Peat Biomass Research Articles

Complex Microlandscape as a Structural Unit of the Study of Spatiotemporal Development of an Ombrotrophic Suboceanic Bog

Ombrotrophic suboceanic bogs are distinguished by a high diversity of complex microlandscapes within the bog massif. Each complex microlandscape is a separate intrabog ecosystem with a specific set of parameters and relationships. This study aims to assess the specifics of the characteristics and parameters of the complex microlandscapes as part of an ombrotrophic suboceanic Sphagnum bog and as stages of bog morphogenesis, and to establish the internal relationships and their relationship with external environmental factors. A comprehensive multidisciplinary approach was used to assess the functioning of the complex microlandscapes. It was found that the relationship with the air temperature is closer than with the bog water table dynamics. It was shown that the morphometric parameters of perennial dwarf shrubs can serve as indicators of the stages of development of bogs. The processes of the self-regulation of complex microlandscapes are weakened with the age of the complex microlandscape, as evidenced by an increase in the amplitude of temperature fluctuations and the level of bog waters, as well as the key physicochemical parameters of the peat deposit. This leads to a gradual, slow reorientation of the physicochemical processes occurring in the deposit, from the deposition of organic matter to the decomposition of peat biomass.

Comparison of the Economic and Environmental Sustainability for Different Peatland Strategies

Previous studies of the literature show that there are great uncertainties regarding costs and gains for peatland restoration strategies and that the monetary estimation of peatland restoration and possible alternatives can be complicated. The research aims to compare the economic costs and benefits of existing peatland restoration strategies and alternative use of peat and peatlands. A core method for the evaluation of the economic aspects of each strategy used is the composite index method. Information for constructing the composite index is based on data from the scientific literature, reports, and local project studies. In the study, peatland strategies, peat extraction, and alternative use in products were mutually compared with existing strategies. The highest composite index among strategies was for the production of insulation boards and cultivation of paludicultures using cattail or sphagnum farming. Cultivation of paludicultures can be an economically viable strategy if costs and gains are evaluated. Cultivation of cattail or sphagnum can make economic gains for landowners and farmers, and solutions for the reduction in necessary initial investments should be sought. Harvested biomass can be used for high-added-value products, in this case, insulation boards from cattail (Typha). Therefore, peat biomass can be used as an economically valuable resource, and raw material for insulation board production is obtained without the extraction of peat. Also, ecosystem services and potential income are not reduced.

Thermokinetics and synergistic effect analysis of peat-lignite coal co-pyrolysis

ABSTRACT In this study, the synergistic effect between peat and lignite coal was investigated in terms of kinetic energy and mass loss trends using a thermogravimetric analyzer. Thermogravimetric non-isothermal studies were conducted at different heating rates under inert nitrogen atmosphere. Kinetic analysis was performed using model-free KAS, OFW, and Starink methods and the average activation energies varied between 88.62 kJ/mol and 204.28 kJ/mol. Differential mass loss trends were determined using experimental and theoretical data. An obvious deviation was obtained at a blend ratio of PT:CL40:60. Thus, results revealed that the PT and CL co-pyrolysis has synergistic effects, especially for sample PT:CL40:60. SEM and BET analyses were performed on the coke sample of peat, coal, and PT:CL40:60 blend ratio samples for further analysis. The surface area of peat and coal was determined to be 416 m2/g and 83.06 m2/g, respectively. It was concluded that the porosity and surface area of coal (187.02 m2/g) increased with the addition of peat. The results are expected to be useful in the design of peat biomass and coal co-pyrolysis systems.

Effect of peat biomass smoke exposure on oxidative stress in Wistar rats

Background: Indonesia ranks third in the world regarding air pollution due to forest and land fires; most of the land burned is a peatland. Particulate matter (PM) 2.5 is the largest component of the total smoke particles. Short-term and long-term exposure to PM2.5 remains a hazard to human health.Objective: This study aims to examine the effect of exposure to peat biomass smoke on serum malondialdehyde (MDA) levels and body weight of Wistar rats.Methods: Experimental animals were randomly divided into three groups: Control group (C) is not given treatment, and treatment groups (X1 and X2) are exposed to smoke from peat biomass of 100 g and 150 g of biomass for 60 seconds per day for 14 days. The body weight was examined before and after treatment, while Serum MDA levels were examined after treatment.Results: The results showed significant differences (p < 0.05) in serum MDA levels between groups. The highest serum MDA levels were found in group X2 (3.03 ± 0.185 nmol/ml), followed by group X1 (2.67 ± 0.212 nmol/ml) compared to the control group (2.24 ± 0.476 nmol/ml). In contrast, increasing body weight between groups did not show a significant difference.Conclusion: Exposure to PM 2.5 from peat biomass smoke increases oxidative stress in experimental animals.

