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Peatlands in OKI Regency are highly flammable during extreme dry seasons and experience flooding during extreme rainy seasons. Research related to peatlands is important to be carried out in disaster mitigation efforts on peatlands. In this study, we aimed to examine the impact of climate anomalies occurring between 2019 and 2022 on the Rainfall (RF), Groundwater Level (GWL), and Soil Moisture (SM) in this region. We analyzed data collected at the CJ2 station to understand the dynamics of these parameters throughout the occurrence of the ENSO and IOD phenomena in 2019–2022. The findings of this study indicate a positive correlation between RF and GWL. Specifically, a higher amount of RF resulted in a stronger correlation. Moreover, the rate of the GWL decline was 0.24 mm/d, while the rate of the SM decline was 0.06%/day. Furthermore, the soil moisture in CJ2 OKI must be maintained at a minimum of 20% to prevent fires. In addition, an empirical equation was derived to express the relationship between GWL (m) and SM (%) as SM = 49,044 GWL + 59,142. The findings of this study provide valuable in-sights for all stakeholders involved in efforts to mitigate the impact of natural disasters on peatlands. [ABSTRACT FROM AUTHOR]

While a few tropical peatlands remain in pristine condition, many of them, especially in Southeast Asia, have been degraded and have been subjected to drainage, deforestation or fires. At the largest peat deposit in Brunei Darussalam, the Badas peat dome, anthropogenic disturbances arising from urbanisation and land use changes in the past decades have resulted in deforestation, peat subsidence and groundwater drainage. We investigated these disturbances along two transects established at the Badas peat dome via a combination of approaches: (1) topographic survey, (2) seismic refraction survey, (3) rain gauge monitoring and (4) groundwater monitoring via piezometers and slug testing. In addition, groundwater samples were taken from piezometers for water chemistry analysis. This research demonstrated how excavations have led to the creation of lagoons, resulting in changes to the structure of the peat dome, leading to groundwater drainage. The drainage has caused 15 cm to 45 cm of peat thickness to dry out. In addition, with the removal of the peat layer and the establishment of artificial lagoons, surface water can now directly infiltrate into the sand layer, causing the second transect to have a lower groundwater level. Finally, groundwater drainage, evapotranspiration from the lagoons, and possibly tidal influence as the peatland is draining towards the South China Sea less than 3 km away, caused changes to the groundwater chemistry, causing increased salinity and Dissolved Organic Carbon (DOC), showing that peat degradation has been occurring in both transects.

Grey sedge (Lepironia articulata Retz. Domin) is a plant endemic to tropical peatlands and is widely used as a handicraft and biodegradable product that brings income to local farmers. However, its habitat has been decreasing due to peatland degradation, which has forced local farmers to harvest L. articulata repeatedly in the same habitat. To examine the effects of repeated shoot cutting at different time intervals on L. articulata growth and biomass yield, a mesocosm experiment was conducted from June 2019 to March 2020 in a tropical peatland in Perigi village, Ogan Ilir District, South Sumatra, Indonesia, using a randomized block design with four treatments and three replicates. The treatments were as follows: P1 (cutting every 1 month), P2 (cutting every 2 months), P3 (cutting every 3 months), and P4 (cutting at 6-months). The results showed that P1 significantly reduced monthly shoot height, shoot diameter, shoot number, dry biomass, cumulative shoot number, and cumulative dry biomass. In contrast, considering L. articulata's regenerative growth, the growth and cumulative biomass yield of P3 (1453.5 ± 518.4 g m−2) were as good as those of P4. These results indicate that the harvesting interval should be longer than 3 months for the sustainable use of L. articulata in tropical peatlands without damaging its regenerative ability. [ABSTRACT FROM AUTHOR]

Reliable biodiversity baseline data are needed to support the monitoring of faunal responses to human activities and the development of species conservation strategies in the Leyte Sab-a Basin Peatland (LSBP). We conducted a ten-day Rapid Biodiversity Assessment (RBA), the first survey of amphibians, reptiles, and mammals to focus specifically on the LSBP. We recorded 24 herpetofauna (17 reptile, seven amphibian) and eight mammal species. Four reptiles were Vulnerable and Near Threatened species according to the IUCN Red List, and another five were classified as Other Threatened species at national level. A possible new location record for Leyte Island was the Indo-Pacific tree gecko (Hemiphyllodactylus typus Bleeker 1860). Four of the mammal species we recorded also belonged to the IUCN and national Vulnerable, Endangered or Near Threatened categories. Our results showed that the LSBP is an important area for biodiversity conservation, hosting endemic and globally threatened species. Creating a Local Conservation Area (LCA) within or near the LSBP could substantially support the survival of threatened species that depend mostly on the peatland as their habitat. Nonetheless, further scientific studies are needed to better understand the value of the LSBP and how to conserve its natural resources.

While a few tropical peatlands remain in pristine condition, many of them, especially in Southeast Asia, have been degraded and have been subjected to drainage, deforestation or fires. At the largest peat deposit in Brunei Darussalam, the Badas peat dome, anthropogenic disturbances arising from urbanisation and land use changes in the past decades have resulted in deforestation, peat subsidence and groundwater drainage. We investigated these disturbances along two transects established at the Badas peat dome via a combination of approaches: (1) topographic survey, (2) seismic refraction survey, (3) rain gauge monitoring and (4) groundwater monitoring via piezometers and slug testing. In addition, groundwater samples were taken from piezometers for water chemistry analysis. This research demonstrated how excavations have led to the creation of lagoons, resulting in changes to the structure of the peat dome, leading to groundwater drainage. The drainage has caused 15 cm to 45 cm of peat thickness to dry out. In addition, with the removal of the peat layer and the establishment of artificial lagoons, surface water can now directly infiltrate into the sand layer, causing the second transect to have a lower groundwater level. Finally, groundwater drainage, evapotranspiration from the lagoons, and possibly tidal influence as the peatland is draining towards the South China Sea less than 3 km away, caused changes to the groundwater chemistry, causing increased salinity and Dissolved Organic Carbon (DOC), showing that peat degradation has been occurring in both transects. [ABSTRACT FROM AUTHOR]

