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Permafrost stability is significantly influenced by the thermal buffering effects of snow and active-layer peat soils. In the warm season, peat soils act as a barrier to downward heat transfer mainly due to their low thermal conductivity. In the cold season, the snowpack serves as a thermal insulator, retarding the release of heat from the soil to the atmosphere. Currently, many global land models overestimate permafrost soil temperature and active layer thickness (ALT), partially due to inaccurate representations of soil organic matter (SOM) density profiles and snow thermal insulation. In this study, we evaluated the impacts of SOM and snow schemes on ALT simulations at pan-Arctic permafrost sites using the Energy Exascale Earth System Model (E3SM) land model (ELM). We conducted simulations at the Circumpolar Active Layer Monitoring (CALM) sites across the pan-Arctic domain. We improved ELM-simulated site-level ALT using a knowledge-based hierarchical optimization procedure and examined the effects of precipitation-phase partitioning methods (PPMs), snow compaction schemes, and snow thermal conductivity schemes on simulated snow depth, soil temperature, ALT, and CO2 fluxes. Results showed that the optimized ELM significantly improved agreement with observed ALT (e.g. RMSE decreased from 0.83 m to 0.15 m). Our sensitivity analysis revealed that snow-related schemes significantly impact simulated snow thermal insulation levels, soil temperature, and ALT. For example, one of the commonly used snow thermal conductivity schemes (quadratic Sturm or SturmQua) generally produced warmer soil temperatures and larger ALT compared to the other two tested schemes. The SturmQua scheme also amplified the model’s sensitivity to PPMs and predicted deeper ALTs than the other two snow schemes under both current and future climates. The study highlights the importance of accurately representing snow-related processes and peat soils in land models to enhance permafrost dynamics simulations.

In Interior Alaska, a slope underlying the Trans Alaska Pipeline System has recently experienced downslope movement, which is attributed to a buried frozen, ice-rich peat layer. We performed a field investigation of the site, including coring and sampling, and conducted a suite of laboratory tests, including mechanical tests at temperatures between −0.56 and −5 °C to quantify the secondary creep behavior and to estimate the impact of soil cooling on the creep deformation. We tested a variety of soils, including ice-rich silt, silty peat, and peat with the majority having an organic content of 10% or greater. The results indicated that temperature has a strong control on the resulting time-dependent mechanical properties. Here we provide secondary creep power law relationships for these soils. The analysis indicates that cooling the soils can be effective in reducing creep movement; for example, cooling by 1.1 °C from −0.56 to −1.67 °C results in an order of magnitude reduction in the shear deformation rates. These results are significant as they add to the limited amount of work done on the time-dependent mechanical behavior of ice-rich peat and organic soils at warm sub-freezing temperatures. [ABSTRACT FROM AUTHOR]

A practical procedure for determining soil parameters when analysing the deformation of peat by finite-element analysis (FEA) using the Cam Clay model is presented. FEA has not been frequently used to predict the deformation of peat soil, even though it can be a powerful prediction tool. The main reason for this is that a practical method for determining parameters has not been established. In this paper, the remarkable correlation between the soil parameters required for FEA using the Cam Clay model and the natural water content (wn) and ignition loss (Li) of peat and organic clay is presented. Then, based on this correlation, a flow chart for determining the soil parameters of peat and organic clay is proposed. Using this chart, it is possible to determine soil parameters directly from triaxial compression, oedometer and other detailed tests or to estimate them from wn, Li and other physical indexes. A trial embankment on peat soil in Hokkaido, Japan, was also created. FEA was performed on the trial embankment using the proposed procedure for determining the soil parameters. The results of the FEA corresponded to the measured settlement behaviour in the trial embankment with an accuracy in the range −4% to +8%. The FEA results also modelled the measured behaviour of pore water pressure and lateral and vertical displacements in the trial embankment very well. [ABSTRACT FROM AUTHOR]

Tropical peatlands degraded by agricultural use with intensive drainage require restoration through rewetting, preferably while agricultural use continues. Sago palm (Metroxylon sagu Rottb.), a starch crop that can grow in high water table peatlands, is suitable for this objective. However, the optimal method of sago palm cultivation on peat soil has not yet been established. To establish an efficient nitrogen (N) fertilization method for sustainable production of sago palm in peatland, the fate of 15N-labelled urea applied to sago palm after transplanting and the effect of controlled-release N fertilizer applied before transplanting on sago palm growth were examined in field experiments in Malaysia. The rate of mineralization of soil organic N was also measured to evaluate the capacity of soil N as another N source for sago palms. The application of chemical fertilizers after transplanting did not improve plant growth or total N uptake. After 1 year, only 2–5% and 9–22% of the fertilized N was detected in aboveground parts (mother plant and suckers) and soil, respectively. The N supplying potential of peat soils exceeded the N requirements of sago palms. In contrast, N application at the nursery stage increased leaf length, number of leaves, aboveground biomass, and leaf chlorophyll content after transplanting. These results suggest that concentrating fertilization at the nursery stage would be an efficient method for sago palm cultivation in tropical peatlands. [ABSTRACT FROM AUTHOR]

Field measurements, after extrapolation, suggest that deep Yedoma deposits (formed during the Pleistocene) and peatlands (formed during the Holocene) account for over 700 Pg C of soil carbon storage. Incorporating this old, deep, cold carbon into land surface models (LSMs) is crucial for accurately quantifying soil carbon responses to future warming. However, it remains underrepresented or absent in current LSMs, which typically include a passive soil carbon pool to represent all 'old carbon' and lack the vertical accumulation processes that deposited deep carbon in the soil layers of peat and Yedoma. In this study, we propose a new, more realistic protocol for simulating deep and cold carbon accumulation in the high latitudes, using the ORCHIDEE-MICT model. This is achieved by 1) integrating deep carbon from Yedoma deposits whose formation is calculated using Last Glacial Maximum climate conditions, and 2) prescribing the inception time and location of northern peatlands during the Holocene using spatially explicit data on peat age. Our results show an additional 157 Pg C in present-day Yedoma deposits, as well as a shallower peat carbon depth (by 1–5 m) and 35 Pg C (43 %) less passive soil carbon in northern peatlands, compared to the old protocol that ignored Yedoma deposits and applied a uniform, long-duration (13,500 years) peat carbon accumulation across all peatlands. As a result, the total organic carbon stock across the Northern Hemisphere (> 30° N) simulated by the new protocol is 2,028 Pg C, which is 226 Pg C higher than the previous estimate. Despite the significant challenge in simulating deep carbon with ORCHIDEE-MICT, the improvements in the representation of carbon accumulation from this study provide a model version to predict deep carbon evolution during the last glacial-deglacial transition and its response to future warming. The methodology implemented for deep carbon initialization in permafrost and cold regions in ORCHIDEE-MICT is also applicable to other LSMs. [ABSTRACT FROM AUTHOR]

Background: To align with climate goals, greenhouse gas (GHG) emissions from agriculture must be reduced significantly. Cultivated peatlands are an important source of such emissions. One proposed measure is to convert arable fields on peatlands to grassland, as the Intergovernmental Panel on Climate Change (IPCC) default emission factors (EF) for organic soils are lower from grasslands. Yet, these EFs are based on limited data with high variability and comparisons are difficult due to differences in climate, soil properties, and crop management. This systematic review synthesizes available evidence on the effects of converting cropland to grassland on GHG emissions from peat and organic-rich soils in temperate and boreal climates using data from comparable fields. Methods: Literature was searched using five bibliographic databases, four archives or search engines for grey literature, and Google Scholar. Eligibility screening was performed in two steps on (1) title/abstract, with consistency among reviewers assessed by double-screening 896 articles, and (2) full text screened by two reviewers. Eligible articles were critically appraised independently by at least two reviewers. Disagreements were reconciled through discussions. Data and key metadata are presented in narrative synthesis tables, including risk of bias assessments. Meta-analyses comparing grasslands with croplands were performed using raw mean difference as the effect size. Review findings: A total of 10,352 unique articles were retrieved through the literature searches, and 18 articles including 29 studies were considered relevant to answer the review question. After critical appraisal, it was concluded that two articles reported the same data, so a total of 28 studies, comprising 34 comparisons were included in the systematic review. Most of the included studies were conducted in the Nordic countries and Germany, one in Belarus and one in Canada. A meta-analysis was conducted on 24 studies pairing cropland and grassland sites. No significant differences in carbon dioxide (CO2) or methane (CH4) emissions were found. Emissions of nitrous oxide (N2O) from grasslands were found to be 7.55 kg ha−1 y−1 lower than from cropland, however the sensitivity analysis showed that the difference was not robust, making it uncertain whether conversion from cropland to grassland has a significant effect on N2O emissions from organic soils. The difference was also smaller when root crops were excluded from the comparator group. Further, net ecosystem exchange (NEE) of CO2 and net ecosystem carbon balance (NECB) were higher in grasslands compared to croplands in cases where the grasslands were fertilized. Conclusions: This systematic review underlines the ambiguity of GHG emissions from peatlands and their relationship to land use. Our understanding of the factors influencing emissions from these soils remains incomplete, and the specific impact of land use on emissions is still unclear. CO2 emissions represent a major part of the climate impact of cultivated peat soils, so the data analyzed allow to draw the conclusion that a conversion from arable to grassland would not lead to large benefits in terms of GHG emissions, especially if root crops are not part of the arable crop rotation, or the grassland is fertilized. [ABSTRACT FROM AUTHOR]