Iron-modified peat and magnetite-pine bark biosorbents for levofloxacin and trimethoprim removal from synthetic water and various pharmaceuticals from real wastewater

Humans are at significant risk of antibiotic resistance genes (ARGs) and antimicrobial resistance (AMR) via exposure to pharmaceutical contaminants in water, so there is a strong need for cost-effective environmental solutions to mitigate this crisis. This study introduces iron-modified peat and magnetite-pine bark as efficient, low-cost and green biosorbents for the adsorption of pharmaceutical contaminants from wastewater. Peat biomass, modified by iron extracted from a groundwater treatment sludge was dissolved in acid to prepare the iron-modified peat biosorbent, and pine (Pinus sylvestris) bark as a forest industry by-product was mixed with iron salts (Fe3+: Fe2+ = 2:1) to obtain the magnetite biosorbent. The adsorption of levofloxacin was little influenced by pH compared to trimethoprim. The equilibrium removal efficiency of antibiotics over both biosorbents was reached after 180 min contact time. The maximum adsorption capacity over iron-modified peat was about 200 mg/g for both antibiotics and over magnetite-pine bark 153.0 mg/g for levofloxacin and 184.1 mg/L for trimethoprim. Possible antibiotic adsorption mechanisms were proposed based on the Fourier transform infrared spectroscopy (FTIR) analysis. Experiments with real wastewater effluent revealed trimethoprim removal of 56.6–84.3% (dosage: 3 g/L). Moreover, a variety of other pharmaceuticals were removed by the biosorbents.

The partial contribution of CO2-emission losses from subsidence in small-holder oil palm plantation on a tropical peatland in West Kalimantan, Indonesia

Abstract. Astiani D, Widiastuti T, Ekamawanti HA, Ekyastuti W, Roslinda E, Mujiman. 2022. The partial contribution of CO2-emission losses from subsidence in small-holder oil palm plantation on a tropical peatland in West Kalimantan, Indonesia. Biodiversitas 23: 6539-6545. Carbon storage in tropical peat ecosystems over thousands of years, especially within peat soil, is in huge quantity. Degradation of peat ecosystems is generally caused by human factors, whether intentional or not, damaging the carbon storage function of tropical peatlands, where forest clearing, drainage development, and burning of land converted to agriculture and plantations result in significant greenhouse gas emissions. Tropical peat in the Kubu Raya District of West Kalimantan, which has a relatively large area of peat, has been degraded as a cause of uncontrolled drainage and land fires caused by a lack of management after its forest cover was lost. The main impact is an increase in peat CO2 emissions due to changes in land use, especially lowering groundwater levels. Subsequently, the subsidence process also occurs after land clearing. This study aims to obtain the proportion of carbon biomass loss due to the CO2 emission process from reducing the peat layer due to subsidence. Data collection was executed for two years, where CO2 emission was monitored bi-weekly, and the subsidence was measured bi-monthly. The results demonstrate groundwater levels dictate the peat CO2 emission and subsidence. Lowering GWL 30 to -85 cm increases CO2 by more than three times, approximately. The rate of peat subsidence shows similar trends to the emission. The proportion of peat biomass loss on CO2 emission was between 58.9 to 73.5%, except for GWL ~5 cm, where the proportion was the highest at 82%. The results of this study are beneficial in explaining the part of the subsidence that impacts the sources of CO2 emissions from the small-holder oil palm and GWL management on peatlands.

