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Chapter 7 Lowland tropical peatlands of Southeast Asia
Abstract and Figures
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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... Tropical peatlands are globally important ecosystems in terms of their biodiversity, their influence on groundwater and hydrology and the large amount of carbon they store above and below ground (Girkin et al. 2022;Green and Page 2017). Tropical peatlands contain an estimated 104.7 petagrams (1Pg = 10 15 kg) of carbon globally (Page, Rieley, and Banks 2011), and although long recognised in Indonesia and Malaysia (Page, Rieley, and Wüst 2006), recent investigations have uncovered their extent and depth in the Congo (Dargie et al. 2017) and Amazonian basins (Draper et al. 2014;Kelly et al. 2017). Tropical ecosystems differ from their temperate counterparts in that they are typically forested (Hoyos-Santillan et al. 2015), with a spatially complex vegetation structure incorporating elements of flooded forest and palms (Phillips, Rouse, and Bustin 1997). ...
Aim
Tropical peatlands are globally significant carbon stores, increasingly threatened by human activities and climate change. However, their ecohydrological responses to shifting water availability remain poorly understood. In this study, we investigate the connections between climate change, hydrology and vegetation dynamics in a coastal tropical peatland in Panama, aiming to understand the effects of future drying on peatland dynamics.
Location
Bocas del Toro, Panama (9°22′54″N, 82°21′59″W).
Taxon
Angiosperms.
Methods
High‐resolution multiproxy palaeoecological data, including pollen and plant macrofossils (vegetation), testate amoebae (water‐table depth) and physical peat properties, are used to explore the relationships between climate change, hydrology and vegetation in a coastal tropical peatland over the past 700 years. Downscaled climate simulations are integrated with this process‐based understanding to project the likely future responses of this coastal peatland to climate change.
Results
We identify a clear connection between precipitation variability, driven by shifts in the Intertropical Convergence Zone and water‐table dynamics, which subsequently influence changes in the peatland vegetation mosaic. Historical drier periods are marked by the expansion of shrub communities into the open peatland plain.
Main Conclusions
Palaeoecological studies incorporating climate and hydrological proxies are essential for understanding both recent and future ecohydrological dynamics of tropical peatlands. Our findings suggest that in response to future climate change, water tables will lower and shrub communities will expand due to rising temperatures and reduced precipitation. Additionally, future sea‐level rise, combined with declining rainfall, may result in seawater intrusion and significant vegetation shifts in coastal tropical peatlands.
... Keberadaannya tergantung pada menahan air dan karakteristiknya tergantung pada asal, volume, kualitas kimia dan variabilitas pasokan air. Lahan gambut adalah jenis lahan basah terestrial yang terbentuk dari akumulasi endapan bahan organik dan dipengaruhi oleh kelembaban, kelembaban, topografi, kondisi geologi, pH, dan ketersediaan unsur hara (Page et al., 2006) (Rohmawati et al., 2016). ...
Peatlands have a crucial role in the global regulation of climate, the sequestration of carbon, and the conservation of biodiversity. Daily human activities and climate change have caused various environmental changes and ecological relationships for peatlands. An important thing to worry about is the decline in water quality, which harms the health and welfare of local communities that depend on clean water sources and drinking water from natural water. Additionally, the escalating demand for clean water necessitates substantial efforts in processing peatland water resources. The degradation in water quality harms the ecology and health of humans who use it for daily needs. Single Flow Ultrafiltration technology has emerged as a promising water treatment method, showing great potential in treating peat water while maintaining the ecological balance of peatlands. This research aims to evaluate the effectiveness of a combined treatment process consisting of filtration, absorption, microfiltration, and single-flow ultrafiltration. The application of this technology is carried out in the South Kalimantan region, with water processing stages, namely raw water filtration, semi-finished raw water filtration, ultrafiltration, and an ultraviolet irradiation process at the final stage so that the water is ready for consumption. Using both techniques, empirical methodologies were utilized to analyze the results of water quality and production capacity. This study proposes single-flow ultrafiltration to treat peat water for daily use. This research shows that the single-stream ultrafiltration treatment method for peat water gives a better water quality result than ordinary ultrafiltration treatment. This is indicated by the percentage difference in decreasing TDS values by 149%, turbidity by 200%, and color by 500%, increasing pH by 14.9%, decreasing nitrite by 135%
... Prolonged waterlogging depletes oxygen supply to roots, reduces the availability of some nutrients, increases the susceptibility of roots to pathogens, and thus reduces water and nutrient uptake and increases the chance of tree mortality (Kozlowski, 1997). Waterlogging can develop through seasonal flooding or occur in permanently waterlogged habitats such as peat or freshwater swamp or flooded forests (Page et al., 2006;Junk et al., 2011;Chong et al., 2021). Hydrology is a master variable controlling species diversity and abundance in wetland habitats, leaving only inundation-tolerant species to thrive (Mitsch & Gosselink, 2015;Chong et al., 2021). ...
