangor forests

AbstractTropical peat swamp forests are carbon‐rich ecosystems both above‐ and belowground, which play a major role in the climate balance of the earth. The majority of the world's tropical peat forest cover is located in Southeast Asia and is increasingly threatened by anthropogenic disturbances. Despite their importance for biodiversity conservation and climatic balance of the earth, pristine peatlands are almost extinct in many parts of Southeast Asia. Peninsular Malaysia is one such region, where there are no undisturbed peatlands left in the west coast. We studied the largest peat forest area in the west coast of Malaysia, located in the state of Selangor. We evaluated variability of peat subsidence (for 1 year), peat physicochemical properties and macronutrient contents between forest regions and between different depths (not for subsidence) covering the top 50 cm, and the complex interactions between them. We found that there was significant peat subsidence in all the studied regions, however, there was no significant difference in subsidence between different forest regions. Physicochemical properties such as peat moisture, pH and carbon (C) content and all macronutrient contents except phosphorus (P), either varied between regions, or showed significant interactions between region and depth in Selangor peat forests. All the measured peat physicochemical properties varied with depth. Among macronutrients, only nitrogen (N), P and calcium (Ca) showed significant change with depth, while there were no changes with depth for sulphur (S), potassium (K) and magnesium (Mg) contents. These changes in each peat physicochemical property and macronutrient contents correlated with changes in other peat physicochemical properties and nutrient contents; however, there is a need for controlled experiments to further understand these significant interactions. The findings show continued carbon loss in secondary peat swamp forests through subsidence, indicating the long‐term impact of selective logging and associated historical drainage. The significant variability of peat physicochemical properties and macronutrient contents with region and depth, also show the need for intensive sampling to characterise large secondary peat swamp forests.

CHANGES IN HYDROGEOLOGICAL CONDITIONS DURING BOGGING IN THE SOUTHEAST OF THE WEST SIBERIAN PLAIN

Link for citation: Savichev O.G. Changes in hydrogeological conditions during bogging in the southeast of the West Siberian plain. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 187-198. In Rus. Relevance of the research is determined by the need to understand the mechanisms of interaction between groundwater, swamp and river waters in conditions of severe swampiness in the taiga zone of Western Siberia to solve a number of scientific and engineering problems both at present and in the future. The aim: quantitative assessment of changes in the levels of groundwaters during the characteristic periods of swamping of the southeast of the West Siberian Plain: 1) the beginning of an intensive spread of peat swamps with a peat deposit thickness of 0,3 m or more; 2) oligotrophization of swamps. Methods: methods of mathematical modeling, statistical methods. Results and conclusions. The author has carried out the analysis of peat deposit structure in the southern part of the Chaya river (a tributary of the Ob river) catchment area. The large-scale formation of peat swamps (with a peat thickness of 0,3 m or more) in the area under consideration occurred approximately 4 thousand years ago; the oligotrophization of the peat deposit (on a regional scale) occurred approximately 2,0…1,5 thousand years ago. In both cases, the main part of the swamps presumably could be attributed to the lowland type, but compared with the modern period in the first case their total area was 2 times less, and in the second was 1,7 times more. Taking into account these estimates, the average values of infiltration Inf and filtration coefficients Kf were determined, the ratio Inf/Kf dependence on the area of low-moor peat swamps was obtained, and groundwater levels were calculated at the present time and for periods of 1,7 and 4,1 thousand years ago. During the oligotrophization of the peat deposit (approximately 2,0...1,5 thousand years ago), with a high probability, there was a deterioration in water exchange between swamps and underground aquifers and an increase in groundwater levels. The beginning of intensive regional swamping (about 4 thousand years ago) occurred against the background of intense water-erosion processes. This results in accumulation of river alluvium accompanied by a rise in the levels of river water and then groundwater.