In order to explore the effects of sludge combined with peat application on the soil of the wasteland in mining areas, in this study, a total of 10 treatments were set up, including single sludge application ( 5%, 10%, and 15%), single peat application ( 5%, 10%, and 15%), sludge and peat combined application ( sludge 5% + peat 10%, sludge 10% + peat 10%, and sludge 15% + peat 10%), and blank control. The effects of different sludge and peat application rates on soil organic matter, total nitrogen, available phosphorus, available potassium, pH, moisture content, polyphenol oxidase and sucrase activities in the wasteland soil were studied by planting ryegrass in pots. The results showed that compared with the control, single application of sludge, single application of peat, and combined application of sludge and peat in the soil of the wasteland in the mining area could increase the content of organic matter, total nitrogen, available phosphorus, and the activities of polyphenol oxidase and sucrase. Sludge application by 15% and peat treatment alone could significantly increase the content of available potassium in soil. Sludge application by 15%, peat application by peat alone, and sludge and peat combined treatment could significantly increase soil moisture content. The results of TOPSIS analysis showed that the comprehensive improvement effect of sludge application on the soil of mine wasteland was better than that of sludge and peat combined application. Among them, compared with the control, soil organic matter, total nitrogen, available phosphorus, available potassium, water content, polyphenol oxidase activity and sucrase activity increased by 151.10%, 495.37%, 1130.83%, 39.71%, 115.04%, 78.98%, and 109.58%, respectively, and the comprehensive effect of soil improvement on mine wasteland was better than that of other treatments. In summary, 15% of sludge alone could be recommended as a soil improvement technology for wasteland in mining areas. [ABSTRACT FROM AUTHOR]

Wetland methane responses to temperature and precipitation are studied in a boreal wetland-rich region in northern Europe using ecosystem process models. Six ecosystem models (JSBACH-HIMMELI, LPX-Bern, LPJ-GUESS, JULES, CLM4.5, and CLM5) are compared to multi-model means of ecosystem models and atmospheric inversions from the Global Carbon Project and upscaled eddy covariance flux results for their temperature and precipitation responses and seasonal cycles of the regional fluxes. Two models with contrasting response patterns, LPX-Bern and JSBACH-HIMMELI, are used as priors in atmospheric inversions with Carbon Tracker Europe–CH4 (CTE-CH4) in order to find out how the assimilation of atmospheric concentration data changes the flux estimates and how this alters the interpretation of the flux responses to temperature and precipitation. Inversion moves wetland emissions of both models towards co-limitation by temperature and precipitation. Between 2000 and 2018, periods of high temperature and/or high precipitation often resulted in increased emissions. However, the dry summer of 2018 did not result in increased emissions despite the high temperatures. The process models show strong temperature and strong precipitation responses for the region (51 %–91 % of the variance explained by both). The month with the highest emissions varies from May to September among the models. However, multi-model means, inversions, and upscaled eddy covariance flux observations agree on the month of maximum emissions and are co-limited by temperature and precipitation. The setup of different emission components (peatland emissions, mineral land fluxes) has an important role in building up the response patterns. Considering the significant differences among the models, it is essential to pay more attention to the regional representation of wet and dry mineral soils and periodic flooding which contribute to the seasonality and magnitude of methane fluxes. The realistic representation of temperature dependence of the peat soil fluxes is also important. Furthermore, it is important to use process-based descriptions for both mineral and peat soil fluxes to simulate the flux responses to climate drivers. [ABSTRACT FROM AUTHOR]

Peatlands are invaluable but threatened ecosystems that store huge amounts of organic carbon globally and emit the greenhouse gasses carbon dioxide (CO2) and methane (CH4). Trophic interactions of microbial groups essential for methanogenesis are poorly understood in such systems, despite their importance. Thus, the present study aimed at unraveling trophic interactions between fermenters and methanogens in a nitrogen-limited, subarctic, pH-neutral fen. In situ CH4 emission measurements indicated that the fen is a source of CH4, and that CH4 emissions were higher in plots supplemented with ammonium compared to unsupplemented plots. The amino sugar N-acetylglucosamine was chosen as model substrate for peat fermenters since it can serve as organic carbon and nitrogen source and is a monomer of chitin and peptidoglycan, two abundant biopolymers in the fen. Supplemental N-acetylglucosamine was fermented to acetate, ethanol, formate, and CO2 during the initial incubation of anoxic peat soil microcosms without preincubation. Subsequently, ethanol and formate were converted to acetate and CH4. When methanogenesis was inhibited by bromoethanesulfonate, acetate and propionate accumulated. Long-term preincubation considerably increased CH4 production in unsupplemented microcosms and microcosms supplemented with methanogenic substrates. Supplemental H2-CO2 and formate stimulated methanogenesis the most, whereas acetate had an intermediary and methanol a minor stimulatory effect on methane production in preincubated microcosms. Activity of acetogens was suggested by net acetate production in microcosms supplemented with H2-CO2, formate, and methanol. Microbial community analysis of field fresh soil indicated the presence of many physiologically unresolved bacterial taxa, but also known primary and secondary fermenters, acetogens, iron reducers, sulfate reducers, and hydrogenotrophic methanogens (predominately Methanocellaceae and Methanoregulaceae). Aceticlastic methanogens were either not abundant (Methanosarcinaceae) or could not be detected due to limited coverage of the used primers (Methanotrichaceae). The collective results indicate a complex interplay of synergy and competition between fermenters, methanogens, acetogens, and potentially iron as well as sulfate reducers. While acetate derived from fermentation or acetogenesis in this pH-neutral fen likely plays a crucial role as carbon source for the predominant hydrogenotrophic methanogens, it remains to be resolved whether acetate is also converted to CH4 via aceticlastic methanogenesis and/or syntrophic acetate oxidation coupled to hydrogenotrophic methanogenesis. [ABSTRACT FROM AUTHOR]

Roof and facade greening infiltration system were simulated to study the purification effect of different roof greening substrates and facade greening substrates on rainwater runoff. The results showed that the pollutant removal rate of glass light stone + ceramsite + river sand was the highest, and the removal rates of total nitrogen (TN), ammonia nitrogen, total phosphorus (TP) and chemical oxygen demand (COD) were 41.31%, 55.07%, 43.65% and 36.36%, respectively. The purification effect of glass light stone + ceramsite as roof greening substrate was not good. The removal rate of TP by glass light stone + ceramsite + peat soil and peat soil was more than 90%, but the removal efficiency of nitrogen was not high. The purification effect of biochar and non-soil was better in the facade greening substrate. The removal rates of ammonia nitrogen and TP by biochar were 98.45% and 92.93%, respectively. The removal effects of nitrogen and phosphorus by rock wool, rock wool + glass light stone and carbon wool were worse. The removal rates of TN and ammonia nitrogen by rock wool treatment were-20.42% and 5.06%, respectively. While, the removal rates of TN and TP by rock wool + glass light stone were negative. [ABSTRACT FROM AUTHOR]

Oil palm cultivation on peatlands is of great importance for improving the wellbeing of farmers. Managing peatlands is challenged by poor nutrient availability and low nutrient retention. Applying ameliorants and fertilizers is required to enhance peat soil properties. This study aimed to assess the effect of biochar and ash from oil palm empty fruit bunches (OPEFBs), dolomite, and mineral fertilizers on peat soil quality and fertility. The field experiment was conducted on young oil palm cultivation in the peatland of Palalawan regency, Riau province, Indonesia, by using a randomized block design with two treatment factors. The first factor was the ameliorant: dolomite, dolomite + ash from OPEFB, and dolomite + biochar from OPEFB. The second factor was the dose of NPK compound fertilizer: NPK with standard recommendation dose, NPK with site‐specific recommended dose, and NPK with farmer's dose. The observed parameters included soil properties, leaf nutrient status, and midrib characteristics. Assessing the treatment effect used an analysis of variation and treatment mean comparison using the Tukey test. The results showed that ash and biochar from OPEFB improved peat soil pH, electrical conductivity, available phosphorus (P) and potassium (K), and the growth of oil palm plants. Applying NPK fertilizer using the site‐specific recommendations dose improved soil properties, leaf nutrient status (N, P, and K), and the growth of one‐year‐old oil palms. The utilization of ash and biochar from OPEFB may reduce agricultural lime on peatlands. [ABSTRACT FROM AUTHOR]

