Peat Swamp Research Articles

Analysis of water physical, chemical and biological properties in different peat swamp forests converted to rice fields

The Indonesian government plans to turn Central Kalimantan into a national food barn by planting rice in several places, including in shallow peatlands. Tropical peatlands actually have limited potential for agricultural use because the growing medium in some cases is not conducive to root development, waterlogged soils that poison plants. The physical, chemical, and biological properties of water can be used as indicators to determine if a land is suitable for growing crops. The objective of this study is to analyze the physical, chemical, and biological properties of water in different aquatic ecosystems in peat swamp forest. This study was conducted in the Peat Techno Park (PTP) of the College of Palangka Raya, Central Kalimantan. Samples were collected from 9 observation stations with different forms of land use for agricultural activities, namely unplowed rice fields, plowed fields, swamps, connecting ditches, beje, natural peat swamp forests, ponds and irrigation ponds. Data collection was taken over a 6-month period and coincided with the peak of the dry season and the rainy season. Water properties were then analyzed by observing the parameters measured directly at the station, namely pH, temperature, dissolved oxygen (DO) and depth. The results showed that there were 4 (four) sites that had suitable water properties for agricultural uses, namely unplowed fields, plowed fields, swamps and ponds. There are only 2 (two) macrozoobenthos groups on PTP peat bogs, namely Annelida and insects. In addition, the most dominant group in insect belongs to the ordo Diptera, and family Chironomidae with the most common genus Chironomus. Conversion of peat swamp forest to rice fields and fish ponds promotes greater diversity and abundance of macroinvertebrate communities, with the depth significantly affecting them.

IDENTIFIKASI POTENSI EKONOMI KAWASAN GAMBUT DI DESA PETANANG, KECAMATAN KUMPEH, KABUPATEN MUARO JAMBI

The peatland have holds enormous potential, but also very complex problems. The complexity is caused by the fragile characteristics of peatlands and the many interests of peatland. The management of peatland, which are often drained for use as agricultural land and residential areas, results in land subsidence. Dry peat is a good fuel, so excessive drying of land can cause land and forest fires to easily occur. Management of peat areas requires selection of suitable tree species for planting, knowledge of specific silvicultural techniques in peat areas, less fertile (nutrient-poor) peat swamp habitat and high acidity so that plants generally have slow growth. The purpose of this study was to obtain data on regional potential related to peatland management techniques in Petanang Village, Muaro Jambi. As well as getting a community based management model on the potential in the area. The results of the identification of economic potential in the peat areas of Petanang Village are expected to provide viable alternative livelihood options to gradually reduce pressure on peatlands, as well as build community capacity in developing economic activities from the proper use of peatlands.

KEANEKARAGAMAN JENIS DAN KELIMPAHAN ORGANISME SERANGGA DI HUTAN RAWA GAMBUT YANG DIKONVERSI MENJADI SAWAH DI PEAT TECHNO PARK UNIVERSITAS PALANGKA RAYA

This study aims to identify the species diversity and abundance of insects in the peat swamp forest converted into rice fields in the Peat Techno Park, University of Palangka Raya. The sampling method used three types of traps, namely yellow trap, swing nets,and light traps. The Shanon -Weiner equation was used to calculate the diversity index of the collected insects. The insects that were caught consisted of 10 orders and 49 families with a total 0f 2,089 individuals. The most caught insects were the order Ephemeroptera with a total 730 individuals. The abundance index of Ephemeroptera was 35.04%, Formicidae 11.20%, Coenagrionidae 10,39%, and Tetragnathidae 9,38%. The four of this insects are classified as dominant. The H’ index is 2.5037 where the level of insect diversity is moderate, the dominance index is 0.1626 so that dominance is classified as moderate. The evenness index is 0.6276, which means moderate evenness.

Allometric equation for Raphia laurentii De Wild, the commonest palm in the central Congo peatlands.

