Coastal Bogs Research Articles

Storminess reconstruction in the northeastern Baltic Sea region over the past 7600 years based on aeolian sand influx into coastal bogs

This study aims to reconstruct the changes in storminess during the past 7600 years in the northeastern Baltic Sea region. For storminess reconstructions, aeolian sand influx (ASI) in coastal peat bog deposits was applied as an indicator of the past storminess. We analyzed cores from four peat bogs in the western and northern coastal areas of Estonia: the cores from Hiiumaa N, Hiiumaa SW, Saaremaa and Juminda study sites covered the past 3700, 3750, 2400, and 8400 years, respectively. The sediment chronologies were established using 36 14C dates. Image-analysis method ( ImageJ) was used to count and measure the grain size of all sand particles at every centimeter to gain high-resolution ASI records. Although minor site-to-site variations exist, all four ASI records were in general consistent, suggesting that stormier periods occurred around 7300, 6600, 5900, 4600, 3600, 2900, 2400, 2100, and 1600 cal yr BP and over the last 1200 years. The results and comparisons with other storminess and climate studies indicate a shift in climatic conditions around 2500 cal yr BP when stormy periods became more frequent. The ASI values were also high during the last millennium, suggesting either higher storminess or more suitable transport mechanisms for sand into the coastal bogs: the niveo-aeolian transport mode could have been favored in winters, especially during the Little Ice Age, and human impact on landscapes has probably increased over the past centuries.

Minimizing vegetation influence on soil salinity mapping with novel bare soil pixels from multi-temporal images

Optical remote sensing satellites provide rapid access to regional topsoil salinization mapping. However, mapping topsoil salinization based on spectral reflectance is always affected by background material like vegetation cover, straw mulching and soil types. In light of these challenges, this study investigates the potential of image fusion, where images of original and bare soil pixels were combined, to minimize the impact of vegetation cover on topsoil salinity mapping. A case study was presented for the typical vegetation cover area using synchronized Sentinel-2 MSI image (named original image) and 255 ground-truth data collected in October 2020, aligning with periods of vegetation cover and salt return. Furthermore, to obtain novel bare soil pixels, multi-temporal Sentinel-2 MSI images were acquired during two distinct intervals: March to May and September to November, spanning the years from 2018 to 2021. The synthetic soil image (SYSI) was obtained by extracting bare soil pixels from multi-temporal images. Two images (original, SYSI) were fused with non-negative matrix factorization (NMF) method, named SYSIfused. Then, the stacking machine algorithm was used for soil salinity mapping under different soil types, with evaluating the impact of SYSIfused on the accuracy of soil salinity prediction. The results showed the SYSIfused outperformed the original image (the R2 of the best models increased by 0.054–0.242, RMSE and MAE decreased by 0.049–0.780 and 0.012–0.546, respectively). Based on the SYSIfused, the order of the effect of soil types was coastal bog solonchaks > alluvial soil > cinnamon soil > coral saline soil > overall samples, and their roles in improving the R2 of the model were 0.141, 0.085, 0.022, 0.012, respectively. Besides, stacking models with the SYSIfused provided the best prediction performances (R2 = 0.742, RMSE = 0.377, MAE = 0.362). This study introduces the concept of merging original images with SYSI, resulting in a significant improvement in the accuracy of soil salinity mapping in areas covered by vegetation.

Foliar Endophytic Fungi from the Endangered Eastern Mountain Avens (Geum peckii, Rosaceae) in Canada.