The interest in studying the distribution of actinomycetes in natural ecosystems is the result of a large-scale use of these organisms in biotechnological industry (actinomycetes produce 45% of all biologically active substances of microbial origin). In this study, the objects for isolating actinomycetes are the eutrophic peat soils of bog ecosystems of different geneses under deciduous, mixed, and coniferous forests (Zapadanaya Dvina district of Tver oblast, European territory of Russia and Tomsk district of Tomsk oblast, Western Siberia). In total, 120 cultures of actinomycetes were isolated from the zone of active organic detritus decomposition represented in the studied soils by litter and eutrophic peat horizon; most of them are identified as Streptomyces (38 species). According to the analysis of antimicrobial activity, 40% of the isolated cultures concurrently display an antagonistic effect against bacteria, fungi, and opportunistic microorganisms, including the strains with a wide range of antagonistic action—Streptomyces globisporus, S. sindenensis, and S. xanthochromogenes. The observed antifungal activity of streptomycetes is higher as compared with the antibacterial effect. S. aburaviensis and S. albaduncus display the highest multiple antibiotic resistance. In total, 82% of the isolates display a cellulolytic activity and 26%, a chitinolytic activity. The cultures of S. bikiniensis, S. varsoviensis, and S. alboflavus have a high hydrolytic activity. [ABSTRACT FROM AUTHOR]

The application of dolomite and shrimp waste liquid organic fertilizer (LOF) is expected to improve the quality of peat soil to support the growth and yield of peanuts. The study was aimed at the role of dolomite and shrimp waste LOF in the development and yield of peanuts on peat soil. The study was conducted in Kubu Raya Regency, West Kalimantan, from April to August 2024. A factorial completely randomized design was used for the field experiment. The treatment factors were the dosage of dolomite (3, 6, and 9 tons ha-1) and the concentration of shrimp waste LOF (200, 300, and 400 mL L-1). The results showed that using dolomite and shrimp waste LOF increased the growth and yield of peanuts on peat soil. The interaction of dolomite 6 tons ha-1 and shrimp waste LOF 400 mL L-1 effectively increased root volume. The best individual dolomite treatment level for peanut growth was 6 tons ha-1, and for production, it was 9 tons ha-1. The best individual shrimp waste LOF treatment level for growth was 300 mL L-1, and for production, it was 400 mL L-1. [ABSTRACT FROM AUTHOR]

The study analysed 2019–2022 summertime canopy height predictions (HICESat) given in ICESat-2 ATLAS dataset ATL08 for hemiboreal forests growing on an area of 40,000 km2 in Estonia around 25.6° E, 58.8° N. In total 12,711 ATL08 20×20 m pixel observations were used from 3,065 forest stands with homogenous canopy structure. Regression modelling was used to explain variability in ground surface elevation estimates, and relationships of HICESat to basal area weighted mean tree height given in the forest inventory database (HFI) and to the 95th percentile of the vertical distribution of airborne laser scanning pulse return (HALS). The other explanatory variables were the ICESat-2 ATLAS observation geographic location, ICESat-2 ATLAS track and beam energy indicators, forest canopy cover, evergreen coniferous tree dominance indicator, and deep peat soil indicator. The linear model between the Estonian digital terrain model elevation and ATL08 ground elevation had a determination coefficient of R2=99.97% and residual standard error of δ=0.51 m when a geographic location was included. The HFI can be predicted from HICESat with R2=85% and δ=2.7 m. A comparison of means indicated that, on average, HICESat was about 0.3 m greater than HFI. All the predictive variables (except the geographic location) were significant in canopy height models, and the best models fitted HICESat with R2=95% and δ=1.6 m, however, there was no notable increase in R2 if more predictors than HALS were added in the models. In practical applications using ATL08 data for forest inventories, the inclusion of weak energy beam observations increases the number of observations, but the beam energy indicator has to be included in the models. [ABSTRACT FROM AUTHOR]

Modeling peatland hydraulic processes in cold regions requires defining near-surface hydraulic parameters. The current study aims to determine the soil freezing and water characteristic curve parameters for organic soils from peatland-dominated permafrost mires. The three research objectives are as follows: (i) Setting up an in situ soil freezing characteristic curve experiment by installing sensors for measuring volumetric water content and temperature in Storflaket mire, Abisko region, Sweden; (ii) Conducting laboratory evaporation experiments and inverse numerical modeling to determine soil water characteristic curve parameters and comparing three soil water characteristic curve models to the laboratory data; (iii) Deriving a relationship between soil freezing and water characteristic curves and optimizing this equation with sensor data from (i). A long-lasting in situ volumetric water content station has been successfully set up in sub-Arctic Sweden. The soil water characteristic curve experiments showed that bimodality also exists for the investigated peat soils. The optimization results of the bimodal relationship showed excellent agreement with the soil freezing cycle measurements. To the best of our knowledge, this is one of the first studies to establish and test bimodality for frozen peat soils. The estimated hydraulic parameters could be used to better simulate permafrost dynamics in peat soils. [ABSTRACT FROM AUTHOR]

Foam mortar is a substitute for sub-base layers and base layers in road pavement construction on peat soil, which has the advantages of lightness, strength, and self-compacting. Sand is one of the building blocks of foam mortar. The purpose of the study was to analyze the effect of the gradation of sand on the resulting physical and mechanical properties of foam mortar (foam concrete). In this research, six gradations of sand were made (gradations of 3 sand sources and 3 gradations based on pusjatan standards) and then used in the manufacture of foam mortar and analyzed for volumetric weigh and compressive strength. Foam mortar from the six gradations of sand, it is concluded that gradation no. 6 (lower limit of pusjatan gradation) with a value of volumetric weigh is 0.97 t/m3 does not float perfectly in water, and no. 1 to 5 (gradation of 3 sand sources and 2 gradations of Pusjatan upper limit and middle) with a volumetric weigh is 0.83 t/m3 - 0.93 t/m3 floats in water. The compressive strength values of the 6 gradations are above 2000 kPa and can be used as foundation layers in road pavements. [ABSTRACT FROM AUTHOR]

The existing drainage infrastructure in Lithuania fails to ensure proper land drainage due to the inefficient or complete malfunctioning of drainage collectors and drains. In some areas, surface water runoff is inadequate, resulting in the inability to effectively utilize land, as land areas become waterlogged. This waterlogging leads to financial losses for farmers, as excess moisture reduces soil fertility. In some cases, the land becomes inaccessible or even abandoned due to these issues. This study analyzes waterlogged areas in Lithuania, with a focus on soil types, terrain features, and variations in the spatial extent of waterlogged regions. An analysis of orthophotographic maps from 1995 to 2023 was conducted to assess changes in waterlogging within the study sites. A forecast of future waterlogging trends was also developed. Additionally, field research was conducted during the 2020-2024 period, which involved evaluating waterlogged areas in selected locations. The findings suggest that soils most commonly become waterlogged due to a combination of factors, including granulometric composition (with clay and peat soils being the most susceptible), unsustainable human activities (such as topsoil compaction), excessive rainfall (as Lithuania is located in a region with a moisture surplus), the condition of drainage systems (72% of which are degraded), and land relief (with waterlogging primarily occurring in depressions, valleys, and saddles). Based on the research, a classification of waterlogged areas was created. Waterlogged land was grouped into three categories based on its suitability for agricultural use. Soils were also classified by their granulometric composition and likelihood of waterlogging. [ABSTRACT FROM AUTHOR]

Abstract Background To align with climate goals, greenhouse gas (GHG) emissions from agriculture must be reduced significantly. Cultivated peatlands are an important source of such emissions. One proposed measure is to convert arable fields on peatlands to grassland, as the Intergovernmental Panel on Climate Change (IPCC) default emission factors (EF) for organic soils are lower from grasslands. Yet, these EFs are based on limited data with high variability and comparisons are difficult due to differences in climate, soil properties, and crop management. This systematic review synthesizes available evidence on the effects of converting cropland to grassland on GHG emissions from peat and organic-rich soils in temperate and boreal climates using data from comparable fields. Methods Literature was searched using five bibliographic databases, four archives or search engines for grey literature, and Google Scholar. Eligibility screening was performed in two steps on (1) title/abstract, with consistency among reviewers assessed by double-screening 896 articles, and (2) full text screened by two reviewers. Eligible articles were critically appraised independently by at least two reviewers. Disagreements were reconciled through discussions. Data and key metadata are presented in narrative synthesis tables, including risk of bias assessments. Meta-analyses comparing grasslands with croplands were performed using raw mean difference as the effect size. Review findings A total of 10,352 unique articles were retrieved through the literature searches, and 18 articles including 29 studies were considered relevant to answer the review question. After critical appraisal, it was concluded that two articles reported the same data, so a total of 28 studies, comprising 34 comparisons were included in the systematic review. Most of the included studies were conducted in the Nordic countries and Germany, one in Belarus and one in Canada. A meta-analysis was conducted on 24 studies pairing cropland and grassland sites. No significant differences in carbon dioxide (CO2) or methane (CH4) emissions were found. Emissions of nitrous oxide (N2O) from grasslands were found to be 7.55 kg ha−1 y−1 lower than from cropland, however the sensitivity analysis showed that the difference was not robust, making it uncertain whether conversion from cropland to grassland has a significant effect on N2O emissions from organic soils. The difference was also smaller when root crops were excluded from the comparator group. Further, net ecosystem exchange (NEE) of CO2 and net ecosystem carbon balance (NECB) were higher in grasslands compared to croplands in cases where the grasslands were fertilized. Conclusions This systematic review underlines the ambiguity of GHG emissions from peatlands and their relationship to land use. Our understanding of the factors influencing emissions from these soils remains incomplete, and the specific impact of land use on emissions is still unclear. CO2 emissions represent a major part of the climate impact of cultivated peat soils, so the data analyzed allow to draw the conclusion that a conversion from arable to grassland would not lead to large benefits in terms of GHG emissions, especially if root crops are not part of the arable crop rotation, or the grassland is fertilized. Graphical abstract

