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Peatlands are terrestrial wetland ecosystems in which the production of organic matter exceeds its decomposition and a net accumulation results. Several factors influence peat formation and preservation, including a positive climatic moisture balance (precipitation minus evaporation), high-relative humidity, topographic and geological conditions that favor water retention, and low substrate pH and nutrient availability. The majority of the world's peatlands occur in boreal and temperate zones where they have formed under high-precipitation, low-temperature climatic regimes. In the humid tropics, however, regional environmental and topographic conditions have enabled peat to form under a high-precipitation, high-temperature regime and, as a consequence, extensive peatlands occur in Southeast Asia, mainland East Asia, the Caribbean and Central America, South America and southern Africa. Most of these are located at low altitudes where rain forest vegetation grows on a thick mass of organic matter accumulated over thousands or tens of thousands of years, to form deposits up to 20m thick.
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... Heath forests, locally known as kerangas forests, occur in Borneo on nutrient-poor, acidic, well-drained sandy soils and contain a thin layer of surface peat (Brunig 1974, Corlett & Primack 2011, MacKinnon et al. 2013. In contrast, peat swamp forests exist on peat deposits, comprising partially decomposed organic matter that can reach depths of over 10 m in places, in a highly acidic, waterlogged environment (Page et al. 2006, Posa et al. 2011, Dommain et al. 2016. A sub-type of kerangas forest occurs where heath soils experience poor soil drainage due to an impermeable hardpan, resulting in permanently waterlogged kerapah forests (Brunig 1990, Proctor 1999. ...
... KF and SAP soils were the most nutrient-rich, as KF recorded the highest total N and Mg concentrations while SAP recorded the highest total P and Ca concentrations. The higher soil nutrient concentrations in KF and SAP plots may be due to nutrient accumulation in the thicker humus layers and peat surface (Page et al. 2006) as nutrient concentrations decrease down the peat profile (Sulistiyanto 2004, Lampela et al. 2014. Although Bornean PSFs are commonly ombrogenous and receive most nutrients from rainfall (Page et al. 2006, Dommain et al. 2016, our SAP plots were not located at the higher parts of the Badas peat dome which may have allowed more nutrients to accumulate in their surface peat. ...
... The higher soil nutrient concentrations in KF and SAP plots may be due to nutrient accumulation in the thicker humus layers and peat surface (Page et al. 2006) as nutrient concentrations decrease down the peat profile (Sulistiyanto 2004, Lampela et al. 2014. Although Bornean PSFs are commonly ombrogenous and receive most nutrients from rainfall (Page et al. 2006, Dommain et al. 2016, our SAP plots were not located at the higher parts of the Badas peat dome which may have allowed more nutrients to accumulate in their surface peat. MSF consistently recorded lower soil nutrient concentrations, except for total K which was the highest as compared to the other forests. ...
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The diverse lowland forests of Southeast Asia and Borneo are globally recognised biodiversity hotspots containing rare and endangered species and high levels of plant endemism. Heath and peat swamp forests are Bornean lowland forest types with distinctive plant communities that primarily correspond to a soil water gradient from dryland heath to waterlogged peat swamps. Although tree diversity of Bornean heath and peat swamp forests is well described, little is known of their woody seedling communities. This study investigated diversity, abundance and community composition of woody seedlings in mixed peat-swamp (MSF), heath (HF), kerapah (KF) and Shorea albida peat-swamp (SAP) forests in Brunei Darussalam, Northwest Borneo. Within twenty-two 3 × 3 m plots in these forest types, seedlings of 50 ≤ cm height ≤ 100 were censused and taxonomically identified, and measurements of selected environmental and soil properties were obtained. In total, 84 species of woody seedlings from 71 genera were recorded, with Myrtaceae most abundant in MSF, KF and SAP, while Dipterocarpaceae and Sapotaceae were most abundant in HF. Mean seedling abundance and diversity indices did not differ between forest types, but mean species richness was significantly higher in MSF than SAP. Woody seedling community composition differed between forest types and was influenced by soil properties, with MSF seedling communities influenced by total K concentration and soil pH, while SAP was influenced by soil gravimetric water content and total P concentration. These findings highlight the need for increased research on seedling ecology in tropical heath and peat swamp forest formations to further elucidate mechanisms underlying species diversity in these forests, and to guide programmes for their conservation, sustainable management and reforestation.