Reliable biodiversity baseline data are needed to support the monitoring of faunal responses to human activities and the development of species conservation strategies in the Leyte Sab-a Basin Peatland (LSBP). We conducted a ten-day Rapid Biodiversity Assessment (RBA), the first survey of amphibians, reptiles, and mammals to focus specifically on the LSBP. We recorded 24 herpetofauna (17 reptile, seven amphibian) and eight mammal species. Four reptiles were Vulnerable and Near Threatened species according to the IUCN Red List, and another five were classified as Other Threatened species at national level. A possible new location record for Leyte Island was the Indo-Pacific tree gecko (Hemiphyllodactylus typus Bleeker 1860). Four of the mammal species we recorded also belonged to the IUCN and national Vulnerable, Endangered or Near Threatened categories. Our results showed that the LSBP is an important area for biodiversity conservation, hosting endemic and globally threatened species. Creating a Local Conservation Area (LCA) within or near the LSBP could substantially support the survival of threatened species that depend mostly on the peatland as their habitat. Nonetheless, further scientific studies are needed to better understand the value of the LSBP and how to conserve its natural resources. [ABSTRACT FROM AUTHOR]

Tropical peatlands store copious amounts of carbon (C) and play a critical role in the global C cycle. However, this C store is vulnerable to natural and anthropogenic disturbances, leading these ecosystems to become weaker C sinks or even net C sources. Variabilities in water table (WT) greatly influence the magnitude of greenhouse gas flux in these biomes. Despite its importance in C cycling, observations of the spatiotemporal dynamics of tropical peatland WT are limited in spatial extent and length. Here, we use in situ WT measurements from tropical peatlands in Indonesia, Malaysia, and Peru to evaluate the satellite‐based Optical Trapezoid Model (OPTRAM). The model uses the pixel distribution in the shortwave infrared transformed reflectance and normalized difference vegetation index (NDVI) space to calculate indices that are then compared against in situ WT data. 30‐m resolution Landsat 7 and Landsat 8 images were utilized for model parameterization. We found OPTRAM to best capture tropical peatland WT dynamics in minimally forested and non‐forested areas (low to intermediate NDVI) (0.7 < R < 1) using the "best pixel" approach (the pixel with the highest Pearson‐R correlation value). In areas with relatively higher NDVI, OPTRAM index did not correlate with WT (average R of −0.04 to 0.24), likely due to trees being less sensitive to WT fluctuations. OPTRAM shows potential for reliably estimating tropical peatland WT without the need for direct measurements, which is challenging due to site remoteness and harsh conditions. Plain Language Summary: Tropical peatlands store copious amounts of carbon in their soil and biomass. The position of the water table (WT) relative to the soil surface plays a large role in how much greenhouse gases (GHGs) (i.e., carbon dioxide, methane, and nitrous oxide) is emitted or taken up and may also give insight into areas most vulnerable to fire. Therefore, estimating tropical peatland WT fluctuations over space and time is essential for understanding the global carbon and GHG budgets. Due to harsh environmental conditions and site remoteness, direct measurements of tropical peatland WT are limited in spatial extent and length. As a result, other methods must be developed to estimate the spatiotemporal variability of this parameter. Through manipulation of satellite surface reflectance, we demonstrate the feasibility of estimating fluctuations in tropical peatland WT from space. This method is tested on sites spanning Peru, Indonesia, and Malaysia. We find that WT fluctuations are accurately quantified over areas that are minimally forested or non‐forested. Our findings provide a pathway to map tropical peatland WT from space leading to improved understanding of WT‐dependent processes such as GHG emissions and fire risk, both of which contribute greatly to global climate change. Key Points: OPTRAM is capable of accurately capturing the temporal variability of tropical peatland water tableOPTRAM performs optimally over minimally forested and non‐forested areas [ABSTRACT FROM AUTHOR]

In this article we propose and apply a methodology for collaboratively creating and reaching agreement over a shared vision for peatland restoration. The purpose is to identify a shared understanding of the various parts of a just, inclusive and sustainable restored peatland as well as productive tensions between and across divergent disciplinary domains focused on peatland restoration. We involved an interdisciplinary group of researchers and practitioners working on various aspects of tropical peatland restoration and management in Indonesia, where there is a recognised need for clearer goals and/or definitions of restoration outcomes to focus manifold stakeholder efforts. To increase opportunities for participation and interaction between participants, our methodology built on and adapted a well-established Delphi survey method by combining it with focus group discussions. This allowed multiple points of view to be considered and new knowledge to emerge. The vision produced through this process bridges across different disciplinary tensions to fulfil ecological and social outcomes. While the vision is specific to the complex political economic and socio-ecological context of Indonesia’s tropical peatland, the phased methodology for collaborative visioning can be adapted for application to other social ecological challenges, or to guide planning and practice by other stakeholder groups aiming to articulate a desired future state.

Abstract There is a pressing need to tackle carbon emissions from oil palm plantations on tropical peatland, which has garnered significant discussion and concern in recent years. In response, compaction techniques were introduced in Malaysia with the aim of mitigating CO2 emissions by improving moisture levels and reducing soil aeration. This research investigates the impact of mechanical compaction on two distinct ecosystems: a peat swamp forest (PSF) and an oil palm plantation (OPP), characterized by their unique physicochemical properties Using a specially designed compaction apparatus, significant changes in carbon emissions were observed in PSF but not in OPP, with means 1263 and 404 mg CO2-eq m−2 h−1, respectively. This disparity can be due to substrate availability between the two ecosystems. Subsequently, in the PSF, a promising pattern of a percentage ratio of approximately 1:3.5 was observed, indicating a substantial reduction in CO2 emissions (from 1295 to 468 mg m−2 h−1; 64%) alongside a corresponding increase in CH4 emissions (from −50 to 60 µg m−2 h−1; 221%). This finding suggests that compaction alters the aerobic peat horizon, bringing the peat surface closer to the groundwater level. The study underscores the importance of considering confounding factors such as decomposition degree and groundwater fluctuation when assessing the effects of compaction on tropical peat. By shedding light on these complexities, the findings contribute to a better understanding of the efficacy of compaction techniques in reducing emissions of these special case atmospheric pollutants.

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,>5-10 years,>10 years, and agricultural land with a land use age of 0-5 years and >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.