Understanding peatland coverage and characteristics is essential for improved utilization and conservation efforts. Peatlands in Bangka Belitung Islands, Sumatra, are under threat of illegal mining activities. Creating detailed maps is challenging in Indonesia amid low accessibility, yet the physiographic approach provides an alternative strategy in peatland map provision. This research aims to update peat data in the Bangka Belitung Islands Province, create peat soil maps at a scale of 1:50,000, and estimate peat soil carbon stocks. This research started with a base map using a 1:50,000 scale, surveyed and sampled the soil on transects perpendicular to the river, analyzed the samples in the laboratory, and created a peat soil map. Compared with the existing map, the new map improves land unit attributes and peat characteristics as well as improves delineation results. Results show that peat soils cover 24,311 hectares, mostly distributed in Central Bangka and South Bangka Regencies, with depths varying between 50 to < 300 cm. Shallow peats dominate with an area of 13,668 hectares (56.22%). The estimated carbon stock contained in peat is 11.6 million tons C. The peat soils are Organosol Saprik, Organosol Hemik, and Organosol Sulfidik. The soils are acidic with low exchangeable cations and base saturation. The study highlights that deep peat soils under bushes and shrubs should be conserved for forests or reforested. Detailed spatial information on peatlands is useful for policymakers related to local peat soils planning and management.

Coastal wetlands are vulnerable to sea level rise with unknown consequences for mercury (Hg) cycling, particularly the potential for exacerbating neurotoxic methylmercury (MeHg) production and bioaccumulation in food webs. Here, the effect of sea level rise on MeHg formation in the Florida Everglades was evaluated by incubating peat cores from a freshwater wetland for 0-20 days in the laboratory at five salinity conditions (0.16-6.0 parts-per-thousand; 0.20-454 mg L-1 sulfate (SO42-)) to simulate the onset of sea level rise within coastal margins. Isotopically enriched inorganic mercury (201Hg(II)) was used to track MeHg formation and peat-porewater partitioning. In all five salinity treatments, porewaters became anoxic within 1 day and became progressively enriched in dissolved organic matter (DOM) of greater aromatic composition over the 20 days compared to ambient conditions. In the four highest salinity treatments, SO42- concentrations decreased and sulfide concentrations increased over time due to microbial dissimilatory SO42- reduction that was concurrent with 201Hg(II) methylation. Importantly, elevated salinity resulted in a greater proportion of produced Me201Hg observed in porewaters as opposed to bound to peat, interpreted to be due to the complexation of MeHg with aromatic DOM released from peat. The findings highlight the potential for enhanced production and mobilization of MeHg in coastal wetlands of the Florida Everglades due to the onset of saltwater intrusion.

Humic acid (HA) is widely used in agriculture as a biostimulant to enhance plant growth and nutrient uptake. Studies on the early growth promotion of agarwood seedlings using plant biostimulants have not been explored. Therefore, the objective of this study was to extract and characterize peat-derived HA and to determine the optimum rate that would exert biostimulant action on the early growth of agarwood seedlings at the nursery stage. HA was extracted from peat soil using a modified rapid alkaline hydrolysis method. Produced peat humic acid (PHA) was compared with commercial humic acid (CHA) for its chemical and spectroscopic characteristics. One-month-old agarwood seedlings were treated with PHA at different rates (0, 20, 40, 80, 160 and 320 mg kg−1) before the commencement of the experiment. The study was conducted for four months. The C/N ratio of both PHA and CHA were 25.85 and 26.93, respectively. Scanning electron microscope (SEM) and fourier-transform infrared spectroscopy (FTIR) spectra observation reveals that PHA and CHA have similar surface morphology and functional groups respectively. Results revealed that agarwood seedlings treated with 80 mg kg−1 of PHA significantly increased the plant height, stem diameter, the number of leaves, leaf area, dry matter weight, N and P concentrations in plant tissues, and N, P and K uptakes. Based on the findings, incorporation of PHA at the rate of 80 mg kg−1 with planting medium could be used as an optimum rate to enhance the growth of agarwood seedlings in the nursery stage. [ABSTRACT FROM AUTHOR]

Background: Ginger is a highly demanded commodity that serves multiple purposes, including as a spice and a key ingredient in medicine. Since Indonesia has experienced a decrease in ginger production from 307,241.52 tons in 2021 to 247,455.49 tons in 2022, it is imperative to boost productivity. Kalimantan is dominated by peatlands, so farmers in West Kalimantan must optimize their management of peat soil to achieve the greatest possible yield. Methods: Research was conducted in Tanjungpura University, Pontianak City, Indonesia from May 1st to November 28th 2023. The study used a factorial randomized block design, with ash type (cow manure, rice husk, wood and coconut fiber) and NPK fertilizer dose (600-1200 kg/ha). Result: Different types of ash have varying effects on the growth and yield of ginger plants in peat soil. Cow manure ash is the most effective based on the dry weight of the plant, the number of tillers and the fresh weight of the rhizomes. However, NPK fertilizer doses did not significantly impact the growth and yield variables of ginger plants in peat soil. [ABSTRACT FROM AUTHOR]

Tropical wetlands and freshwaters are major contributors to the growing atmospheric methane (CH4) burden. Extensive peatland drainage has lowered CH4 emissions from peat soils in Southeast Asia, but the canals draining these peatlands may be hotspots of CH4 emissions. Alternatively, CH4 oxidation (consumption) by methanotrophic microorganisms may attenuate emissions. Here, we used laboratory experiments and a synoptic survey of the isotopic composition of CH4 in 34 canals across West Kalimantan, Indonesia to quantify the proportion of CH4 that is consumed and therefore not emitted to the atmosphere. We find that CH4 oxidation mitigates 76.4 ± 12.0% of potential canal emissions, reducing emissions by ~70 mg CH4 m−2 d−1. Methane consumption also significantly impacts the stable isotopic fingerprint of canal CH4 emissions. As canals drain over 65% of peatlands in Southeast Asia, our results suggest that CH4 oxidation significantly influences landscape-scale CH4 emissions from these ecosystems. Canals draining vast areas of peatland in Southeast Asia may be hotspots for methane emissions. Perryman et al. surveyed dozens of canals in Indonesia and found that methane-eating microbes reduce emissions from these waterways by over 50%. [ABSTRACT FROM AUTHOR]

The response of soil carbon to climate change and anthropogenic forcing depends on the relationship between the physicochemical variables of the environment and microbial communities. In anoxic soils that store large amounts of organic carbon, it can be hypothesized that the low amount of catabolic energy available leads microbial organisms to minimize the energy costs of biosynthesis, which may shape the composition of microbial communities. To test this hypothesis, thermodynamic modeling was used to assess the link between redox gradients in the ombrotrophic peatland of the Marcell Experimental Forest (Minnesota, USA) and the chemical and taxonomic composition of microbial communities. The average amino acid composition of community‐level proteins, called hereafter model proteins, was calculated from shotgun metagenomic sequencing. The carbon oxidation state of model proteins decreases linearly from −0.14 at 10 cm depth to −0.17 at 150 cm depth. Calculating equilibrium activities of model proteins for a wide range of chemical conditions allows identification of the redox potential of maximum chemical activity. Consistent with redox measurements across peat soils, this model Eh decreases logarithmically from an average value of 300 mV at 10 cm depth, close to the stability domain of goethite relative to Fe2+, to an average value of −200 mV at 150 cm, within the stability domain of CH4 relative to CO2. The correlation identified between the taxonomic abundance and the carbon oxidation state of model proteins enables predicting the evolution of taxonomic abundance as a function of model Eh. The model taxonomic abundance is consistent with the measured gene and taxonomic abundance, which evolves from aerobic bacteria at the surface including Acidobacteria, Proteobacteria, and Verrumicrobia, to anaerobes at depth dominated by Crenarchaeota. These results indicate that the thermodynamic forcing imposed by redox gradient across peat soils shapes both the chemical and taxonomic composition of microbial communities. By providing a mechanistic understanding of the relationship between microbial community and environmental conditions, this work sheds new light on the mechanisms that govern soil microbial life and opens up prospects for predicting geochemical and microbial evolution in changing environments. [ABSTRACT FROM AUTHOR]