... Tropical peatlands are important terrestrial carbon pools storing 40 to 90 Gt C [6,7] and account for one-third of the world's soil C pool [8]. In Southeast Asia, peatlands are primarily found in Sumatra, the Malay Peninsula, Borneo (Kalimantan, Sarawak, and Brunei), and New Guinea [9]. ...
... The Philippines have 10,700 hectares of peatland area out of the 29 million hectares of peatland existing in Southeast Asia [9]. However, the identification of more peatland sites in the country is ongoing. ...
... This finding is not surprising since peatland soils have stored huge amounts of carbon for over a millennium. In Indonesian peatland, the aboveground biomass in peat swamp forest was 100-150 Mg ha −1, whereas soil carbon was 2772 Mg ha −1 [9]. ...
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Although tropical peatlands are huge carbon reservoirs, they are threatened by climate change and anthropogenic disturbances. Here, we assessed two contrasting peatland sites in the Philippines in terms of aboveground biomass and carbon content, soil carbon stock, and CO2 fluxes in the soils. The Caimpugan peatland in Agusan del Sur was considered the ‘undisturbed’ site, while the Bambanin peatland in Mindoro Oriental was the ‘disturbed’ site. The aboveground biomass at the undisturbed site was 35.8 ± 30.0 Mg ha−1) while at the disturbed site, it was 2.0 Mg ha−1 ± 1.9 Mg ha−1. The aboveground C content at the undisturbed site varied from 1.29 Mg C ha−1 to 37.2 C Mg ha−1, while the disturbed site only ranged from 0.1 Mg C ha−1 to 2.1 Mg C ha−1. A trend of increasing soil carbon content as the soil gets deeper was observed in both sites. At the undisturbed site, the average soil carbon content was 750 ± 710 Mg ha−1 and 595 ± 406 Mg ha−1 at the disturbed site. In terms of soil carbon emission, the undisturbed site had 3.6 ± 3.0 g C m−2d−1 and was only one-third the emission rate at the disturbed site (11.2 ± 6.4 g C m−2d−1). Our study highlights the dire condition of a disturbed peatland in terms of vegetation/soil carbon dynamics. We underscored the need to address the pressing issues on peatland drainage, agricultural activities, and human settlement within the peatland sites geared towards effectively managing this important carbon reservoir in the Philippines.
... Pristine tropical peatlands are formed under environmental conditions of high humidity and high water tables in which peat is constantly submerged leading to a slower rate of peat decomposition than the rate of peat formation (Page et al. 2006, Page & Hooijer 2016). This peat is composed of partially decomposed woody vegetation consisting of usually over 99 % organic matter (Andriesse 1964, Anderson 1983. ...
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Tropical peatlands in Southeast Asia are a significant carbon sink, but are under major threat of fire resulting in significant carbon emissions. This study focused on the residual ash method, which has not been applied before for a tropical peatland, to determine the amount of carbon lost due to fire along two transects. To evaluate the method in a tropical peatland, we sampled peat cores to a depth of 150 cm along two transects in a drainage-affected peatland in Brunei Darussalam and analysed Landsat images to determine burn count at individual sampling locations between 1988 and 2020. The ash residue method indicated that the carbon release from the two transects was 3.61 ± 1.08 kg m-2 and 3.77 ± 0.80 kg m-2 respectively due to peat decomposition and fire. However, our results show that although some locations burned up to five times, the expected ash content (of at least 4 %) was not found in the surface peat. Therefore, the majority of the resulting ash from these fires must have been transported out of the peatland, possibly in smoke or washed away via ground and surface water transport. We conclude that the residual ash method to determine carbon loss is not a reliable method to determine carbon loss in degraded tropical peatlands.
... From the total tropical peatland area, the maximum areas are distributed in Southeast Asia, South America, and Africa's Congo Basin Gumbricht et al. 2017). Further, it has the most diverse and most threatened peatland environment and is associated with significant carbon emissions by natural decomposition, fires, and biodiversity loss (Page et al. 2006;Yule 2010;Turetsky et al. 2015). In Southeast Asia, particularly in Malaysia, Sumatra, and Kalimantan, peat forest cover has declined from 119,000 km 2 to 46,000 km 2 from 1990 to 2015, while agricultural areas on peatland increased from 17,000 km 2 to 78,000 km 2 during the same study period (Miettinen et al. 2016). ...