Vast tropical peat swamp forests in Sebangau, Central Kalimantan, Indonesia, make it difficult for officials to fight forest fires. Peat swamp forest fires are recurring events caused by anthropogenic activities around the forest. This research aimed to develop a new canal bulkhead design that prevents blockage of river flow. The approach employed involves enhancing current structures through engineering design in order to decrease the occurrence of structural breakdowns that impede the flow of rivers. The research yielded a new design for a canal bulkhead, featuring an enhanced one-meter-wide sluice gate in a "U" shape, as well as an upgraded boat ladder for passage. The novelty of the present study resides in the design of the canal bulkhead dwelling, which incorporates a ladder, enabling the inhabitants to utilize the canal without obstructing its flow. As a result, there is an enhancement in environmental safety as there are now efficient methods to promptly suppress wildfires. [ABSTRACT FROM AUTHOR]

Compaction is recognized as an effective method for mitigating the risk of fires by enhancing soil moisture levels. This technique involves restricting peat pore spaces through compaction, facilitating improved capillary action for water retention and rehydration. The compaction of tropical peatlands, while beneficial for fire prevention, has the potential to influence biogeochemical processes and subsequent carbon emissions. The magnitude of compaction and groundwater level are strongly coupled in such environments, making it difficult to distinguish the control of physicochemical properties. Therefore, this study seeks to understand how peat compaction affects its properties, carbon emissions, and their relationship, with a focus on geophysical processes. Intact peat samples were collected from a secondary peat swamp forest and an oil palm plantation in Selangor, Peninsular Malaysia. Compaction treatments were applied to achieve three levels of volume reduction. CO2 and CH4 emissions were measured using an automated gas analyzer, and the physicochemical properties of the peat were determined. The results revealed that mechanical compaction significantly altered the physicochemical properties of the secondary forest peat, displaying an opposite pattern to the oil palm plantation, particularly regarding total nitrogen and sulfur. Moreover, the average reduction percentage ratio of CO2 emissions (from 275.4 to 182.0 mg m-2 hr-1; 33.9%) to CH4 uptakes (from -17.8 to -5.2 µg m-2 hr-1; 70.1%) (~1:2) indicated distinct stages of decomposition and translocation of less decomposed peat to deeper layers due to compaction, predominantly in secondary peat swamp forest samples. The oil palm plantation samples were unaffected by compaction in terms of physicochemical properties and carbon emissions, indicating the ineffectiveness of this approach for reducing fire risk in already drained systems. This study underscores the necessity of understanding the effects of compaction in the absence of groundwater to accurately evaluate the widespread application of this technique. [ABSTRACT FROM AUTHOR]

In this article we propose and apply a methodology for collaboratively creating and reaching agreement over a shared vision for peatland restoration. The purpose is to identify a shared understanding of the various parts of a just, inclusive and sustainable restored peatland as well as productive tensions between and across divergent disciplinary domains focused on peatland restoration. We involved an interdisciplinary group of researchers and practitioners working on various aspects of tropical peatland restoration and management in Indonesia, where there is a recognised need for clearer goals and/or definitions of restoration outcomes to focus manifold stakeholder efforts. To increase opportunities for participation and interaction between participants, our methodology built on and adapted a well-established Delphi survey method by combining it with focus group discussions. This allowed multiple points of view to be considered and new knowledge to emerge. The vision produced through this process bridges across different disciplinary tensions to fulfil ecological and social outcomes. While the vision is specific to the complex political economic and socio-ecological context of Indonesia's tropical peatland, the phased methodology for collaborative visioning can be adapted for application to other social ecological challenges, or to guide planning and practice by other stakeholder groups aiming to articulate a desired future state. [ABSTRACT FROM AUTHOR]

Compaction is recognized as an effective method for mitigating the risk of fires by enhancing soil moisture levels. This technique involves restricting peat pore spaces through compaction, facilitating improved capillary action for water retention and rehydration. The compaction of tropical peatlands, while beneficial for fire prevention, has the potential to influence biogeochemical processes and subsequent carbon emissions. The magnitude of compaction and groundwater level are strongly coupled in such environments, making it difficult to distinguish the control of physicochemical properties. Therefore, this study seeks to understand how peat compaction affects its properties, carbon emissions, and their relationship, with a focus on geophysical processes. Intact peat samples were collected from a secondary peat swamp forest and an oil palm plantation in Selangor, Peninsular Malaysia. Compaction treatments were applied to achieve three levels of volume reduction. CO2 and CH4 emissions were measured using an automated gas analyzer, and the physicochemical properties of the peat were determined. The results revealed that mechanical compaction significantly altered the physicochemical properties of the secondary forest peat, displaying an opposite pattern to the oil palm plantation, particularly regarding total nitrogen and sulfur. Moreover, the average reduction percentage ratio of CO2 emissions (from 275.4 to 182.0 mg m-2 hr-1; 33.9%) to CH4 uptakes (from -17.8 to -5.2 µg m-2 hr-1; 70.1%) (~1:2) indicated distinct stages of decomposition and translocation of less decomposed peat to deeper layers due to compaction, predominantly in secondary peat swamp forest samples. The oil palm plantation samples were unaffected by compaction in terms of physicochemical properties and carbon emissions, indicating the ineffectiveness of this approach for reducing fire risk in already drained systems. This study underscores the necessity of understanding the effects of compaction in the absence of groundwater to accurately evaluate the widespread application of this technique.