When studying the carbon cycle in the biosphere, special attention is paid in Russia to the transformation of organic matter in the surface layer of supergene zone. The group composition of the organic matter (OM) in peats of different genesis in the taiga zone of Western Siberia is studied. Our data show that it is important to take into account the botanical composition of peat that make up natural and reclaimed forest swamps, well as their spatial heterogeneity, which is a necessary component when estimating the carbon stocks in peat soils of forest ecosystems within the national monitoring system for carbon pools and greenhouse gas fluxes. The experiments on peat OM transformation demonstrate that its efficiency is determined by its botanical composition. According to the rate of OM decomposition, the oligotrophic peats form a sequence: sphagnum–hollow > complex > fuscum > scheuchzeria–sphagnum > cotton grass–sphagnum > scheuchzeria > cotton grass peats and eutrophic peats: hypnum > sedge > sedge–hypnum > menyanthes > woody > wood–sedge peats. According to two-year field experiments on the transformation rate and direction of the OM of peat-forming plants, the component and chemical compositions of their OM significantly changes but in an individual manner for each plant. The content of aromatic polyconjugated systems and carboxyl groups increases, while the amount of carbohydrate fragments decreases. A 60 years long forest amelioration influences the transformation of peat OM. The degree of grass and sedge peat species in the process of amelioration increases by 5% in the 75-cm layer; the content of bitumens decreases, whereas the contents of easily hydrolyzable substances, humic acids, and lignin, increases. The microbiomes and enzymes of the peats in forest swamps of Western Siberian taiga are characterized. Our results confirm the hypothesis by V.E. Rakovsky that the differences in the species composition of peat-forming plants manifest themselves in the chemical and biological characteristics of peat. [ABSTRACT FROM AUTHOR]

Peatland drainage can affect the natural state of hydrological conditions and nutrient loading but is rarely included in catchment-scale models. To understand the gap, we aimed to use the soil and water assessment tool (SWAT) to observe drained peatlands and their properties to predict nutrients and suspended solids (SS) in the peatland-dominated Simojoki catchment. We integrated drainage networks in SWAT to (i) identify drainage parameters; (ii) determine annual loads and mean concentrations of SS, organic phosphorus (Org-P), total phosphorus (TP), organic nitrogen (Org-N), and total nitrogen (TN); (iii) understand spatial variation of nutrients and SS; and (iv) investigate uncertainty ranges for the estimates. The calibrated model showed a 9.6 per cent bias between the simulated flow and the observations with low-to-medium loading variations for the water quality parameters. For Org-N and TN, the highest loading per year was at the downstream outlet, whereas for SS, Org-P, and TP, it was higher at the upstream outlet of the catchment. This approach of representing the drained peatland in SWAT indicated maximum spatial distributed load in the peat soil in the clear-cut area and can be beneficial in future hydrological modelling efforts in identifying the status of nutrients or SS. [ABSTRACT FROM AUTHOR]

Calophyllum brasiliense is a hydrophilous tree species widely distributed in Brazil. It often dominates tropical swamp forests and shows morphophysiological responses to flooding and sensitivity to water deficits. To investigate the edaphic influence on the xylem structure of this species, wood samples were obtained from adult C. brasiliense trees in two soil types, Podzol and Histosol, both covered by lowland Atlantic Forest, in a coastal plain in southern Brazil. The sandy texture of Podzol and its microrelief often lead to more mesic conditions compared to Histosol, which is an organic and hydromorphic soil. Permanent slides with histological sections and dissociated material were prepared for qualitative and quantitative anatomical analysis. Principal component analysis and mean comparison tests were performed to assess variations in anatomical traits between soil conditions. Vessel density and fiber length were higher in trees from Podzol compared to Histosol, while the width of the rays was greater in Histosol. Additionally, the cross-sectional area and mean lumen diameter of vasicentric tracheids were larger in populations from Histosol than in Podzol. Furthermore, Vulnerability and Mesomorphy indices showed higher values in Histosol compared to Podzol. While the response associated with vessel occurred in density (higher in Podzol), the response in tracheid is reflected in cell diameter (higher in the soil with more water: Histosol). This publication is likely the first to demonstrate intraspecific variation of vasicentric tracheids in a hydrophilous species. The anatomical structure and functional implications of the observed variations are discussed regarding the efficiency and safety of the conductive system, considering the ecology of the species and the characteristics of the sampled soils. [Display omitted] • The xylem structure of C. brasiliense is closely related to its hydrophilous status. • More numerous vessels and narrower vasicentric tracheids occur in mesic soil: Podzol. • Narrower fibers occur in the hydromorphic and more unstable soil: Histosol. • Vasicentric tracheids and vessels form a tridimensional water conduction network. [ABSTRACT FROM AUTHOR]

Highly organic soil and peat are problematic soils due to their low bearing capacity and high compressibility. In tropical regions, the presence of woody material in these soils often affects the stress-compression and time-compression curves in load-increment consolidation tests, leading to unusual shapes. Consequently, conventional inorganic soil theory and the Cα/Cc concept are inadequate for analyzing their compression behavior. As an alternative, the Gibson and Lo model can be used to obtain compression parameters from single-load consolidation tests. However, this method introduces considerable discrepancies when predicting the primary settlement. To address this issue, this paper proposes a formula for predicting the primary settlement in highly organic soil and peat in the field, especially in tropical regions. Samples were collected from several locations in Indonesia. The formula was constructed from the stress-strain relationship during the primary compression stage, obtained from numerous single-load consolidation tests. Long-term field settlement is predicted by combining this empirical equation for primary settlement with the Gibson and Lo model for secondary settlement. The proposed formula was verified using field soil monitoring data, demonstrating reasonable accuracy in predicting the primary settlement of highly organic soil and peat. [ABSTRACT FROM AUTHOR]

The phylum Verrucomicrobiota is one of the main groups of soil prokaryotes, which remains poorly represented by cultivated organisms. The major recognized role of Verrucomicrobiota in soils is the degradation of plant-derived organic matter. These bacteria are particularly abundant in peatlands, where xylan-type hemicelluloses represent one of the most actively decomposed peat constituents. The aim of this work was to characterize the microorganisms capable of hydrolyzing xylan under the anoxic conditions typical of peatland soils. The laboratory incubation of peat samples with xylan resulted in the pronounced enrichment of several phylotypes affiliated with the Verrucomicrobiota, Firmicutes, and Alphaproteobacteria. Sequencing of the metagenome of the enrichment culture allowed us to recover high-quality metagenome-assembled genomes (MAGs) assigned to the genera Caproiciproducens, Clostridium, Bacillus (Firmicutes), and Rhizomicrobium (Alphaproteobacteria), Cellulomonas (Actinobacteriota) and the uncultured genus-level lineage of the family Chthoniobacteraceae (Verrucomicrobiota). The latter bacterium, designated "Candidatus Chthoniomicrobium xylanophilum" SH-KS-3, dominated in the metagenome and its MAG was assembled as a complete closed chromosome. An analysis of the SH-KS-3 genome revealed potential endo-1,4-beta-xylanases, as well as xylan beta-1,4-xylosidases and other enzymes involved in xylan utilization. A genome analysis revealed the absence of aerobic respiration and predicted chemoheterotrophic metabolism with the capacity to utilize various carbohydrates, including cellulose, and to perform fermentation or nitrate reduction. An analysis of other MAGs suggested that Clostridium and Rhizomicrobium could play the role of primary xylan degraders while other community members probably took advantage of the availability of xylo-oligosaccharides and xylose or utilized low molecular weight organics. [ABSTRACT FROM AUTHOR]

Erythropalum scandens Bl. is a medicinal woody vegetable found in southern China and parts of Southeast Asia. Studies have shown improper substrate hindered E. scandens seedling growth, causing water accumulation and nutrient deficiency. In pursuit of an ideal growth medium for E. scandens seedlings during the early stages, this study conducted a pot experiment to identify a mixed substrate with optimal water permeability and fertility. In this study, pure Alfisols soil treatment as the control (CK), and two soilless substrates (peat soil and perlite) were combined with Alfisols soil into different volume ratios, in order to better use soil resources from understory space and balance the texture of mixed substrates. The growth, physiological characteristics and nutrient status of 24-month-old E. scandens seedlings were determined after planting in different mixed ratios. The results showed that as the proportion of peat soil increased in the mix, most indexes exhibited an initial increase followed by a decline, while soluble protein content decreased consistently. Conversely, an increasing perlite ratio resulted in a general decline in most growth and physiological indexes. Root growth, biomass accumulation and chlorophyll content, peaked in the 66.67% Alfisols soil + 33.33% perlite (T4) treatment. Notably, T3 (66.67% Alfisols soil + 33.33% peat soil) showcased the best above-ground growth, while T1 (50.00% Alfisols soil + 50.00% peat soil) excelled in element content accumulation. In conclusion, the cultivation substrate should primarily consist of Alfisols soil, constituting at least 50%. The addition of peat soil enhances above-ground growth and nutrients accumulation, while perlite contributes to robust root development. One third of peat soil and a small amount of perlite can be added to the substrate during E. scandens seedling cultivation, and proper fertilization should also be used in order to increase nutrient accumulation in aboveground and underground parts. This research provides valuable insights into maximizing the potential of E. scandens seedlings through precise cultivation methods. [ABSTRACT FROM AUTHOR]

