Peat Layers Research Articles

Thermal-deformation behavior of a crushed-rock embankment along a high-grade highway in permafrost regions

Numerous studies have been conducted to investigate the thermal stability of crushed rock embankments (CREs). In this study, we developed an automatic field monitoring system for a CRE during the construction of the Gonghe–Yushu High-grade Highway (GYHH) to explore both the convective cooling and the deformation controlling effect of the crushed rock layer (CRL). We evaluated the thermal-deformation performance of a the CRL based on the long-term field monitoring data. The results reveal that the upper peat layer could slow down the degradation of shallow permafrost. However, the heat absorbed by the black asphalt pavement significantly contributed to the degradation of the permafrost beneath the contrast embankment without the CRL. The CRL had an obvious cooling effect range for the shallow stratum, where an effective cooling zone formed (about 4 m deep in the 4th year after the construction of embankment). Nevertheless, deep permafrost beyond this effective cooling range continued to warm owing to the downward heat flux. Consequently, the total settlement of the CRE decreased by 23% compared with the contrast embankment in the 5th year. This work is expected to provide a reference for the design of the CREs in permafrost regions.

Soil GHG dynamics after water level rise – Impacts of selection harvesting in peatland forests

Managed boreal peatlands are widespread and economically important, but they are a large source of greenhouse gases (GHGs). Peatland GHG emissions are related to soil water-table level (WT), which controls the vertical distribution of aerobic and anaerobic processes and, consequently, sinks and sources of GHGs in soils. On forested peatlands, selection harvesting reduces stand evapotranspiration and it has been suggested that the resulting WT rise decreases soil net emissions, while the tree growth is maintained. We monitored soil concentrations of CO2, CH4, N2O and O2 by depth down to 80 cm, and CO2 and CH4 fluxes from soil in two nutrient-rich Norway spruce dominated peatlands in Southern Finland to examine the responses of soil GHG dynamics to WT rise. Selection harvesting raised WT by 14 cm on both sites, on average, mean WTs of the monitoring period being 73 cm for unharvested control and 59 cm for selection harvest. All soil gas concentrations were associated with proximity to WT. Both CH4 and CO2 showed remarkable vertical concentration gradients, with high values in the deepest layer, likely due to slow gas transfer in wet peat. CH4 was efficiently consumed in peat layers near and above WT where it reached sub-atmospheric concentrations, indicating sustained oxidation of CH4 from both atmospheric and deeper soil origins also after harvesting. Based on soil gas concentration data, surface peat (top 25/30 cm layer) contributed most to the soil-atmosphere CO2 fluxes and harvesting slightly increased the CO2 source in deeper soil (below 45/50 cm), which could explain the small CO2 flux differences between treatments. N2O production occurred above WT, and it was unaffected by harvesting. Overall, the WT rise obtained with selection harvesting was not sufficient to reduce soil GHG emissions, but additional hydrological regulation would have been needed.

Forest Stands Formation on Exhausted Peat Bogs in the North-East of the European Part of Russia

It has been established that the directed construction of forest-meadow-bog agricultural landscapes in the place of territories that have been abandoned from industrial peat extraction is the most promising and environmentally friendly way to restore the biospheric functions of disturbed bog ecosystems. A special role in the ecological framework of the emerging agricultural landscape belongs to forest cultures. Long-term studies show that Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula) form the basis of future cultivated forest stands. With artificial reforestation, the best result was obtained on residual gley-degraded peat soils, where the peat layer does not exceed 20–30 cm, and the drainage rate is 80–100 cm. The most optimal conditions for the development of all the tree and shrub species were found to be near open reclamation canals. In this case, forest plantations are arranged in the form of shelterbelts 10–15 m wide. Natural reforestation as an alternative is possible, but it is characterized by slower dynamics and only a slight increase in commercial timber stocks. The process of self-recovery also largely depends on the degree of depletion of the residual deposit and the degree of its water content. In the structure of the post-bog forest-meadow landscape, the share of forest should be at least 20–30%.

