Tropical Peat Research Articles

Soil nitrous oxide and methane fluxes from a land-use change transition of primary forest to oil palm in an Indonesian peatland

Despite the documented increase in greenhouse gas (GHG) emissions from Southeast Asian peat swamp forest degradation and conversion to oil palm over recent decades, reliable estimates of emissions of nitrous oxide (N2O) and methane (CH4) are lacking. We measured soil fluxes of N2O and CH4 and their environmental controls along a peatland transition from primary forest (PF) to degraded drained forest (DF) to oil palm plantation (OP) over 18 months in Jambi, Sumatra, Indonesia. Sampling was conducted monthly at all sites and more intensively following two fertilization events in the OP. Mean annual emissions of N2O (kg N ha−1 yr−1) were 1.7 ± 0.2 for the PF, 2.3 ± 0.2 for the DF and for the OP 8.1 ± 0.8 without drainage canals (DC) and 7.7 ± 0.7 including DC. High N2O emissions in the OP were driven by peat decomposition, not by N fertilizer addition. Mean CH4 annual fluxes (kg C ha−1 yr−1) were 8.2 ± 1.9 for the PF, 1.9 ± 0.4 for the DF, and 1.6 ± 0.3 for the OP with DC and 1.1 ± 0.2 without. Considering their 20-year global warming potentials (GWP), the combined non-CO2 GHG emission (Mg CO2-equivalent ha−1 yr−1) was 3.3 ± 0.6 for the PF and 1.6 ± 0.2 for the DF. The emission in the OP (3.8 ± 0.3 with or without DC) was similar to the PF because reductions in CH4 emissions offset N2O increases. However, considering 100-year GWP, the combined non-CO2 GHG emission was larger in the OP (3.4 ± 0.3 with DC and 3.5 ± 0.3 without) compared to both the PF and the DF (1.5 ± 0.2 and 1.2 ± 0.1, respectively). The increase in peat N2O emissions associated with the land-use change transition from primary forest to oil palm plantation at our sites provides further evidence of the urgent need to protect tropical peat swamp forests from drainage and conversion.

Characterizing subsidence in used and restored peatland with Sentinel SAR data

Peatland is a fragile ecosystem in the tropical region which is prone to subsidence. Until now, there is still lack of procedure to rapidly assess a tropical peatland subsidence in a large area. Our objective was to compare subsidence in a used and restored zone in a peatland hydrological unit using synthetic aperture radar data from Sentinel-1A products (SAR data) in South Sumatra, Indonesia from the period of 2014–2021. The subsidence rate of used peatland estimated by the D-InSAR procedure were in the range of 28–80 cm year−1 in the early period of its utilization and becoming less for the consecutive year (16–48 cm year−1). Meanwhile, the subsidence rate based on the field surveys was in the range of 4–50 cm year−1 in the early period of peatland utilization. The subsidence rate in the used peatland zone (agriculture and plantations) was higher than that in the restoration zone for all SAR data pairs used in our study. The SAR data is a potential tool for the assessment, monitoring and differentiating subsidence rates among different peatland uses in a large area. This tool will help the Directorate of Peat Ecosystem Degradation Control, Directorate General of Environmental Pollution and Degradation Control, and Ministry of Environment and Forestry to plan for better peatland management and restoration.

First estimates of fine root production in tropical peat swamp and terra firme forests of the central Congo Basin

Tropical peatlands are carbon-dense ecosystems because they accumulate partially-decomposed plant material. A substantial fraction of this organic matter may derive from fine root production (FRP). However, few FRP estimates exist for tropical peatlands, with none from the world’s largest peatland complex in the central Congo Basin. Here we report on FRP using repeat photographs of roots from in situ transparent tubes (minirhizotrons), measured to 1 m depth over three one-month periods (spanning dry to wet seasons), in a palm-dominated peat swamp forest, a hardwood-dominated peat swamp forest, and a terra firme forest. We find FRP of 2.6 ± 0.3 Mg C ha−1 yr−1, 1.9 ± 0.5 Mg C ha−1 yr−1, and 1.7 ± 0.1 Mg C ha−1 yr−1 in the three ecosystem types respectively (mean ± standard error; no significant ecosystem type differences). These estimates fall within the published FRP range worldwide. Furthermore, our hardwood peat swamp estimate is similar to the only other FRP study in tropical peatlands, also hardwood-dominated, from Micronesia. We also found that FRP decreased with depth and was the highest during the dry season. Overall, we show that minirhizotrons can be used as a low-disturbance method to estimate FRP in tropical forests and peatlands.

