Bog Conditions Research Articles

Organic petrology and geochemistry data reveal depositional and thermal history of coal in the Guaduas formation, Colombian Eastern Cordillera

Colombia is a country rich in coal deposits; however, there are few published studies characterizing these coals in detail from a scientific perspective. This study investigates the thermal maturity and depositional environment of a coal seam from the Guaduas formation (Maastrichtian-Paleocene) of the Eastern Colombian Cordillera Basin, providing insight into burial and temperature history and changes in the depositional environment over time. This three-meter-thick hard coal seam reflects about 20 m of former peat deposition, representing a period of roughly 10.000 years.Five large, fresh samples (A to E) were collected from the seam every thirty centimeters and divided into seventeen sub-samples analyzed using organic petrological methods, Rock-Eval pyrolysis and organic geochemistry. Different thermal maturity- and depositional environment-related parameters have been determined. Results reveal a maturity of approximately 0.9% vitrinite reflectance, and relatively high HI values (kerogen type II-III). Correspondingly, high values of νCHx over γCH indicate a high relative abundance of aromatic rings over aliphatic groups. Moreover, high CH2/CH3 ratios suggest long and simple aliphatic chain structures. Molecular data indicate a balanced odd- over even n-alkane distribution and a high amount of long-chain n-alkanes. High Pr/Ph ratios and hopanoid biomarkers reveal an oxidizing depositional environment. The coal seam investigated in this study is characterized by low ash yields and low sulfur contents particularly in the central part of the seam, while percentages of inertinite are high (up to 54 Vol.-%). This data supports a low water table and oligotrophic, raised bog conditions during deposition in a humid, tropical climate which is consistent with the almost equatorial position of the study area during deposition of the Guaduas Formation. Water was mainly supplied via rainfall leading to overall low ash yields. In contrast, the top of the coal seam is strongly enriched in sulfur revealing that rapid marine flooding ultimately ceased peat accumulation leading to authigenic pyrite formation.

Mosses and vascular plants show diverging diversity patterns along a latitudinal gradient in boreal bogs and fens

AbstractQuestionsThe latitudinal biodiversity gradient; i.e., the increase in biodiversity towards the equator, is one of the most prominent biodiversity patterns. Nevertheless, many questions remain to be answered about the influence of multiple environmental factors on the latitudinal biodiversity gradient, especially for mosses, and the functional diversity of mosses and vascular plants. This study aims at evaluating the influence of latitude, climate, environmental variables, and habitat types (bog vs fen) on taxonomic and functional diversity (α‐diversity and β‐diversity) and the composition of vascular plant and moss species.Location49° N to 55° N in Northwestern Quebec, Canada.TaxonMosses, vascular plants.MethodsWe used a database containing 376 phytosociological plots (400 m2) sampled in boreal peatlands located along a 600‐km latitudinal gradient. We evaluated changes in α‐diversity and β‐diversity in response to latitude, longitude, climate, and local abiotic variables for both taxonomic groups using linear mixed effect models. We evaluated the effects of these variables on taxonomic and functional composition using variance partitioning by redundancy analysis.ResultsMoss diversity increased with latitude, although the effects were masked by environmental variables, whereas vascular plant diversity decreased with latitude in fens and did not vary with latitude in bogs. We observed a decrease in taxonomic and functional uniqueness with latitude. Moss and vascular plant taxonomic and functional composition were primarily structured by contrasting local conditions in bogs and fens, whereas climatic variations along the latitudinal gradient played a secondary role.ConclusionsOur results highlight the contrasting biodiversity patterns in both peatland types and the importance of local habitat conditions in structuring vascular plant and moss diversity. These patterns varied depending on the diversity indicator used, as α‐ and β‐diversity and functional and taxonomic diversity were often decoupled. Future studies should therefore include more than one diversity indicator and consider the differences between ecosystems and taxon groups.