Variations in the archaeal community and associated methanogenesis in peat profiles of three typical peatland types in China

BackgroundPeatlands contain about 500 Pg of carbon worldwide and play a dual role as both a carbon sink and an important methane (CH4) source, thereby potentially influencing climate change. However, systematic studies on peat properties, microorganisms, methanogenesis, and their interrelations in peatlands remain limited, especially in China. Therefore, the present study aims to investigate the physicochemical properties, archaeal community, and predominant methanogenesis pathways in three typical peatlands in China, namely Hani (H), Taishanmiao (T), and Ruokeba (R) peatlands, and quantitively determine their CH4 production potentials.ResultsThese peatlands exhibited high water content (WC) and total carbon content (TC), as well as low pH values. In addition, R exhibited a lower dissolved organic carbon concentration (DOC), as well as higher total iron content (TFe) and pH values compared to those observed in T. There were also clear differences in the archaeal community between the three peatlands, especially in the deep peat layers. The average relative abundance of the total methanogens ranged from 10 to 12%, of which Methanosarcinales and Methanomicrobiales were the most abundant in peat samples (8%). In contrast, Methanobacteriales were mainly distributed in the upper peat layer (0–40 cm). Besides methanogens, Marine Benthic Group D/Deep-Sea Hydrothermal Vent Euryarchaeotic Group 1 (MBG–D/DHVEG–1), Nitrosotaleales, and several other orders of Bathyarchaeota also exhibited high relative abundances, especially in T. This finding might be due to the unique geological conditions, suggesting high archaeal diversity in peatlands. In addition, the highest and lowest CH4 production potentials were 2.38 and 0.22 μg g−1 d−1 in H and R, respectively. The distributions of the dominant methanogens were consistent with the respective methanogenesis pathways in the three peatlands. The pH, DOC, and WC were strongly correlated with CH4 production potentials. However, no relationship was found between CH4 production potential and methanogens, suggesting that CH4 production in peatlands may not be controlled by the relative abundance of methanogens.ConclusionsThe results of the present study provide further insights into CH4 production in peatlands in China, highlighting the importance of the archaeal community and peat physicochemical properties for studies on methanogenesis in distinct types of peatlands.

Groundwater exploration using 2D resistivity method in water supply for prevention of peatland fire at Kahayan Kuala area, Central Kalimantan

Resistivity data acquisition using the two-dimensional (2D) resistivity method has been carried out at 8 locations in the Kahayan Kuala area, Pulang Pisau District, Central Kalimantan. The aim of the study was to identify the distribution type and depth of aquifer layers and other geological materials in subsurface based on their resistivity characteristics. The study results showed that resistivity values at the northern part of the study area ranging from 13.28–282 and 2.09–88.37 ohm-meter, while at the southern part, the resistivity values ranging from 0.32–25.75 ohm-meter. At the northern part of the study area, the resistivity values range of 41.77–88.37 to 67.7–187.79 ohm-meter are peat and mud layers, range of 25.35–88.37 to 55.29–282.28 ohm-meter are sandstone layers, and range of 2.09–34.31 to 13.28–67.78 ohm-meter were clay and sandy clay layers. At the southern part, the range of resistivity values from 5.97–25.75 ohm-meter are peat and mud layers, range of 4.46 - 25.75 ohm-meter are sandstone layers, and range of 0.32–5.97 ohm-meter are clay and sandy clay layers. Sandstone layers are interpreted as confined aquifers, peat and mud layers as unconfined aquifers, and clay and sandy clay layers as non-aquifer or sealing layers. At the northern part of the survey area, the depth of aquifer layers ranging from 10–40 meter and at the southern part the depth of aquifer layers ranging from 20–50 meter.

Assessment of Present-Day Heavy Metals Pollution and Factors Controlling Surface Water Chemistry of Three Western Siberian Sphagnum-Dominated Raised Bogs

This study investigated the heavy metal concentrations in bog and stream water compared to present-day atmospheric deposition, and concentrations in peat and vegetation within three typical raised bogs in Western Siberia located in urban area, close to oil and gas facilities and in the natural background area. Our data showed that elevated heavy metals deposition occurs not only near industrial centres but also in remote areas, which is a sign of regional atmospheric deposition of heavy metals associated with long-range transport and wildfires. Present-day atmospheric depositions of heavy metals are not always consistent with their contents in waters, and the content of Zn, Pb, Cu and Cd in waters is more correlated with their concentrations in vegetation and in the upper peat layer; this indicates a significant role of biological processes in heavy metal cycling. Temperature plays an important role in increasing the mobility and vegetation uptake of heavy metals. Heavy metals removal is largely determined by the size of the bog and its stage of development, which determines bog–river interaction. The seasonal catchment-scale budget indicated that 80–97% of Zn and Pb and 47–74% of Cu and Cd from atmospheric inputs remained within the catchments.