There is a pressing need to tackle carbon emissions from oil palm plantations on tropical peatland, which has garnered significant discussion and concern in recent years. In response, compaction techniques were introduced in Malaysia with the aim of mitigating CO2 emissions by improving moisture levels and reducing soil aeration. This research investigates the impact of mechanical compaction on two distinct ecosystems: a peat swamp forest (PSF) and an oil palm plantation (OPP), characterized by their unique physicochemical properties Using a specially designed compaction apparatus, significant changes in carbon emissions were observed in PSF but not in OPP, with means 1263 and 404 mg CO2-eq m−2 h−1, respectively. This disparity can be due to substrate availability between the two ecosystems. Subsequently, in the PSF, a promising pattern of a percentage ratio of approximately 1:3.5 was observed, indicating a substantial reduction in CO2 emissions (from 1295 to 468 mg m−2 h−1; 64%) alongside a corresponding increase in CH4 emissions (from −50 to 60 µg m−2 h−1; 221%). This finding suggests that compaction alters the aerobic peat horizon, bringing the peat surface closer to the groundwater level. The study underscores the importance of considering confounding factors such as decomposition degree and groundwater fluctuation when assessing the effects of compaction on tropical peat. By shedding light on these complexities, the findings contribute to a better understanding of the efficacy of compaction techniques in reducing emissions of these special case atmospheric pollutants.Article highlights: The first data on in-situ compaction on tropical peatland carbon emissions. Peat physicochemical properties were not affected by compaction when in contact with groundwater. Appropriate clarity of mechanical compaction on tropical peatland. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Tropical peat with low bulk density affects the ability of peat soil to support plant growth. To improve the bulk density of peat, mineral soil is mixed to peat soil. However, mineral soil sources near peatlands are typically ultrabasic parent material with high nickel (Ni) content up to 5000 ppm. The acidic peat condition and low topography of peatlands may increase the solubility of Ni if in flooding condition. Therefore, mixing soil materials and water treatments are aimed at measuring Ni solubility at pH equilibrium after mixing and extracting using NH4OAc 1.0 N pH 7.0; 4.8; 4.2, HCl 1.0 N; 0.1 N, and H2SO4 1.0 N. The pH equilibrium after mixing soil materials was at pH 5.2-6.1, indicating Ni solubility is shown by the results of NH4OAc 1.0 N pH 7.0 - 4.8 extraction. Within this pH range, the Ni solubility value in the saturation (J) and drying (K) treatments did not differ significantly at a 5% level of significance. However, the Ni solubility with each addition of peat weight differed significantly under the saturated and moist-dried conditions (JK). [ABSTRACT FROM AUTHOR]

Water table conditions in drained peatlands affect peat decomposition, fluvial carbon and greenhouse gas emissions, and plant growth in oil palm plantations. This study illustrates the spatial heterogeneity of soil moisture profiles in cultivated tropical peat under oil palm plantation and uncultivated secondary forest, using maps. At a study plot under each land use the geographical coordinates of sampling points, tree locations and other features were recorded. Peat soil samples were taken at depths of 0–50 cm, 50–100 cm, 100–150 cm and 150–200 cm, and their moisture contents were determined. Overall, soil moisture content was higher in secondary forest than in oil palm plantation due to land management activities such as drainage and peat compaction in the latter. Significant differences were observed between the topsoil (0–50 cm) and deeper soil layers under both land uses. Soil moisture maps of the study plots interpolated using geographical information system (GIS) software were used to visualise the spatial distributions of moisture content in soil layers at different depths (0–50 cm, 50–100 cm, 100–150 cm, 150–200 cm). Moisture content in the 0–50 cm soil layer appeared to be inversely related to elevation, but the correlation was not statistically significant. On the other hand, there was a significant positive correlation between soil moisture content and the diameters of oil palm trunks. Palm trees with negative growth of trunk diameter were mostly located in subplots which were relatively dry and/or located near drains. The results of this study indicate that soil moisture mapping using GIS could be a useful tool in improving the management of peatland to promote oil palm growth.

Extreme climate is one of the important variables which determine the capability of tropical peatland to act as either carbon sink and/or carbon source. The purpose of this study is to reveal the spatio-temporal trend in the long-term time series of extreme rainfall and temperature in Sarawak peatland cause by climate change. Gridded-based Princeton datasets were used for trend analysis spanning 68-year (1948–2016) based on Modified Mann-Kendall (m-MK) test which has the capability of distinguishing unidirectional trend with multi-scale variability. The m-MK test was also used to confirm the increasing or decreasing trend produce by Mann-Kendall (MK), and to discriminate the exaggeration in trend caused by serial auto-correlation due to the high effect of large scale climate events regulating the climate in the region. By using R-based program, RClimDex for extreme climate indices output, extreme climate under Northeast (NE) and Southwest (SW) monsoon showed lower grid point with significant changes under m-MK test compared to MK test at 95% significance level. Here, the exaggeration of trend by MK test has been reduced by using m-MK test which can accommodate the scaling effect in the time series due to inherent natural climate variability. Diurnal temperature range (DTR) was expected to decrease for both monsoons in the central-coastal region as minimum temperature (TN) increased more than maximum temperature (TX). Significant increase in extreme rainfall (R10, R20, Rnn) was spatially observed more during SW monsoon compared to NE monsoon, although with high spatial variability. Significant increase of TN indices of TNn and TN90p might cause increased rainfall intensity in the south and central-coastal region, while high TX indices of TXn might cause increased rainfall intensity in the north. Due to the imminent threat of climate change, this study gives scientists an essential view on the behavior of different extreme climate variables and its potential impact on the peatland area which is susceptible to flood and risk of fire during the NE and SW monsoon, respectively.

Most peat domes in Southeast Asia are crisscrossed by networks of drainage canals. These canals are a potentially important source of methane to the atmosphere because the groundwater that discharges into them carries high concentrations of dissolved methane that is produced within peat. In this study, we present an isotope‐enabled numerical model that simulates transport, degassing, and oxidation of methane and dissolved inorganic carbon (DIC) along a drainage canal. We then estimate methane fluxes through a 5‐km canal that crosses a disturbed, forested, but undeveloped, peat dome in Brunei Darussalam by applying this model to field data: concentrations and stable carbon isotopic ratios of both methane and dissolved inorganic carbon from both peat porewater and canal water. We estimate that approximately 70% of the methane entering the canal is oxidized within the canal, 26% is degassed to the atmosphere, and 4% is transported toward the ocean, under low to moderate flow conditions. The flux of methane to the atmosphere is lowest at the maximum elevation of the canal, where flow is stagnant and methane concentrations are highest. Downstream, as flow velocity increases, methane emissions plateau even as methane concentrations decrease. The resulting methane emissions from the canal are large compared to emissions from the peat surface and vegetation on a per‐area basis. However, since the canal covers only a small portion of the catchment area, the canal may be a substantial but not dominant source of methane from the peatland. Plain Language Summary: Peatlands in Southeast Asia store large amounts of organic carbon as waterlogged, partially decayed plant matter (peat). Over recent decades, half of the region's peatlands have been drained for conversion to agricultural and forestry plantations using canal networks. This drainage lets oxygen enter the peat, enabling microbes to breakdown the peat, drastically increasing the amount of carbon dioxide emitted to the atmosphere. However, the impacts of drainage on methane, another important greenhouse gas, are poorly understood. In this study, we use the naturally occurring variation in the weight of carbon atoms (carbon isotopes) to track microbial methane consumption and emission to the atmosphere in drainage canals. We created a mathematical model that uses the carbon isotope data to track what happens to methane in a drainage canal. We determined that a large amount of methane is transported with shallow groundwater flow into the drainage canals and that most of the methane that flows into drainage canals is consumed by microbes in the canal. The remaining methane is emitted to the atmosphere, making drainage canals an important but not dominant contributor to the overall methane budget of a disturbed tropical peatland. Key Points: Methane emissions increase over the first kilometer of a canal, before leveling off, even as methane concentrations decrease downstreamCanals may be substantial contributors to both methane and carbon dioxide emissions of disturbed tropical peatlandsUnder low to moderate flow conditions, 70% of methane advected into a drainage canal was oxidized and 26% was emitted to the atmosphere [ABSTRACT FROM AUTHOR]