Differences in demographic and environmental niches facilitate plant species coexistence in tropical forests. However, the adaptations that enable species to achieve higher demographic rates (e.g. growth or survival) or occupy unique environmental niches (e.g. waterlogged conditions) remain poorly understood. Anatomical traits may better predict plant environmental and demographic strategies because they are direct measurements of structures involved in these adaptations.
We collected 18 leaf and twig traits from 29 tree species in a tropical freshwater swamp forest in Singapore. We estimated demographic parameters of the 29 species from growth and survival models, and degree of association toward swamp habitats. We examined pairwise trait–trait, trait–demography and trait–environment links while controlling for phylogeny.
Leaf and twig anatomical traits were better predictors of all demographic parameters than other commonly measured leaf and wood traits. Plants with wider vessels had faster growth rates but lower survival rates. Leaf and spongy mesophyll thickness predicted swamp association.
These findings demonstrate the utility of anatomical traits as indicators of plant hydraulic strategies and their links to growth–mortality trade‐offs and waterlogging stress tolerance that underlie species coexistence mechanisms in tropical forest trees.
... >62% of global tropical peatland (ca. 23 million ha) is located in the lowland and coastal areas of Southeast Asia (Page et al., 2006). Indonesia alone accounts for about 36% of global tropical peatland and accommodates the largest tropical peatland in the world with 13,4 million ha (Warren et al., 2017). ...
Tropical peatland ecosystems in Southeast Asia offer essential ecological services but face various threats such as sea level alterations, climate change and human activities. However, our understanding of the origins of peatlands and their dynamics is still limited. Reconstruction of historical vegetation and environmental changes is imperative to comprehend tropical peatlands' origins, evolution and responses to natural factors (e.g., precipitation, sea level) and to human influences (e.g., agriculture). This study employed a multi-proxy palaeoecological analysis, encompassing pollen and spore analysis, macro-charcoal examination, and radiocarbon dating, using a sediment core extracted from the Bram Itam Peatland protection area in Tanjung Jabung Barat, Jambi province. The investigation highlights four distinct palynological periods: from ca. 4750 to 1250 cal yr BP, a dominant mangrove forest thrived in the study area during high sea levels; from 1250 to 450 cal yr BP, as sea levels receded, the mangrove forest was replaced by swampy vegetation, and peatland forests developed under the influence of high precipitation, while agricultural activities with possible rice cultivation were conducted remote from the study area; from 450 cal yr BP to 1950 CE, a mature peatland forest developed. There was no evidence of agricultural practice during this period. After 1950, intensive human activities, including logging, oil palm plantation, and rice cultivation, profoundly impacted the peatland vegetation. The presence of cereal pollen dates back to around 1250 cal yr BP and the introduction of oil palm (Elaeis guineensis) since roughly 1950 CE may indicate potentially enduring changes in agricultural practices of local people in the study area. This study of peatland vegetation dynamics and environmental changes in the Bram Itam peatlands highlights its change from mangrove forest to a matured peatland forest influenced by climate, sea level and human activities.
... The major reservoirs of nitrogen in peat soils and marine ecosystems include the reduction of nitrate and anammox [9]. Peat soils contribute to the maintenance of diverse ecosystem facilities, such as the reduction of excess nutrient runoff, conservation of biodiversity, sources of surface water and groundwater, and removal and storage of carbon dioxide [10]. ...
Nitrogen is an essential nutrient for living organisms in peat and marine soils, and its transformation within the soil matrix is a complex process mediated by various microbes that inhabit these ecological niches. The metabolism of nitrogen is governed by microbially mediated biogeochemical transformations, such as nitrification, anammox, and denitrification, which contribute to the assimilated pool of nitrogen and fixed nitrogen loss. One of the major challenges facing the field of peat and marine microbiology is the lack of understanding of the correlation between ecosystem-driven nitrogen transformation and microbial diversity. This is crucial because of growing concerns regarding the impacts of human-induced activities and global climate change on microbial nitrogen-cycling processes in peat and marine soils. Thus, this review aimed to provide a comprehensive overview of the current understanding of the microbial communities involved in peat and marine nitrification, anammox, and denitrification; the factors influencing the niche differentiation and distribution of the main functional components; the genes involved; and the main effects of human-induced activities and global climate change on the peat and marine nitrogen cycle. The implications of this review will facilitate an understanding of the complex mechanisms associated with ecosystem function in relation to nitrogen cycling, the role of peat and marine soils as carbon sinks, pollution remediation using naturally occurring populations of diverse microbes, and the development of policies to mitigate the effects of anthropogenic influences in peat and marine soils.