Eastern Mountain Avens (Geum peckii Pursh, Rosaceae) is a globally rare and endangered perennial plant found only at two coastal bogs within Digby County (Nova Scotia, Canada) and at several alpine sites in the White Mountains of New Hampshire (USA). In Canada, the G. peckii population has declined over the past forty years due in part to habitat degradation. We investigated the culturable foliar fungi present in G. peckii leaves at five locations with varying degrees of human impact within this plant species’ Canadian range. Fungal identifications were made using ITS rDNA barcoding of axenic fungal cultures isolated from leaf tissue. Differences in foliar fungal communities among sites were documented, with a predominance of Gnomoniaceae (Class: Sordariomycetes, Phylum: Ascomycota). Habitats with more human impact showed lower endophytic diversities (10–16 species) compared to the pristine habitat (27 species). Intriguingly, several fungi may represent previously unknown taxa. Our work represents a significant step towards understanding G. peckii’s mycobiome and provides relevant data to inform conservation of this rare and endangered plant.

Nitrogen addition (NH4NO3) mitigates the positive effect of warming on methane fluxes in a coastal bog

Methane (CH4) fluxes in boreal peatlands could be impacted by global warming and N deposition. However, the interaction of these factors remains poorly understood and has not been considered in coupled climate-carbon models. In this study, manipulated warming and N deposition (ammonium nitrate) were conducted for five years in a coastal bog in western Newfoundland, Canada. Consistent with previous studies, warming significantly increased CH4 emission by 52%, which might be due to the increase of microbial activity and vegetation growth. Although N addition alone did not alter CH4 emissions, it significantly reduced the positive effect of warming on CH4 fluxes. We attributed this finding to three possible reasons: (1) N addition caused a shift in root allocation from deep to shallow roots, which decreased labile substrates for CH4 production under warming; (2) warming promoted vegetation uptake of ammonium (NH4+), which alleviated the inhibition of NH4+ to methanotrophs and subsequently increased CH4 oxidation under N addition; and (3) the combination of warming and N addition increased maintenance respiration of vascular plants compared with warming alone, thus reducing net primary production and root exudates for CH4 production. In addition, we found that soil temperature, soil moisture, DOC and TN were the main controls on CH4 fluxes. Our results indicate that the combined effect of N deposition and warming should not be ignored. Otherwise, the emission of CH4 in bogs will be overestimated under future scenarios of climate warming and N deposition increase. Our study can be further applied as empirical evidence for the parameterization of temperature-dependence and nutrient-dependence of CH4 fluxes in biogeochemical models of boreal peatlands.

Adaptation of restoration target with climate change: the case of a coastal peatland

As a rise in sea level is expected with climate change, peat-extracted peatlands located in coastal zones are more vulnerable to saltwater intrusion. Seawater contamination may prevent revegetation of typical bog species (e.g., Sphagnum, ericaceous shrubs) generally intolerant to saline conditions. Spontaneous revegetation was studied in a 27-year post-extracted bog that has been contaminated with seawater in New Brunswick (Eastern Canada). This study aimed (i) to evaluate spontaneous plant regeneration on saline but still acidic, organic soil; and (ii) to relate the recolonized vegetation patterns to the main environmental conditions. Of the seven plant communities found in the sea-contaminated bog, none were typical of bogs, and Sphagnum mosses were poorly represented. Plants communities and chemical properties were rather representative of salt marsh ecosystems (i.e., Carex paleacea, Sporobolus michauxianus, Empetrum nigrum, Myrica gale; neutral pH and nutrient-rich, namely P, Mg, and NH4+). Areas with low levels of spontaneous revegetation were associated with harsh chemical conditions (i.e., acid pH, high electrical conductivity, and nutrient-poor). Considering the aggravating factors that will persist with climate change, restoration of coastal bogs contaminated with seawater should aim to re-establish salt marsh ecosystems, given that spontaneous revegetation patterns and chemical conditions clearly do not allow the establishment of bog plant communities.