Background: Recurring wildfires on degraded peatlands throughout Central Kalimantan have resulted in severe economic and social impacts for local people along with globally significant environmental impacts. The interdependence between the livelihoods of local villagers and wildfire is not well understood in areas of degraded peat in proximity to urban environments. Aims: The aim of the study was to consider fire hotspots in two villages close to the regional capital of Palangka Raya. These were Kalampangan, a Javanese transmigrant farming village, and Tumbang Nusa, a Dayaknese fishing village. Methods: A system dynamics model was constructed to study the factors contributing to greenhouse gas emissions and wildfire extent resulting from long-term peatland degradation. The model was used to analyse existing policy scenarios where degraded peatlands are cultivated in perpetuity, and then consider hypothetical future policy scenarios where efforts are made to rewet and rehabilitate peatland while alternative livelihoods are enabled. Conclusions: Analysis reveals that the assumption within the model of unconstrained alternative livelihoods is insufficient to facilitate full rewetting where the incumbent livelihood is reliant on drained peatland. Implications: Only when livelihood alternatives displace drained peatland cultivation is full rewetting and sustained reduction in fire risk achievable in both villages. Significant greenhouse gas (GHG) emissions reductions were only achieved with full rewetting. Unconstrained availability of livelihood alternatives will not lead to full rewetting where drained peatland cultivation supports the incumbent livelihood. Livelihood alternatives displacing drained peatland cultivation are essential for sustained reduction in fire risk and GHG emissions. [ABSTRACT FROM AUTHOR]

Rewetting peatland is an ongoing effort in Indonesia to restore the hydrological cycle and carbon balance of the ecosystem. However, quantifying the impact of rewetting on mitigating fire remains a challenge. Here, we assess the impact of large-scale rewetting on fire risks and occurrences (duration, coverage area, and the number of events) in 2015–2021. The weather research and forecasting (WRF) model was integrated with a drought–fire model to spatially quantify fire hazards in Riau, Sumatra. The results show that rewetting has resulted in decreasing the frequency of extreme events in the study area (pre- and post-rewetting, respectively, were seven and four events). Although the area influenced by extreme events reduced following rewetting by 5%, the mean duration of extreme events increased. Our findings reveal that widespread prolonged extreme fire hazards only occurred during drying El Niño events in 2015 and 2019. The findings obtained in this case study provide quantitative evidence of the reduced fire hazard resulting from peat restoration in Indonesia. Further, the findings assist in assessing the success of peatland restoration programs and improve our knowledge of the ability to monitor and forecast fire risks in tropical peatlands. [ABSTRACT FROM AUTHOR]

Peatland is a unique ecosystem that is key in regulating global carbon cycle, climate, hydrology, and biodiversity. Peat moisture content is a key variable in ecohydrological and biogeochemical cycles known to control peatland's greenhouse gas emissions and fire vulnerability. Peat moisture is also an indicator of the success of peat restoration projects. Here we present datasets of peat moisture dynamic and retention capacity of degraded tropical peatlands. The data were collected from automatic daily monitoring and field campaigns. The peat moisture content data consists of daily data from 21 stations across three peatland provinces in Sumatra Island, Indonesia, from 2018 to 2019. In addition, peat water retention data were collected from field campaigns in Riau province. This dataset represents human modified peatlands which can be used as a benchmark for hydrological and biogeochemical models.

Tropical peatland in Southeast Asia has undergone rapid degradation and shows large subsidence due to oxidation and peat shrinkage. The measurement of those deformations is thus valuable for evaluating the peat condition and assessing peat restoration. The time series interferometric synthetic aperture radar (TInSAR), especially with the small baseline subsets (SBAS) method, is capable of measuring long-term deformation. However, the dynamic surface scatterers often change in tropical peatland, which degrades the coherent scatterer (CS) distribution density. This article presents a simple and efficient TInSAR approach that enhances the CS density under such dynamic surface scatter variation based on the SBAS method. In the presented approach, a long-time series of single-look complex images is separated into subsets, and deformation estimation is performed for each subset. The effectiveness of this simple solution was investigated by InSAR simulation and validated using SAR observation data. We applied the subset SBAS approach to the three-year Sentinel-1A C-band SAR dataset acquired over tropical peatland in Indonesia. The analyses showed an improved number of CSs for the introduced subset approach. We further introduce the color representation of CS temporal behavior per subset for visual interpretation of scatterer change. [ABSTRACT FROM AUTHOR]

Tropical peatlands are unique wetland ecosystems which provide various ecosystem services such as carbon storage and nutrient cycling. However, they have been substantially altered and transformed by land use conversion. The present study investigated the effects of land use conversion on the physico-chemical properties of peat in the Leyte Sab-a Basin Peatland, a tropical peatland on Leyte Island, Philippines. Peat core samples (1 m long) were collected from peat swamp forest, grassland and cultivation areas. Samples were analysed for gravimetric water content, volumetric water content, dry bulk density, porosity, pH, organic matter, total nitrogen and total phosphorus. Notably, conversion of peat swamp forest to other land uses (grassland and cultivation) has resulted in changes in peat physical properties such as reduced water content and porosity, and increased bulk density. A reduction in peat water content can be a direct consequence of peatland drainage while an increase in peat bulk density with reduced porosity reflects compaction owing to the passage of agricultural equipment and peat decomposition. Land use conversion altered chemical properties characterised by reduced organic matter and nutrients (total nitrogen and total phosphorus) in grassland or cultivation, indicating peat decomposition and mineralisation. In addition, decrease in peat water content due to drainage and increase in bulk density can be accompanied by losses of organic matter and nutrients. Finally, changes in peat physico-chemical properties as a consequence of land use conversion serve as important indicators of peat soil degradation.