Genes and genome-resolved metagenomics reveal the microbial functional make up of Amazon peatlands under geochemical gradients.

The Pastaza-Marañón Foreland Basin (PMFB) holds the most extensive tropical peatland area in South America. PMFB peatlands store ~7.07 Gt of organic carbon interacting with multiple microbial heterotrophic, methanogenic, and other aerobic/anaerobic respirations. Little is understood about the contribution of distinct microbial community members inhabiting tropical peatlands. Here, we studied the metagenomes of three geochemically distinct peatlands spanning minerotrophic, mixed, and ombrotrophic conditions. Using gene- and genome-centric approaches, we evaluate the functional potential of the underlying microbial communities. Abundance analyses show significant differences in C, N, P, and S acquisition genes. Furthermore, community interactions mediated by toxin-antitoxin and CRISPR-Cas systems were enriched in oligotrophic soils, suggesting that non-metabolic interactions may exert additional controls in low-nutrient environments. Additionally, we reconstructed 519 metagenome-assembled genomes spanning 28 phyla. Our analyses detail key differences across the geochemical gradient in the predicted microbial populations involved in degradation of organic matter, and the cycling of N and S. Notably, we observed differences in the nitric oxide (NO) reduction strategies between sites with high and low N2 O fluxes and found phyla putatively capable of both NO and sulfate reduction. Our findings detail how gene abundances and microbial populations are influenced by geochemical differences in tropical peatlands.

Prediction of Peatlands Forest Fires in Malaysia Using Machine Learning

The occurrence of fires in tropical peatlands poses significant threats to their ecosystems. An Internet of Things (IoT) system was developed to measure and collect fire risk factors in the Raja Musa Forest Reserve (RMFR) in Selangor, Malaysia, to address this issue. In this paper, neural networks with different layers were employed to predict peatland forests’ Fire Weather Index (FWI). The neural network models used two sets of input parameters, consisting of four and nine fire factors. The predicted FWI values were compared with actual values obtained from the Malaysian meteorological department. The findings revealed that the five-layer neural network outperformed others in both the four-input and nine-input models. Specifically, the nine-input neural network achieved a mean square error (MSE) of 1.116 and a correlation of 0.890, surpassing the performance of the four-input neural network with the MSE of 1.537 and the correlation of 0.852. These results hold significant research and practical implications for precise peatland fire prevention, control, and the formulation of preventive measures.

Macrofungal diversity in small-holder oil palm plantations on tropical peatlands

Abstract. Ekyastuti W, Astiani D, Ekamawanti HA, Jamiat. 2023. Macrofungal diversity in small-holder oil palm plantations on tropical peatlands. Biodiversitas 24: 3454-3461. Mushrooms play an important role in ecosystems and human life. They can be found in various places including in oil palm plantations. The aim of this study was to survey and identify the population of macroscopic mushrooms or macrofungi in small-holder oil palm plantations on tropical peatlands in Kampung Baru Village, Kubu Raya District, West Kalimantan, Indonesia using the field survey method. In the research area, a dam has been constructed to regulate the water level at 30 cm, 40 cm, 50 cm, and 60 cm from the surface. Sampling was carried out in these four conditions. The study revealed the presence of 34 species of macrofungi belonging to the Basidiomycota. A groundwater level ranging from 40-60 cm from the surface was identified as favorable for macrofungal growth. Meanwhile, a groundwater level of 30 cm from the surface was found to be unsuitable for macrofungal growth in the peatlands. The level of macrofungal species diversity in small-holder oil palm plantations on the peatlands was determined to be moderate.