Permafrost development in northern Fennoscandian peatlands since the mid-Holocene

ABSTRACT Increased permafrost temperatures have been reported in the circum-Arctic, and widespread degradation of permafrost peatlands has occurred in recent decades. The timing of permafrost aggradation in these ecosystems could have implications for the soil carbon lability upon thawing, and an increased understanding of the permafrost history is therefore needed to better project future carbon feedbacks. In this study, we have conducted high-resolution plant macrofossil and geochemical analyses and accelerator mass spectrometry radiocarbon dating of active layer cores from four permafrost peatlands in northern Sweden and Norway. In the mid-Holocene, all four sites were wet fens, and at least three of them remained permafrost-free until a shift in vegetation toward bog species was recorded around 800 to 400 cal. BP, suggesting permafrost aggradation during the Little Ice Age. At one site, Karlebotn, the plant macrofossil record also indicated a period of dry bog conditions between 3300 and 2900 cal. BP, followed by a rapid shift toward species growing in waterlogged fens or open pools, suggesting that permafrost possibly was present around 3000 cal. BP but thawed and was replaced by thermokarst.

Restoring organic matter, carbon and nutrient accumulation in degraded peatlands: 10 years Sphagnum paludiculture

Drained peatlands emit large amounts of greenhouse gases and cause downstream nutrient pollution. Rewetting aids in restoring carbon storage and sustaining unique biodiversity. However, rewetting for nature restoration is socio-economically not always feasible. Cultivation of Sphagnum biomass after rewetting allows agricultural production. In the short term, Sphagnum paludiculture is productive without fertilization but it remains unclear whether it sustains its functionality in the longer-term. We studied nutrient dynamics, organic matter build-up, and carbon and nutrient accumulation at a 16-ha Sphagnum paludiculture area in NW-Germany. Site preparation included topsoil removal and inoculation with Sphagnum and it was rewetted five and ten years ago and managed with mowing, irrigation, and ditch cleaning. The unfertilized sites were irrigated with (compared to bog conditions) nutrient-rich surface water and exposed to atmospheric nitrogen deposition of 21 kg N/ha/yr. Our data reveal that ten years of Sphagnum growth resulted in a new 30 cm thick organic layer, sequestering 2,600 kg carbon, 56 kg nitrogen, 3.2 kg phosphorus, and 9.0 kg potassium per ha/yr. Porewater nutrient concentrations were low and remained stable over time in the top layer, while ammonium concentrations decreased from 400–700 to 0–50 µmol/L in the peat profile over 10 years. Hydro-climatic fluctuations most likely caused the variation in ammonium in the top layer. We conclude that Sphagnum paludiculture enables rapid carbon and nutrient accumulation without active fertilization provided the biomass is not harvested, and provides perspective for bog restoration on agricultural peatlands. Large-scale application of Sphagnum paludiculture may mitigate environmental issues of unsustainable peatland-use.

Summer soil CO2 emission from bog surface: controlling factors

The peatlands in the northern hemisphere cover just 3% of the global landmass but their impact to the carbon emission is huge. The current climate changes exert influence on these ecosystems by changing water supply, temperature regime, plant growing activity and others. Nowadays studies predicted the important role of the northern bogs and peatlands as an additional source of atmospheric CO2. In our study we estimated how microrelief and microclimatic conditions can control the CO2 emission from the bog area. We compared also the waterlogged bog conditions and forest ecosystem to find out the main drivers of soil emission dynamics during the summer season. The rate of CO2 emission varies widely within bog area depending on the microrelief of the area: hollow – 0.74±0.03, ridge – 1.69±0.08 kg CO2 m–2. The comparative analysis versus the forest area showed that the upland parts of the bog area are not inferior to the forest area in terms of the emission rate. Moisture conditions determined the CO2 efflux for the hollow site (r=0.49, p<0.05) and forested area (r=0.39, p<0.05). The temperature impact is observed for all sites and it is significant throughout the season.

