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Transfer of organic carbon from topsoil horizons to deeper horizons and to the water table is still little documented, in particular in equatorial environments, despite the high primary productivity of the evergreen forest. Due to its complexing capacity, organic carbon also plays a key role in the transfer of metals in the soil profile and, therefore, in pedogenesis and for metal mobility. Here we focus on equatorial podzols, which are known to play an important role in carbon cycling. We carried out soil column experiments using soil material and percolating solution sampled in an Amazonian podzol area in order to better constrain the conditions of the transfer of organic carbon at depth. The dissolved organic matter (DOM) produced in the topsoil was not able to percolate through the clayey, kaolinitic material from the deep horizons and was retained in it. When it previously percolated through the Bh material, there was production of fulvic-like, protein-like compounds and small carboxylic acids able to percolate through the clayey material and increase the mobility of Al, Fe and Si. Podzolic processes in the Bh can, therefore, produce a DOM likely to be transferred to the deep water table, playing a role in the carbon balances at the profile scale and, owing to its complexing capacity, playing a role in deep horizon pedogenesis and weathering. The order of magnitude of carbon concentration in the solution percolating at depth was around 1.5–2.5 mg L -1. Our findings reveal a fundamental mechanism that favors the formation of very thick kaolinitic saprolites. [ABSTRACT FROM AUTHOR]

Improvement of carbon sequestration in soils for a more sustainable environment and prevention of climate change require not only knowledge about soil organic carbon (SOC) stocks, but also about interactions between land use and total amount and distribution of carbon. In North Germany (state: Schleswig-Holstein) about 925 soil profiles in the four dominant geological regions [Weichselian glacial region, the sandy outwash region (Lower ―Geest), the Saalian glacial region Higher ―Geest), and the marshland with alluvial deposits] were sampled down to at least the 90 cm depth. Carbon content, pH, bulk density, and grain size distribution were analyzed for the major characteristic soil horizons. The four dominant geological regions possess different SOC stocks as well as SOC contents. The total amount of SOC stored within the representative soil profiles down to the 90 cm depth was analyzed for three depths: 0 – 30, 30 – 60, 60 – 90 cm; for the total area of Schleswig Holstein (15.369 km²), they summed to 244 Mt. SOC stocks, however, differed depending on the land use management system and clay content. Arable soils were most sensitive to soil deformation and the higher the clay content the less rigid they were, if the SOC to clay ratio were used as an index for structural quality. Grassland topsoils showed the highest SOC stocks and a mediate structural quality. The latter was highest for forest soils, which, however, had a higher SOC content but, at the same time, a less fertile SOC composition (litter with high C: N ratio). Further research on the carbon composition (labile, active, intermediate, or passive pools) would help to get a better insight into the role of SOC on soil strength and soil functions.

Aims: We investigated morphological variations in podzols caused by changes in soil porosity and permeability upon the growth of large tree-roots in a tropical barrier island (Ilha Comprida, Brazil). Methods: Soil morphology was described in a continuous lateral sequence of podzols on a 35 m-long cliff. A soil thin section was used to characterize organic matter (OM) accumulation and to estimate soil porosity, permeability, and saturated hydraulic conductivity (Ksat). Soil texture and the contents of organic carbon, Al, and Fe were determined for each pedogenic horizon containing large tree-roots. The evolution of podzol morphology was interpreted in the context of age determinations by optically stimulated luminescence and 14C. Results: Taproots of cashew trees (Anacardium occidentale) penetrated the cemented Bhm horizon and the massive-clayey 2Cgj horizon. Aligned with the taproot, we found a vertical OM-band with lower porosity, permeability, and Ksat than the adjacent Bh and E horizons. Irregular or broken boundaries between the E and Bh horizons were caused by large tree-roots. While the maximum age of these podzols is 3390 ± 530 years, significant and rapid changes in the Bh-horizon morphology occurred within the lifetime of the cashew trees (~ 50 years). Conclusions: The interplay between reduction in flow adjacent to large taproots and the enhanced vertical infiltration at depth has resulted into the development of irregular and broken boundaries between the E and Bh horizons. Because tree-roots alter both local soil porosity and water flow paths, they simultaneously cause the formation and degradation of podzol Bh-horizon. [ABSTRACT FROM AUTHOR]