The world's largest tropical peatland lies in the central Congo Basin. Raphia laurentii De Wild, the most abundant palm in these peatlands, forms dominant to mono-dominant stands across approximately 45% of the peatland area. R. laurentii is a trunkless palm with fronds up to 20 m long. Owing to its morphology, there is currently no allometric equation which can be applied to R. laurentii. Therefore it is currently excluded from aboveground biomass (AGB) estimates for the Congo Basin peatlands. Here we develop allometric equations for R. laurentii, by destructively sampling 90 individuals in a peat swamp forest, in the Republic of the Congo. Prior to destructive sampling, stem base diameter, petiole mean diameter, the sum of petiole diameters, total palm height, and number of palm fronds were measured. After destructive sampling, each individual was separated into stem, sheath, petiole, rachis, and leaflet categories, then dried and weighed. We found that palm fronds represented at least 77% of the total AGB in R. laurentii and that the sum of petiole diameters was the best single predictor variable of AGB. The best overall allometric equation, however, combined the sum of petiole diameters (SDp), total palm height (H), and tissue density (TD): AGB = Exp(-2.691 + 1.425 × ln(SDp) + 0.695 × ln(H) + 0.395 × ln(TD)). We applied one of our allometric equations to data from two nearby 1-hectare forest plots, one dominated by R. laurentii, where R. laurentii accounted for 41% of the total forest AGB (with hardwood tree AGB estimated using the Chave et al. 2014 allometric equation), and one dominated by hardwood species, where R. laurentii accounted for 8% of total AGB. Across the entire region we estimate that R. laurentii stores around 2 million tonnes of carbon aboveground. The inclusion of R. laurentii in AGB estimates, will drastically improve overall AGB, and therefore carbon stock estimates for the Congo Basin peatlands.

Influence of disturbance on transpiration and evaporation in tropical peat swamp forests

Disturbances in tropical peat swamp forests greatly impact water transport into the atmosphere through evapotranspiration (ET). However, transpiration (T) and evaporation (E) are affected by disturbances in different manners. Based on eddy fluxes and meteorological data, we used three methods to estimate T and E separately at three tropical peat swamp forest sites with different degrees of disturbance. Each method utilizes the i) water use efficiency, ii) linear relationship between ET and gross primary production, and iii) conductance of T and E in each. The results showed that the conductance method was the most reasonable for estimating T and E. The other two methods could not be applied because of the large variance in the water use efficiency and lack of a strong relationship between ET and gross primary production, among other reasons. Inter-site comparisons suggested that lowering the groundwater level (GWL) reduced T, but T subsequently recovered. This was likely because the trees acclimated to the dry environment. There was no clear difference in E among the three sites under conditions of lower GWLs. The mean T/ET in the almost undisturbed forest (0.60) was greater than that at the burned site with sparse vegetation (0.21). Overall, El Niño events decreased both T and E during the dry season at all sites. In the almost undisturbed forest, T and E decreased by 1.14 and 0.27 mm day−1, respectively. During El Niño events, precipitation decreased to near zero, fire sizes increased, and the downward photosynthetic photon flux density decreased. The decreases in T and E were mainly due to attenuation of incoming radiation by the fire-induced haze. In addition, significant soil desiccation due to lowered GWL impaired root water uptake, resulting in decreased T. In addition, E was decreased by soil surface drying. However, the direct effect of further atmospheric drying on E and T was small during the dry season. Our results show that both drainage and El Niño events reduced T and E in different manners.

Detecting tropical peatland degradation: Combining remote sensing and organic geochemistry.

Tropical peatlands are important carbon stores that are vulnerable to drainage and conversion to agriculture. Protection and restoration of peatlands are increasingly recognised as key nature based solutions that can be implemented as part of climate change mitigation. Identification of peatland areas that are important for protection and restauration with regards to the state of their carbon stocks, are therefore vital for policy makers. In this paper we combined organic geochemical analysis by Rock-Eval (6) pyrolysis of peat collected from sites with different land management history and optical remote sensing products to assess if remotely sensed data could be used to predict peat conditions and carbon storage. The study used the North Selangor Peat Swamp forest, Malaysia, as the model system. Across the sampling sites the carbon stocks in the below ground peat was ca 12 times higher than the forest (median carbon stock held in ground vegetation 114.70 Mg ha-1 and peat soil 1401.51 Mg ha-1). Peat core sub-samples and litter collected from Fire Affected, Disturbed Forest, and Managed Recovery locations (i.e. disturbed sites) had different decomposition profiles than Central Forest sites. The Rock-Eval pyrolysis of the upper peat profiles showed that surface peat layers at Fire Affected, Disturbed Forest, and Managed Recovery locations had lower immature organic matter index (I-index) values (average I-index range in upper section 0.15 to -0.06) and higher refractory organic matter index (R -index) (average R-index range in upper section 0.51 to 0.65) compared to Central Forest sites indicating enhanced decomposition of the surface peat. In the top 50 cm section of the peat profile, carbon stocks were negatively related to the normalised burns ratio (NBR) (a satellite derived parameter) (Spearman's rho = -0.664, S = 366, p-value = <0.05) while there was a positive relationship between the hydrogen index and the normalised burns ratio profile (Spearman's rho = 0.7, S = 66, p-value = <0.05) suggesting that this remotely sensed product is able to detect degradation of peat in the upper peat profile. We conclude that the NBR can be used to identify degraded peatland areas and to support identification of areas for conversation and restoration.