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Peat swamp forests are playing important role in climate change by carbon storage, biodiversity conservation, and crucial local livelihoods. The construction of drainage channels in Sebangau National Park, Indonesia negatively affects the Peatland ecosystem and degrades the vegetation diversity. This research aims to study the composition and vegetation diversity of secondary peat swamp forests in Sebangau National Park (SNP), especially around large and small drainage channels. For the observation of vegetation composition and diversity, each observation block consisted of 3 transects that were 300 m apart from each other, and perpendicular to the channel. For observations on small drainage channel blocks, transects are made to continue the previous transect at a distance of 500 m from the end of the large drainage channel. On each transect, 5 plots of vegetation were made using the plot line method with a distance of 50 m between each plot. A total of 15 plots of 30mx30m size were prepared for each drainage channel category. Observations were made on the growth rate of seedlings in a 2m x 2m plot, poles in a 5m x 5m plot, saplings in a 10m x 10m plot, and trees in a 20m x 20m plot. The results of the study showed that Shorea spp., Combretocarpus rotundatus, Cratoxylum arborencens, and Calophyllum sp. are the dominant plant species of the study area. Overall 92 species were reported from the Large Drainage Channel block and 86 species from the Small Drainage Channel block. Further, the Species Diversity ranged between 1.43 - 1.57 while Species Richness ranged from 16.80 – 23.03, and the Evenness Index ranged from 0.83 – 0.92 at all levels of vegetation growth. Results of the study can be concluded that the channel dimensions do not have any effect on species number, diversity index, species richness, and species evenness at all levels of vegetation growth. The Similarity Index of species at seedlings, saplings, and poles is more than 50%, while at the tree level it was reported less than 50%.
... Based on the number recorded in standardized belt transects, peat forests contain fewer termite species (7-17 species) compared with tropical rainforests located in the same biogeographical Sunda region (28-34 species; Jones and Eggleton 2000, Gathorne-Hardy et al. 2001, Jones et al. 2003, Vaessen et al. 2011. Two explanations may account for the lower species richness: 1) tropical peat swamp forests are geologically recent compared with tropical rain forests, as most were formed over the past 5,000 to 11,000 yr (Page et al. 2006); and 2) a soil surface inundated with peat water does not favor termite colonization, especially for hypogeal-nesting termites that mostly occur in tropical dipterocarp forests. Only those termites that live inside wood (wood-nesting termites) or on trees (arboreal-nesting termites) and those that have a high tolerance for acidic soil could have adapted to the peat swamp forest (Vaessen et al. 2011). ...
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Tropical peatlands are among the most carbon-dense ecosystems on Earth, and their water storage dynamics strongly control these carbon stocks. The hydrological functioning of tropical peatlands differs from that of northern peatlands, which has not yet been accounted for in global land surface models (LSMs). Here, we integrated tropical peat-specific hydrology modules into a global LSM for the first time, by utilizing the peatland-specific model structure adaptation (PEATCLSM) of the NASA Catchment Land Surface Model (CLSM). We developed literature-based parameter sets for natural (PEATCLSM Trop,Nat) and drained (PEATCLSM Trop,Drain) tropical peatlands. Simulations with PEATCLSM Trop,Nat were compared against those with the default CLSM version and the northern version of PEATCLSM (PEATCLSM North,Nat) with tropical vegetation input. All simulations were forced with global meteorological reanalysis input data for the major tropical peatland regions in Central and South America, the Congo Basin, and Southeast Asia. The evaluation against a unique and extensive data set of in situ water level and eddy covariance-derived evapotranspiration showed an overall improvement in bias and correlation compared to the default CLSM version. Over Southeast Asia, an additional simulation with PEATCLSM Trop,Drain was run to address the large fraction of drained tropical peatlands in this region. PEATCLSM Trop,Drain outperformed CLSM, PEATCLSM North,Nat and PEATCLSM Trop,Nat over drained sites. Despite the overall improvements of PEATCLSM Trop,Nat over CLSM, there are strong differences in performance between the three study regions. We attribute these performance differences to regional differences in accuracy of meteorological forcing data, and differences in peatland hydrologic response that are not yet captured by our model.