The Amazonian biome has a fundamental role in the global climate change scenario and the understanding the physicochemical aspect in Amazonian soils is of great importance. The nine horizons constituting a typical Amazonian Spodosol profile were studied by different complementary techniques: X-ray powder diffraction (XRPD), high-resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED) and scanning electron microscopy-energy-dispersive X-ray spectrometry (SEM–EDX). The XRPD analysis revealed the presence of different minerals along the profile, i.e. quartz from 0 to 214 cm (horizons from A1 to Bhs) and kaolinite from 215 to 290 cm (horizons from Tr to K2). The HR-TEM images and SAED patterns revealed the presence of kaolinite in the horizon A1, which was not detected by XRPD. Application of the Rietveld refinement enabled the quantification of the minerals in each horizon. The SEM–EDX analyses allowed to identifying changes in the horizon surface morphology as a consequence of ongoing deformation. A significant decrease of particle sizes and a marked variations of their surface features with increasing depth were measured by SEM. In conclusion, the results of this work provide new insights into the relationship between chemical properties and mineral changes along the soil profile. [ABSTRACT FROM AUTHOR]

The dynamics of the content of water-soluble organic matter (WSOM) and its resistance to microbiological transformation in the Entic Folic Podzol of the postfire succession in the dwarf-shrub mountain tundra of the Khibiny Mountains are studied. A medium-intensity fire does not cause a statistically significant decrease in the soil WSOM content as compared to the reference plot. The activity of WSOM mineralization is mainly determined by the WSOM properties rather than by the microbial community. The dynamics of biodegradation is adequately described by a two-component first-order exponential model with a statistically significant existence of fast-mineralized (mean residence time, <1 day) and slow-mineralized (mean residence time, 33 to 111 days) pools. The maximum share of the fast pool is typical of the soil immediately after a fire and smoothly decreases during further postfire succession. During biodegradation, a biokinetic selection of the aromatic hydrophobic compounds most resistant to microorganisms is observed, while the simple nitrogen-containing components of WSOM are the first to be consumed by microorganisms. [ABSTRACT FROM AUTHOR]

Invasive earthworms can increase both pH and the nitrate concentrations in northern hardwood forests while nitrification is an acidification source. To obtain the nitrogen deposition impact, the soil pH, Ca, greenhouse gas emissions, and inorganic nitrogen forms have been compared for NH4+-N added and not added spodosol soils at aggregate scale inhabited by Amynthas agrestis (A) (ivasive/non-calciferous), Lumbricus rubellus (R) (non-invasive/calciferous), or no earthworm (C). Soils were classified into the three earthworm treatments by Naïve Bayes classification using all gas emissions, Ca, and pH (misclassification rate of 9.3%). There were significant differences among the earthworm treatments in pH, Ca, N2O, and CO2 emissions. pH varied among earthworm treatments (A < C < R) and reduced over time for all three treatments. Water-soluble Ca and N2O emissions were greater in R than in A soils. Both earthworm treatments had greater NO3–N concentrations than the control. Stepwise regression identified Ca (4 out of 5 incubations, positive effect, explaining 11% to 26% of pH variance) and CO2 evolution (4 out of 5 incubations, negative effect 4% to 47% of pH variance) as the two most consistent predictors of pH. We consider the earthworm invasion may be an alternative buffering agent for the nitrogen deposition for forests. [ABSTRACT FROM AUTHOR]