Examining soil organic carbon in the mountainous peat swamps of the Zoigê Plateau in China's Qinghai‐Tibet Plateau

AbstractMountainous peatlands are one of the most important terrestrial ecosystems for carbon storage and play an important role in the global carbon cycle. An insight into the carbon cycle of peat swamps located in mountainous regions can be obtained by studying the distribution of soil organic carbon (SOC) and its relationships with environmental factors. This study focused on the development conditions of peat swamps in the Gahai wetlands, located on the Zoigê Plateau, China, with four different altitudinal gradients as experimental sample sites. The distribution of SOC and its relationship with environmental factors were analysed through vegetation surveys and a generalized additive model (GAM). The results show that with increasing altitude, soil temperature decreased while the soil pH and bulk density initially decreased then increased. On the contrary, the topographic wetness index (TWI), SOC content, above‐ground biomass and litter count initially increased then decreased. The SOC content of the 0–30 cm soil layer was in the range 226–330 g·kg−1 (coefficient of variation (CV) = 21.4%), and the 30–60 cm layer was 178–257 g·kg−1 (CV = 17.5%) and was significantly correlated (p &lt; .05) with above‐ground biomass and litter count. Meanwhile, the SOC content in the 60–90 cm soil layer was in the range 132–167 g·kg−1 (CV = 9.2%) with a significant correlation (p &lt; .05) with soil temperature, pH, bulk density and topographic moisture index. The study showed that the SOC content exhibited more pronounced spatial patterns with increasing altitude, with the peak value in the shallow soil layer appearing in lower elevation areas compared with the deep soil layer. The level of variation changed from medium to low, reflecting the stable mechanism for maintaining SOC within the heterogeneous peat swamp environment.

Differences in CO2 Emissions on a Bare-Drained Peat Area in Sarawak, Malaysia, Based on Different Measurement Techniques

The drainage and cultivation of peatlands will lead to subsidence and mineralisation of organic matter, increasing carbon (C) loss as more CO2 is emitted. There is little information about carbon emissions from bare peat soil. A study was undertaken to measure the CO2 emissions from a logged-over peat swamp area that was purposely vegetation-free. We aimed to report CO2 emissions from a bare, drained peatland developed for an oil palm plantation. For 12 months, we used eddy covariance (EC), closed chambers, and soil subsidence measurements to derive CO2 emissions from a logged-over peat swamp area. Significant variations in the estimated soil CO2 efflux were observed in the three tested measurement techniques. The average CO2 flux rate measured by the EC technique was 4.94 ± 0.12 µmol CO2 m−2 s−1 (or 68.55 tonnes CO2 ha−1 year−1). Meanwhile, the soil CO2 efflux rate measured by the closed chamber technique was 4.19 ± 0.22 µmol CO2 m−2 s−1 (or 58.14 tonnes CO2 ha−1 year−1). Subsidence amounted to 1.9 cm year−1, corresponding to 36.12 tonnes CO2 ha−1 year−1. The estimation of the C loss was found to be highest by the EC technique, lower by the soil chamber technique, and lowest by the peat subsidence rate technique. The higher CO2 emission rate observed in the EC technique could be attributed to soil microbial respiration and decomposing woody residues in the nearby stacking rows due to the large EC footprint. It could also be affected by CO2 advection from oil palms adjacent to the study site. Despite the large differences in the CO2 emission rates by the different techniques, this study provides valuable information on the soil heterotrophic respiration of deep peat in Sarawak. Carbon emissions from a bare peat area cover only a fraction of the soil CO2 respiration component, i.e., the soil heterotrophic respiration. Further investigations are needed to determine the CO2 emissions by soil microbial activities and plant roots from other peat areas in Sarawak.