The late-Holocene relationship between peatland water table depth and summer temperature in northern Poland

Although the contribution of current summer warming to the widespread drying of European peatlands is undeniable, summer temperature fluctuations alone are unable to explain all the hydrological shifts of these ecosystems. We aim to determine whether the current coupling of high summer temperatures and low water tables of peatlands in northern Poland is recent or has been stable over long timescales, and to infer the climatic context driving past relationships between temperature and peatland hydrology. We compare the previously published 4000-year long paleohydrological record from Kusowo bog with a new chironomid-based summer temperature record covering the last 4.5 ka from nearby (~7 km) Lake Spore. Although several simultaneous shifts in our hydrological and temperature reconstructions are evident on multi-decadal to centennial timescales, for instance during the peak cooling of the Migration Period or Little Ice Age (~1.4 and 0.4 cal ka, respectively), the records reveal mostly independent fluctuations. However, the relatively high uncertainty of our quantitative estimates suggests caution is warranted when inferring the strength of the relationship between the reconstructed variables at this temporal resolution. However, at centennial to millennial timescales, the relationship between the records is surprisingly strong. Overall, warmer summers (mean July temperature = 18.7 °C) before ~2.3 cal. ka corresponded well with lower ground water tables at Kusowo bog (mean = 11.2 cm), whereas cooler summers in the following period (mean = 17.4 °C) were accompanied by higher water tables (mean = 7.9 cm). Particularly wet bog conditions during the last ~0.7 ka were also the coldest. The finding that on long timescales the drying of Kusowo bog coincided with warming suggests a persistent regional climate pattern in which drought conditions change along with summer temperatures. If this millennial-scale pattern holds for the projected warming, further peatland drying can be expected in northern Poland. • We compare paleohydrological record from a bog with a summer temperature reconstruction • On millennial timescales, dry conditions at the bog were concurrent with high temperatures • Conditions at the bog were generally drier before 2.3 cal. ka BP and wetter thereafter • Temperature rise above the late-Holocene maximum can result in unprecedented drying

Key periods of peatland development and environmental changes in the middle taiga zone of Western Siberia during the Holocene.

The response of peatlands to climate change can be highly variable. Through understanding past changes we can better predict the response of peatlands to future climate change. We use a multi-proxy approach to reconstruct the surface wetness and carbon accumulation of the Mukhrino mire (Western Siberia), describing the development of the mire since peat formation in the early Holocene, around 9360cal. year BP. The mire started as a rich fen which initiated after paludification of a spruce forest (probably in response to a wetter climate), while the Mukhrino mire progressed to ombrotrophic bog conditions (8760cal. year BP). This transition coincided with the intensive development of mires in Western Siberia and was associated with active carbon accumulation (31gm-2 year-1). The ecosystem underwent a change to a tree-covered state around 5860cal. year BP, likely in response to warming and possible droughts and this accompanied low carbon accumulation (12gm2 year-1). If the future climate will be warmer and wetter, then regional mires are likely to remain a carbon sink, alternatively, a reversion to the wooded state with reduced carbon sink strength is possible.

Monitoreo a corto y largo plazo en ensayos de restauración de la conífera longeva y de lento crecimiento Pilgerodendron uviferum

Long-term monitoring is essential to understand responses to restoration actions in slow-growing species such as the native conifer Pilgerodendron uviferum. After catastrophic fires, most trees and seeds of this conifer were eliminated, limiting its natural recovery. The objective of this study was to analyze the implications of short-term and long-term monitoring on the interpretation of results in passive and active restoration experiments with Pilgerodendron uviferum in Chiloe Island. For 10 years, the processes of seed production and natural plant recruitment, and assisted regeneration through plantations of P. uviferum were evaluated in different microsite conditions in bogs, and light availability in sites with better drainage. The production of P. uviferum seeds was irregular and abundant every seven years (~200 seeds m-2). The natural regeneration after eight years increased by 80 %, especially in substrates with mosses and in association with Donatia fascicularis and Astelia pumilia. The abundance of natural regeneration was positively associated with older trees, the height and diameter of plants was favored by the protection of shrubs. In bogs, plants established on mounds reached higher levels of survival (78 %) and in sites with better drainage, survival was higher under canopy protection (100 %). Our results suggests that slow-growing species, such as P. uviferum, require long periods of monitoring to adequately interpret the results of restoration experiments in burned forests.