Application of image analysis technique for measurement of sand grains in sediments

This paper provides a methodological protocol for measuring diameter and other properties of mineral sand grains using an image analysis technique. The aeolian sand influx (ASI) from coastal bogs has been used to reconstruct changes in the past storminess. However, concentrations of sand grains in peat deposits, from which the ASI is calculated, tend to be low, and sieving and laser diffractometry cannot be applied. Manual counting of sands under microscope is time-consuming and less efficient because of possible human errors. This paper describes a protocol for an image analysis method used in our recent paper (Vandel et al. 2019) that overcomes those issues in sand grain measurements. After preliminary sample preparations, including loss-on-ignition and chemical pretreatments, this study uses ImageJ - a semi-automated image processing program – to analyze images captured under microscope. With proper sample size selection, pre-treatment, image capturing and image analysis settings in ImageJ described in this paper, the approach proved to be:•objective and efficient for analysing grain-size distribution even with low concentrations of sands in samples,•increasing reliability of the measurement and providing reproducible results by avoiding manual measuring processes, and•non-destructive and enabling further analyses on mineral composition and other properties of sand grains.

Biogeochemical Characteristics of the Last Floating Coastal Bog Remnant in Europe, the Sehestedt Bog

With the current risks caused by sea level rise and increased extreme weather events, the study of natural coastal systems has never been more important. Erosion and anthropogenic forcing led to disappeared of the majority of coastal bogs in Europe. Here, we report on case study of a unique bog remnant still under influence by seawater which floats during storm floods. We investigated biogeochemical characteristics and discuss mechanisms that influence buoyancy, which is of vital importance for the conservation of the bog and can provide insights into the functioning of coastal bogs and potential consequences of future sea level rise. The studied area is characterized by a steep salinity gradient and marine clay deposits provide the ‘hinge’ that allows the upper peat layers to float. Our results show out that buoyancy is driven by a combination of factors: the density differences, desiccation along the edges and methane production. If the ability to float is reduced in coastal bogs, the impact of erosion and the sum of several other processes (i.e., peat decomposition, salt stress, clay sedimentation, internal eutrophication and reduced methanogenesis) can cause a shift in environmental conditions and lead to loss of this unique habitat and its characteristic species.

Restoration of denitrification in agricultural wetlands

Wetland restoration of abandoned farmland may replace some of the wetland area originally lost to development, but these restoration opportunities pose unique challenges due to the agricultural legacy of the soil. Understanding how wetlands restored on agricultural lands develop and function is critical not only for improving restoration practice, but for developing our ecological understanding of wetlands. In New England, cranberry farming has dominated the agricultural industry for over a century, but decreases in yield, increases in costs, and competition from more productive cultivars grown primarily in the upper Midwest and Canada are forcing many New England cranberry farms to close. Because most cranberry farms developed in the late 1800’s and 1900’s are located in low-elevation coastal bogs in densely populated areas, the potential of restoring wetland functions lost to agricultural development is particularly significant. The objective of this study was to assess soil-based ecosystem functions in an actively farmed cranberry bog, a retired cranberry bog, a restored bog, and a natural reference bog that had not been farmed. At each site we measured a suite of soil processes and properties including denitrification potential, soil organic matter, moisture, and microbial biomass as indicators of wetland development and functioning. Denitrification potential increased with increasing soil moisture, organic matter, and microbial biomass. However, all measures were significantly lower in the retired and restored bogs compared to natural wetlands. A trajectory model based on short-term trends suggests that restoration provides a quicker path to wetland development and functional equivalence than site retirement with no restoration, although the process appears to be slow.

Regional patterns and controlling factors in plant species composition and diversity in Canadian lowland coastal bogs and laggs

Regional patterns and controlling factors in plant species composition and diversity in Canadian lowland coastal bogs and laggs