Zonal Patterns of Changes in the Taxonomic Composition of Culturable Microfungi Isolated from Permafrost Peatlands of the European Northeast

This paper provides the results of a study on fungal species diversity in the active and permafrost layers of peatlands within frozen peatbogs in the flatland areas of the cryolitozone, European Northeast of Russia (forest-tundra zone, southern and northern tundra subzones). Fungal taxonomic list includes eighty-three species from seventeen genera and two forms of Mycelia sterilia. The phylum Mucoromycota is represented by fifteen species (18% of total isolate number), and these species exhibit the following distribution by genus: Mucor (four), Mortierella (seven), Umbelopsis (three), Podila (one). Ascomycota is represented by sixty-eight species from thirteen genera. The genus Penicillium dominates the species saturation (thirty-seven species, 44%). Soil microfungal complex is represented by rare species (51%), random species (32%), frequent species (15%), and dominant species (2%). In peat soils, dominant species are Penicillium canescens (72%) and non-pigmented (albino) Mycelia sterilia (61%); abundant species are Talaromyces funiculosus (41%), Pseudogymnoascus pannorum (36%), albino Mycelia sterilia (29%), Umbelopsis vinacea (25%), Mortierella alpina (17%), Penicillium decumbens (21%), P. spinulosum (20%), and P. canescens (17%). In active layers of peat soils, abundant species are Penicillium thomii (14%), Mycelia sterilia (13%), Penicillium spinulosum (13%), Penicillium simplicissimum (13%) in forest-tundra; Talaromyces funiculosus (21%), albino Mycelia sterilia (15%), Umbelopsis vinacea (14%) in southern tundra; Penicillium decumbens (23%), P. canescens (17%), P. thomii (13%) in northern tundra. In permafrost peat layers, abundant species are Penicillium spinulosum (17%), Talaromyces funiculosus (34%), and Umbelopsis vinacea (15%) in forest-tundra; Pseudogymnoascus pannorum (30%) and Mortierella alpina (28%) in southern tundra; Pseudogymnoascus pannorum (80%) in northern tundra.

Partition of Carbon Losses on CO2 Emission and Peat Subsidence in an Open-Drained Tropical Peatlands: A Consideration for Agroforestry Practices

Open-abandoned peatland commonly were not hydrologically well-managed in West Kalimantan causing continuous degradation of peat ecosystems, due to peat drying. This condition damage the carbon balance and function of tropical peatlands, 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 due to uncontrolled drainage and land fires caused by lack of management post the landcover changes. This study aims to clarify the partition of carbon loss in open peatlands due to the heterotrophic respiration (CO2 emission) process, which is part of the declining peat layer due to subsidence. The CO2 emission and subsidence assessments were accomplished for two years. The results show an increase in peat CO2 emissions to ~300% when groundwater level (GWL) lowered from ~0-5cm to >80cm. The trend is similar to the subsidence process due to changes in GWL. Carbon dioxide emissions range from 55,8 to 58,9% of peat layer losses, dependent on GWL. In undrained peatland, the CO2 emission was the lowest among others yet mainly loss in CO2 emission. The results of this study can provide considerations on small-holder agroforestry or other agricultural practices which wide-spread developed recently in this area. It is explaining the part of the subsidence that impacts the sources of CO2 emissions and practices to manage GWL to mitigate CO2 emission from open-drained peatlands.

Methanogenic archaea community in relation to methane production in oil palm planted on tropical peatland