Enhancing faecal sludge derived biocrude quality and productivity using peat biomass through co-hydrothermal liquefaction

Faecal sludge (FS) and drained peatlands have become the hotspots research area in recent years, causing significant environmental pollution and greenhouse gas (GHGs) emissions. Hence, this study explored the co-hydrothermal liquefaction (co-HTL, 300 °C for 60 min) of peat (P) and FS at different ratios (100:0, 25:75, 50:50, 75:25, and 0:100% of P: FS) to produce high-quality biocrude as a “waste to energy” approach. A positive synergistic effect was observed in P and FS co-HTL with higher biocrude yield and enhanced quality than individual HTL. Among the co-HTL ratios, the optimum biocrude yield of 44.58% was observed for the 50-50 ratio (P50FS50) with a conversion rate of 55.8% and energy recovery of 72%. However, the highest HHV was obtained from co-HTL of P75FS25 (35.5 MJ/kg), where biocrude had higher C (70.5%) and H (10.4%) contents with less amount of N (0.01%). The elemental composition of co-HTL indicated that biocrude had potential similarities to petro-crude. FTIR analysis confirmed that biocrude samples had aliphatic hydrocarbons, phenols, and esters, where the oil quality was immature to premature grade oil of kerogen type I (highly oil-prone). GC-FID hydrocarbon fractionation analysis revealed that the optimum lighter fraction crude (35.3%) was produced from co-HTL of the P50FS50 sample. In this context, the findings demonstrated that the co-HTL of P and FS might be an alternative approach for green biocrude oil production.

Lower Gondwana megaflora, palynoflora, and biomarkers from Jagannath Colliery, Talcher Basin, Odisha, India, and its biostratigraphic significance

The study of megafossils, palynomorphs, and biomarkers has been carried out from a fossiliferous section of Jagannath Colliery, Talcher Basin, Odisha, India. The megafloral assemblage recovered from the carbonaceous shale bed of the investigated section comprises 15Glossopterisspecies (leaf form),Vertebraria indica(root form), and stem cast of the order Glossopteridales. The megafloral assemblage and lithology (grey shale, carbonaceous shale, sandy shale, and coal seams) of the litho‐column suggest that the sediments belong to the Barakar Formation (Artinskian‐Kungurian age). Palynoflora recovered from the section is dominated byStriatopodocarpitesspp. (35–44%) and subdominated byFaunipollenitesspp. (29–35%) along with a good percentage ofDensipollenitesspp. Stratigraphically significant taxa of this palynoassemblage show its affinity toward the late Permian (Wuchiapingian‐Changhsingian) palynoflora which is geologically mapped as Barakar Formation of early Permian (Artinskian‐Kungurian) age. As a result, to clearly delimit the distribution of different lower Gondwana strata in this area, more precise palynological sampling and extensive geological mapping should be undertaken. The dominant occurrence of short‐chainn‐alkanes in the samples suggests the abundance of algal and microbial sources that are deposited in moderate water level conditions in the basin. Pristane/phytane ratio suggests oxic settings while the hopane distribution in the studied samples suggests significant bacterial degradation of the peat biomass in the depositional milieu.

Studies on individual pyrolysis and co-pyrolysis of peat–biomass blends: Thermal decomposition behavior, possible synergism, product characteristic evaluations and kinetics

Chemical reaction engineering of pine branches and peat is crucial yet challenging in enhancing pyrolysis products quality for the synergistic effect and kinetic parameters distribution. Herein, the three-phase product yield and tar component distribution were studied through a series of characterization methods. Thermogravimetric analysis (TGA) data at different heating rates was obtained and synergistic effect in the CPBP were discussed. Through the three kinetic models to calculate the obtained TGA data and determine the kinetic parameters. The characteristics of mass loss from individual pyrolysis and co-pyrolysis registered in TGA during temperature programmed heating is attributed mainly to devolatilization of volatile fragments, and the heating rate and the mixing ratio of the samples experienced significant change on the weight loss. A weaker interaction in the process of co-pyrolysis of pine branches and peat (CPBP) is observed under the condition of multiple factors investigated in this work. The pyrolysis temperature is lower than 400 °C, the volatiles are not released in time, and remain in the pores of the pyrolysis char, which increases the yield difference of char. The relative abundance of the number of substituents in the monocyclic aromatic structure in tar is C3 < C0 < C1 < C2. The relative abundance of two methyl groups in the benzene series in tar exhibited the largest value, as indicated from GC–MS results. Conventional gas products such as H2O, CO2, CO, CH4 and H2 were detected. The activation energy was not a constant value, but changed with the progress of the reaction, indicating that the decomposition reaction mechanism changed as the reaction progressed. The activation energy and linear correlation determined using the KAS and FWO methods were higher. The aforementioned methods were more appropriate and reliable for the thermo-kinetics studies in CPBP.