Warm summer nights and the growth decline of shore pine in Southeast Alaska

Shore pine, which is a subspecies of lodgepole pine, was a widespread and dominant tree species in Southeast Alaska during the early Holocene. At present, the distribution of shore pine in Alaska is restricted to coastal bogs and fens, likely by competition with Sitka spruce and Western hemlock. Monitoring of permanent plots as part of the United States Forest Service Forest Inventory and Analysis program identified a recent loss of shore pine biomass in Southeast Alaska. The apparent loss of shore pine is concerning, because its presence adds a vertical dimension to coastal wetlands, which are the richest plant communities of the coastal temperate rainforest in Alaska. In this study, we examined the shore pine tree-ring record from a newly established plot network throughout Southeast Alaska and explored climate-growth relationships. We found a steep decline in shore pine growth from the early 1960s to the present. Random Forest regression revealed a strong correlation between the decline in shore pine growth and the rise in growing season diurnal minimum air temperature. Warm summer nights, cool daytime temperatures and a reduced diurnal temperature range are associated with greater cloud cover in Southeast Alaska. This suite of conditions could lead to unfavorable tree carbon budgets (reduced daytime photosynthesis and greater nighttime respiration) and/or favor infection by foliar pathogens, such as Dothistroma needle blight, which has recently caused widespread tree mortality on lodgepole pine plantations in British Columbia. Further field study that includes experimental manipulation (e.g., fungicide application) will be necessary to identify the proximal cause(s) of the growth decline. In the meantime, we anticipate continuation of the shore pine growth decline in Southeast Alaska.

The importance of pH and sand substrate in the revegetation of saline non-waterlogged peat fields

A partially peat-extracted coastal bog contaminated by seawater was barren and required revegetation as a wetland. Peat fields were rectangular in shape, cambered in cross-section profile, and separated by drainage ditches. Common to all peat fields were symmetrical patterns in micro-topography with slopes between differences in elevation. Saline non-waterlogged slopes of ∼5% occurred as a symmetrical pair on each side of the crest of the cambered profile, at one end of each peat field. Three rows were laid across this slope (Top, Middle, and Bottom rows) and transplanted with naturally-growing plant species with their sand substrate, in three experiments, and grown for a year. In the Spartina pectinata experiment, bare root stem sections were also planted. Another experiment was conducted to determine changes in the characteristics of a volume of sand when incubated in saline peat fields. We found the salinity of peat increased with moisture downslope, and pH decreased with increase in salinity. S. pectinata grew best when planted with its sand substrate compared with bare root stem section, and when planted in Bottom rows. Juncus balticus had excellent growth in all rows. Unexpectedly, Festuca rubra that was inconspicuous beneath the J. balticus canopy in the natural donor site grew densely within the J. balticus sods. Agrostis stolonifera grew well but seemed to show intolerance to the surrounding acidic peat by curling up its stolons. The pH of the incubated sand volume was much higher than the surrounding peat. These studies suggest that recognition of plant niches and pH manipulation are important in the revegetation of disturbed Sphagnum peatlands that are found abundantly in the northern hemisphere. Results are also relevant to the reclamation of other disturbed lands.

Многолетняя динамика и гибель растительности маршей Колоколковой губы Баренцева моря

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

Dynamics of jack pine at the southern range boundary in downeast Maine

Great Wass Island in Maine supports a large population of Pinus banksiana Lamb. (jack pine) at its southern range boundary. Nearly monospecific stands occur on outcrops and coastal plateau bogs. In contrast to typical populations of this species, six stands exhibited old trees, multiaged structure, and continuous but pulsed establishment despite a lack of widespread fire. Unfavorable soil conditions appear to explain the presence of self-perpetuating populations in this study area, across the geographic range for P. banksiana, and for similar shade-intolerant pine species. Pinus banksiana stands on outcrops exhibited synchronous age structure peaks and included many trees over 150 years old. In contrast, coastal plateau bog stands were younger, were not synchronized in terms of age structure, and contained few large dead trees, suggesting turn-of-the-20th century invasion of these bogs. Analysis of historical aerial photographs furthermore reveals substantial infilling of bogs by P. banksiana since 1940. Although it appears to be an inconsistent and slow process, coastal plateau bog infilling warrants further investigation because of the regional rarity of this ecosystem type.