Disentangling the effects of methanogen community and environment on peatland greenhouse gas production by a reciprocal transplant experiment

Abstract Northern peatlands consist of a mosaic of peatland types that vary spatially and temporally and differ in their methane (CH4) production. Microbial community composition and environment both potentially control the processes that release carbon from anoxic peat either as CH4 or as carbon dioxide (CO2), a less potent greenhouse gas than CH4. However, the respective roles of these controls remain unclear, which prevents incorporating microbes in the predictions of peatland CH4 emissions. Here, a reciprocal transplant experiment was carried out to separate the influences of microbial community and environment in CH4 and anaerobic CO2 production. Peat from an acidic Sphagnum bog and a sedge fen with higher pH was enclosed in membrane bags with a pore size of 0.2 µm, preventing microbial colonization from the outside, and transplanted in the field for 2 months. Potential CH4 production was primarily controlled by the environment. The conditions in the bog suppressed the initially higher activity of fen methanogens and reduced CH4 production by 79%. Against expectations, the inhibition was not specific to acetate‐using Methanotrichaceae. Reciprocal transplantation favoured Methanosarcinaceae and potentially methylotrophic methanogenesis in general. Bog methanogens, mostly hydrogenotrophic Methanoregulaceae, retained their community structure and activity in the fen with a slight increase (+37%) in CH4 production. Anaerobic CO2 production was controlled by both the microbial community and the environment. Transplantation led to increased CO2 production in both bog (+50%) and fen peat (+57%) with distinct bacterial community, showing that the new environment directed more carbon to other anaerobic processes than methanogenesis. Taken together, these results relate differences in CH4 production of bogs and fens to ecophysiology of specific methanogen groups. The sensitiveness of fen methanogens to the acidic conditions in Sphagnum bogs can help explain the decrease in CH4 emission in the typical boreal peatland succession from young fens to older bogs. Increase in anaerobic CO2 versus CH4 production with transplantation shows that disturbances of boreal peatlands can activate poorly defined pathways of anaerobic decomposition. A free Plain Language Summary can be found within the Supporting Information of this article.

Measuring restoration progress using pore- and surface-water chemistry across a chronosequence of formerly afforested blanket bogs

During the restoration of degraded bogs and other peatlands, both habitat and functional recovery can be closely linked with nutrient cycling, which is reflected in pore- and surface-water chemistry. Several peatland restoration studies have shown that the time required for recovery of target conditions is slow (>10 years); for heavily-impacted, drained and afforested peatlands of northern Scotland, recovery time is unknown. We monitored pore- and surface-water chemistry across a chronosequence of formerly drained, afforested bog restoration sites spanning 0–17 years, using a space-for-time substitution, and compared them with open blanket bog control sites. Our aims were to measure rate of recovery towards bog conditions and to identify the best suite of water chemistry variables to indicate recovery.Our results show progress in recovery towards bog conditions over a 0–17 year period post-restoration. Elements scavenged by trees (Mg, Na, S) completely recovered within that period. Many water chemistry variables were affected by the restoration process itself, but recovered within 11 years, except ammonium (NH4+), Zn and dissolved organic carbon (DOC) which remained elevated (when compared to control bogs) 17 years post restoration. Other variables did not completely recover (water table depth (WTD), pH), exhibiting what we term “legacy” effects of drainage and afforestation. Excess N and a lowered WTD are likely to slow the recovery of bog vegetation including key bog plants such as Sphagnum mosses.Over 17 years, we measured near-complete recovery in the chemistry of surface-water and deep pore-water but limited progress in shallow pore-water. Our results suggest that at least >17 years are required for complete recovery of water chemistry to bog conditions. However, we expect that newer restoration methods including conifer harvesting (stem plus brash) and the blocking of plough furrows (to increase the WTD) are likely to accelerate the restoration process (albeit at greater cost); this should be evaluated in future studies. We conclude that monitoring pore- and surface-water chemistry is useful in terms of indicating recovery towards bog conditions and we recommend monitoring WTD, pH, conductivity, Ca, NH4+, phosphate (PO43−), K, DOC, Al and Zn as key variables.