Composition and feeding guilds bird community in tropical peatland of Orang Kayo Hitam Forest Park buffer area, Jambi, Indonesia

Abstract. Pangestu PG, Iswandaru D, Wulandari C, Novriyanti, Prasetia H. 2023. Composition and feeding guilds bird community in tropical peatland of Orang Kayo Hitam Forest Park buffer area, Jambi, Indonesia. Intl J Bonorowo Wetlands 13: 57-65. Tropical peat ecosystems are vulnerable to fire damage and conversion, including in the Orang Kayo Hitam (OKH) Forest Park buffer villages, Jambi Province, Indonesia. The peat ecosystem is a habitat for various birds. In the ecosystem, birds act as seed dispersers, pest controllers, and pollinators, so their presence can be used as bioindicators of environmental quality. This study aims to analyze the composition and feed guilds of the bird community. The line transect method is used to explore the path in bird watching. The data were then analyzed using descriptively and qualitatively. In total, 29 species from 18 families comprised five species of waterbirds and 25 species of land birds. The families with the highest number of species were Alcedinidae, with a percentage of 13.79% each (4 species). At the same time, the lowest were Apodidae, Bucerotidae, Hirundinidae, Laniidae, Meropidae, Psittacidae, Rallidae, Cisticolidae, Turnicidae, Ploceidae, and Passeridae, with only one species (3.45%) identified per family. Based on the feed guild, there were nine types of guilds, with the highest rate being granivore (24,14%), while the lowest was insectivore on the forest floor (3.45%). The presence of bird species based on the feed guild indicates that shrubs or weeds dominate the land cover of the buffer village around the OKH Forest Park.

Wildfire smoke linked to vocal changes in wild Bornean orangutans

Tropical peatlands are the sites of Earth's largest fire events, with outsized contributions to greenhouse gases, toxic smoke, and haze rich with particulate matter. The human health risks from wildfire smoke are well known, but its effects on wildlife inhabiting these ecosystems are poorly understood. In 2015, peatland fires on Borneo created a thick haze of smoke that blanketed the region. We studied its effects on the long call vocalizations of four adult male Bornean orangutans (Pongo pygmaeus wurmbii) in a peat swamp forest. During the period of heavy smoke, orangutans called less often and showed reduced vocal quality-lower pitch, increased harshness and perturbations, and more nonlinear phenomena-similar to changes in human smokers. Most of these changes persisted for two months after the smoke had cleared and likely signal changes in health. Our work contributes valuable information to support non-invasive acoustic monitoring of this Critically Endangered primate.

Mapping Water Levels across a Region of the Cuvette Centrale Peatland Complex

Inundation dynamics are the primary control on greenhouse gas emissions from peatlands. Situated in the central Congo Basin, the Cuvette Centrale is the largest tropical peatland complex. However, our knowledge of the spatial and temporal variations in its water levels is limited. By addressing this gap, we can quantify the relationship between the Cuvette Centrale’s water levels and greenhouse gas emissions, and further provide a baseline from which deviations caused by climate or land-use change can be observed, and their impacts understood. We present here a novel approach that combines satellite-derived rainfall, evapotranspiration and L-band Synthetic Aperture Radar (SAR) data to estimate spatial and temporal changes in water level across a sub-region of the Cuvette Centrale. Our key outputs are a map showing the spatial distribution of rainfed and flood-prone locations and a daily, 100 m resolution map of peatland water levels. This map is validated using satellite altimetry data and in situ water table data from water loggers. We determine that 50% of peatlands within our study area are largely rainfed, and a further 22.5% are somewhat rainfed, receiving hydrological input mostly from rainfall (directly and via surface/sub-surface inputs in sloped areas). The remaining 27.5% of peatlands are mainly situated in riverine floodplain areas to the east of the Congo River and between the Ubangui and Congo rivers. The mean amplitude of the water level across our study area and over a 20-month period is 22.8 ± 10.1 cm to 1 standard deviation. Maximum temporal variations in water levels occur in the riverine floodplain areas and in the inter-fluvial region between the Ubangui and Congo rivers. Our results show that spatial and temporal changes in water levels can be successfully mapped over tropical peatlands using the pattern of net water input (rainfall minus evapotranspiration, not accounting for run-off) and L-band SAR data.