Intertidal peats and the archaeology of coastal change in the Severn Estuary, Bristol Channel and Pembrokeshire

Abstract Dates for the beginning and end of intertidal and coastal peat formation are reviewed in the Severn Estuary, Bristol Channel and Pembrokeshire. Peat formation at many sites started between c. 6000–4000 Cal bc and in the Severn Estuary continued until c. 200 Cal bc . Archaeological evidence is concentrated at two main stages within the coastal sequences. Throughout the area Mesolithic sites underlie the earliest peat and relate to coastal exploitation just prior to the transgression represented by peat formation. During the main period of peat formation from the later Mesolithic to the early Bronze Age there is only small-scale human activity within the coastal peats. A second episode of concentrated human activity is confined to the Severn Estuary and occurs in the middle Bronze Age and Iron Age. Round and rectangular buildings and trackways are associated with the initial stages of marine transgressions which led to the burial of a coastal bog by minerogenic silts. A transgression in the middle Bronze Age c. 1400 Cal bc was followed by a regression phase, the main period of human activity at Goldcliff, this ended with a widespread transgression centred on in the third century bc . The factors which attracted human activity at particular stages within the coastal sequence are considered, as is the relative visibility of human activity during each sedimentary stage. The contribution which archaeological evidence, particularly dendrochronological dating of wooden structures, can make to the dating of coastal change is emphasized.

A Geomagnetic Secular Variation Record for the Last Glacial Period, Reconstructed from Coastal Bog Sediments on the Inland Sea of Japan.

A paleomagnetic secular variation record of geomagnetic field direction for the time span from 25 to 16ka was obtained from oriented bog sediment samples in a coastal area of the eastern Inland Sea, Japan. The plot of this secular variation record, combined with Holocene secular variation data, shows that a long-term westerly declination feature began after 16ka and ended at 7.5ka. This feature lasted more than 4, 000 years and less than 8, 500 years. The declinations at 25-16ka are dominated by easterly values, and no westerly declination was observed in the time span of 24-19.5ka. The inclinations at 25-16ka are characterized by slightly shallow values with small amplitude changes, compared to those in the Holocene. Prior to 18ka a large clockwise looping was dominant in the motion of the geomagnetic vector, while counter-clockwise rotations were dominant after it. Many features of secular variation in the last glacial period have the potential to yield good age constraints for use in paleomagnetic dating.

Influences on the Distribution of Carex Exilis: An Experimental Approach

Carex exilis occurs in bogs and fens along the Atlantic coast, but only in fens in the midcontinent. I experimentally tested five hypotheses explaining this pattern. Reciprocal transplants were made, and no differences were found among populations, implying that there are no bog—adapted ecotypes. Instead, C. exilis growth and reproduction depended most on conditions under which plants were grown. Plants from all populations studied could complete their life cycle in coastal bogs, coastal fens, and midcontinental fens, but not in midcondinental bogs. Greenhouse experiments showed that salinity and acidity had no significant effect on germination and growth; increased nutrient supply and water table level did. Seedlings of C. exilis grew vigorously on peat from a midcontinental bog when the water table was kept artificially near the moss surface, but most died when the water table was at its natural level, 20 cm or more below the moss surface. The water table of coastal bogs is normally high. Water level affected competition for light between Sphagnum moss and C. exilis seedlings. Under the drier conditions of midcontinental bogs, Sphagnum overgrew the seedlings; under wetter conditions typical of coastal bogs, seedlings grew faster than Sphagnum, and coexisted with the moss.