Understanding the microbial processes that regulate methane emissions in the tropical peatlands can facilitate their future management. However, the microbiota of Malaysian tropical peatlands specifically the methanogens (methane producers) and methanotrophs (methane consumers) remains poorly characterised. This study aimed to determine the key players in methane production and to assess their spatial distribution in different oil palm management zones (i.e., avenue, cover crop, frond pile, and weeded circle) across depths namely 0–15 cm, 15–30 cm, and 30–45 cm in an 11-year-old oil palm plantation that was established on the peatland of Sarawak. Based on high-throughput Illumina sequencing targeting the 16S hypervariable V4–V5 regions of archaeal rRNA amplicon, the diversity indices (Shannon and Simpson) and richness (Chao1 and ACE) were highest in the upper peat layers across management zones, and the microbial diversity and composition are influenced by depths. Taxonomic profiling revealed that the domain Archaea was dominated by Halobacteriota, Thermoproteota, and Thermoplasmatota that increased with depth across management zones. Meanwhile, the order Methanomassiliicoccales was predominant, with Methanomethylophilus sp002495325 as the most abundant species in the upper peat layers in the frond pile zone due to a high decomposition rate of organic matter. The key players of methanogenic archaea belonging to Methanomassiliicoccales, Methanosarcinales, Methanomicrobiales, and Methanobacteriales were detected in oil palm peat soils, providing indirect genetic evidence for the biogeochemical processes associated with methane production in the oil palm plantation. Having established the feasibility of utilising high-throughput sequencing to characterise the archaeome of Malaysian oil palm plantation, future works in correlating the relative abundance of methanogens and methanotrophs with methane production will be instrumental in providing valuable insights for prediction and mitigation of methane emissions in oil palm cultivation on peat.

Investigation of buried karst sinkholes under a bog using ground penetrating radar (GPR) and electrical resistivity tomography (ERT)

AbstractActive evaporite karst processes in the Baltic states are associated with a few relatively small regions where gypsum rocks can be found close to the Earth's surface. One of these areas lies in the vicinity of the Pandu bog. However, such a possibly active karst region, which is covered by peat and in which the mapping of karst formations is complex, has not been previously investigated. In this study, we present a buried and peat‐filled karst cover‐collapse sinkhole mapping approach that involves a combination of ground‐penetrating radar (GPR), electrical resistivity tomography (ERT) and conventional boreholes. A detailed map of the bog's substratum topography was constructed from a geophysical surveying dataset. It reveals 15 distinctly expressed sinkholes with diameters of several tens of metres. Overall, 140 potential sinkholes were also mapped using remote sensing data in the vicinity of the bog. Higher electrical resistivity anomalies were identified inside the peat; they coincide with scatter‐free zones in GPR data and water layers in boreholes. Highly disturbed internal peat layering was also detected in these sinkholes. It is suggested that these water layers and disturbed peat layering may have formed due to the subsidence of the lower peat layers, and thus they represent relatively younger sinkholes. This is also supported by evidence from orthophoto maps, which showed the formation and disappearance of surficial lakes and depressions on the bog surface. Our results revealed the presence of active and widespread karst processes under the bog that have not been previously noticed despite the fact that they have implications for the assessment of geohazards in this area.

The Spatial Analysis of Vegetation Cover and Permafrost Degradation for a Subarctic Palsa Mire Based on UAS Photogrammetry and GPR Data in the Kola Peninsula

Subarctic palsa mires undergo substantial transformation under climate impacts, and today a reliable marker of their degradation is the vegetation cover. We studied the correspondence between the surface traits of palsa degradation, as expressed in the vegetation composition, and the interior condition of permafrost within subarctic palsa mires in the central part of the Kola Peninsula. We have employed a set of methods to collect the data, including geobotanical relevés, unmanned aerial system (UAS) photogrammetry, and ground-penetrating radar (GPR) survey. Based on RGB orthophoto values and morphometric variables, we produced a land cover classification (LCC) consistent with the vegetation classes identified during field measurements. The outcome proves that the additional morphometric predictors improve the accuracy of classification algorithms. We identified three major patterns in GPR cross-sections defining (i) permafrost in palsas, (ii) water saturated peat, and (iii) the regular peat layer. As a result, our GPR data demonstrated a high correlation with land cover classes and pointed to some vegetation features controlled by the peat deposit inner structure. Under our results, palsas with thawing permafrost can be appraised using sequences of LCC. This is primarily the lichen hummock—tall shrub—carpet vegetation (LH–TSh–C) sequence from palsa top to foot. We have also detected an asymmetric configuration of permafrost in some palsas in the west-to-east direction and hypothesized that it can relate to the wind regime of the area and snow accumulation on the eastern slopes. Our results highlight that the combined application of the remote UAS photogrammetry and GPR survey enables a more precise delineation of the lateral degradation of palsas.