FOOD SELF-SUFFICIENCY AT THE LOCAL LEVEL: A CASE STUDY IN PEATLANDS OF SOUTH SUMATRA

The COVID-19 pandemic has brought attention to the need for Indonesia to prepare for future food challenges. The government is focusing on developing underdeveloped areas, including peatlands, which have great potential for integrated farming systems. Bangsal is a village with peat swamp lands that serve as a source of food in OKI Regency, South Sumatera. During the dry season, the land is used for agriculture, while during the rainy season, it is used for fisheries. This paper analyzes (a) the village-based farming patterns in peatland areas, (b) the institutional framework of peatland farmer groups in Bangsal, and (c) the strategy for sustainable peatland utilization for food security. The study used both qualitative and quantitative data analysis methods. The research showed that the role of the Ulak Kuto Mandiri effectively and efficiently increased community income and food self-sufficiency. Integrated farming systems, including swamp buffalo farming, swamp fish farming, and swamp agriculture, optimally and sustainably increased the potential of peatlands. Sustainable peatland utilization through integrated farming systems technically preserves the peatland ecosystem from land conversion, is economically feasible, increases the income of farmers, livestock breeders, and local cultural traditions, and empowers women in farming activities. It also reduces forest fire risks, chemical fertilizer and pesticide use, and increases peatland productivity.

Chemical Composition of Organic Carbon in Tropical Soils Under Agricultural Cultivation and Peat-Swamp Forest

ABSTRACT Soil organic carbon (SOC) is important for agricultural production and from an environmental perspective. This research determined the chemical composition of SOC and studied factors related to its distribution for various crops and peat-swamp forests in the tropical region. In total, 21 topsoil samples were collected from areas of paddy rice, sugarcane, cassava, pineapple, oil palm, para rubber, and peat-swamp forest in Thailand. Four groups of SOC chemical composition were investigated (carbonyl C, aromatic C, O-alkyl C, and alkyl C) using solid-state 13C nuclear magnetic resonance spectroscopy (NMR). The dominant peak of the NMR spectra indicated that SOC originated from a variety of lignin compound units. The results revealed the dominant SOC chemical component was O-alkyl C (36.57–50.90%), followed by alkyl C (22.32–32.60%), aromatic C (16.65–23.41%), and carbonyl C (7.99–10.95%), respectively. Most of the SOC chemical components were derived from plant debris, particularly biodegraded lignin compounds. There were slightly differences between the distributions of the SOC functional groups in each vegetation type, perhaps partially as a result of the specific management activities for each crop, including tillage. Furthermore, alkyl C was related to some soil properties (silt and clay fractions), while O-alkyl C was related to available P in the soil. The hydrophobicity index, aromaticity index, and degree of humification were in the ranges 0.69–1.12, 0.17–0.23, and 0.46–0.92, respectively. These findings provided SOC chemical composition data of several economic crops to further support soil management for crop production and carbon stock preservation in tropical soils.

Dynamics of Tropical Peatlands Characteristics and Carbon Stocks as Affected by Land Use Conversion and Ages of Land Use in Riau Province, Indonesia

The dynamics and patterns of relationships between the characteristics of Indonesian tropical peat involving a function of time (ages of land use) in the context of land conversion have yet to be widely reported. The effects of tropical peatland use change are generally discussed regarding C emissions, with the limited literature identifying dynamic soil characteristics as these changes occur. This study used a survey method. We identified the physical, chemical, and C stock characteristics of peat in forest locations, oil palm plantations with a land use age of 0-5 years,&gt;5-10 years,&gt;10 years, and agricultural land with a land use age of 0-5 years and &gt;5-10 years to find out the dynamics of soil characteristics. Land use changes from peat swamp forests to oil palm plantations and agricultural land, and the longer age of land use results in an increase in BD (especially at the top layer), ash content, pH, Total-N, total-P2O5, total-K2O, but there was a decrease in water content, fiber content, Organic-C, E400/E600, and soil C stocks. The alignment of economic, social, and ecological interests was directed to water and land management by regulating the area’s hydrological system and increasing peat stability.

Contrasting genetic and morphological differentiation among geographical lineages of a stenotopic miniature rasborine, Boraras maculatus, in Peninsular Malaysia.