Observation of an Eastern Wolf (&lt;i&gt;Canis&lt;/i&gt; sp. cf. &lt;i&gt;lycaon&lt;/i&gt;) Caching Food in a Sphagnum Bog in Algonquin Provincial Park, Ontario

We report summer caching of a partial carcass of a White-tailed Deer (Odocoileus virginianus) fawn by an Eastern Wolf (Canis sp. cf. lycaon) in a Sphagnum bog in Algonquin Provincial Park, Ontario, Canada. The microhabitat conditions in bogs (i.e., low temperature, acidity, and organochemical compounds) likely inhibit food spoilage, making bogs potentially important sites for food caching. Wolves in Algonquin Park experience low summer food availability and high pup mortality from starvation. Caches likely serve as necessary reserve food stores for adults and pups. Recent research has shown that wetland habitats are important den and rendezvous sites for Algonquin Eastern Wolves based on prey availability and, we suggest, perhaps for food storage and accessibility. This caching behaviour was recorded on video. We recommend that future research investigate Eastern Wolf selection of food-caching sites, as a complement to other spatial ecology studies.

The effects of ecotope, microtopography and environmental variables on diatom assemblages in hemiboreal bogs in Northern Europe

Bogs comprise various niches that are ideal habitats for diatoms. Even though diatoms are widely used bioindicators in many aquatic ecosystems, little is known about their within-site distribution and versatility in bogs. The abundance of bogs in hemiboreal region offers a good opportunity to study the variability of diatom assemblages in different bog habitats and factors influencing it. This study aims to describe the diatom assemblages (1) in the most common bog ecotopes and (2) along the microtopography, and (3) to evaluate the extent to which abiotic environmental parameters (i.e. water table, electric conductivity, pH, moisture and shading) affect the diatom assemblages. According to our results, the most widespread and abundant species are typical bog-inhabiting acidophilic taxa, such as Eunotia paludosa, Kobayasiella parasubtillissima and E. bilunaris. Multivariate analyses showed that some patterns in different microhabitats and ecotopes can be distinguished according to diatom assemblages. In this study, the diatom assemblages were affected by moisture, shading and pH. The study demonstrates the potential usefulness of diatom assemblages as bioindicators to provide additional information about the microsite conditions in bogs.

Biomarkers and inorganic proxies in the paleoenvironmental reconstruction of mires: The importance of landscape in Las Conchas (Asturias, Northern Spain)

We determined the lipid distributions (n-alkanes, n-alkan-2-ones, n-alkanoic acids), total organic carbon (TOC), total nitrogen (TN), Ca/Mg and ash content in Las Conchas mire, a 3.2m deep bryophyte-dominated mire in Northern Spain covering 8000calyr BP. Bog conditions developed in the bottom 20cm of the profile, and good preservation of organic matter (OM) was inferred from n-alkanoic acid distribution, with the exception of the uppermost 20cm (last ca. 200yr). Microbial synthesis of long chain saturated fatty acids from primary OM likely produced a dominance of short chain n-alkanoic acids with a bimodal distribution, as well as the lack of correspondence between the n-alkane and n-alkanoic acid profiles in the upper 20cm. This was accompanied by an increase in ash content, a decrease in TOC and variation in n-alkane ratios, thereby suggesting significant changes in the mire, namely drainage and transformation to a meadow, in the last ca. 200yr. The distribution of n-alkan-2-ones indicated an increase in bacterial source from the bottom of the record to 94cm, whereas their distribution in the upper part could be attributed mainly to plant input and/or the microbial oxidation of n-alkanes. The different n-alkane proxies showed variations, which we interpreted in terms of changes in vegetation (Sphagnum vs. non-Sphagnum dominated phases) during the last 8000calyr BP. C23 was the most abundant homolog throughout most of the record, thereby suggesting dominant humid conditions alternating with short drier phases. However, such humid conditions were not linked to paleoclimatic variation but rather to geomorphological characteristics: Las Conchas mire, at the base of the Cuera Range, receives continuous runoff—even during drier periods—which is not necessarily accompanied by additional mineral input to peat, producing the development of Sphagnum moss typical of waterlogged ecotopes and damp habitats. Thus, although geochemical proxies indicated an ombrotrophic regime in the mire, geomorphological characteristics may make a considerable contribution to environmental conditions.