Local knowledge on landscape sustainable-hydrological management reduces soil CO2 emission, fire risk and biomass loss in West Kalimantan Peatland, Indonesia

Abstract. Astiani D, Taherzadeh MJ, Gusmayanti E, Widiastuti T, Burhanuddin. 2019. Local knowledge on landscape sustainable-hydrological management reduces soil CO2 emission, fire risk and biomass loss in West Kalimantan Peatland, Indonesia. Biodiversitas 20: 725-731. Local knowledge in managing peatlands, especially in the area of peat hydrology, has been practiced through generations to manage peatlands for agriculture and small scale gardens. Farmers in West Kalimantan have developed the way to conserve water by making simple dams using soil or woody plants to hold water from the peat upstream areas on small channels or rivers. To reduce puddles during rain or tides, people make small trenches, so-called parit cacing in the middle of the larger channel. The trench cross-section size is ~30-40 cm2. This channel can maintain the peat water level to the extent of the depth of the channel. These channels, at the same time, are useful, for a clear, easy land ownership border for one farmer family land. The results of CO2 emissions assessment at various water levels on the peatland landscape demonstrate that the landscape which surrounded by the parit cacing trenches can maintain lower CO2 emissions compared to the one that has deeper water levels. The knowledge to develop this channel has also reduced the risk of peatland fire hazard and the amount of peat biomass loss on a fire event. An assessment on the effect of water level on the loss of peat biomass when burned, reduce 30-78% loss risks if compared to water table depth of 60-80cm, which is assumed as general practices on peatland recently. The practices of the knowledge on peatlands hydrology management can reduce the risk of peatland soil CO2 emission as well as loss of peat mass through decomposition and during peat fires.

Depositional palaeoenvironment and economic potential of Khadsaliya lignite deposits (Saurashtra Basin), western India: Based on petrographic, palynofacies and geochemical characteristics

The lignite and associated shale of the Khadsaliya Clays Formation (Eocene) of Saurashtra Basin, India have been studied. Organic petrographic, palynofacies and organic geochemical analyses have been carried out to deduce the depositional palaeoenvironment, including the assessment of the hydrocarbon potential of this sequence. Petrographically, the lignites constitute huminite macerals in dominance (av. 60%). The organic facies, as derived from maceral composition and biomarker data, suggests that the peat biomass was formed from woody forest vegetation consists of angiosperms and pteridophytes. Microbial activity was also prominent over the peat biomass. The peat biomass was deposited in tropical-subtropical humid climatic conditions under deltaic control and brackish water influence. Further, there are signatures of intermittent floods in the mire, and is evident from the shift from mesotrophic to rheotrophic conditions. The organic matter has been categorized into two palynofacies and is derived from degraded terrestrial biomass. The extrapolation of Tyson's APP diagram and Pr/n-C17vs. Ph/n-C18 plot suggest that deposition took place in dysoxic to sub-oxic conditions.The huminite reflectance values (0.30–0.38%, av. 0.34% Rr) suggest that lignites are less mature and have reached up to lignitic stage (low rank B) of coalification. The geochemical (proximate+ultimate) analyses reveal that the lignites are characterized by high moisture content (av. 18%) and relatively low ash yield (av. 27%). The volatile matter yields and carbon contents are moderately high, whereas fixed carbon, sulphur and oxygen contents are average and hydrogen and nitrogen contents are relatively low. Rock-Eval pyrolysis data indicate that the hydrogen index values of the samples vary between 23 and 477mgHC/gTOC (av. 188mgHC/gTOC). The Tmax values of the lignites range between 377 and 433°C (av. 418°C), along with the presence of ββ hopanes suggesting the immature nature of the deposits. HI vs. Tmax, S2 vs. TOC, HI vs. OI and H/C vs. O/C plots of the studied samples indicate that the organic matters are a mix of type II/III kerogens. The types of kerogen along with high TOC contents (av. 33wt.%) indicate the ability of lignite-bearing sequence of Khadsaliya to generate mix of oil/gaseous hydrocarbons upon maturation.