The variability in the stenotopic miniature rasborine Boraras maculatus (Cypriniformes: Danionidae: Rasborinae) across acidic-water habitats of Peninsular Malaysia (PM) was investigated using two molecular markers (the mitochondrial cytochrome c oxidase subunit I [COI] gene and the nuclear rhodopsin gene), as well as morphological evidence. Molecular phylogenetic analyses revealed differentiation among populations of B. maculatus in PM with the distinction of four allopatric lineages. Each of them was recognized as a putative species by automatic species delimitation methods. These lineages diverged from each other between 7.4 and 1.9 million years ago. A principal component analysis (PCA) was conducted to examine the multivariate variation in 11 morphometric measurements among three of these lineages. PCA results showed a significant overlap in morphological characteristics among these lineages. Additionally, a photograph-based machine learning approach failed to fully differentiate these lineages, suggesting limited morphological differentiation. B. maculatus represents a case of morphological stasis in a stenotopic miniature species. Strong habitat preference, coupled with long-term habitat fragmentation, may explain why each lineage of B. maculatus has a restricted distribution and did not disperse to other regions within and outside of PM, despite ample possibilities when the Sunda shelf was emerged and drained by large paleodrainages for most of the past 7 million years. The conservation status of B. maculatus and its peat swamp habitats are discussed, and it is concluded that peat swamps comprise several evolutionary units. Each of these units is considered a conservation unit and deserves appropriate protection.

Revegetation of Tropical Peat Swamp Forest of Former Fires Using Local Tree Species in South Sumatra (Indonesia)

Revegetation of tropical peat swamp forests (PSF) from former fires with local tree species has strategic value for the recovery of PSF, which has been largely lost and severely degraded by logging, conversion, drainage, and repetitive fires. The PSF recovery will be followed by increased forest cover, CO2 sequestration, O2 production, and peat ecosystem biodiversity. The method of revegetation that guarantees successful planting is still very lacking and has not been widely publicized. The study aimed to analyze the growth of revegetated plants on PSF of former fires. It used a field experiment design with four types of local peat plants, namely ramin (Gonystylus bancanus), punak (Tetramerista glabra), tembesu (Fragraea fragrans), and pulai (Alstonia pneumatophora). The results of the study showed that until the age of 2 years, the survival rate of revegetated plants ranged from 92.56%–94.69%, with growth of 32.53–44.94 cm/year and diameter growth of 0.87–1.21 cm/year. The growth of revegetated plants still accelerated in observations until the age of 3 years. This study provides optimism that PSF revegetation degraded by the fires could be carried out with satisfactory results.

Impacts of agricultural drainage on the quantity and quality of tropical peat soil organic matter in different types of forests

Tropical peatlands serve as huge carbon (C) pools in the global C balance, and degradation due to agricultural use is a major concern. The objective of the present study was to examine the relationship between the C loss rate in agriculturally drained tropical peat soils in relation to groundwater level (GWL) and the chemical structure of the resulting soil organic matter (SOM). Soil mesocosms containing three peat soils collected from three forest types in Malaysia, Mixed peat swamp (MPS), Alan Batu (ABt), and Alan Bunga (ABg) forests, which are classified based on dominant plant species, species diversity, and forest structure, were buried in an oil palm plantation for a period of five years. Soil samples packed in the top layer (0–20 cm depth) and the bottom (60–80 cm depth) layer were then analyzed and the results were compared with the initial values for these soils. Weight loss, total C and N contents, ash content, and pyrophosphate solubility index (PSI; an index of the degree of humification) were measured. Changes in the chemical structure of the SOC were investigated using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy with phase-adjusted spinning side bands and thermally assisted hydrolysis and methylation-gas chromatography/mass spectrometry (THM-GC/MS). The C loss in the MPS forest soil, 2–12%, was smaller than that in the ABt and ABg forest soils, 20–37%, especially in the bottom layer. The higher C loss in the ABt and ABg soils, without significant difference between the top and bottom layers, can be attributed to the greater accumulation of less decomposed plant components as evidenced by the larger yields of lignin-derived phenols and polysaccharide-related compounds in THM-GC/MS analysis. The C composition as estimated by 13C NMR did not vary during incubation of the ABt and ABg soils while the yields of lignin-derived and other phenols as well as polysaccharide-related compounds in THM-GC/MS were decreased, especially in the top layer. These findings suggest that plant components with a low degree of decomposition are susceptible to drainage regardless of their structure. The progression of the oxidative degradation of lignin in the top layer of all soils was also suggested by the increases in PSI and the vanillic acid/vanillin ratio. The % O-alkyl C and % alkyl C may control the rate of C loss positively and negatively, respectively. PSI also appears to be useful for roughly estimating the decomposability of tropical peat SOM in various GWLs.