Biochemical processes and gas conditions in bogs of different geneses

Biochemical processes forming the gas conditions in oligotrophic and eutrophic peat deposits in bogs of Western Siberia during vegetation periods of 2011–2013 have been studied. It has been shown that the dynamics of CO2 and CH4 formation in a peat deposit is controlled by microflora activity. Correlations of CO2 and CH4 emissions with gas conditions in peat deposits have been determined. Specific features of biochemical processes in oligotrophic and eutrophic peat deposits have been determined.

Long-term successional changes in peatlands of the Hudson Bay Lowlands, Canada inferred from the ecological dynamics of multiple proxies

Peatlands in northern Ontario, Canada, archive multiple biological indicators, including macrofossils, algae, testate amoebae, and pollen. These proxies can provide insights concerning the timing and nature of long-term climatic and environmental changes. The Hudson Bay Lowlands (HBL) of central Canada contain one of Earth’s largest continuous peatland complexes, and thus comprehensive spatial and temporal studies are needed to understand the implications of climate change on carbon cycling. Diatom assemblages were examined in three cores retrieved from ombrotrophic bogs across two Canadian terrestrial ecozones. Comparisons were made with testate amoebae and macrofossil data previously analyzed from these cores, as well as with regional pollen records from surrounding peatlands. From ~2000 to ~600 cal. BP, changes in diatom composition likely reflect hydrosere succession within the peatland, including fluctuations in connectivity to the water table and pH changes. From ~600 cal. BP to present, the synchronous timing of changes in diatoms and testate amoebae are tracking drying conditions and subsequent microhabitat variations that occur within bogs. It is possible that diatoms are tracking subtle changes in the stability of peat microforms including bog hollows and hummocks, highlighting their sensitivity to small chemical change, whereas testate amoebae are tracking the lowering of a peatland water table and subsequent drying of the peatland. The use of multiple proxies provides a more holistic approach to interpreting past ecological succession and responses to climate within peatlands. When present and well preserved, diatoms can be applied to track drying conditions in bogs, in terms of both hydrosere succession and present climatic change.

Mid-Holocene pine woodland phases and mire development - significance of dendroecological data from subfossil trees from northwest Germany

Question: Can investigations of subfossil bog-pine woodlands contribute to the understanding of mire development, especially the influence of climate fluctuations on the fen‐bog transition? Location: Lowlands of northwest Germany. Methods: We investigated pine (Pinus sylvestris L.) tree remains (stumps and trunks) buried in peat deposits. Dendrochronology was used to date each sampled tree to calendar years and to reconstruct population dynamics of the pine woodlands. Ecological changes, especially changes in site hydrology during the pine woodland phases were inferred from peat stratigraphic analyses and investigations of stem and root morphology of the tree remains. Results: The subfossil pine woodlands occurred mostly during the transition from fen to raised bog conditions within the mire development. The population dynamics are strikingly wave-like whereas woodland phases of 100 to 250 years duration are separated by much shorter (10‐50 years) phases of high germination and dying-off rates (GDO phases). Such GDO phases are often synchronous at different sites and are also linked to growth depressions of the independent regional oak master chronology (LSBOC), indicating a climate trigger. Conclusions: The development of raised bogs started about 7000 BC and had a main phase between 5100 and 3600 BC in northwest Germany. The subfossil bog-pine woodlands document the transitional phase towards the onset of raised bog formation, as characterized by initial dry conditions that were followed by increasing wetness of the sites, whereas this development is at least partly the result of climate variations.