... Table 11) indicate quite acidic conditions. Such pH values can be found in low latitude (tropical) ombrotrophic peatlands (bogs sensu Inglis et al., 2018) of Southeast Asia (Anshari et al., 2010;Inglis et al., 2018;Ishikura et al., 2018;Murayama and Bakar, 1996;Page et al., 2006) and/or in raised bogs (Økland et al., 2001). The latter argues for ombrothrophic rather than minerotrophic mire and accounts for its low fertility and buffering by humic acids. ...
Second Miocene Seam Complex (2nd MFK; germ.: 2. Mioz¨aner Fl¨ozkomplex) holds many in-situ, not permineralised
fossil tree stumps and trunks with high-cellulose contents. The state of preservation of a set of in-situ fossil
trees (Taxodioxylon cryptomerioides, Sciadopityoxylon wettsteinii, and Quasisequoioxylon piskowitzense) collected
from three open-cast mines (Welzow-Süd, Meuro, and Piskowitz) in Lusatia lignite mining district, Federal Republic
of Germany was investigated using a multi-method research schema.
Examination of preservation state of thermally immature fossil woods revealed: (1) well-preserved (nondeformed,
non-degraded, and non-flattened) textinite, (2) a retained structural integrity represented by multilayered
(multi-zoned) cells with primary, secondary cell wall, and middle lamella, (3) microfracturing restricted
to secondary walls only, (4) preservation of polyphenolic parenchyma cells (PP cells), (5) excellent preservation
of pits in ray tracheids, (6) presence of amorphous silica (opal-A) coating, and (7) crystalline silica (opal-CT)
fillings of small-bladed crystals.
Thermogravimetric analysis results showed dissimilar gelification status of fossil samples, supporting chlorite
holocellulose assay results. The latter indicated anomalously high-cellulose values (15.6–37.6% holocellulose).
The micro-FTIR data obtained revealed an excellent preservation of both hemicellulose (bands at 1740 and 1245
cm 1) and cellulose (bands at 1110 and 1040 cm 1). Micro-FTIR spectrometry indicated lack of preferential
hydrolytic removal of polysaccharides in examined samples
... Table 11) indicate quite acidic conditions. Such pH values can be found in low latitude (tropical) ombrotrophic peatlands (bogs sensu Inglis et al., 2018) of Southeast Asia (Anshari et al., 2010;Inglis et al., 2018;Ishikura et al., 2018;Murayama and Bakar, 1996;Page et al., 2006) and/or in raised bogs (Økland et al., 2001). The latter argues for ombrothrophic rather than minerotrophic mire and accounts for its low fertility and buffering by humic acids. ...
Peatlands store disproportionally large amounts of carbon per unit area, a function that is dependent on maintaining high and stable water tables. Climate change is likely to negatively impact carbon storage in peatlands, in part due to increases in vapour pressure deficit (VPD) driving higher evaporation (E) rates. However, the response of E to increasing VPD depends on the dominant vegetation type within peatlands. In this study, we used multiple years of eddy covariance (EC) measurements to compare E regimes at two peatlands with contrasting vegetation types – Kopuatai bog in Aotearoa / New Zealand, dominated by the vascular wire rush Empodisma robustum, and Mer Bleue bog in Canada, a “typical” shrub- and moss-dominated Northern Hemisphere peatland. We examined seasonal variability in E and equilibrium E (Eeq), energy balance partitioning, and the response of E, evaporative fraction (EF), and canopy conductance (gc) to VPD. Mean annual E was 45 % lower than mean annual Eeq at Kopuatai but only 16 % lower at Mer Bleue, demonstrating much greater limitations on E at Kopuatai. In addition, the mean midday (10:00–14:30 local standard time) dry-canopy Bowen ratio (β) at Kopuatai was 2.0 compared to 0.8 at Mer Bleue; therefore, the sensible heat flux (H) dominated over the latent heat flux (LE) at Kopuatai and vice versa at Mer Bleue. The responses of E, EF, and gc to increasing VPD at Kopuatai demonstrated stronger limitations on evaporative water loss for VPD > 0.7 kPa compared to Mer Bleue. The observed limitations at Kopuatai were attributed to strong stomatal control by E. robustum due to the rapid decrease in gc with increasing VPD; however, surface E could also be limited by its dense standing litter. At Mer Bleue, however, E was only weakly limited at VPD > 2 kPa, likely due to weak stomatal control over transpiration by the sparse shrub canopy and relatively large surface E from Sphagnum carpets. As such, the results of this study suggest that E. robustum drives a greater “hydrological resistance” to increasing VPD than the vegetation at Mer Bleue, leading to greater water retention at Kopuatai. This may enable greater resilience of the carbon sink function at Kopuatai to climatic warming and drying than at Mer Bleue.
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.
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