Degraded tropical peatlands lack tree cover and are often subject to seasonal flooding and repeated burning. These harsh environments for tree seedlings to survive and grow are therefore challenging to revegetate. Knowledge on species performance from previous plantings represents an important evidence base to help guide future tropical peat swamp forest (TPSF) restoration efforts.We conducted a systematic review of the survival and growth of tree species planted in degraded peatlands across Southeast Asia to examine (1) species differences, (2) the impact of seedling and site treatments on survival and growth and (3) the potential use of plant functional traits to predict seedling survival and growth rates.Planted seedling monitoring data were compiled through a systematic review of journal articles, conference proceedings, reports, theses and unpublished datasets. In total, 94 study‐sites were included, spanning three decades from 1988 to 2019, and including 141 indigenous peatland tree and palm species. Accounting for variable planting numbers and monitoring durations, we analysed three measures of survival and growth: (1) final survival weighted by the number of seedlings planted, (2) half‐life, that is, duration until 50% mortality and (3) relative growth rates (RGR) corrected for initial planting height of seedlings.Average final survival was 62% and half‐life was 33 months across all species, sites and treatments. Species differed significantly in survival and half‐life. Seedling and site treatments had small effects with the strongest being higher survival of mycorrhizal fungi inoculated seedlings; lower survival, half‐life and RGR when shading seedlings; and lower RGR and higher survival when fertilising seedlings. Leaf nutrient and wood density traits predicted TPSF species survival, but not half‐life and RGR. RGR and half‐life were negatively correlated, meaning that slower growing species survived for longer.Synthesis and applications. To advance tropical peat swamp reforestation requires expanding the number and replication of species planted and testing treatments by adopting control vs. treatment experimental designs. Species selection should involve slower growing species (e.g. Lophopetalum rigidum, Alstonia spatulata, Madhuca motleyana) that survive for longer and explore screening species based on functional traits associated with nutrient acquisition, flooding tolerance and recovery from fire. [ABSTRACT FROM AUTHOR]

In recent decades, catastrophic wildfire episodes within the Sumatran peatland have contributed to a large amount of greenhouse gas emissions. The El-Nino Southern Oscillation (ENSO) modulates the occurrence of fires in Indonesia through prolonged hydrological drought. Thus, assessing peatland vulnerability to fires and understanding the underlying drivers are essential to developing adaptation and mitigation strategies for peatland. Here, we quantify the vulnerability of Sumatran peat to fires under various ENSO conditions (i.e., El-Nino, La-Nina, and Normal phases) using correlative modelling approaches. This study used climatic (i.e., annual precipitation, SPI, and KBDI), biophysical (i.e., below-ground biomass, elevation, slope, and NBR), and proxies to anthropogenic disturbance variables (i.e., access to road, access to forests, access to cities, human modification, and human population) to assess fire vulnerability within Sumatran peatlands. We created an ensemble model based on various machine learning approaches (i.e., random forest, support vector machine, maximum entropy, and boosted regression tree). We found that the ensemble model performed better compared to a single algorithm for depicting fire vulnerability within Sumatran peatlands. The NBR highly contributed to the vulnerability of peatland to fire in Sumatra in all ENSO phases, followed by the anthropogenic variables. We found that the high to very-high peat vulnerability to fire increases during El-Nino conditions with variations in its spatial patterns occurring under different ENSO phases. This study provides spatially explicit information to support the management of peat fires, which will be particularly useful for identifying peatland restoration priorities based on peatland vulnerability to fire maps. Our findings highlight Riau's peatland as being the area most prone to fires area on Sumatra Island. Therefore, the groundwater level within this area should be intensively monitored to prevent peatland fires. In addition, conserving intact forests within peatland through the moratorium strategy and restoring the degraded peatland ecosystem through canal blocking is also crucial to coping with global climate change. [ABSTRACT FROM AUTHOR]

Indonesia has 673 peat hydrological units (PHUs) covering more than 26.5 million hectares, of which approximately 70% are located on the Kalimantan and Sumatra Islands. Merang-Kepahyang PHUs in South Sumatra cover a total area of approximately 1.094 km2, comprising three watersheds, namely Merang (360.3 km2), Buring (458.5 km2), and Kepahyang (275.3 km2). This area is globally known as a carbon (C)-rich ecosystem. However, there is still a lack of understanding of the C cycle in this area, primarily associated with land use and cover changes. This study spatially estimates belowground carbon stocks and relates them to land elevation, land use, and soil unit. To reduce inaccurate estimates, the volume of the peat is discretized by a 200 m × 200 m grid as a grid based analysis. This assessment aimed to obtain the baseline data with particular attention to provide information on the peat carbon and its spatial distribution in each watershed. We conducted field surveys and image analysis based on SPOT 6 (1.5 m/pixel with raster format 200 m/pixel) to produce interpolated data and maps of land use, soil unit, land elevation, peat thickness, and peat carbon. We found that the land elevation ranged from 1.5 to 13.0 m-MSL in Merang, from 1.1 to 13.5 m-MSL in Buring, and from 0.2 to 11.6 m-MSL in Kepahyang. Peat thickness in ranged from 1.3 m to 12.9 m in Merang, from 0.8 m to 13.2 m in Buring, and from 0.4 m to 11.4 m in Kepahyang. Peat carbon was 220 M t in Merang, 225.8 M t in Buring, and 116.8 M t in Kepahyang. On average, peat carbon density was 6.11 kt ha−1 in Merang, 4.92 kt ha−1 in Buring, and 4.24 kt ha−1 in Kepahyang. The cumulative area covering the peat with a thickness greater than 3 m was 334.9 km2 (93%) in in Merang, 379.4 km2 (83%) in Buring, and 193.9 km2 (70%) in Kepahyang. There is a relationship between carbon content and elevation, where most of the high carbon content is in the higher elevation. Furthermore, the trees in the secondary forest are primarily found at higher elevations, while the shrubs are located at lower elevations. This is due to water table conditions below the land surface at higher elevations, and close to land surface at lower elevations. In conclusion, these watersheds are carbon-rich areas which are worthy of conservation while a small portion (<30%) may be used for cultivation. [ABSTRACT FROM AUTHOR]