Article
Peatlands in Southeast Asia are of global significance for biodiversity conservation and climate regulation as well as of national and local significance for water management and livelihood support. Despite this, these ecosystems are among the least studied and monitored of the world, and are increasingly threatened by anthropogenic activities. Peatland degradation is responsible for the largest greenhouse gases (GHG) emission source from the agriculture, forestry and other land use (AFOLU) sectors in the region. Peatland restoration is a key mitigation and preventative intervention to halt the degradation of these ecosystems. In recent years, a small number of studies have aimed to define peatland restoration processes and approaches, the latest being the 4Rs approach ‐ Rewetting, Reduction of fire, Revegetation, and Revitalization. The latter component being focussed on the local communities benefits, in terms of promoting diversified sustainable livelihoods. Based on evidence of successful peatland restoration interventions in Southeast Asia ‐ which we define as being ‘community‐led’ ‐ we propose a 5Rs approach to peatland restoration instead, with community participation embedded in each component of the approach, beyond Revitalization, as well as in a fifth crosscutting component: Reporting and monitoring (R5). The new community‐led 5Rs approach can support the ongoing formulation, refinement and implementation of peatland restoration strategies and activities in Southeast Asia and beyond by achieving ecological restoration goals, while obtaining local communities endorsement and support, needed for the long‐term sustainability of the restoration interventions. This article is protected by copyright. All rights reserved.
Chapter
Tropical and subtropical freshwater wetland ecosystems are a function of their hydrology, geomorphology, and underlying soils. The hydrology of tropical freshwater wetlands is greatly influenced by intraannual (rainy and dry season) and interannual (decadal) weather patterns combined with high rates of evapotranspiration throughout most of the year, especially in subtropical wetlands. Like boreal and temperate wetlands, tropical and subtropical wetland geomorphology depends on their underlying geology and soils, as well as the type, frequency, and duration of hydrologic inputs. Soils are often high in organic matter resulting in acidic soil pH ranges due to high primary production from vegetation, which is typically associated with warm, wet climates.
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Restoration and water table control on peatlands to limit fire risk are national priorities in Indonesia. The present study was initiated at Padang Island, Sumatra, to increase understanding on peatland hydrology in the tropic. At the pilot site, water table and precipitation were monitored at different stations. The results show variation in water table depths (WTDs) over time and space due to spatial and temporal variability in rain intensity and drainage networks. In part of the island, large-scale drainage for plantations led to deep WTD (−1.8 m) and high WTD recession rates (up to 3.5 cm/day). Around villages, farm-scale drainages had a smaller impact with a lower recession rate (up to 1.8 cm/day) and shallow WTD, typically below −0.4 m, the threshold for sustainable peatland management in Indonesia. The recession rates levelled off at 1.0 cm/day near the drained forest/plantation and at 0.5 cm/day near the farm. Deeper layers had much lower specific yield (Sy), 0.1 at −1.5 m depth, compared with top peat soils with Sy up to 0.3. Proximity to drainages extended discharge flow to deeper layers. The results highlighted the severity of peatland drainage impact on most coastal zones of Padang Island, which have intensive drainage networks. HIGHLIGHTS High spatial and temporal variability of water table was observed in Padang Island.; The variability was partially driven by variation in land use and farm drainages.; Recession rate near pulp plantations remained high (0.01 m/day) at −1.5 m depth.;
Chapter
Aim - Peat swamps are a unique class of tropical forest characterized by their deep organic soils, which accrue from slowly decomposing plant debris. Main Concepts Covered - We overview the environmental conditions that permit the development of peat swamp forests, from local processes that allow peat to accumulate, to the regional processes that determine their global distribution. We then turn to assess the relevance of peat swamps to biodiversity and the myriad ways in which local floras and faunas inhabit and interact with them. Outlook - While peat swamps have functioned as carbon sinks over millennia, ongoing degradation will continue to convert many into globally significant carbon sources.
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Palynological investigations of a 20-m-thick Miocene lignite from southeastern Kalimantan, Indonesia, reveal that there are distinct vertical variations in palynofloral characteristics. Three palynofloral zones likely represent large-scale successional changes that were a product of long-term ecological and depositional changes within the original mire. All three zones are represented by palynofloras of both bog-forest and mangrove affinity. The abundance and diversity of these bog-forest palynofloras, accompanied by extremely low sulphur contents (<0.4%), suggests predominantly freshwater, terrestrial deposition. It is probable that the mangrove pollen is allochthonous and was transported into the mire by winds. Increasing relative abundances of mangrove pollen within the total palynofloral assemblage suggests encroachment of the mangrove swamp toward the bog-forest. Pollen common and abundant within all assemblages includes that of species of the genera Calophyllum, Melanorrhea and Dactylocladus. Overall, the vegetation that formed this Miocene lignite is virtually identical to the present-day peat-forming vegetation of Indonesia.
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This site is at an altitude of 1300m and SW of two sites already described. The record is dominated by Eugenia comp. and presumably represents trees grown for their fruit. The other pollen present suggests a largely unforested landscape, again presumably the result of human interference. The assumption is that the deposits are of relatively recent age. -K.Clayton