Peat biomass degradation: Evidence from fungal and faunal activity in carbonized wood from the Eocene sediments of western India

An integration of reflected light and transmitted light study of Eocene lignite along with Scanning Electron Microscope (SEM) examination of carbonized wood from Kapurdi lignite of the Barmer Basin has yielded abundant fungal components and arthropod appendages. The carbonized wood section under SEM shows tyloses, a physiological process as a response to fungal infection. Scolecodonts and annelid body parts were also recovered from the studied sediments, indicating the peat biomass was a thriving habitat for detritivores. In petrographic examination of the lignite beds which underlay and overlay the carbonized wood section, the funginite is found to be associated with resinite, indicating that the funginite inclusion was not accidental but encapsulation of fungi by exuded resin of the plant as a defense mechanism. Funginite is found in higher percentages in detrohuminite (attrinite) groundmass in lignites. The degradation of the humic matter is attributed to the fungal infestation as well as faunal activity in the peat mire. This fungal–faunal interaction resulted in alteration of the organic matter and origin of macerals belonging to inertinite group.

Marine influence helps preserve the oil potential of coaly source rocks: Eocene Mangahewa Formation, Taranaki Basin, New Zealand

Many Cretaceous–Cenozoic coaly source rocks in Australasian and southeast Asian basins were deposited in coastal plain environments, yet the effect of early diagenetic marine influence on their oil potential is not well understood. An integrated organic geochemical and petrographic study of humic coals from the Eocene Mangahewa Formation (Taranaki Basin, New Zealand) was undertaken with coals predominantly from raised mire petrofacies, with subordinate proportions from planar mires. The total S content of 0.63–4.4% (dry, ash-free) indicated very slight to strong degrees of marine influence. Other than minor addition of inferred mangrove derived suberinite and associated liptodetrinite, the degree of marine influence had no obvious effect on maceral or plant tissue abundance. However, hydrogen index (HI) values were up to ca. 150% (109mgHC/gTOC) higher, and total (C6+) oil potential up to ca. 140% (43mg/gTOC) higher among the more strongly marine influenced coals. Correlation of organic S with solvent extract parameters pristane/phytane, C27–C29 diasteranes/steranes, C29 steranes/hopanes, C35/(C35+C34) homohopanes and oleanane index suggested that inundation of brackish water into the early diagenetic peat forming environment enhanced the bio-resistance of higher plant and other lipids through sulfurization, thereby helping to preserve more of the inherent H content and total oil potential of the original peat biomass. Conversely, marine influence had only a minor effect on the capacity of Mangahewa coals to generate paraffinic oil. Total (n-C6+) and non-volatile (n-C15+) paraffinic oil potentials were instead controlled primarily by the abundance of leaf derived cutinite and associated liptodetrinite. This, in turn, was dependent on the type of peat mire facies, with planar mire facies having better potential for preservation of leaf litter than raised mire facies because of their generally higher groundwater level. Marine influence is nonetheless beneficial for paraffinic oil charge from coaly source rock sequences in that the associated higher HIs enhance the efficiency and quantum of paraffinic oil expulsion through increased saturation of the coal pore system.

Characterization of Mangrol lignite (Gujarat), India: Petrography, palynology, and palynofacies

A multidisciplinary approach (petrographical, palynological and palynofacies) has been adopted to characterize and assess the depositional conditions of Eocene Mangrol lignite deposit from western India. The petrographic study reveals that the lignite is composed predominantly of huminite macerals produced from a woody forest. The reflectance values range from 0.27% to 0.32%, indicating a lignite rank. The variable values of tissue preservation index (TPI) and gelification index (GI) as well as the maceral composition indicate fluctuating ground water conditions and difference in the type of vegetation during peat accumulation. The palynofloral spectrum suggests the presence of angiosperms (including mangrove) and pteridophytes belonging to families of Bombacaceae, Annonaceae, Alangiaceae, Ctenolophonaceae, Liliaceae, Osmundaceae, Schizaeaceae, Matoniaceae, Cyatheaceae, among others as the peat biomass source materials for the origin of these lignites. The palynomorphs indicate that a tropical to sub-tropical climatic condition was present during deposition of the peat biomass and that the original mire likely occurred in a coastal setting. This interpretation is strongly supported by palynomorphs with affinity to brackish-water taxa. Palynofacies studies suggest peat deposition under dysoxic conditions in a marginal marine setting. High amount of amorphous matter (kerogen type I) in the shale bed above the lignite and very high content of liptinite in lignite, mainly comprised of resinite and liptodetrinite, suggest the potential of both shale and lignite for the generation of hydrocarbon.