Tropical peatlands have high potential function as a major source of atmospheric methane (CH4) and can contribute to global warming due to their large soil carbon stock, high groundwater level (GWL), high humidity and high temperature. In this study, a process-based denitrification–decomposition (DNDC) model was used to simulate CH4 fluxes in a pristine tropical peatland in Sarawak. To test the accuracy of the model, eddy covariance tower datasets were compared. The model was validated for the year 2014, which showed the good performance of the model for simulating CH4 emissions. The monthly predictive ability of the model was better than the daily predictive ability, with a determination coefficient (R2) of 0.67, model error (ME) of 2.47, root mean square error (RMSE) of 3.33, mean absolute error (MAE) of 2.92 and mean square error (MSE) of 11.08. The simulated years of 2015 and 2016 showed the good performance of the DNDC model, although under- and overestimations were found during the drier and rainy months. Similarly, the monthly simulations for the year were better than the daily simulations for the year, showing good correlations at R2 at 0.84 (2015) and 0.87 (2016). Better statistical performance in terms of monthly ME, RMSE, MAE and MSE at − 0.11, 3.38, 3.05 and 11.45 for 2015 and − 1.14, 5.28, 4.93 and 27.83 for 2016, respectively, was also observed. Although the statistical performance of the model simulation for daily average CH4 fluxes was lower than that of the monthly average, we found that the results for total fluxes agreed well between the observed and the simulated values (E = 6.79% and difference = 3.3%). Principal component analysis (PCA) showed that CH4, GWL and rainfall were correlated with each other and explained 41.7% of the total variation. GWL was found to be relatively important in determining the CH4 fluxes in the naturally inundated pristine tropical peatland. These results suggest that GWL is an essential input variable for the DNDC model for predicting CH4 fluxes from the pristine tropical peatland in Sarawak on a monthly basis. [ABSTRACT FROM AUTHOR]

Peatlands rewetting for hydrological restoration plays an important role in fire prevention and peatland restoration of degraded peatland. One of the methods for the rewetting is canal blocking. The impact of canal blocking for peatland rewetting is further analyzed in this research. This study focused in Pulau Tebing Tinggi peatland hydrological unit (PHU), which is located in Kepulauan Meranti Regency, Riau Province. To analysis the rewetting impact, 15 dipwells were installed with the distance of 1 m, 51 m, 101 m, 201 and 301 m from the canal for each transect of the three transects. A transect was set in the downstream and two transects were set in the upstream of canal block. The ground water level (GWL) in the 15 dipwells was recorded using water-loggers for one year. This research found that canal blocking has a good effect on maintaining groundwater levels and keeping peatlands in always wet or humid conditions up to a distance of 201 m perpendicular to the canal if the rise in water level in the canal due to canal blocking is more than 0.6 m. It is able to maintain the ground water depth in peatlands around 0.4 m, where the peatlands become low risk to the fire, emission rates and subsidence.

The 2015’s massive forest fires have left large areas of burned peatlands that need to be restored, demanding substantial number of resources. To understand natural regeneration on burned peatland and how planting might accelerate its recovery process, we measured recruitment on burned peatland with different fire frequency. Three transects were established each consisting of five 20x20 m2plots developed at a 30 m interval. Our finding suggests that the absence of remnant trees due to frequent or severe fires does not always impede the emergence of new recruitments, although diversity of forest regrowth is likely to be affected by its proximity to forest remnant. The floristic composition also showed a domination of pioneer species, giving evidence that forest recovery is initiated. We conclude that to support the recovery process through planting activity, the successional stage of the designated sites should be determined first. During the early phase of succession, stand initiation should be addressed first by the colonization of rapidly recruiting species to ensure continuous regeneration. Therefore, the common planting method on large areas with mixed climax-high valuable trees is unbeneficial unless the restoration sites have reached the later stages of succession.

Indonesia is one of the countries with the largest area of tropical peatlands in the world. These wide peatlands have a vital role in the carbon cycle and carbon storage in huge quantities, thus strict conservation in the area is necessary. One effort to carry out conservation is to understand the spatial distribution of carbon stock in peatlands. This study aims to map the spatial distribution of carbon stock based on peat thickness modeling using machine learning algorithms, i.e., Random Forest (RF), Quantile Regression Forests (QRF), and Cubist. A case study was conducted in a part of Lake Sentarum National Park, Indonesia where human interference is still limited. Digital elevation model (DEM) and synthetic aperture radar (SAR) data were included as the input variables. The results showed that RF performed the best among other models to estimate peat thickness (mean = 1.877 m) with an RMSE (root mean square error) of 0.483 m and an R2 of 0.786. DEMs are the most important parameters in our analysis compared to SAR data. Based on the best model, we estimated the total volume of 5,112,687 m3 in the study area, produced at 12.5 m resolution, which was then converted to a total of carbon stock at 0.337 ± 0.106 Mt carbon. [ABSTRACT FROM AUTHOR]

Water table conditions in drained peatlands affect peat decomposition, fluvial carbon and greenhouse gas emissions, and plant growth in oil palm plantations. This study illustrates the spatial heterogeneity of soil moisture profiles in cultivated tropical peat under oil palm plantation and uncultivated secondary forest, using maps. At a study plot under each land use the geographical coordinates of sampling points, tree locations and other features were recorded. Peat soil samples were taken at depths of 0-50 cm, 50-100 cm, 100-150 cm and 150-200 cm, and their moisture contents were determined. Overall, soil moisture content was higher in secondary forest than in oil palm plantation due to land management activities such as drainage and peat compaction in the latter. Significant differences were observed between the topsoil (0-50 cm) and deeper soil layers under both land uses. Soil moisture maps of the study plots interpolated using geographical information system (GIS) software were used to visualise the spatial distributions of moisture content in soil layers at different depths (0-50 cm, 50-100 cm, 100-150 cm, 150-200 cm). Moisture content in the 0-50 cm soil layer appeared to be inversely related to elevation, but the correlation was not statistically significant. On the other hand, there was a significant positive correlation between soil moisture content and the diameters of oil palm trunks. Palm trees with negative growth of trunk diameter were mostly located in subplots which were relatively dry and/or located near drains. The results of this study indicate that soil moisture mapping using GIS could be a useful tool in improving the management of peatland to promote oil palm growth. [ABSTRACT FROM AUTHOR]