Analysis of Land Cover Change Using Sentinel-2 Images at Natural Laboratory of Peat Swamp Forest Area CIMTROP University of Palangka Raya

The Natural Laboratory of Peat Swamp Forest Area known as the Center For International Co-operation in Management of Trofical Peatland (CIMTROP) University of Palangka Raya has been set as specific research area of tropical peat swamps since 1993 and has a 50.000 hectares total area. Natural Laboratory of Peat Swamp Forest Area – CIMTROP University of Palangka Raya is peat and sandy land and as a catchment water area, that is crucial to preserve and protect its ecosystem. This research used remote sensing and GIS technology for land cover monitoring utilize Sentinel-2 images. The purpose of this research was to determine (1) land cover changes in the Natural Laboratory/CIMTROP UPR in 2016 and 2021, (2) The rate of land cover change in the Natural Laboratory/CIMTROP UPR and (3) the causes of land cover change in the Natural Laboratory/CIMTROP UPR. Land cover analysis by interpreting Sentinel-2 images in 2016 and 2021 used Supervised Classification Technique. Based on results of the analysis, there were five land cover classes: forest, shurbs, brush, swamp grass and open land. The accuracy testing process performed uses a confusion matrix method to produce mapping accuracy values for each land cover class. Between 2016 to 2021, the change in forest class decreased from 31.809,40 hectares (67,37%) to 29.888,10 hectares (63,30%). Contrary to the shrub class, there was and increase of 1.762,30 hectares (3,73%) to 2.585,20 hectares (5,47%). The increase in shrub area was due to forest reforestation, degradation and deforestation from the forest and land fires which occurred in previors years.

Biomass and carbon stocks of four vegetation types in the Llanos Orientales of Colombia (Mapiripán, Meta)

Agricultural lands occupy 38% of global land surface and are expected to grow significantly in the next years, increasing the need for more sustainable practices, as well as better informed conservation practices of natural ecosystems. Carbon stocks are important estimates for the assessment of potential emissions caused by deforestation, and therefore widely used in strategies to mitigate climate change in agroforestry systems. Although research on biomass and carbon accumulation in agricultural lands is well documented, comparisons with adjacent natural forest areas are uncommon, mainly in tropical regions. Here, we used forest inventory data and allometric models to estimate biomass and carbon stocks of natural vegetation types (gallery forest-GF, morichal-MOR, and savanna-SAV) and oil palm (Elaeis guineensis) crops in the Orinoquía bioregion, in Eastern Colombia. We found that natural forests (GF and MOR) hold 542.45 Mg ha−1 of aboveground biomass, whereas oil palm plantations store 284.87 Mg ha−1. Morichal vegetation, commonly known as peat swamp forests, accumulated the highest aboveground biomass and carbon per hectare among all vegetation types (natural and agricultural), with an estimate of 402.76 Mg ha−1. Thus, although oil palm crops are great reservoirs of biomass and carbon at the landscape level, it is the combination of natural and agricultural lands which assure highest carbon sequestration in the study area. These results highlight the importance of preserving natural areas in agricultural landscapes for climate mitigation and conservation of biodiversity, which may jointly benefit plantations sustainable development.

Analysis of Environmental, Social and Economic Conditions of the Ecosystem Restoration Area of PT. The Best One Unitimber Kampar Peninsula

Kampar Peninsula ecosystem restoration activity by PT. The Best One Unitimber has the potential to create an innovative and creative conservation and protection of the peat swamp forest ecosystem in the Kampar Peninsula, namely establishing support from the private sector to increase the ability to maintain the peat swamp forest ecosystem, both physically and socially and economically. Given the huge potential of the Kampar Peninsula ecosystem restoration area by PT. The Best One Unit, it is necessary to carry out an in-depth analysis of its environmental, social and economic conditions. The purpose of this study was to analyze the environmental, social and economic conditions of the Kampar Peninsula ecosystem restoration area by PT. The Best One United. The environmental conditions observed consisted of land cover change data, vegetation and fauna data. While socio-economic data were obtained directly by observation (direct observation) and in-depth interviews with the people living around the concession and interacting with the IUPHHK-RE area of PT. The Best One Unit in Pelalawan Regency. The results showed that the Kampar Peninsula ecosystem restoration area by PT. The Best One Unitimber has high natural resources, as evidenced by the changing conditions of land cover, the diverse potential of vegetation and fauna in it. Not only environmental conditions, but socio-economic conditions which are also very closely related to environmental conditions in the Kampar Peninsula ecosystem restoration area by PT. The Best One United.