Carbon exchange and primary production in a High-Arctic peatland in Svalbard

Moss tundra with a thick peat layer dominated by bryophytes is one of the most important ecosystems in the High Arctic of Svalbard, but little is known about the carbon dynamics of moss tundra. Here, we estimated the net primary production (NPP) and net ecosystem production (NEP) of moss tundra on Brøggerhalvøya (Brøgger Peninsula) of north-western Svalbard (79°N). The net photosynthetic and respiration rates of the two dominant moss species, Calliergon richardsonii and Tomenthypnum nitens, were measured under laboratory conditions. On the basis of the photosynthetic and respiration characteristics and climatic data, we estimated the cumulative NPP of the dominant moss species during the growing season to be 143–207 gC m-2. Net CO2 exchange, which was determined by subtracting the respiration of the brown moss layer from NPP, was similar to that estimated using field gas flux measurements. The field measurements indicated that methane emissions contributed little to carbon flow. The NEP estimated in this study was much larger than the long-term carbon accumulation rate reported in a previous study. These data suggest that a significant amount of fixed carbon was lost from the peat layer or that carbon accumulation has recently increased. The NPP and NEP values of the moss tundra are larger than those reported for other vegetation types in this area, suggesting that moss tundra is an active site with high rates of carbon fixation.

The Impact of Profile Genesis and Land Use of Histosol on Its Organic Substance Stability and Humic Acid Quality at the Molecular Level

This study is designed to evaluate soil organic matter (SOM) quality indicators: molecular indicators of dissolved organic matter (DOM) and hydrophobicity of humic acid (HA), distribution of quantity in humified and labile fractions of histosols during renaturalization. The aim is to determine the differences in the qualitative composition of humic acids at the molecular level, which are decided by the previous tillage and genesis, and to evaluate the impact of anthropogenization on the peat soil according to hydrophobicity, as well as to estimate the impact of soil genesis and removing peat layer. Soil samples were taken from the three Sapric Histosol (according to WRB2022) profiles and the 0–30 cm layer in three field replicates (Lithuania, Radviliskis mun.). Our study suggested that in the differently managed drained Sapric Histosol under renaturalization, the most significant changes occurred in the topsoil layer (0–30 cm), in which an increase in the content of SOM particles 106–2 µm in size. It is expedient to grow perennial grasses and legumes to maintain the soil organic carbon stability mobile humic acids to mobile fulvic acids ratio (MHA:MFA 0.83 to 0.86). An evaluation of the quality of HA (E4:E6) revealed their highest maturity in the unfertilized perennial grasses (3.88) and crop rotation (3.87) with grasses. The highest concentrations of hydrophilic groups (ratio of the C=O to O-H) were found in Sapric Histosol under deciduous hardwood forest (12.33). The lowest hydrophilicity (9.25 and 9.36) was of the crop rotation Sapric Histosol with removed peat layer. The most sustainable use of drained Sapric Histosol in the context of the sustainability and quality of its humus substances should be associated with the formation of perennial grass and clover grassland and the cultivation of deciduous hardwood. Therefore, the horizon forms on the top part of the profile, which protects deeper Histosolic material layers from its mineralization.

Detecting tropical peatland degradation: Combining remote sensing and organic geochemistry.

Tropical peatlands are important carbon stores that are vulnerable to drainage and conversion to agriculture. Protection and restoration of peatlands are increasingly recognised as key nature based solutions that can be implemented as part of climate change mitigation. Identification of peatland areas that are important for protection and restauration with regards to the state of their carbon stocks, are therefore vital for policy makers. In this paper we combined organic geochemical analysis by Rock-Eval (6) pyrolysis of peat collected from sites with different land management history and optical remote sensing products to assess if remotely sensed data could be used to predict peat conditions and carbon storage. The study used the North Selangor Peat Swamp forest, Malaysia, as the model system. Across the sampling sites the carbon stocks in the below ground peat was ca 12 times higher than the forest (median carbon stock held in ground vegetation 114.70 Mg ha-1 and peat soil 1401.51 Mg ha-1). Peat core sub-samples and litter collected from Fire Affected, Disturbed Forest, and Managed Recovery locations (i.e. disturbed sites) had different decomposition profiles than Central Forest sites. The Rock-Eval pyrolysis of the upper peat profiles showed that surface peat layers at Fire Affected, Disturbed Forest, and Managed Recovery locations had lower immature organic matter index (I-index) values (average I-index range in upper section 0.15 to -0.06) and higher refractory organic matter index (R -index) (average R-index range in upper section 0.51 to 0.65) compared to Central Forest sites indicating enhanced decomposition of the surface peat. In the top 50 cm section of the peat profile, carbon stocks were negatively related to the normalised burns ratio (NBR) (a satellite derived parameter) (Spearman's rho = -0.664, S = 366, p-value = <0.05) while there was a positive relationship between the hydrogen index and the normalised burns ratio profile (Spearman's rho = 0.7, S = 66, p-value = <0.05) suggesting that this remotely sensed product is able to detect degradation of peat in the upper peat profile. We conclude that the NBR can be used to identify degraded peatland areas and to support identification of areas for conversation and restoration.