Background: Sulfate-reducing bacteria (SRB) are frequently encountered in anoxic-to-oxic transition zones, where they are transiently exposed to microoxic or even oxic conditions on a regular basis. This can be marine tidal sediments, microbial mats, and freshwater wetlands like peatlands. In the latter, a cryptic but highly active sulfur cycle supports their anaerobic activity. Here, we aimed for a better understanding of how SRB responds to periodically fluctuating redox regimes. Results: To mimic these fluctuating redox conditions, a bioreactor was inoculated with peat soil supporting cryptic sulfur cycling and consecutively exposed to oxic (one week) and anoxic (four weeks) phases over a period of > 200 days. SRB affiliated to the genus Desulfosporosinus (Bacillota) and the families Syntrophobacteraceae, Desulfomonilaceae, Desulfocapsaceae, and Desulfovibrionaceae (Desulfobacterota) successively established growing populations (up to 2.9% relative abundance) despite weekly periods of oxygen exposures at 133 µM (50% air saturation). Adaptation mechanisms were analyzed by genome-centric metatranscriptomics. Despite a global drop in gene expression during oxic phases, the perpetuation of gene expression for energy metabolism was observed for all SRBs. The transcriptional response pattern for oxygen resistance was differentiated across individual SRBs, indicating different adaptation strategies. Most SRB transcribed differing sets of genes for oxygen consumption, reactive oxygen species detoxification, and repair of oxidized proteins as a response to the periodical redox switch from anoxic to oxic conditions. Noteworthy, a Desulfosporosinus, a Desulfovibrionaceaea, and a Desulfocapsaceaea representative maintained high transcript levels of genes encoding oxygen defense proteins even under anoxic conditions, while representing dominant SRB populations after half a year of bioreactor operation. Conclusions: In situ-relevant peatland SRB established large populations despite periodic one-week oxygen levels that are one order of magnitude higher than known to be tolerated by pure cultures of SRB. The observed decrease in gene expression regulation may be key to withstand periodically occurring changes in redox regimes in these otherwise strictly anaerobic microorganisms. Our study provides important insights into the stress response of SRB that drives sulfur cycling at oxic-anoxic interphases. 1UtHR5dBbf2f8WaGLBYUtH Video Abstract [ABSTRACT FROM AUTHOR]

Sequential (S) and equal-time (ET) methods were applied to assess the temperature sensitivity of respiration of peat soils in different terrestrial ecosystems: southern tundra, northern taiga, and mixed coniferous–broadleaved forests. The Q10 values varied widely (1.3–4.8) and in case of the ET method decreased from northern to temperate latitudes. In the cold range (5–15°С), Q10 increased from the southern tundra (3.5) to the northern taiga (4.8) and then sharply decreased in the zone of mixed forests (2.5). Meanwhile, warm range (15–25°С) showed a clear decline of Q10 from northern to temperate latitudes: southern tundra (2.6) > northern taiga (1.6) > coniferous–broadleaved forests (1.3). Application of the S method resulted in low variability of Q10 values. Our results demonstrate a higher temperature sensitivity of the respiration of peat soils in northern latitudes as compared to that in the temperate zone. The Q10 values obtained in this study can be useful for calibration of regional carbon cycle datasets that consider the contribution of peat soils. [ABSTRACT FROM AUTHOR]

The study of hydraulic conductivity is essential for the effective management of peat drainage systems, particularly in West Sumatra, Indonesia, where peatlands are layered with sand and clay substratum. These substrate variations are believed to influence soil conductivity, indirectly impacting plant growth. This study aimed to compare saturated hydraulic conductivity between peat soils with sand and clay substratum, analyze the characteristics of peat pores affecting conductivity, and establish relationships between soil parameters and peat drainage in both systems. Conducted in Pesisir Selatan, West Sumatra, the study involved 12 observation points for soil hydraulic conductivity. Results indicated that peat soil with a sand substratum exhibited an average hydraulic conductivity (HC) of 1.13 x 10-3 cm.s-1, five times faster than peat with a clay substratum (2.21 x 10-4 cm.s-1). Interestingly, soil HC values did not correlate with pore characteristics in the peat layer but were significantly associated with those in the substratum layer. Specifically, substratum layer HC positively correlated with Aeration Pores (AP) (r=0.680) and Drainage Pores (DP) (r=0.031), and negatively correlated with Available Water Pores (AWP) (r=-0.817, p<0.047, r²=0.667). Notably, AWP in the sand substratum layer was lower (22.50%vol) than in the clay substratum layer (30.53%vol). Therefore, precise regulation of peat drainage in a sand substratum is crucial to mitigate the potential increase in water levels in peatlands. [ABSTRACT FROM AUTHOR]

Permafrost degradation varies spatially; however, the underlying mechanism remains partially unclear. In this study, we predicted permafrost variation under the influence of climate change to investigate the sensitivity of permafrost degradation to geological and climatic conditions. The results revealed that geological strata can strongly impact the permafrost degradation process. Mainly due to the greater thermal conductivity of sandy gravel in the Arctic, the complete thaw of permafrost will be greatly delayed by more than 160 years compared with that on the Qinghai–Tibet Plateau (QTP). Climatic conditions, such as snow depth, can also greatly affect the degradation process of permafrost: The thaw of permafrost will be delayed by more than 140 years when the snow depth decreases from 0.7 to 0.1 m. Peat soil thickness at ground surface can also affect permafrost degradation. The permafrost temperature increases as peat soil thickens when the thickness is less than 1.0 m, whereas there is a critical peat soil thickness (approximately 0.2 and 0.5 m on the QTP and in the Arctic, respectively) under which permafrost will thaw at the fastest rate. The findings highlight the influence of geology and climate over permafrost degradation. [ABSTRACT FROM AUTHOR]

In the UK uplands, prescribed burning of unenclosed heath, grass and blanket bog ('moorland') is used to support game shooting and grazing. Burning on moorland is contentious due to its impact on peat soils, hydrology and habitat condition. There is little information on spatial and temporal patterns of burning, the overlap with soil carbon and sensitive habitats and, importantly, whether these patterns are changing. This information is required to assess the sustainability of burning and the effectiveness of new legislation. We developed a method for semi‐automated detection of burning using satellite imagery – our best performing model has a balanced accuracy of 84.9%. We identified annual burn areas in Great Britain in five burning seasons from 2017/18 to 2021/22 of 8333 to 20 974 ha (average 15 250 ha year−1). Annual extent in England in 2021/22 was 73% lower than the average of the four previous seasons. Burning was identified over carbon‐rich soils (mean 5150 ha or 34% by area of all burning annually) and on steep slopes – 915 ha across the five seasons (1.3%), contravening guidance. Burning (>1 ha) was recorded in 14% of UK protected areas (PAs) and, within these, the percentage area of moorland burned varied from 2 to 31%. In England in some years, the percentage area of moorland burned inside PAs was higher than outside, while this was not the case in Scotland. Burning in sensitive alpine habitats totalled 158 ha across the five seasons. The reduction in burned area in England in 2021/22 could relate to England‐specific legislation, introduced in May 2021, to prohibit burning on deep peat in PAs. This suggests that regulation can be effective. However, the continued overlap with sensitive features suggests that burning falls short of sustainable practices. Our method will enable repeatable re‐assessment of burning extents and overlap with ecosystem services. [ABSTRACT FROM AUTHOR]

In response to the challenges of poor engineering properties and the high difficulty in improving peat soil, a composite cement solidification agent (CCS) comprising ultra-fine cement (UFC) and ordinary Portland cement (OPC) was proposed for the solidification of simulated peat soil. The influence of UFC on the permeability of cement-soil samples was investigated through osmotic pressure tests and X-ray diffraction (XRD) experiments. Osmotic pressure tests results indicate that, under constant CCS dosage, the permeability coefficient k of specimens decreases with increasing UFC mass fraction, with a significant attenuation of the decreasing trend observed when the UFC mass fraction exceeds 12%. For CCS with a UFC mass fraction of 12%, k decreases with increasing CCS dosage, and the declining trend is notably attenuated when the dosage exceeds 25%. XRD results indicate that the diffraction peak intensity of calcium silicate hydrate (C-S-H) in the samples increases with both the increase in the UFC mass fraction and the curing time. Compared to OPC, CCS achieves superior solidification efficiency with a reduced cement dosage, facilitating the attainment of carbon reduction objectives. [ABSTRACT FROM AUTHOR]