Variations in above- and below-ground vascular plant biomass and water table on a temperate ombrotrophic peatland

In wetland ecosystems, little is known about the relationships between above- and below-ground plant biomass and water table, a primary driver of their distribution in these systems. These relationships can provide a means for estimating belowground stocks over large areas with variable biomass and predicting vascular plant responses to changing water tables resulting from climate change. We measured above- and below-ground vascular plant biomass across species and microtopography (i.e., hummocks and lawns) in a bog in eastern Ontario. We examined the relationships between above- and below-ground vascular plant biomass their variation with water table and species richness. We took 56 cores during a growing season, separating above- and below-ground biomass by species and plant part (small and coarse root, leaf, stem). Hummocks had greater above- and below-ground biomass, and significantly greater aboveground:belowground ratios than lawns. Lawns had a more even distribution of biomass across species than hummocks aboveground, indicating that only a few species (e.g., Vaccinium myrtilloides Michx. and Chamaedaphne calyculata Moench) are able to thrive in the driest bog conditions. Additionally, fewer species contributed to root biomass at depth, suggesting possible resource partitioning among species. Lower water tables lead to greater belowground biomass. Total above- to below-ground plant biomass relationships were strongest when separated by plant species.

Isolation and characterization of nitrogen-fixing bacteria of the genus Azospirillum from the soil of a Sphagnum peat bog

The presence of nitrogen-fixing bacteria of the genus Azospirillum in the soils of acidic raised Sphagnum bogs is revealed for the first time. Three Azospirillum strains, B2, B21, and B22, were isolated as a component of methane-oxidizing enrichment cultures, whereas attempts to isolate them directly from peat samples have failed. The results of comparative analysis of the nucleotide sequences of 16S rRNA genes, DNA-DNA hybridization, and the analysis of the sequences of the functional genes encoding nitrogenase and ribulose-1, 5-bisphosphate carboxylase reveal that all the newly obtained strains can be classified as Azospirillum lipoferum. Yet, unlike A. lipoferum. the isolates do not require biotin and utilize sucrose, inositol, and glycerol for growth. The cell morphology of strain B2 differs from that of the type strain and strains B21 and B22. The results obtained indicate the variability of morphological, physiological, and biochemical properties in closely related Azospirillum strains and suggest the existence of metabolic relationships between methanotrophic bacteria and the representatives of the genus Azospirillum under peat bog conditions.

Regional and local patterns of peat humification in three raised peat bogs in Värmland, south-central Sweden

Peat humification in five cores from three ombrotrophic bogs in Värmland, south-central Sweden, was analysed in an attempt to investigate local and regional responses to climate changes during the Holocene. The chronology of the five peat sequences was constrained by means of AMS radiocarbon dates and tephrochronology. Four tephras were geochemically correlated with the Askja AD 1875, Hekla-3, Kebister and Hekla-4 tephras. A further tephra, the Stömyren tephra, dated by interpolation to 2200–2100 cal yr BP was found in one bog. A composite record of peat humification changes show several periods of wetter bog conditions. These occur during the later part of the Holocene, corresponding to known climate changes in the North Atlantic region, especially around 4500–4000, 3700–3200, 3000–2700 and 1700–700 cal yr BP. Wet shifts are inferred from individual peat cores and the composite record at c. 5500, 4200, 3700, 3500, 2900, 1700, 850, 650, 500 and 250 cal yr BP. Development of composite records could be a powerful tool to smooth the palaeohydrological records in order to reduce the influence of local fluctuations in the proxy data and to extract the regional climatic signal.

Fourier transform infrared analyses of bog and modern oak wood ( Quercus petraea ) extractives

Bog and modern oak wood extractives were studied to see the impact of bog conditions upon the nature of extractives using Fourier transform infrared analyses. Except for the ethanol-toluene extracts of modern oak acidic components predominate in the bogwood, ester forms prevail in modern or non-bog wood. In both cases, toluene extractives were mostly fatty acids and their esters, whilst the extracts recovered by the remaining solvents were mainly polar aromatic substances of cyclic nature. Tests revealed these components to be mainly tannins and low molecular polysaccharides.