Computational study of the multidimensional spread of smouldering combustion at different peat conditions

Smouldering combustion is the slow, low-temperature, flameless burning of porous fuels, which propagate both laterally and in-depth. In this study, we build a physics-based two-dimensional model to simulate lateral and in-depth smouldering spread simultaneously based on open-source code Gpyro. We first validate the model against a shallow-reactor experiment (of 1.6 cm thickness) in the literature. Based on the validated model, we then investigate 2D smouldering in a 3 times deeper peat layer at different soil conditions. We found that lateral and in-depth spread rates depend on the organic density and the Oxygen supply. Because of the larger Oxygen supply close to the free surface, the lateral spread is 10 times faster than in-depth spread. In addition, for lateral spread the influence of inorganic density and moisture can be explained by a unified parameter, heat sink density, agreeing with previous experimental results. The model predicts the effects of peat conditions on multidimensional smouldering spread and reveals the controlling mechanisms both lateral and in-depth spread, providing a better understanding of this complex phenomenon.

Neolithic wood use at the Scheldt river banks in Bouchain (France)

Archaeological sites in wetlands or under waterlogged conditions provide excellent preservation conditions for organic material, particularly wood, and therefore constitute one of the most important prehistoric sources for dendroarchaeological studies available.The site of Bouchain in the North of France, is located on the bank of a palaeochannel close to the Scheldt River, a North Sea tributaty. Regular floods of varying intensity led to formation of peat and waterlogged site conditions, providing vast amounts of wooden artefacts sampled for dendroarchaeological analyses within an interdisciplinary research effort, further involving palynological, malacological and anthracological studies. Here we present a study on a total of 1858 individual wood objects, including architectural elements (posts, stakes and planks), tools and hunting weapons (axe handles, arrow shafts and bows, throwing sticks, slingshot balls), tableware, production waste from woodworking (chips) and finally two log boats. In addition, natural wood residues from peat and alluvial layers have been collected and analysed to obtain a more comprehensive picture of the Neolithic forest vegetation on-site. After an early occupation of the site during the Mesolithic period, the archaeological sequence is placed between the Middle Neolithic and the end of the Late Neolithic (∼4200–2700 BCE). However, the main occupation is in the Late Neolithic, broadly between 3400 BCE and 2950 BCE.The interdisciplinary approach allows to specify the nature of the forest stands on the periphery of the site as riparian forest of alder type, associated with a mixed forest and heliophilous vegetation.The dendroarchaeological investigations enabled precise tree-ring dating and provides important insights into the selection and processing of wood in Neolithic times in the context of weaponry production, shipbuilding and food consumption.

Efficacy of Biological and Chemical Control Agents against Heterobasidion Spore Infections of Norway Spruce and Scots Pine Stumps on Drained Peatland

Treatment of conifer stumps with a control agent effectively prevents Heterobasidion spore infections in summer cuttings and protects the residual stand and the next tree generation from damage caused by Heterobasidion root rot. Thus far, stump treatment experiments have been carried out in mineral soils, and no information is available on the efficacy of stump treatment agents in boreal peatland conditions. In the present study, biological and chemical control agents (Phlebiopsis gigantea and urea, respectively) were tested in Scots pine and Norway spruce stands subjected to thinning, cap cutting, and clearcutting on drained peatland in Central Finland. The control efficacy of urea was high in both spruce and pine stumps (on average 99.5 and 85.3%, respectively), while the efficacy of P. gigantea was highly variable on both tree species and ranged from full protection down to negative control effect, i.e., there were more Heterobasidion infections on the treated than untreated half of the stumps. The moisture content of the stump wood or the thickness of the peat layer did not affect the control efficacy of either control agent. These results emphasize a need for further studies to determine the reasons for the unsteadiness of the biological control in peatland conditions.