Dissolved N2O concentrations in oil palm plantation drainage in a peat swamp of Malaysia

Oil palm plantations in Southeast Asia are the largest supplier of palm oil products and have been rapidly expanding in the last three decades even in peat-swamp areas. Oil palm plantations on peat ecosystems have a unique water management system that lowers the water table and, thus, may yield indirect N2O emissions from the peat drainage system. We conducted two seasons of spatial monitoring for the dissolved N2O concentrations in the drainage and adjacent rivers of palm oil plantations on peat swamps in Sarawak, Malaysia, to evaluate the magnitude of indirect N2O emissions from this ecosystem. In both the dry and wet seasons, the mean and median dissolved N2O concentrations exhibited over-saturation in the drainage water, i.e., the oil palm plantation drainage may be a source of N2O to the atmosphere. In the wet season, the spatial distribution of dissolved N2O showed bimodal peaks in both the unsaturated and over-saturated concentrations. The bulk δ15N of dissolved N2O was higher than the source of inorganic N in the oil palm plantation (i.e., N fertilizer and soil organic nitrogen) during both seasons. An isotopocule analysis of the dissolved N2O suggested that denitrification was a major source of N2O, followed by N2O reduction processes that occurred in the drainage water. The δ15N and site preference mapping analysis in dissolved N2O revealed that a significant proportion of the N2O produced in peat and drainage is reduced to N2 before being released into the atmosphere.

Inventory of Non-Timber Species in Ayer HitamUtaraForest Reserve, Johor

Ayer Hitam Utara Forest Reserve (AHUFR) is one of the permanent reserved forests (PRFs) in Johor, which is consisted of lowland and peat swamp ecosystems.In AHUFR, there has been little progress in the study of non-timber species. Non-timber forest products (NTFPs) are forest products other than timber that are obtained from both plants and animals and are vital to all species, including people. Among the objectives of this research project were the creation of a checklist of non-timber species in the AHUFR,the identification of non-timber species in the forest reserve, and the measurement of the diversity of non-timber species in the forest reserve. Survey was conducted in 10m ×5m quadrats, in which three quadrats were established in two different ecosystems, namely site A (lowland forest) and site B (peat swamp). The preliminarystudy documented92individuals from19 families and 33 speciesof non-timber plants.Melastomataceae wasthe most dominant family,whilstClidemia hirta (L.)D.Donwas the most dominant species. Based on the Shannon-Wiener and Margalef indices, lowland forest indicatedhigherdiversity of non-timber species compared to peat swamp forest.

Species Diversity and The Importance of Charismatic Medicinal Plants in Ayer Hitam Utara Forest Reserve, Johor

Medicinal plants in peat swamp have not received much attention in Malaysia in recent years due to land conversion in this peat swamp area. This study aimed to record species diversity of medicinal plants in Ayer Hitam Utara Forest Reserve, to develop an interactive website containing medicinal plants in Ayer Hitam Utara Forest Reserve and to collect feedback on user experience using the website by using an online survey. Data about species diversity was measured by Shannon-Wiener Index by doing random sampling with 10 m x 5 m quadrat. There are 21 species (14 families) of medicinal plants were identified. Clidemia hirta, Spondias dulcis andVitex pinnatawere among the highest number of individuals of each species that could be found. Fever, wound treatment, and stomachache, were the most common illness that uses these medicinal plants. Decoction method was the most typical way to prepare this herbal medicine. Koompassia excelsa is one of the new records of medicinal plants found in this Ayer Hitam Utara Forest Reserve which can lower cardiovascular risk, act as an antioxidant and help in wound healing. An interactive website was developed using StoryMap ArcGIS to document the collection. Based on feedback for the website, most of the respondents agreed that the website has good content and user-friendly. This documentation is crucial to preserve our natural resources for the future generation.

Genetic structure and population history of a peat swamp forest tree species, Shorea albida (Dipterocarpaceae), in Brunei Darussalam.