Increasing bulk density with depth in a peat profile has been seen as key to the formation of peat. Increasing bulk density with depth causing the changes in porosity and permeability of peat soils has been proposed as a mechanism to explain how waterlogged, stagnant conditions persist in peat bog soils. However, a previous study (Clay & Worrall, 2015; Soil Use & Management, 31, 77) observed, in passing, that this was not always the case, but this previous study could not test the nature of the peat bulk density profile. Thus, this present study examined 22 peat cores from 13 locations across climatic gradients of the UK, including valley fens, blanket and raised bogs, and both intact peatlands and former peat extraction sites. At none of the 13 locations was there a significant increase in dry bulk density with depth in the peat profile. The oxidation state of the organic carbon (Cox) in the peat profile showed no common pattern of change with depth. The only measured property that showed a consistent change down the peat profile among all 13 locations was an increase in the degree of unsaturation of C bonds. The change in degree of unsaturation shows a trend away from vegetation biomass composition and toward lignin‐like compositions with an average rate of change of 0.2 π‐bonds/ka. The measured pattern of bulk density between locations and types of peat shows that peat density reflects the contemporary peat environment, rather than the nature of peat formation. The bulk density profile likely reflects average water table position, as determined by topographic and land‐management factors, with peat compaction and accelerated decomposition within the aerobic zone. The presence of gas bubbles may also contribute to low bulk density at depth. The common bulk density profile found across the UK for peat ecosystems shows that peat formation is not controlled by porosity change but more specifically by water flow and hydraulic conductivity. [ABSTRACT FROM AUTHOR]

Aquilaria crassna Pierre ex Lecomte is a principal species renowned for its production of agarwood. However, the active components of agarwood are not universally in compliance with the standards set by the Chinese Pharmacopoeia. We have identified an elite A. crassna tree with agarotetrol and alcohol extract levels that exceed these standards and have successfully established a stable in vitro micropropagation system using stem segments from this elite tree. The effects of auxins and minerals on axillary-bud induction, shoot multiplication, and rooting were investigated. The most effective medium for axillary-bud induction was a half-strength Murashige and Skoog (1/2MS) medium supplemented with 0.50 mg/L 6-benzylaminopurine (6-BA), achieving an induction rate of 53.33% with minimal hyperhydricity. The optimal shoot proliferation medium was an MS medium with 0.40 mg/L 6-BA, yielding a propagation coefficient of 2.96 without hyperhydricity. The best rooting medium comprised quarter-strength MS (1/4MS) macroelements and 1/2MS microelements with 0.10 mg/L naphthaleneacetic acid (NAA), resulting in an 82.54% rooting rate. Substrate effects on transplant survival and growth were also evaluated, and peat soil was identified as the best substrate, achieving a survival rate of 96.67%. This study introduces a straightforward and efficient in vitro micropropagation system utilizing mature A. crassna as explants. It holds significant importance for the consistent production of agarwood that complies with the standards of the Chinese Pharmacopoeia and provides a model for the targeted breeding of medicinal plants. [ABSTRACT FROM AUTHOR]

Submerged plants are an important part of aquatic ecosystems, and the restoration of submerged plants is a key step in the reconstruction of aquatic ecosystems. However, little is known about the role of modified sediments in helping submerged plants recover under low light. In this study, we set up four sediment types and two light intensities to explore the effects of modified sediments on the growth of Vallisneria natans under two low light conditions. The results showed that the independent and interactive effects of light intensity and sediment type significantly affected the biomass, morphology, photosynthetic pigment content and antioxidant enzyme activity of V. natans. At 5% and 20% natural light intensity, the sediment modified with 40% peat soil had a larger root biomass and the highest leaf and root C/N ratio, the sediment modified with 40% vermiculite had a longer root length and more ramets. At 5% natural light intensity, the sediments modified with fly ash had shorter root length and smaller leaf biomass. The sediments modified with fly ash had the greatest chlorophyll content at 20% natural light intensity. It can be concluded that the addition of 40% peat soil or 40% vermiculite in sediment is conducive to the growth of V. natans under low light conditions. Our study indicates the positive effects of the modified sediment on the growth of V. natans under low light conditions, and our study will provide a reference for the restoration of submerged plants in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Understanding the nuances of soil health is more important than ever to improve the quality and sustainability of agroecosystems. However, it is poorly understood how the variety of metrics currently in use to evaluate soil health relate to each other, and in what situations their use is not sensitive enough to indicate environmental changes. The use of faunal co‐occurrence networks is a novel, potentially valuable tool that has hitherto received little attention in the context of soil health. Here, we used a meadow land‐use intensity gradient to compare the response of a number of soil community metrics, including chemical and ecological indicators as well as faunal co‐occurrence network parameters. Our findings indicate that the examined metrics displayed distinct, often contrasting patterns to one another, and that network analysis detected patterns that strongly aligned with the land‐use effects. This pattern was qualitatively different from patterns arising from traditionally used metrics. The soils with conventional farming, that is, the least regenerative land‐use, generally scored well in traditionally used metrics, including C:N ratio, faunal abundance and the ratio of Acari to Collembola. Regenerative farming was comparable with conventional farming in all conventional metrics—however, network analysis revealed that the soil faunal communities under regenerative farming had the highest species connectivity out of all research areas potentially due to grazing increasing the connectivity of faunal networks. Overall, these results suggest that network analyses are best suited to capture subtle land‐use intensity differences while traditional metrics performed well in big changes. While more research is needed to better interpret soil faunal co‐occurrence networks, our findings imply that it could be a useful method to provide further insight in aspects of soil health. [ABSTRACT FROM AUTHOR]

Worldwide, the drainage of peatlands has turned these systems from CO2 sinks into sources. In the Netherlands, where ∼7 % of the land surface consists of peatlands, drained peat soils contribute >90 % and ∼3 % to the country's soil-derived and total CO2 emissions, respectively. Hence, the Dutch National Climate Agreement has set targets to cut these emissions. One potential mitigation measure is the application of subsurface water infiltration systems (WISs) consisting of subsurface pipes connected to ditchwater. WISs aim to raise the water table depth (WTD) in dry periods to limit peat oxidation while maintaining current land-use practices. Here, we used automated transparent chambers in 12 peat pasture plots across the Netherlands to measure CO2 fluxes at high frequency and assess (1) the relationship between WTD and CO2 emissions for Dutch peatlands and (2) the effectiveness of WISs in mitigating emissions. Net ecosystem carbon balances (NECBs) (up to 4 years per site, 2020–2023) averaged 3.77 and 2.66 tCO2-Cha-1yr-1 for control and WIS sites, respectively. The magnitude of NECBs and the slope of the WTD–NECB relationship fall within the range of observations of earlier studies in Europe, though they were notably lower than those based on campaign-wise, closed-chamber measurements. The relationship between annual exposed carbon (C; defined as the total amount of carbon within the soil above the average annual WTD) and NECB explained more variance than the WTD–NECB relationship. The magnitude of the NECB represented 1.0 % of the annual exposed C on average, with a maximum of 2.4 %. We found strong evidence for a reducing effect of WISs on CO2 emissions, reducing emissions by 2.1 (95 % confidence interval 1.2–3.0) tCO2-Cha-1yr-1 , and no evidence for an effect of WISs on the WTD–NECB and annual exposed carbon–NECB relationships. This means that relationships between either WTD or exposed carbon and NECB can be used to estimate the emission reduction for a given WIS-induced increase in WTD or exposed carbon. High year-to-year variation in NECBs calls for multi-year measurements and sufficient representative measurement years per site as demonstrated in this study with 35 site-year observations. [ABSTRACT FROM AUTHOR]

The behavior of slow mass movements like soil creep is well known to be governed by soil composition, slope, and cycles in temperature and rainfall. However, their magnitude and importance vary dramatically in often unpredictable ways, with important consequences for creep rate and infrastructure damage prediction. Here, we present long-term (2015–2022) creep measurements for four regions of the UK characterized by intense mass movement activity but different bedrock lithologies. We also obtained co-located temperature and precipitation time series over this period, as well as local measurements of slope and soil thickness and composition. Our goal was to deconvolve the relative importance of each observable on creep behavior. Our results imply that parent lithology governs first-order creep rates indirectly via hillslope repose angles and soil thickness and composition. Rates of ground movement on peat and sandstone soils are dictated by annual fluctuations in precipitation and temperature, respectively. By employing a simple error-minimizing regression routine, we demonstrate how creep rates can be predicted in these settings as a function of climatological observables. Over thinner limestone and thicker clay soils, however, our model fails: in these settings, we suggest that creep behavior is instead dominated by variations in regolith thickness, and slope and clay mineral content, respectively. [ABSTRACT FROM AUTHOR]