Peatlands are unique wetland ecosystems that provide various ecosystem services such as carbon storage and biogeochemical cycling, however being threatened by anthropogenic activities. The present study was conducted to explore the impact of land use conversion on carbon stocks and peat properties in a tropical peatland in the Leyte Sab-a Basin Peatland (LSBP) in Northeastern Leyte, Philippines. The carbon stocks (aboveground and belowground) and physico-chemical properties of peat soil were compared among peat swamp forest, grassland and peatland with cultivation. Land use conversion resulted in the significant reduction of the total aboveground carbon stock. The peat swamp forest had the highest carbon stocks (38.56 ± 4.58 Mg ha−1), and when converted to grassland and peatland with cultivation, it has resulted to carbon loss of as much as 86.59 and 90.45%, respectively. The belowground root carbon stock was highest in the peat swamp forest (5.05 ± 0.64 Mg ha−1), also while highest peat carbon stock (1 m depth) was observed in the cultivation areas (45.28 ± 2.25 – 61.27 ± 3.07 Mg ha−1). However, peat swamp forests with very deep peat deposits potentially store a significant amount of carbon than in peatland with cultivation that was characterized by shallower compressed peats. In addition, land use conversion altered the physico-chemical properties of peat such as water content, organic matter, and porosity, and bulk density which all indicated peatland degradation. Finally, the overall result of this study highlights the importance to develop and implement management and conservation plans for LSBP. [ABSTRACT FROM AUTHOR]

Tropical peatlands are fragile ecosystems with an important role in conserving biodiversity, water quality and availability, preventing floods, soil intrusion, erosion and sedimentation, and providing a livelihood for people. However, due to illegal logging, fire and conversion into other land use, the peatlands in Indonesia are under serious threat. Efforts to restore Indonesia's tropical peatlands have been accelerated by the establishment of the Peatland Restoration Agency in early 2016. The restoration action policy includes the rewetting, revegetation and revitalisation of local livelihood (known as the 3Rs). This paper summarises the regulatory, institutional and planning aspects of peatland restoration, in addition to the implementation of the 3Rs in Indonesia, including failures, success stories, and the criteria and indicators for the success of peatland restoration. [ABSTRACT FROM AUTHOR]

Abstract The loss of huge areas of peat swamp forest in Southeast Asia and the resulting negative environmental effects, both local and global, have led to an increasing interest in peat restoration in the region. Satellite remote sensing offers the potential to provide up‐to‐date information on peat swamp forest loss across large areas, and support spatial explicit conservation and restoration planning. Fusion of optical and radar remote sensing data may be particularly valuable in this context, as most peat swamp forests are in areas with high cloud cover, which limits the use of optical data. Radar data can ‘see through’ cloud, but experience so far has shown that it doesn't discriminate well between certain types of land cover. Various approaches to fusion exist, but there is little information on how they compare. To assess this untapped potential, we compare three different classification methods with Sentinel‐1 and Sentinel‐2 images to map the remnant distribution of peat swamp forest in the area surrounding Sungai Buluh Protection Forest, Sumatra, Indonesia. Results show that data fusion increases overall accuracy in one of the three methods, compared to the use of optical data only. When data fusion was used with the pixel‐based classification using the original pixel values, overall accuracy increased by a small, but statistically significant amount. Data fusion was not beneficial in the case of object‐based classification or pixel‐based classification using principal components. This indicates optical data are still the main source of information for land cover mapping in the region. Based on our findings, we provide methodological recommendations to help those involved in peatland restoration capitalize on the potential of big data.

Tropical peatlands are one of the largest reservoirs of terrestrial organic carbon. However, present-day tropical peat swamp forests are under threat by anthropogenic disturbances and have already been widely degraded. Anthropogenic pressures on peatland ecosystems have resulted in ecological and biogeochemical changes and the release of carbon to the atmosphere. In Southeast Asia, the conversion of peatlands to oil palm plantations has accelerated significantly during the last 2 decades. This research analyzed direct and indirect land-use changes (DLUC and ILUC) that have been associated with oil palm expansion and anthropogenic impacts in the Princess Sirindhorn Wildlife Sanctuary (PSWS), Narathiwat, southern Thailand. Our analysis is based on land-use and land-cover data of the Land Development of Thailand from two different periods: 2000–2009 and 2009–2016. For the purpose of comparison, the data were reclassified into 12 types of land use: oil palm, para rubber, paddy field, abandoned paddy field, orchard, other agriculture lands, wetlands and peatlands, mangrove, evergreen forest, water area, build-up area, and unused area. In addition, the area of net change due to DLUC and ILUC was calculated, and carbon stock changes were estimated from above- and below-ground biomass and soil organic carbon. The results show that the total oil palm plantation area has increased from 0.04% in 2000 to 6.84% in 2016, because of a Thai government policy promoting the use of biodiesel and increasing capacity of palm oil production in 2005. Paddy field, evergreen forest, wetlands, and peatlands were the main areas being replaced. The clearance of natural forest greatly increased in the period of 2000–2009. The ILUC indicates that the expansion of oil palm plantations invades other croplands (paddy field, para rubber, and orchard). The results demonstrate that the conversion of natural landscapes (evergreen forest, mangrove, wetlands, and peatlands) to oil palm plantations at Princess Sirindhorn Wildlife Sanctuary area had a negative effect, with carbon stock changes of 4 million Mg C during 2000–2016 (0.25 million Mg C/year). Given the significance of carbon stock changes arising from land-use changes, this research highlights the need for sustainable land-use management and long-term monitoring.