Southeast Asia supports high biodiversity, in a mosaic of forest types formed by the expansion and contraction of habitats through past climate changes. Among the region's forest types, the geographical distribution of peat swamp forests has fluctuated intensely over the past 120,000 years. Most peat swamp forests in Southeast Asia are found in coastal regions and formed within the last 7,000 years after a decline in sea level. However, some peat swamps were initiated earlier on substrates of slightly higher elevation, and these peat swamps might have been refugia for peat swamp species in the last glacial period and the high sea level period. We assessed genetic diversity, genetic structure and divergence time of current genetic groups for Shorea albida in Brunei, an endemic tree species of Bornean peat swamp forests, using 18 microsatellite markers. Genetic diversity was not lower than has been found in other Shorea species, possibly because of the high density of S. albida in Brunei. Although overall genetic divergence between populations was low, two populations (Ingei and Labi Road 3) were distinct from the other populations. Analysis using DIYABC estimated that three genetic groups (Ingei, Labi Road 3 and others) diverged simultaneously from their ancestral population, whose effective size was very small, about 7,500 years ago, corresponding to a recent sea level peak in the Belait-Baram river basin. In that high sea level period, some higher-elevation lands remained, and peat formation had already started in this region. We propose that the current genetic structure of S. albida in Brunei was formed from small refugial populations that survived the period of higher sea level in these higher-elevation areas. Because of their relatively high genetic diversity, Brunei's S. albida populations should become an important genetic resource for the recovery of genetically healthy populations in other parts of northwest Borneo.

Agroforestry as Rehabilitation Strategy System in Orang Kayo Hitam Peat Swamp Park Forest, Jambi - Indonesia

Tropical peat forest ecosystems are unique and have multiple social, economic, and ecological benefits. Factors such as excessive drainage and frequent fires cause peatland degradation. Rehabilitation of deforested and drained tropical peat swamp forests is globally relevant in the context of deforestation and forest degradation. One management system that can be implemented in these conditions combines crops and forest plants (agroforestry). The challenges of the agroforestry application strategy in forest parks are the status of the land, which is a conservation area, and the characteristics of the surrounding community and field conditions. Based on these conditions, it is necessary to conduct this research to support the Orang Kayo Hitam (OKH) forest park development strategy appropriately. The research was conducted in May – June 2021 and used Force Field Analysis based on the opinions of 231 respondents. Based on the research results, it is known that respondents stated that the highest internal driving force is motivation to improve family’s economic from agroforestry products (score 52) and the external one is availability of endemic plants (score 45). The respondent’s opinion about the highest internal inhibiting factor is related to public knowledge of benefits from endemic plant species (score 39), while for external is related to market networks for Non Timber Forest Products (NTFP) market (score 43).

Odonata (Insecta) Communities in a Lowland Mixed Mosaic Forest in Central Kalimantan, Indonesia

Assessing a taxon’s response to change in environmental variables is fundamental knowledge to understanding trends in species diversity, abundance, and distribution patterns. This is particularly needed on Borneo, where knowledge on Odonata populations in different habitats is poor. To address this gap, we present the first study investigating the relationship between morphology and species distribution of Odonata communities in a heath (kerangas)-dominated mixed-mosaic-lowland forest in southern Borneo. We sampled 250-m line transects in three habitat types: mixed peatcswamp, kerangas, and low-pole peatcswamp, with weekly surveys from December 2019 to February 2020. A total of 309 individuals were detected from 25 species. Anisoptera and Zygoptera diversity was the highest in mixed peatcswamp and lowest in low pole, while abundance was the highest in low pole and lowest in kerangas; with kerangas notably harboring a very small sample size. Odonata community assemblages differed most between mixed peat swamp and low pole. Morphological data were compared between suborders and habitats. Anisoptera showed significantly larger thoraces, hindwings, and hindwing-to-body ratio than Zygoptera. Anisoptera in low pole were significantly smaller in body, thorax, and hindwing compared to both kerangas and mixed peat swamp. Anisoptera showed a strong association with pools and Zygoptera with flowing water. Heterogeneity, habitat characteristics, presence of specialists, body size, and the interaction between species’ morphological traits and habitat characteristics likely explained the trends observed.

Kasimovian floristic change in tropical wetlands and the Middle–Late Pennsylvanian Boundary Event