Streptomyces silvisoli sp. nov., a polyene producer, and Streptomyces tropicalis sp. nov., two novel actinobacterial species from peat swamp forests in Thailand.

Two novel actinobacterial strains, designated RB6PN23T and K1PA1T, were isolated from peat swamp soil samples in Thailand and characterized using a polyphasic taxonomic approach. The strains were filamentous Gram-stain-positive bacteria containing ll-diaminopimelic acid in their whole-cell hydrolysates. Phylogenetic analysis of their 16S rRNA gene sequences revealed that strain RB6PN23T was most closely related to Streptomyces rubrisoli (99.1 % sequence similarity) and Streptomyces ferralitis (98.5%), while strain K1PA1T showed 98.8 and 98.7% sequence similarities to Streptomyces coacervatus and Streptomyces griseoruber, respectively. However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values were below the species-level thresholds (95-96 % ANI and 70 % dDDH). The genomes of strains RB6PN23T and K1PA1T were estimated to be 7.88 Mbp and 7.39 Mbp in size, respectively, with DNA G+C contents of 70.2 and 73.2 mol%. Moreover, strains RB6PN23T and K1PA1T encode 37 and 24 putative biosynthetic gene clusters, respectively, and in silico analysis revealed that these new species have a high potential to produce unique natural products. Genotypic and phenotypic characteristics confirmed that strains RB6PN23T and K1PA1T represented two novel species in the genus Streptomyces. The names proposed for these strains are Streptomyces silvisoli sp. nov. (type strain RB6PN23T=TBRC 17040T=NBRC 116113T) and Streptomyces tropicalis sp. nov. (type strain K1PA1T=TBRC 17041T=NBRC 116114T). Additionally, a giant linear polyene compound, neotetrafibricin A, exhibiting antifungal activity in strain RB6PN23T, was identified through HPLC and quadrupole time-of-flight MS analysis. The crude extract from the culture broth of strain RB6PN23T exhibited strong antifungal activity against Fusarium verticillioides, Fusarium fujikuroi and Bipolaris zeicola. This finding suggests that strain RB6PN23T could be a promising candidate for biological control of fungal diseases.

The Effect of Different Fertilization Frequency on Some Nutrient Content of Palm Plant Grown in Peat Swamp

The lack of suitable land (S1) for oil palm plantations is the reason for the current use of marginal land (S3) in oil palm plantations, both for companies and smallholders. Peat swampland has good potential if the care and fertilization of plants is carried out according to the standards according to the conditions of the land. Peat swampland has high acidity, and land conditions are often flooded. Application of fertilizer in a timely manner and the right dose is one of the keys to the success of oil palm plantations. This study aimed to determine the effect of the frequency of fertilizer application on the nutrient content of oil palm leaves. There were three fertilization treatments, namely 1) 0.6 kg/tree was applied once a month, 2) 1.8 kg/tree was applied once per three months, and 3.6 kg/tree was applied once per six months. Data were analyzed using a completely randomized design. The results showed that the frequency of fertilization significantly affected the nutritional content of oil palm leaves. The average nutrient content of fertilization with a frequency of six months has the lowest nutrition compared to other frequencies. The best frequency of fertilization is 0.6 kg/tree, which is applied every month. Fertilization on peatlands that is carried out regularly and in a balanced dose is more important than the application of high doses of fertilizer with a long frequency of fertilization. This is related to palm oil feeding root distribution, which is limited to a swamp depth of 0-60 cm.

Streptomyces rugosispiralis sp. nov., a Novel Actinobacterium Isolated from Peat Swamp Forest Soil That Produces Ansamycin Derivatives and Nocardamines.