Scour ponds from unusually large tsunamis on a beach-ridge plain in eastern Hokkaido, Japan

Scour ponds from unusually large tsunamis cut across the crest of a beach ridge in Kiritappu marsh, eastern Hokkaido. No fewer than ten of these ponds were imaged by photogrammetry as elongate topographic depressions as large as 5 m by 30 m. Sediments in these ponds are underlain by unconformities that were detected with ground-penetrating radar and observed directly in cores and a slice sample. Sediment deposits in the ponds contain peat and volcanic ash layers, the ages of which suggest that the scouring occurred during tsunamis generated by spatially extensive thrust ruptures along the southern Kuril trench, most recently during the early seventeenth century and its predecessor during the thirteenth–fourteenth century. Some of the ponds appear to have been formed during one tsunami and refreshed during later successors. This evidence of recurrent erosion suggests that the shoreline may retreat as part of earthquake-related cycles of coastal uplift and subsidence.

Geochemical Characteristics of the Vertical Distribution of Heavy Metals in the Hummocky Peatlands of the Cryolithozone.

One of the main reservoirs depositing various classes of pollutants in high latitude regions are wetland ecosystems. Climate warming trends result in the degradation of permafrost in cryolitic peatlands, which exposes the hydrological network to risks of heavy metal (HM) ingress and its subsequent migration to the Arctic Ocean basin. The objectives included: (1) carrying out a quantitative analysis of the content of HMs and As across the profile of Histosols in background and technogenic landscapes of the Subarctic region, (2) evaluating the contribution of the anthropogenic impact to the accumulation of trace elements in the seasonally thawed layer (STL) of peat deposits, (3) discovering the effect of biogeochemical barriers on the vertical distribution of HMs and As. The analyses of elements were conducted by atom emission spectroscopy with inductively coupled plasma, atomic absorption spectroscopy and scanning electron microscopy with an energy-dispersive X-ray detecting. The study focused on the characteristics of the layer-by-layer accumulation of HMs and As in hummocky peatlands of the extreme northern taiga. It revealed the upper level of microelement accumulation to be associated with the STL as a result of aerogenic pollution. Specifically composed spheroidal microparticles found in the upper layer of peat may serve as indicators of the area polluted by power plants. The accumulation of water-soluble forms of most of the pollutants studied on the upper boundary of the permafrost layer (PL) is explained by the high mobility of elements in an acidic environment. In the STL, humic acids act as a significant sorption geochemical barrier for elements with a high stability constant value. In the PL, the accumulation of pollutants is associated with their sorption on aluminum-iron complexes and interaction with the sulfide barrier. A significant contribution of biogenic element accumulation was shown by statistical analysis.

Micropropagation of belarusian cultivars of blue honeysuckle (Lonicera caerulea L. var. kamtschatica)

For blue honeysuckle cultivars of Belarusian selection (Zinri and Sinyavokaya), a method of micropropagation for the production of high-quality planting material is proposed. Initiation of in vitro culture: in the period of intensive growth of shoots – the first decade of June. Explants were apical points isolated from the apical and axillary buds of green shoots. The nutrient medium was WPM supplemented with 6-BA at a concentration of 1.0 mg/l. Micropropagation stage: MS medium containing double strength iron chelate with 1.5 mg/l of 6-BA. In vitro rhizogenesis: in MS medium the concentration of macroand microsalts and iron chelate was reduced to half strength, the sucrose concentration was reduced to 20 g/l, IBA – 1.5–2.0 mg/l). Ex vitro adaptation: substrate – perlite. It is possible to reduce the cost of obtaining the planting material by eliminating in vitro rooting stage from micropropagation scheme. Simultaneous direct ex vitro rooting and adaptation of microplants should be carried out on the substrate of Sphagnum L. moss with a surface layer (0.5 cm) of peat. Long-term storage (up to 12 months) at low positive temperatures (+3–4 °C) in refrigerator should be carried out at rooting stage (in MS medium the concentration of macro- and microsalts and iron chelate was reduced to half strength, the sucrose concentration was reduced to 20 g/l, IBA – 1.0 mg/l).