ABSTRACT The classification of Spodosols on the second categorical level (suborder), according to the Brazilian Soil Classification System (SiBCS), is done by observing the colors of genetic horizons in the field. The presence or absence of iron oxides is the main factor for this classification, and the color of the horizon is the criterion currently adopted. However, the simple observation of color in the field can be mistaken and cause an error in the definition of the second categorical level. This occurs when spodic horizons that do not contain iron oxides show high chroma color, or dark color due to the organic matter content, which masks the presence of iluviated Fe produced by podzolization. This can lead to errors, such as classifying Humiluvico horizons as Ferriluvico, and Ferri-humiluvico horizons as Humiluvico. These misunderstandings are currently solved through complex analyses using specific extractors and sophisticated equipment. Thus, obtaining a simple, fast, and inexpensive method to confirm the presence or absence of iron oxides in samples of spodic horizons is needed. This study tested an alternative method to assist in the determination of the second categorical level of the class of coastal plain Spodosols. The method consists of calcining samples in a muffle at 600 °C for 6 h. The calcination enabled to identify spodic horizons with and without presence of iron quickly; the result was compared with selective extraction analyses carried out using three different extractors: sodium pyrophosphate, ammonium acid oxalate, and sodium dithionite-citrate. The results obtained from these methods (calcination in muffle and selective extraction of iron oxides) enabled the identification of samples presenting colors varying from yellow to reddish, indicating the presence of iron, whereas those with the whitish color indicated absence or very low iron oxide levels. The 12 profiles of Spodosols were described and classified according to the SiBCS, and six profiles needed to be reclassified after the calcination procedure, which proved to be efficient.

Soil organic matter at high latitudes is an important and sensitive indicator of climate change. This article describes the main morphological features, chemical properties, and composition of organic matter in the main types of soils along the altitudinal gradient of the Subpolar Urals. Soils formed in the mountain tundra zone (gleyic humus-illuvial podbur/Skeletiс Stagnic Entic Podzol (Turbic)), in the mountain subalpine zone (gray-humus soil/Skeletiс Umbrisol), in the mountain taiga zone (iron-illuvial podzol/Skeletiс Albic Podzol), and in the mountain tundra zone with permafrost (permafrost-affected gleyic humus-illuvial podbur/Skeletiс Folic Cryosol (Humic)) were studied. The method of densimetric fractionation was applied to study soil organic matter; it enabled us to distinguish its three fractions, differing in carbon participation in the biological turnover: free particulate organic matter (fPOM<1.6), occluded particulate organic matter (oPOM<1.6), and heavy organic matter bound with the mineral phase (MaOM>1.6). The latter fraction dominated in the upper mineral soil horizons and comprised 89–93% of the total organic carbon. The content of light fractions was significantly lower (0.6–4.7%). However, the content of organic carbon and nitrogen in the studied soils directly correlated with the contents of light fractions fPOM<1.6 (r = 0.40 and r = 0.79, p < 0.05) and oPOM<1.6 (r = 0.68 and r = 0.83, p < 0.05). Aliphatic fragments dominated in the composition of POM; their content varied from 74.5 to 80.5% for fPOM<1.6 and from 77.9 to 84.2% for oPOM<1.6. In addition, it was found that the organic matter of the oPOM<1.6 fraction was characterized by a higher decomposition rate (0.4–2.4) and hydrophobicity (34.7–66.5%). [ABSTRACT FROM AUTHOR]

Aims: We investigated whether tree species growing in mixtures and under different water supply would segregate their fine roots vertically, produce more fine roots overall, or only in specific soil layers. Methods: We examined the biomass, morphology, and distribution of fine roots down to 90 cm (forest floor, 0–5, 5–15, 15–30, 30–60, 60–90 cm) in pure and mixed stands of 10-year-old birch and pine trees, planted on a sandy podzol with discontinuous hardpan and seasonal high water table, following a randomized block design with four blocks receiving irrigation and four blocks left unirrigated during summer. Results: Our results did not show any vertical root segregation between birch and pine in mixed plots. None of the species overyielded belowground throughout, but pine developed more roots in the top soil layer under irrigation. Both species had shallower fine root distributions in wet conditions, especially birch that was more plastic than pine in response to irrigation. Conclusions: Both species followed similar ecological strategies, occupying and competing for the same layers of the soil profile, under both control and irrigated conditions. However, the greater allocation of pine roots at the top soil horizons under irrigated conditions suggests locally favourable niches can lead to depth-specific asymmetric competition. This sheds new light on vertical niche partitioning of young tree mixtures under varying environmental conditions. [ABSTRACT FROM AUTHOR]