Peat biomass and early diagenetic controls on the paraffinic oil potential of humic coals, Canterbury Basin, New Zealand

Early mature, Pukeiwitahi Formation (Late Cretaceous) coals from Galleon-1 and Endeavour-1 wells in the Canterbury Basin, New Zealand have been analysed by petrographic, bulk chemical and thermal extraction- and pyrolysis-GC techniques and compared with similar coals in the Taranaki Basin to determine the primary controls on their paraffinic oil potential. The Pukeiwitahi coals, which are moderately perhydrous (HI 180–305 mgHC g −1 TOC), vitrinite-rich (73–95%) and relatively liptinite-poor (&lt;10%), accumulated in gymnosperm-dominated, planar mires in a temperate, coastal plain environment. Pyrolysate compositions are representative of high-wax, paraffinic–naphthenic–aromatic crude oil-generating coals. Petrographic data and the n -alkyl chain length distributions of extracts and pyrolysates suggest that the long-chain aliphatic hydrocarbons are derived primarily from leaf-derived liptinites (cutinite and liptodetrinite). The paraffinic oil potential of the coals is accordingly dependent on the net amount of leaf biomass in the precursor peats, following partial degradation of the available leaf litter under generally high surface water levels and dilution with other, less paraffinic biomass, particularly wood. The coals in Endeavour-1 generally contain more leaf-derived liptinites than those in Galleon-1 and, thus, have greater paraffinic oil potentials despite commonly lower HI values. Brackish conditions within the depositional environment caused the Galleon-1 and Endeavour-1 coals to be variably enriched in hydrogen but not in aliphatics. HI is, therefore, not a reliable indicator of the paraffinic oil potential of marine-influenced coals.

Development of multimetal binding model and application to binary metal biosorption onto peat biomass

Biosorption of Cr 3+, Cu 2+ and Cd 2+ from binary metal solutions onto peat in the batch systems was investigated at pH 4. The order of maximum uptake was Cr⩾Cu>Cd and maximum uptake levels of ca. 0.4 mmol/g were observed for chromium and copper while cadmium was taken up to a maximum of ca. 0.2 mmol/g. Co-ion competition resulted in up to 70 percent decrease of primary metal uptake. A novel approach to multicomponent sorption modelling involving regression to the total metal taken up was adopted. Two extended Langmuir-type models were found to exhibit good fit to the experimental data. Using the simpler model of these, three-dimensional sorption surfaces were generated which describe the metal uptake as a function of equilibrium concentrations of both metals. These methods allow prediction of metal uptakes over a continuum of concentrations of both metals in binary systems.

Organic facies and depositional palaeoenvironment of lignites from Rio Maior Basin (Portugal)

The Rio Maior Basin (Portugal) is a tectonic depression, filled by a Pliocene sequence that comprises, from floor to roof: (i) kaoliniferous fine sands, (ii) diatomites and lignites, (iii) recent deposits of sandstone and clay. The diatomites and lignites form a small dissimetric syncline with alternating seams. Ten lignite seams were identified and named from floor to roof as F, E, D, C.2, C.1, C, B, A, a and a′. Seams A, D, E and F are considered to be the main seams. The organic fraction consists mainly of macerals of the huminite group, with small percentages of inertinite and liptinite groups. However, the petrographic composition of each seam is distinct, particularly with regards to macerals of the huminite and liptinite groups. Calculation of petrographic indices permitted to plot the coals in facies and palaeoenvironment diagrams. Five facies have been defined: (i) aquatic, (ii) herbaceous swamp, (iii) mixed swamp with forest and herbaceous vegetation, (vi) forest swamp (wetter) and (v) forest swamp (drier). These lignites are humic coals formed from organic matter of terrestrial origin. The peat biomass at the origin of these coals formed from a very diverse vegetation comprising gymnosperms and angiosperms. In seams F, and occasionally in seams E and D, Botryococcus algae have also contributed to the biomass. Peat deposition corresponded to a rheotrophic hydrological regime: the water level always remained above the topographic surface of the basin. Nevertheless, during the deposition of seam A in the northern part of the basin, the water level was slightly below the topographic surface. The organic matter was preserved in anaeorobic conditions.