A process-based model for quantifying the effects of canal blocking on water table and CO2emissions in tropical peatlands

Abstract. Drainage in tropical peatlands increases CO2 emissions, the rate of subsidence, and the risk of forest fires. To a certain extent, these effects can be mitigated by raising the water table depth (WTD) using canal or ditch blocks. The performance of canal blocks in raising WTD is, however, poorly understood because the WTD monitoring data are limited and spatially concentrated around canals and canal blocks. This raises the following question: how effective are canal blocks in raising the WTD over large areas? In this work, we composed a process-based hydrological model to assess the peatland restoration performance of 168 canal blocks in a 22 000 ha peatland area in Sumatra, Indonesia. We simulated daily WTD over 1 year using an existing canal block setup and compared it to the situation without blocks. The study was performed across two contrasting weather scenarios representing dry (1997) and wet (2013) years. Our simulations revealed that, while canal blocks had a net positive impact on WTD rise, they lowered WTD in some areas, and the extent of their effect over 1 year was limited to a distance of about 600 m around the canals. We also show that canal blocks are most effective in peatlands with high hydraulic conductivity. Averaging over all modeled scenarios, blocks raised the annual mean WTD by only 1.5 cm. This value was similar in the dry (1.44 cm) and wet (1.57 cm) years, and there was a 2.13 fold difference between the scenarios with large and small hydraulic conductivities (2.05 cm versus 0.96 cm). Using a linear relationship between WTD and CO2 emissions, we estimated that, averaging over peat hydraulic properties, canal blocks prevented the emission of 1.07 Mg ha−1 CO2 in the dry year and 1.17 Mg ha−1 CO2 in the wet year. We believe that the modeling tools developed in this work could be adopted by local stakeholders aiming at a more effective and evidence-based approach to canal-block-based peatland restoration.

Genome-resolved carbon processing potential of tropical peat microbiomes from an oil palm plantation

Tropical peatlands in South-East Asia are some of the most carbon-dense ecosystems in the world. Extensive repurposing of such peatlands for forestry and agriculture has resulted in substantial microbially-driven carbon emissions. However, we lack an understanding of the microorganisms and their metabolic pathways involved in carbon turnover. Here, we address this gap by reconstructing 764 sub-species-level genomes from peat microbiomes sampled from an oil palm plantation located on a peatland in Indonesia. The 764 genomes cluster into 333 microbial species (245 bacterial and 88 archaeal), of which, 47 are near-complete (completeness ≥90%, redundancy ≤5%, number of unique tRNAs ≥18) and 170 are substantially complete (completeness ≥70%, redundancy ≤10%). The capacity to respire amino acids, fatty acids, and polysaccharides was widespread in both bacterial and archaeal genomes. In contrast, the ability to sequester carbon was detected only in a few bacterial genomes. We expect our collection of reference genomes to help fill some of the existing knowledge gaps about microbial diversity and carbon metabolism in tropical peatlands.

Uncertainty in the Management of Tropical Peatlands for Oil Palm Plantations due to Drainage Practices

The conversion of tropical peatlands to oil palm plantations has affected the long-term storage stability of water and carbon. The conversion requires a drainage system that results in land subsidence and, in turn, reduces the carrying capacity of water storage and carbon stocks. This study aims to analyze subsidence from long-term observations (2004-2020) to obtain an appropriate water management measure for three scenarios of drainage depths at the oil palm plantations in Jambi Province. It is found that the reduction is quite variable depending on the level of drainage depths. The subsidence was 55 cm, 49 cm, and 34.7 cm for deep, moderate, and shallow drainage conditions. The groundwater level was deeper than 100 cm, which is far below the threshold of 40 cm, as stated in the government regulations. However, the regulations are still debated since subsidence must occur in drained peatlands regardless of the water level. The observed large subsidence implies that better water management in a new site is crucial and necessary to reduce the impact of peatlands degradation relative to current conditions and that high rates of land subsidence should be accepted as an inevitable change from the conversion of tropical peatlands to oil palm plantations.