The deforestation of the upland landscapes in southwest Britain during prehistory is an established archaeological narrative, documenting human impacts on the environment and questioning the relationship of prehistoric societies to the upland landscapes they inhabited. Allied to the paleoenvironmental analyses of pollen sequences, which have provided the evidence of this change, there has been some investigation of prehistoric paleosols fossilized under principally Bronze Age archaeological monuments. These analyses identified brown earth soils that were originally associated with temperate deciduous woodland, on occasion showing evidence of human impacts such as tilling. However, the number of analyses of these paleosols has been limited. This study presents the first analysis of a series of pre‐podzol brown earth paleosols on Exmoor, UK, two of which are associated with colluvial soil erosion sediments before the formation of peat. This study indicates these paleosols are spatially extensive and have considerable potential to inform a more nuanced understanding of prehistoric human impacts on the upland environments of the early‐mid Holocene and assess human agency in driving ecosystem change. [ABSTRACT FROM AUTHOR]

Purpose: Several studies related to CH4 cycling focus on the effect of elevated atmospheric CO2 levels on soil methanogenesis and methanotrophy. However, periodically waterlogged soils are characterized by much higher CO2 concentrations, while aggregates forming in arable soils due to traditional cultivation may be a natural CH4 source for low-affinity methanotrophs. We present a comprehensive laboratory investigation into both methanogenesis and methanotrophy in three different soils under ambient and high CO2 concentrations. Materials and methods: The tested materials were agricultural soils widely distributed in Europe: Eutric Cambisol, Haplic Podzol and Mollic Gleysol with determined properties: Corg, Ntot, clay, silt, sand, pH, NO3−, NH4+. We conducted two independent experiments on methanogenesis (flooded conditions) and methanotrophy (non-flooded conditions). All samples for both studies were divided into three sets which differed in the initial CO2 concentration in headspace: ambient CO2 (0.03% v/v ± 0.005), and two high CO2 levels (5% ± 0.4 and 10% ± 0.5 v/v CO2). Moreover, 1% (v/v) of CH4 was added to all sets prepared for the methanotrophy test since low-affinity methanotrophy in the tested soils had been reported previously. Gas concentrations (CH4, CO2, O2) in headspace were measured using gas chromatography method. Results and discussion: We observed that the examined soils differed in their ability to produce CH4 as follows: Haplic Podzol = Eutric Cambisol > Mollic Gleysol, as well as to consume CH4: Mollic Gleysol > Haplic Podzol > Eutric Cambisol. The CH4 emissions started faster in Gleysol, but the final CH4 concentration and CH4 production rate in this soil were significantly lower than in the two other soils. The CH4 uptake rate significantly differed among the tested soils. The MANOVA confirmed the significance of the soil-type factor in determining both process rates, whereas the effect of CO2 level and the interaction between both factors were not significant. The amount of consumed O2 during CH4 oxidation was also characteristic for examined soil, but did not differ significantly between CO2 variants. Conclusions: CH4 production and consumption in three different soils (Eutric Cambisol, Haplic Podzol and Mollic Gleysol) collected from periodically waterlogged arable fields were more strongly affected by soil properties than by high CO2 concentration. In contrast, the high CO2 level significantly decreased CO2 production accompanying tested the CH4-related processes. [ABSTRACT FROM AUTHOR]