Paleobotanical and paleoecological constraints on models of peat formation in the Late Carboniferous of Euramerica

The dominant plants of the Late Carboniferous lowland tropics were taxonomically and structurally distinct from those of any later time periods. Dominance was distributed among lycopsids, ferns, sphenopsids, pteridosperms and cordaites, and each of these groups had distinctive and different ecological preferences and amplitudes. Peat-forming habitats were dominated by lycopsids throughout the Westphalian, with a significant cordaitean element in the middle Westphalian; during the Stephanian tree ferns were dominant, following major extinctions near the Westphalian-Stephanian transition. Each of the major plant groups had distinctive architectures and tissue composition. Trees contributed up to 95% of the peat biomass and tree forms of lycopsids. Psaronius and Medullosa lack good modern analogues. The cordaites were the only woody plant group to contribute significantly to peat, and then only during the mid-Westphalian. Structurally wood-like lycopsid bark is the major “woody” tissue encountered in most Westphalian coals. Tree ferns and pteridosperms were largely parenchymatous in construction; the stigmarian root systems of lycopsids also were largely parenchymatous. The tissue structure of these dominant plant suggests the need for extreme caution in the inference of mire ecological conditions or vegetational structure from coal petrographic data. Peat formed under arborescent ferns or pteridosperms, or peat repeatedly exposed to decay and rerooting by stigmarian root systems of lycopsids, would have a distinctly non-woody signature and yet would have formed in a forested environment. A summary is presented of the autecology and synecology of mire plants, emphazing the structural framework provided by lycopsids during the Westphalian. Certain constraints in the links between peat biomass and miospore palynology are discussed in terms of over-representation, under-representation and non-representation. The formulation of Smith's four-phase hydroseral model is discussed and compared with more recent data available from plant paleoecology. The current debate over an ombrotrophic vs. rheotrophic origin of Late Carboniferous peats relies in large part on paleobotanical data, almost entirely palynological, in combination with petrographic analyses. Ecological studies of miospores and of coal-ball and compression macrofossils, and the linkage of miospores to source plants, permit the re-evaluation of mire successional models. Evidence for tree lycopsids, sphenopsids, pteridosperms and cordaites suggests growth mainly in rheotrophic mires. Tree ferns are likely candidates for growth in domed mires, although evidence is ambiguous and some tree ferns clearly grew under rheotrophic conditions. Densospores, produced by at least Sporangiostrobus lycopsid subtrees, have been considered diagnostic of ombrotrophic conditions; abundant evidence refutes this simplistic interpretation and suggests broad ecological amplitudes for densospore producers, including growth under rheotrophic conditions. Although plant fossils alone can not resolve most of the major debates in modern coal geology, paleobotany does contribute significantly to our understanding of ancient mires. An approach combining paleobotanical data with petrography, sedimentology and geochemistry, on a case by case basis, is most likely to produce a clear picture.

Paleoecology of the Middle Pennsylvanian-age Herrin Coal Swamp (Illinois) near a contemporaneous river system, the Walshville paleochannel

Coal-ball peats were sampled quantitatively in seven profiles from the Old Ben Coal Company No.24 Mine in southern Illinois. The coal and the coal-ball peats are thicker in this near-channel area than at any site sampled so far. Lycopods dominate the peat-swamp flora, as at other Herrin Coal sites, with Lepidophloios hallii being the most important (30–78% of whole-profile peat biomass). Ferns (5–15% biomass), and pteridosperms (1–15% biomass), also are important in the swamp flora. Shoot-root ratios in profiles are relatively high, 1.4–2.8. Fusain abundance is concentrated in several mid-seam zones (above the blue-band clastic parting) with the highest pteridosperm abundances. Three major plant associations (“communities”) are detected by multivariate analyses. The most common assemblage is dominated by Lepidophloios hallii (>70% of biomass), with low-diversity and little representation of ground-cover and free-sporing plants; this is interpreted as representative of standing-water, high abiotic-stress conditions. Lepidophloios assemblages are common in all profiles. Diaphorodendron scleroticum and D. dicentricum characterize a second assemblage (>20% of biomass) that can include a diversity of species and growth forms; these associations appear to be structured by disturbance. Diaphorodendron is most abundant just above the seat earth and in several consecutive zones near the top of the seam. Medullosa (>20% biomass) characterizes the third major assemblage; Medullosa assemblages are most common at the base of the seam, in proximity to the blue-band clastic parting, and in a mid-seam interval of “dirty” coal. The association of Medullosa with zones of >10% fusain and abundant mineral matter suggests alternation of flooded and dry conditions. Psaronius tree ferns form an overprint on these distributions, occurring widely in all but Lepidophloios-dominated assemblages.