Abstract A threshold-like vegetational change in tropical wetlands occurred in the early Kasimovian (the US Desmoinesian–Missourian boundary) – Event 3. Two earlier significant changes occurred, first in the mid-Moscovian (Atokan–Desmoinesian; ∼Bolsovian–Asturian) – Event 1, and the second in the late Moscovian (mid-Desmoinesian; mid-Asturian) – Event 2. These changes occurred during a time period of dynamic and complex physical change in Euramerican Pangaea driven by changes in polar ice volume and accompanying changes in sea level, atmospheric circulation, rainfall, and temperature. During the Event 3 change, hyperbolized as ‘the Carboniferous rainforest collapse’, lycopsid dominance of (mostly peat) swamps changed to marattialean tree-fern and medullosan pteridosperm dominance, and biodiversity decreased. Event 3 encompassed one glacial–interglacial cycle and included vegetational turnover in other wetland habitats. For several subsequent glacial–interglacial cycles peatland dominance varied, known from palynology, before stabilizing. These vegetational changes likely reflect climatic events driving unidirectional, non-reversible wetland vegetational changes, during cooler, wetter parts of glacial–interglacial cycles. Discussion is complicated by different placements of crucial stratigraphic boundaries, but under the same names, compromising both clear communication and understanding of the literature. Not the least is the floating base of the Cantabrian Substage, together with the position of the Westphalian–Stephanian Stage boundary.

Streptomyces macrolidinus sp. nov., a novel soil actinobacterium with potential anticancer and antimalarial activity.

A novel actinomycete, strain RY43-2T, belonging to the genus Streptomyces, was isolated from a peat swamp forest soil collected from Rayong Province, Thailand. The strain was characterized by using a polyphasic approach. The cell-wall peptidoglycan contained ll-diaminopimelic. Ribose and glucose were detected in its whole-cell hydrolysates. The strain contained anteiso-C15:0, iso-C14:0 and iso-C16:0 as the predominant fatty acids, and MK-9(H4), MK-9(H6) and MK-9(H8) as the major menaquinones. The phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, three unidentified ninhydrin-positive phospholipids and two unidentified phospholipids. Strain RY43-2T showed the highest 16S rRNA gene similarity to Streptomyces misionensis JCM 4497T (98.9 %) and Streptomyces lichenis LCR6-01T (98.9 %). The draft genome of RY43-2T was 6.7 Mb with 6078 coding sequences with an average G+C content of 70.8 mol%. Genomic analysis revealed that the average nucleotide identity (ANI) values based on blast (ANIb) and MUMmer (ANIm) between strain RY43-2T and S. misionensis JCM 4497T were 80.1 and 86.1%, respectively. The ANIb and ANIm values between strain RY43-2T and S. lichenis LCR6-01T were 77.0 and 85.5%, respectively. The digital DNA-DNA hybridization values were 25.2 and 23.0% in comparison with the draft genomes of S. misionensis JCM 4497T and S. lichenis LCR6-01T, respectively. The results of taxonomic analysis suggested that strain RY43-2T represented a novel species of the genus Streptomyces for which the name Streptomyces macrolidinus sp. nov. is proposed. The type strain is RY43-2T (=TBRC 7286T=NBRC 115640T). Strain RY43-2T exhibited antimicrobial activity against Enterococcus faecium ATCC 51559, Colletotrichum capsici BMGC 106 and Colletotrichum gloeosporioides BMGC 107 with the minimum inhibitory concentration values of 25.0, 12.5, and 6.25 µg ml-1. It also exhibited potent antimalarial activity against Plasmodium falciparum K1 with IC50 of 0.0031 µg ml-1. In addition, it showed cytotoxicity against Vero, KB, MCF-7 and NCI-H187 with IC50 values of 0.0347, 6.15, 3.36 and 0.0352 µg ml-1, respectively.

Lake Tagimaucia Montane Lake as a Potential Late Holocene Environmental Archive in Fiji's Volcanic Highlands

Lake Tagimaucia, a montane volcanic lake on Taveuni Island, is Fiji's only high-elevation lake. This study examined a lacustrine sediment core to explore the lake's potential as a palaeoenvironmental archive through the Late Holocene. Dating reveals no simple age–depth relationship due to sediment age-reversals. However, phases of fire activity are evidenced by two distinct charcoal bands. Catchment burns were probably related to significant ENSO-driven drought, although fire ignition by volcanic eruptions on Taveuni cannot be ruled out. Above the dominant charcoal band, the sediment profile exhibits notable positive shifts in organic matter, bulk density, δ13C, and C:N ratio. These peaks suggest a phase of accelerated catchment erosion, possibly triggered by post-burn instability. We introduce a conceptual model to explain the influence of sedge peat swamps on lake sedimentation processes. Surrounding sedge-dominated peatlands have extensively encroached Lake Tagimaucia. Floating peat mats, gradually accumulating through time, act as a repository of organic material that is stored directly on the lake surface. Episodes of drought and fire release old organics directly into the lake itself, probably contributing to the complex chronological sequence in the Late Holocene stratigraphy.