Immobilized metal affinity chromatography (IMAC) has been used to fractionate organic compounds in alkaline extracts from forest soils of the Komi Republic by their ability to form complexes with copper ions. An algorithm for chromatographic fractionation of substances into the groups of homogeneous molecular compounds is proposed by selecting the separation conditions; this algorithm comprises sequential change in pH and ionic strength of the eluent. As is shown, the alkaline extract contains three fractions, the components of which differ in their ability to form complexes with copper. The humic substances of iron-illuvial podzol (Albic Podzol), podzolic (Glossic Retisol), and peaty-podzolic gleyic (Histic Retisol) soils are shown to differ in their relative contents of ligand-forming organic compounds. The maximum content (according to Corg) of copper complexones is recorded in the organic matter of forest litters of the examined soils (14–21 g/kg). The corresponding values of the organic matter content in the eluvial horizons are 0.5–1.5 g/kg. The highest content of the carbon compounds able to bind copper ions is characteristic of podzolic soils, while the organic matter components of podzols and peaty-podzolic gleyic soil display somewhat lower affinity for copper. The proposed algorithm can be used to assess the soil vulnerability to heavy metal pollution. [ABSTRACT FROM AUTHOR]

Phosphorus (P) fertilizer that remains in the soil after harvest and into the subsequent rotation is referred to as carryover P. Carryover P is not well understood in loblolly pine (P. taeda) silviculture, especially on highly P responsive sites, where this effect could potentially have the greatest benefit to land managers. Our study aims to determine the duration of the P carryover effect and the magnitude of response to soil P as it relates to previously applied P fertilizer rates from the previous rotation. To address this knowledge gap, we studied two highly weathered sites on the lower Atlantic coastal plain: a somewhat poorly drained Spodosol and a poorly drained Alfisol over three years from pre- to post-harvest. Two years post planting, carryover fertilizer treatments resulted in a 13% increase in height for the 121 kg P ha-1, a 15% for the 81 kg P ha-1, and a 17% increase for the fertilized 40 + 45 kg P ha-1 treatments compared to the control for the Alfisol. Spodosols appeared to respond to any additional fertilization compared to the control group regardless of rate. Importantly, we found that O horizon mass and P content from the first rotation, approximately seven years before harvest, exhibited a positive linear relationship with one-year-old heights in the Spodosol and one- and two-year-old heights in the Alfisol. These findings shed light on the importance of the O horizon characteristics and its potential as an indicator for tree growth in subsequent rotations. • High P Fertilization rates carry over into the next rotation on Alfisols. • Spodosols cycle fertilizer P more rapidly than Alfisols. • horizon Phosphorus pools are strongly related to long-term forest productivity. • Resin-P was responsive to mineral soil P but not related to tree productivity. [ABSTRACT FROM AUTHOR]

Soils represent the largest terrestrial organic carbon sink. Less-anthropized ecosystems, like grasslands, generally sequester more soil organic carbon (SOC) than croplands under similar conditions. The purpose of this study was to determine SOC and soil total nitrogen (TN) stocks and their variability within grassland soils under diverse ecological conditions. We studied 159 grassland soils, ranging from steppe-specific soils like chernozems to mountain-soils like spodosols. We tested the relationships between essential soil properties, environmental variables, SOC and TN, identifying also differences between soil classes and types. The paper novelties refer to how environmental and soil factors influence grasslands SOC and TN storage. Climate has less influence on SOC and NT contents and on stocks from deeper soil horizons than from topsoil; conversely, soil properties have a stronger influence on SOC and TN stocks deeper in soil profiles. The best predictive multiple model explains 62% of the SOC content variability in the surface layer, and 48% in the 0.5 m layer; in the case of soil TN content, the model explains 54% of TN content variability in the surface layers, and 40% in 0.5 m depth layers. There were significantly higher SOC and TN stocks in spodosols, vertisols, followed by cambisols, chernozems, as well as in finer-texture soils, except loamy-sandy texture soils, which were only met in spodosols. Soil acidity also differentiated the SOC and TN contents generally decreasing from alkaline to acid range. The results can be useful in various regions worldwide when designing grassland management programs/policies. • Soil organic carbon (SOC) and total nitrogen (TN) show specific patterns in grassland. • Climate has less influence on deeper soil horizons than on topsoil SOC and TN stocks. • Soil properties have a strong influence on SOC and TN stocks deeper in soil profiles. • The strongest correlations are found between bulk density, K, clay, SOC and TN stocks. • The multiple-regression model explains 48–62% of SOC variability depending on depth. [ABSTRACT FROM AUTHOR]