Assessment of differences in peat physico-chemical properties, surface subsidence and GHG emissions between the major land-uses of Selangor peatlands

Tropical peatlands are globally important ecosystems for carbon storage, biodiversity conservation, water storage and regulation, and several other valuable ecosystem services. Despite their importance, peatlands in Southeast Asia have been heavily degraded by anthropogenic disturbances such as drainage, agricultural conversion, and fire. In this spatially extensive study we characterised peat properties, nutrient concentrations, surface subsidence rates and greenhouse gas emissions from peatlands of Selangor, Peninsular Malaysia under different land-uses: Secondary Forest, Fire affected and replanted forest (Burnt), Pineapple Plantation, Mixed Agriculture, Smallholder Oil Palm Monoculture, and Industrial Oil Palm Monoculture. All the measured peat physico-chemical properties and nutrient concentrations were significantly different between land-uses. Principal component analyses indicated that peat under the Mixed Agriculture and Burnt land-uses showed the greatest degree of modification relative to peat under the Secondary Forest land-use. Burnt land-use also showed a significantly higher subsidence rate (4.4 ± 1.2 cm yr−1) than all the other land-uses (ranging between 1.8 ± 0.47 and 3.2 ± 0.5 cm yr−1). Water table was significantly higher at the Burnt land-use (-26 cm) than all other land-uses, likely reflecting fire-prevention drain blocking measures as well as lower land surface heights post fire. Smallholder oil palm land-use had the lowest water table (−68 cm), while water table level in all other land-uses did not significantly differ from that of Secondary Forest (−43 cm). Peat surface level changes were positively related to increase in drainage, showing the importance of maintaining a high water table level in reducing peat degradation and carbon loss from peatlands. Total CO2 (mean range 492 to 1019 mg m−2 hr-1) and CH4 emissions (mean range 637 to 1422 µg m−2 hr-1) did not significantly differ between land-uses or seasons. CH4 emissions were negligible under all land-uses and higher emissions were correlated with a higher water table level. Taken together, the results show that anthropogenic land-use change impacts the physico-chemical properties and nutrient content of peat, and that increased drainage alongside changes in other peat properties leads to increased peat subsidence and carbon loss.

Time bomb or gold mine? Policy, sustainability and media representations of tropical peatlands in Malaysia

Tropical peatlands represent an acute site of contested development on the front line of global climate change and action. Media analysis reveals how and why these ecosystems are understood in the context of local and national discourse, and the implications of these representations for peatland policy-making. In this study, we provide an instructive account of media representations of tropical peatlands in Malaysia – a country home to 6% of the world’s tropical peat by area and 12% by magnitude of the peat carbon pool. Set against an examination of the policy context for peatland media representations, we analyse how this critical ecosystem is framed in Malaysian media, and explore how these representations cast light on current sustainability-related policy and management debates. Drawing on media framing methodology, we analysed three English language newspapers (News Straits Times, The Star and Borneo Post) and one popular news website (Malaysiakini) from 1995 to 2018. From a sample of 1359 news articles, we found four dominant frames: development, conservation/protection, sustainable development and fire/haze. Within these frames, a number of key themes emerged including ecological benefits, community livelihoods, threats to peatland, integrated management approaches, and the value of peatland research. Our findings also reveal a polarising representation present across the study period – peatlands portrayed as a ‘time-bomb’ of ecological destruction and as a ‘gold mine’ in terms of their opportunities for development. We argue that contrasting interpretations of the sustainable development of peatlands may serve to obfuscate rather than facilitate current peatland policy discourses. Finally, we conclude that the fate of Malaysian peatlands hinges on recognising the localised challenges faced by peatland communities. We urge policy makers to consider food systems transformation approaches to move beyond a vision that relies entirely on drainage-based development.