The behaviour of major and trace elements in complete vertical peat profiles from three Sphagnum bogs

The distribution of major elements (Al, Ca, K, Mg, Na) in peat profiles from two contrasting ombrotrophic Sphagnum bogs is interpreted in respect to the abundance and mineralogical composition of ash, atmospheric deposition, plant bioaccumulation and leaching. High concentrations of Ca are found in the minerotrophic peats from a continental bog underlain by calcareous sediments (Luther bog, Ontario). Aluminum is more abundant in the minerotrophic peats from a coastal bog in a siliceous terrain (Barrington bog, Nova Scotia). The peats at the coastal site contain an average of 3 times as much Na and Mg as the peats from the continental bog because of sea spray. Potassium is highly enriched in the surface peats at both sites because of plant bioaccumulation. The behaviour of trace metals (Cr, Cu, Fe, Mn, Ni, Pb, U, V, Zn) in peat profiles is explained in terms of the abundance and distribution of mineral matter, plant bioaccumulation, the response of metals to acidic, anaerobic conditions, and anthropogenic atmospheric deposition. The distribution of Ni, V and Cr in the peats from a third bog (Galbraith Bog, Ontario) follows that of mineral-matter content, and the metals are highly correlated with ash. Relative to the mean composition of the underlying mineral sediments (clays) collected at 30 other sites, the peats are neither significantly (> 2 times) enriched nor depleted in Ni, V and Cr. Manganese is strongly enriched in surface and near-surface peat layers because of plant bioaccumulation. In contrast, Fe and Mn are relatively depleted in subsurface peats due to their enhanced solubilities in acidic, anaerobic waters. The opposite is true for Cu and U which accumulate in peats because of their diminished solubilities in anaerobic environments. Enrichments of Zn and Pb also occur, but these are restricted to surface peats, and are due to anthropogenic metal deposition.

Algae of selected continental and maritime bogs in North America

Algal taxa (281) were identified from 31 ombrotrophic bogs and 3 weakly minerotrophic fens from Manitoba to Newfoundland. Species richness increases from continental to maritime and coastal bogs, mainly as a result of an increase in Chlorophyta, especially Desmidiaceae. Species richness is related to (i) availability of open water and (ii) habitat types. Desmids shift from Actinotaenium, Penium, and Cylindrocystis in continental bogs to Euastrum, Staurastrum, and Arthrodesmus in maritime and coastal bogs. Diatoms shift likewise from Eunotia, Navicula, and Pinnularia to Frustulia, Tabellaria, and Pinnularia. Diatom species richness is similar in continental, maritime, and coastal sites. Algal biomass is usually dominated by filamentous Zygnematales, Ulotrichales, Oedogoniales, and Nostocales. Abundant Cyanophyta with heterocysts may be significant for nitrogen budgets in bogs.

Environment and climate in the early tertiary of spitsbergen

Two plant horizons occur in the Tertiary strata of Spitsbergen, the lower of which was deposited in the Danian and the upper in the Paleocene or at the latest in the lower Eocene. The flora of the lower horizon was growing on coastal bogs; that of the upper horizon was of continental origin. The conifers in the flora are excellent climatic indicators. They suggest that winter temperatures in the lower Tertiary of Spitsbergen could only temporarily have fallen below 0°C.

A NEW METHOD FOR THE REPRESENTATION OF SEDIMENTARY SEQUENCES IN COASTAL REGIONS

Coastal lowlands usually consist of a body of unconsolidated sediments of up to 30 m thickness which have been deposited under the influence of a rising sea level during the past 10,000 years. These lowlands increasingly are acquiring importance for industrial plants, harbour construction, pipelines, and for the exploration of mineral resources. Consequently a basis for planning is required which will permit an economic exploitation of the coastal zone. Geological mapping at scale of 1 : 25 000, which has been going on in Germany for more than 100 years, is of fundamental importance for this. Especially the newest type of geologic maps - the sequence map - offers the possibility of classifying and representing (BARCKHAUSEN, PREUSS & STREIF 1977) the costal deposits in a way that is well suited for technical and scientific purposes. Its range of application covers tidal flat areas, marshes and coastal bogs, as they occur for example in the coastal zone of the southern North Sea. Combined with a documentation system of the field data and the techniques of automatic data processing this type of map offers new aspects which by far exceed the possibilities of conventional geological mapping.