Actinomycetes, especially the genus Streptomyces, are one of the most promising sources of bioactive natural products. In this study, a novel Streptomyces strain, RCU-064T, was isolated from a soil sample collected from a peat swamp forest in Thailand. Strain RCU-064T showed the highest 16S rRNA gene sequence similarity (99.06%) with Streptomyces malaysiensis NBRC 16446T. Based on a polyphasic approach, strain RCU-064T represents a novel species of the genus Streptomyces, for which the name Streptomyces rugosispiralis sp. nov. is proposed. The chemical isolation of the crude ethyl acetate extracts of the strain led to the isolation of six compounds: (1) geldanamycin, (2) 17-O-demethylgeldanamycin, (3) reblastatin, (4) 17-demethoxyreblastatin, (5) nocardamine, and (6) dehydroxynocardamine. These compounds were evaluated for their biological activities. All compounds showed no antimicrobial activity against tested microorganisms used in this study. Compounds (1)-(4) displayed cytotoxic activity against the NCI-H187 cell line, with IC50 values ranging from 0.045-4.250 µg/mL. Cytotoxicity against the MCF-7 cell line was found in compounds (1) and (3) with IC50 values of 3.51 and 1.27 µg/mL, respectively. Compounds (5) and (6) exhibited cytotoxicity only against Vero cells (IC50 of 16.57 µg/mL) and NCI-H187 cells (IC50 of 13.96 µg/mL), respectively. These results indicate that peat swamp forest soil remains a promising reservoir of novel actinomycetes capable of producing bioactive natural products.

The genetic characteristics of intermittency and continuity in peat formation and accumulation processes

The formation and accumulation of peat shows the characteristics of continuity and intermittency. The continuity and intermittency of peat formation and accumulation are actually short-cycle features in the evolution of peat swamp environments. In this study, two basins which were formed during the same period of the Paleogene in China. The coal-forming Huangxian Basin in Shandong Province and the Qiongdongnan Basin were selected for comparative analysis using such methods and techniques as drilling lithology observations and logging comparison data. The Huangxian Basin is a continental lake basin, and the Qiongdongnan Basin is a marginal sea basin in the northern part of the South China Sea. The research results revealed that the Paleogene peat formation and accumulation processes in Qiongdongnan Basin were accompanied by intermittency. As a result, thin coal seams were formed, and the content levels of inorganic substances reached as high as 40%. Those findings indicated that the peat swamp environment of the Qiongdongnan Basin had been unstable and had suffered constant damage. However, the peat formation and accumulation in the Huangxian Basin had a high continuity. As a result, the formed coal seams were relatively thick. The intermittency was manifested as interference caused by changes in the peat accumulation environment, without reaching the level of complete destruction. In addition to the ash yield in the coal, the changes in the sulfur content, ash composition index, and elements in the coal had also reflected the characteristics of sediment and water medium changes during the formation of the coal seams. It was determined that those characteristics had marked the sequential changes of the peat and non-organic matter alternation during the peat accumulation processes, as well as revealing the changes in the peat swamp environmental conditions. This was also one of the manifestations of the continuity and intermittency of the peat accumulation process. It could be ascertained from this study’s experimental results that the intermittency and continuity of the formation and accumulation processes of the peat in the study areas were actually caused by the destruction and reconstruction processes of the peat swamps. Those repetitive processes had formed the observed alternations of peat and non-peat substances, finally resulting in the complexity of the coal seam structures, as well as the overall complexity of the coal compositions in the regions.

Diversity, distribution and conservation status of the world’s smallest fish, Paedocypris progenetica

Paedocypris progenetica, the smallest fish in the world and recorded as Near Threatened by the IUCN Red List due to a large population declined. This condition caused survival threats on the population of Paedocypris. Thus, the objective of this study is to examine the species of Paedocypris in the selected peat swamp area based on their diversity, distribution, and conservation status. A total of 66 individuals were collected from February 2019 to September 2021 from three out of four selected sampling area, comprising of two species namely Paedocypris progenetica (TL: 6.63-12.50 mm) and Paedocypris mircromegethes (TL: 8.89-10.60 mm). The results displayed that P. progenetica was found at two sampling locations and dsitinguished the greater in local distribution (LD) which is 50% followed by P. micromgethes (25%) represented the lowest distribution. Moreover, parameter measurements (in situ) of water quality in the blackwater peat swamp revealed temperatures ranging from 23°C to 25.3°C while pH between 4.0-6.9. The population trend for Paedocypris genus is declining due to continuing loss and degradation of blackwater peat swamp habitat which is considered to be the greatest threat.