Absorbance spectral slopes for monitoring tropical peat water dissolved organic matter fractions during microbubble pre‐ozonation

AbstractThe dissolved organic matter (DOM) protonated fractions of various hydrophobicities were correlated with the tropical peat waters' UV–Vis spectral slopes. This study was conducted to determine how microbubble pre‐ozonation affects UV–Vis spectral slopes in tropical peat water treatment processes This study was conducted to determine how microbubble pre‐ozonation affects UV–Vis spectral slopes in tropical peat water treatment processes. Microbubble pre‐ozonation was carried out at pH 7 followed by alum coagulation and activated carbon (AC) adsorption. The results showed that the log‐transformed UV–Vis absorption of processed peat water had four spectral slopes in the range of 220 to 420 nm. The degradation of the transphilic (TPH) DOM fraction had a strong negative correlation with the S220‐240 and S241‐272 values (R2 > 0.85). Similarly, the hydrophilic‐charged (HPIC) and hydrophilic‐neutral (HPIN) fractions had a strong negative correlation with the S220‐240 and S241‐272 values (R2 > 0.84 and R2 > 0.70). Meanwhile, the S273‐350 S>350 values had a low and negligible correlation with all analyzed DOM fractions (R2 < 0.30). The lower wavelength spectral slopes ratio (S220‐240/S241‐272) was moderately correlated with the DOM fraction, while the correlation with higher wavelength values was negligible. Based on these findings, the UV–Vis spectral slopes ratio at lower wavelengths appears to be useful information for developing a surrogate parameter of DOM fractions in peat water treatment processes.

CH4 and N2 O emissions from smallholder agricultural systems on tropical peatlands in Southeast Asia.

There are limited data for greenhouse gas (GHG) emissions from smallholder agricultural systems in tropical peatlands, with data for non-CO2 emissions from human-influenced tropical peatlands particularly scarce. The aim of this study was to quantify soil CH4 and N2 O fluxes from smallholder agricultural systems on tropical peatlands in Southeast Asia and assess their environmental controls. The study was carried out in four regions in Malaysia and Indonesia. CH4 and N2 O fluxes and environmental parameters were measured in cropland, oil palm plantation, tree plantation and forest. Annual CH4 emissions (in kg CH4 ha-1 year-1 ) were: 70.7 ± 29.5, 2.1 ± 1.2, 2.1 ± 0.6 and 6.2 ± 1.9 at the forest, tree plantation, oil palm and cropland land-use classes, respectively. Annual N2 O emissions (in kg N2 O ha-1 year-1 ) were: 6.5 ± 2.8, 3.2 ± 1.2, 21.9 ± 11.4 and 33.6 ± 7.3 in the same order as above, respectively. Annual CH4 emissions were strongly determined by water table depth (WTD) and increased exponentially when annual WTD was above -25 cm. In contrast, annual N2 O emissions were strongly correlated with mean total dissolved nitrogen (TDN) in soil water, following a sigmoidal relationship, up to an apparent threshold of 10 mg N L-1 beyond which TDN seemingly ceased to be limiting for N2 O production. The new emissions data for CH4 and N2 O presented here should help to develop more robust country level 'emission factors' for the quantification of national GHG inventory reporting. The impact of TDN on N2 O emissions suggests that soil nutrient status strongly impacts emissions, and therefore, policies which reduce N-fertilisation inputs might contribute to emissions mitigation from agricultural peat landscapes. However, the most important policy intervention for reducing emissions is one that reduces the conversion of peat swamp forest to agriculture on peatlands in the first place.