Dissolved organic matter (DOM) plays a significant role in the nutrient supply, energy flow, and pollutant transportation in the wetland ecosystem. However, little is known about the effect of the decomposition of different organic materials in alpine wetland water on the DOM characteristics. By conducting a 90-day decomposition experiment with the addition of different organic materials (peat soil, yak manure, and plant litter) alone or their combinations into alpine wetland water, we characterized the water DOM using three-dimension excitation-emission matrix spectroscopy. The results showed that the decomposition of organic materials significantly affected the chemical properties, sources, humification degree, and composition of the water DOM. The decomposition increased dissolved organic carbon and dissolved total nitrogen in the water. For most of the water samples, a fluorescence index ranging from 1.4 to 1.7 and a biological index of less than 0.8 may indicate that both autochthonous and allochthonous sources contributed to the water DOM, which may primarily rely on allochthonous sources. UVA (37.55–46.81% of total fluorescent components) and UVC fulvic-like substances (29.91–35.53% of total fluorescent components) dominated the water DOM compositions. Among the treatments, additions of peat soil and yak manure led to the highest and the lowest humification degree of the water DOM, respectively. For the treatment of the combination decomposition of all three organic materials, the yak manure may stimulate microbial activity and facilitate the decomposition of plant litter and peat soil and, therefore, boost the humic-like substances in the water DOM. These findings may help the development of wetland biomass management with the objective of maintaining alpine wetland ecosystem services. [ABSTRACT FROM AUTHOR]

Factors influencing the geochemical migration of elements during the development of artificial phytocenoses on industrially polluted peat soil with a high level of copper and nickel content using serpentine-containing materials are considered. Monitoring of the remediation sites during a four-year field experiment showed that the grass cover is capable of sustainable functioning by neutralizing the acidity of peat soil, reducing the toxicity of soil solutions, and eliminating the imbalance of macronutrients. Serpentine minerals act as an alkaline barrier, reducing the intensity of migration of copper and nickel compounds. [ABSTRACT FROM AUTHOR]

Aims: The release of the major greenhouse gas N2O from peatlands may be affected by current global change. We tried to answer how N2O emission from peatlands responds to phosphorus (P) addition and the co-addition of P and nitrogen (N). Methods: We investigated the long-term (12 years) effects of N (50 and 100 kg ha−1 yr−1) and P (5 kg ha−1 yr−1) additions and their interaction on N2O fluxes in Hani peatland during the 2019 growing season. Results: The addition of P, a low level of N or their co-addition had no effect on the source/sink function of N2O in the peatland. However, a high level of N addition turned the peatland into a sink of N2O with a cumulative flux of −164 ± 51 g m−2 during the growing season. This was probably due to the acceleration of plant litter decomposition, stimulation of hydrolase activity, and changes in the stoichiometric ratio of the peat soil. The co-addition of P and a high level of N turned the peatland into a source of N2O with a cumulative flux of 144 ± 54 g m−2 during the growing season by relieving nutrient limitation, accelerating the growth of vascular plants, and altering the litter input. Conclusions: We suggest that the increase in nutrient availability caused by N deposition and agriculture fertilization can alter the N2O source/sink function of peatlands. These changes may have significant implications for the overall balance of greenhouse gas emissions and the role of peatlands in mitigating climate change. [ABSTRACT FROM AUTHOR]

Peat particulate organic matter (POM) in the anoxic subsurface of peatlands is increasingly recognized as an important terminal electron acceptor (TEA) in anaerobic respiration. While POM reduction has been demonstrated in laboratory peat‐soil incubations and (electro‐) chemical reduction assays, direct demonstration of POM reduction in peat soils under in situ, field conditions involving quantification of transferred electrons remain missing. Herein, we demonstrate that deployment of an oxidized reference POM in the anoxic, methanogenic subsurface of three ombrotrophic bogs, followed by one year incubation, resulted in the transfer of approximately 150–170 μmol of electrons per gram POM to the deployed reference POM. The capacity of this reduced POM to accept electrons was partially restored upon subsequent exposure to dissolved oxygen. These findings provide direct evidence for POM acting as regenerable and sustainable TEA for anaerobic respiration in temporarily anoxic parts of peat soils. Based on the number of electrons transferred to POM and thermodynamic considerations, we estimate that anaerobic respiration to POM may largely suppress methanogenesis in peat soils, particularly close to the oxic‐anoxic interface across which POM is expected to undergo redox cycling. Plain Language Summary: In oxygen‐depleted peat soil, microbes slowly break down peat material to CO2 in a series of processes summarized under the term anaerobic respiration. These processes have in common that they require a chemical substance to which microbes can transfer electrons liberated in anaerobic respiration. Previous studies provided evidence that peat particulate organic matter (POM), the organic material primarily making up peat soils, can act as this electron acceptor. In this work, we buried a reference POM, placed in small mesh bags, in three Swedish peat soils. After 1 year, analysis of the recollected POM indeed showed that it had taken up electrons. Some of these electrons could be subsequently removed from the POM by bringing it in contact with dissolved oxygen. Taken together, our study supports that POM in peatlands accepts electrons, temporarily stores them, and then transfers them to oxygen when it becomes available. In this role of electron acceptor, POM may significantly decrease the formation of large amounts of methane, a gas that, when released from peatlands, largely contributes to warming of the atmosphere. Electron transfer to POM in peatland soils thus may play an important and desirable role in lowering natural methane release from peatland ecosystems. Key Points: Oxidized reference peat particulate organic matter (POM) was reduced in the anoxic subsurface of three ombrotrophic bogs over 1 yearOn average, 160 μmol electrons were transferred per gram reference POM across the three bogsThe reduced POM was partially re‐oxidized by dissolved oxygen, supporting that POM is a sustainable terminal electron acceptor [ABSTRACT FROM AUTHOR]

Peat soil exhibits significant creep deformation, and its consolidation law differs from that of soft soil. This study examines the strain characteristics of peat soils during three stages of consolidation using indoor one-dimensional creep consolidation tests. The results showed that the rebound deformation after the primary consolidation stage and the secondary consolidation stage is equivalent to the deformation seen during the primary consolidation stage, about 1.003 times. However, once the deformation stabilizes, the rebound deformation decreases to 0.32–0.85 times that of the deformation observed during the primary consolidation stage. The elastic and time-independent plastic strains of the peat soil showed two-stage linear changes with ln σ z ′ . When the load was greater than the pre-consolidation pressure, the deformation modulus increases by approximately 2.10 and 1.56 times, respectively. On this basis, this study, for the first time, defines the creep rate according to the strain rate in the tertiary consolidation stage in the strain versus the time curve ( ε z ~ t ). Based on the timeline, a one-dimensional creep consolidation model is established that can accurately predict the strain during the consolidation of the peat soil foundation. The results reveal distinct strain behaviors during each stage and improve the theoretical basis for the study of creep. [ABSTRACT FROM AUTHOR]

The groundwater table (GWT) is widely recognized as a key factor influencing CO2 emissions in tropical peatlands. However, previous studies investigating this relationship have reported diverse results. This variability likely stems from the dynamic nature of field-based groundwater conditions. To address this, our study investigated the relationship between controlled GWT and CO2 emissions in a laboratory experiment using PVC columns filled with peat soil. GWT depths were adjusted to 20 cm, 30 cm, 40 cm, 50 cm, and 60 cm within a large container filled with peat pore water. CO2 emissions were measured using an Infra Red Gas Analyzer - Environmental Gas Monitoring-4 instrument, with a closed-chamber system. Our findings revealed significant differences in CO2 emissions between treatments, except for the transition from 20 cm to 30 cm GWT. Correlation analysis showed a positive correlation (R² = 0.25). Notably, CO2 emission factor values based on average yearly emission rates displayed a substantial increase with decreasing GWT, exhibiting a strong exponential relationship (R² = 0.99).

Coix lacryma-jobi L., an annual or perennial plant belonging to the Poaceae family, has long been cultivated as a food and medicine plant in China. In recent years, coix cultivation for high yields and good quality has become a research hotspot in Southwest China. Soil optimization is essential for improving crop growth. To ensure the robust establishment of coix plants, eight soil substrates, prepared from three typical soils, i.e., red clay soil, peat soil, and sandy soil, were used to cultivate two local coix varieties (Pu coix from Fujian Province, China; Qi coix from Hebei Province, China), and the plant growth and root coixol content of the two coix varieties were investigated. It was found that coix plants could maintain growth when cultivated with peat soil or sandy soil, but red clay soil was unfavorable for coix growth. The mixtures of sandy soils and peat soils resulted in synergistic benefits for coix growth and root coixol levels over the effects of sandy soil or peat soil alone. In conclusion, the mixtures of sandy soils and peat soils with appropriate proportions (sandy soils/peat soils = 2:1) were suggested as an ideal soil substrate for coix cultivation. The results provide valuable guidance for the establishment of coix plants, which could contribute to high yields and good quality in coix cultivation. [ABSTRACT FROM AUTHOR]