GRAIN YIELD STABILITY OF SWAMP RICE LINES ACROSS SWAMPLAND AGROECOSYSTEMS IN BENGKULU PROVINCE OF INDONESIA

Multi-environment experiment undertakings in 2020 recognized the stability and adaptability of promising swamp rice genotypes on five types of swampland agroecosystems. Grain yield data recording occurred on 10 swamp rice favorable lines and two check cultivars, transplanted on swamps consisting of alluvial mud, lowland peaty, lowland peat, middle estuarine tidal, and lower estuarine tidal swamp, then subjected to a combined analysis of variance. The AMMI model employed illuminated the effects of environments on a genotype’s grain yield stability across the surroundings. Among the tested conditions, alluvial mud and lowland peat swamps showed as the most predictable environments for rice grain yield evaluation, with the former also representing a rich surrounding, whereas the latter a poor one, despite their provided weak genotype discrimination. Lowland peaty swamp was also a productive environment and conferred strong genotypic discrimination. Both middle and lower estuarine tidal swamps were less fruitful and had rationally durable genotype discrimination. Rice lines UBPR 1, UBPR 8, UPBR 2, and UBPR 4 indicated more desirable than the check cultivars (Inpara 6 and Inpara 4) for grain yield and stability across the test environments. The lines UBPR 3 and UBPR 10 enunciated desirable adaptive performance at the lowland peaty swamp.

GC-MS and LC-MS/MS Analysis of Secondary Metabolites in the Methanolic Extract of Uncaria callophylla Blume ex Korth. Stems

Uncaria callophylla Blume ex Korth. is a wild plant species belonging to the Rubiaceae family. These plants thrive in the peat swamp forest of Kalimantan, Indonesia. The stems of Uncaria callophylla have been used by the Dayak Ngaju tribe to treat various diseases and to restore stamina while they work in the forest. The present study was conducted to identify the secondary metabolites in the methanolic extract of Uncaria callohylla stems to increase the knowledge about this plant and its potential in medicinal applications and drug discovery. The analysis was conducted using GC-MS and LC-MS/MS. GC-MS analysis was performed with the Agilent Technologies 7890 Gas Chromatography equipped with an Auto Sampler and 5975 Mass Selective Detector. The LC-MS analysis was carried out in the C18 column of the Waters Acquity UPLC system. MS analysis was performed with an electrospray ionization source (ESI) in positive and negative ion modes, and the compounds were identified using a UNIFI data processor with a mass spectrum library of natural active substances from the Waters Traditional Medical Scientific Library database based on UPLC/QTof MSE Data Acquisition. GC-MS analysis revealed the presence of 24 peaks, and nine of them showed quality 90% or higher, namely n-Hexadecanoic acid (16.63%), 1,3,7-Trimethyl-3,7-Dihydro-1H-Purine-2,6-Dione (13.07%), Hexadecanoic Acid, Methyl Ester; 1,2-Benzenedicarboxylic Acid, Diethyl Ester; 9,12-Octadecadienoic Acid, Methyl Ester; Methyl 14-Methylheptadecanoate; (9E,12E)-9,12-Octadecadienoic Acid; Z, E-3,13-Octadecadien-1-o1; and 2,6,10,14,18,22-Tetracosahexaene, 2,6,10,15,19,23-hexanethyl-, (all-E)-. LC-MS/MS analysis revealed the presence of five compounds, namely Arecatannin A1, Sweroside_2, Uncarine A, Epianhydrobelachinal, and Betulonic acid. All the secondary metabolites identified from GC-MS and LC-MS/MS analysis have biological activity, which indicates their medicinal potencies. From the result, it can be concluded that Uncaria callophylla stem methanolic extract contains various bioactive compounds justifies its traditional use, and therefore it can be developed further for new drug discovery.