Spatial and temporal patterns of methane emissions from mountain peatlands in the northern Andes across a disturbance gradient

Methane emitted by wetlands accounts for nearly 30% of the global methane emissions and is expected to double by 2,100. Methane fluxes from peatlands are related to m soil temperature, water table, and vegetation. Disturbances, mostly drainage, are considered to have a more limited impact on CH4 fluxes from peatlands. Here, we studied the temporal and spatial patterns of methane emissions from four peatlands across and elevation and disturbance gradient in the northern Andes. Our research seeks to understand the effects of disturbance legacies and soil temperature, flooding patterns, and vegetation on methane emissions in Andean peatlands. Our results indicated a strong control of CH4 emissions by soil temperature with a stronger effect at intermediate elevations. The removal of peat forming vegetation from the surface had the higher effect on CH4 emissions, increasing methane fluxes by an order of magnitude. Methane fluxes from conserved cushion vascular plants were low, but nearby hollows had relatively high emissions. Our research provides evidence of high methane emissions from degraded peatlands in the tropical Andes. However, the role of climate change and disturbance legacies on methane emissions from tropical Andean peatlands remains unknown affecting our ability to predict future emission patterns and our ability to incorporate climate mitigation strategies.

Methanogenic archaea community in relation to methane production in oil palm planted on tropical peatland

Understanding the microbial processes that regulate methane emissions in the tropical peatlands can facilitate their future management. However, the microbiota of Malaysian tropical peatlands specifically the methanogens (methane producers) and methanotrophs (methane consumers) remains poorly characterised. This study aimed to determine the key players in methane production and to assess their spatial distribution in different oil palm management zones (i.e., avenue, cover crop, frond pile, and weeded circle) across depths namely 0–15 cm, 15–30 cm, and 30–45 cm in an 11-year-old oil palm plantation that was established on the peatland of Sarawak. Based on high-throughput Illumina sequencing targeting the 16S hypervariable V4–V5 regions of archaeal rRNA amplicon, the diversity indices (Shannon and Simpson) and richness (Chao1 and ACE) were highest in the upper peat layers across management zones, and the microbial diversity and composition are influenced by depths. Taxonomic profiling revealed that the domain Archaea was dominated by Halobacteriota, Thermoproteota, and Thermoplasmatota that increased with depth across management zones. Meanwhile, the order Methanomassiliicoccales was predominant, with Methanomethylophilus sp002495325 as the most abundant species in the upper peat layers in the frond pile zone due to a high decomposition rate of organic matter. The key players of methanogenic archaea belonging to Methanomassiliicoccales, Methanosarcinales, Methanomicrobiales, and Methanobacteriales were detected in oil palm peat soils, providing indirect genetic evidence for the biogeochemical processes associated with methane production in the oil palm plantation. Having established the feasibility of utilising high-throughput sequencing to characterise the archaeome of Malaysian oil palm plantation, future works in correlating the relative abundance of methanogens and methanotrophs with methane production will be instrumental in providing valuable insights for prediction and mitigation of methane emissions in oil palm cultivation on peat.

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.

Partition of Carbon Losses on CO2 Emission and Peat Subsidence in an Open-Drained Tropical Peatlands: A Consideration for Agroforestry Practices

Open-abandoned peatland commonly were not hydrologically well-managed in West Kalimantan causing continuous degradation of peat ecosystems, due to peat drying. This condition damage the carbon balance and function of tropical peatlands, result in significant greenhouse gas emissions. Tropical peat in the Kubu Raya District of West Kalimantan, which has a relatively large area of peat, has been degraded due to uncontrolled drainage and land fires caused by lack of management post the landcover changes. This study aims to clarify the partition of carbon loss in open peatlands due to the heterotrophic respiration (CO2 emission) process, which is part of the declining peat layer due to subsidence. The CO2 emission and subsidence assessments were accomplished for two years. The results show an increase in peat CO2 emissions to ~300% when groundwater level (GWL) lowered from ~0-5cm to >80cm. The trend is similar to the subsidence process due to changes in GWL. Carbon dioxide emissions range from 55,8 to 58,9% of peat layer losses, dependent on GWL. In undrained peatland, the CO2 emission was the lowest among others yet mainly loss in CO2 emission. The results of this study can provide considerations on small-holder agroforestry or other agricultural practices which wide-spread developed recently in this area. It is explaining the part of the subsidence that impacts the sources of CO2 emissions and practices to manage GWL to mitigate CO2 emission from open-drained peatlands.