Developing biomass allometric equations for small trees in mixed-species forests of tropical rainforest ecozone

Allometric equations for the small trees that dominate many forests recovering from disturbance, such as fire, are relatively rare, increasing the uncertainty of aboveground biomass (AGB) estimates in young regrowth forests. In this study we sampled 516 small trees (diameter <5 cm at 1.3 m height) from 105 species within Indonesian mixed forests to develop multispecies biomass allometric models and root to shoot ratio. Small trees were sampled across three ecosystems: peat swamp forests, heath forests and dryland forests. Several combinations of weighted log-linear regression analyses of tree diameter (D) and tree height (H) versus tree biomass were applied to identify the best model for estimating AGB. The allometric models developed in this study used a power function with diameter (D) and diameter and height (D2H) as predictors and ecosystem as an additional predictor in the D model. Seemingly unrelated regression (SUR) was used to generate equations of biomass components incorporating additivity. For the additive biomass equation components, the allocation of biomass for these small trees was stem > leaves > branches. AGB estimates based on allometric equations developed for larger trees, sourced from the literature, overestimated small tree biomass by up to 25% when compared with AGB estimates from equations developed in this study. The allometric models of small trees and the root-to-shoot ratio values obtained in this study will improve biomass estimates for young regrowth forests of Indonesia and the tropical region in general.

Insights for restoration: Reconstructing the drivers of long-term local fire events and vegetation turnover of a tropical peatland in Central Kalimantan

Fire events in tropical peatlands often relate to dry peat conditions associated with climate variability (drought) and anthropogenic-driven ecosystem degradation. However, drought is not the only driver of long-term fire events and peatland ecosystem changes. This study used palaeoecological and geochemical proxies to investigate the long-term drivers of charcoal influx to identify local fires and examine the associated responses to the tropical peatland ecosystem in Central Kalimantan, Indonesia. The results showed local fire events increased after 756 cal. yr BP, and possible drivers of charcoal influx include changes in sea level, increased frequency of El Niño events, increased biomass, and anthropogenically-driven ecosystem degradation. However, the vegetation composition showed changes since ∼2300 cal. yr BP from a mix of peat swamp forest (PSF) and open vegetation (OV) during the late Holocene (∼2300 to 1129 cal. yr BP), to predominantly PSF from 1128 to 375 cal. yr BP, dry lowland mixed with swamp forest (LMS) and open vegetation (OV) from 374 to 135 cal. yr BP, and predominantly OV and freshwater swamp forest (FSF) from 134 to −62 cal. yr BP. The possible drivers of the vegetation turnover were hydrological conditions and the availability of peat nutrients, while the vegetation turnover affected the accumulation and decomposition of recalcitrant organic matter in peat. The thresholds of the peatland ecosystems over longer-term timeframes provided the following restoration insights: 1) PSF species (i.e. Eurya and Ilex) showed high fire tolerance and increased in abundance up to charcoal influx threshold of ∼23 grains mm−2 cm−3 yr−1 while LMS and OV species increased up to a lower threshold of ∼13 grains mm−2 cm−3 yr−1before declining; 2) PSF species expanded during periods of wet conditions and high peat nutrients (i.e. TN - enriched); and 3) Future revegetation in the region can focus on tree taxa such as Euphorbiaceae, Arenga, Ficus, and Trema as they were historically able to thrive in fire events and dry hydrological conditions.

Tropical peat surface oscillations are a function of peat condition at North Selangor peat swamp forest, Malaysia

Tropical peatland condition across southeast Asia is deteriorating as a result of conversion to agriculture and urban zones. Conversion begins by lowering the water table, which leads to peat decomposition, subsidence and increased risk of large-scale forest fires. Associated changes in mechanical peat properties impact the magnitude and timing of changes in peatland surface motion, making them a potential proxy for peatland condition. However, such a relationship is yet to be observed in a tropical peatland setting. This study aimed to establish whether patterns of tropical peatland surface motion were a function of peat condition at North Selangor Peat Swamp Forest in Selangor, Malaysia. Results showed that subsidence was greatest at fire-affected scrubland sites, whilst the lowest mean water table levels were found at smallholder oil palm sites. Peat condition and magnitude of tropical peat surface oscillation were significantly different between peat condition classes, whilst peat condition differed with depth. More degraded tropical peats with high bulk density throughout the peat profile due to high surface loading and low mean water table levels showed greater surface oscillation magnitudes. The dominant peat surface oscillation mechanisms present at all sites were compression and shrinkage from changes in water table level. Mean water table level and subsidence rate were related to surface oscillation magnitude. However further work towards measuring surface and within-water table range bulk densities and surface loading is required to better understand the controls on surface oscillation magnitudes.