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Ichnofossils of ghost shrimps (e.g., Ophiomorpha nodosa and Callichirus major) are interpreted worldwide as records of sea level fluctuations and provide reliable evidence of sedimentation rate, salinity, and substrate type. The preservation of these ichnofossils was previously ascribed to the polysaccharide mucus produced by ghost shrimps when burrows were built. We found evidence that these ichnofossils were preserved due to the impregnation of the burrow walls by dissolved organic matter (DOM) during podzolisation that took place after the galleries had been abandoned. Our study was conducted on a tropical barrier island in southeastern Brazil with a spatial gradient of podzolisation intensity. We made a detailed macromorphological description of the ichnofossils at the soil profile scale. Then, we used thin sections of undisturbed soils to identify sand grain arrangements and organic matter (OM) accumulation. We detected three macromorphological structures, (i) tubular gallery wall, (ii) sandy infilling of the gallery, and (iii) soil matrix outside the gallery. In the micromorphology analysis, we identified that the tubular wall is impregnated with monomorphic OM also found outside the burrow but in lower concentration. Sand grains in the wall of the gallery are tightly packed, causing a lower porosity than inside and outside the trace fossil. The precipitation of monomorphic OM is due to stagnation of DOM that percolated through the soil. Water with DOM is trapped in the wall of the tubule because of its smaller pores. The ghost shrimps constructed their burrows in marine sediments without podzolisation. Then, with the progradation of the shoreline, the sediments were colonized by restinga forest adding DOM to the soil and podzolisation started. The extent to which DOM is produced depends on vegetation development, therefore, the accumulation of DOM in the B horizon that enables the preservation of the ichnofossils is constrained by vegetation development and progradation of the shoreline. • Dissolved organic matter is retained in the burrows by porosity contrast. • The preservation of ichnofossils increases with podzol and vegetation development. • Podzolisation enhances fossilization in coastal environment. [ABSTRACT FROM AUTHOR]

Lignin is a key component of soil dissolved organic carbon (DOC) and is recently suggested to track 14C-young DOC components. However, direct evidence is still lacking to prove this hypothesis in the soil. Here, utilizing molecular radiocarbon dating, we present the first 14C dataset on dissolved lignin through a Podzol soil profile. Dissolved lignin and hydroxy phenols had similar 14C content as soil organic carbon (SOC) and DOC in the surface organic layer. However, in contrast to SOC, both DOC and dissolved lignin phenols exhibited consistent and higher Δ14C values in the mineral soils. Coupled with lignin phenol concentration data, our results suggest that dissolved lignin comprises a key DOC component throughout this Podzol profile and is mainly supplied by surface leachates with young 14C ages. Image 1 • We present the first 14C dataset on dissolved lignin along a Podzol profile. • Dissolved phenols exhibited similar Δ14C values to SOC and DOC in surface organic layer. • Unlike SOC, DOC and dissolved lignin were enriched in 14C in mineral soils. • Surface leachate was the main source of DOC components in this Podzol profile. • Dissolved lignin may exhibit larger 14C variability in other (non-Podzol) profiles. [ABSTRACT FROM AUTHOR]

The spatial variability in soil physical and hydraulic properties for a managed podzol was assessed using soil apparent electrical conductivity (ECa). Two EMI sensors, the multi-coil (MC) and multi-frequency (MF), were adopted for measurement of ECa on a silage- corn experimental plot in western Newfoundland, Canada. Results demonstrated a significant relationship between the ECa mean relative differences (MRD) and the soil moisture content MRD (R2 = 0.33 to 0.70) for both MC and MF sensors. The difference in depth sensitivity between MC and MF sensors accounted for the variation (0.015 to 0.09) in ECa standard deviation of the relative differences. A significant linear relationship was found between the ECa MRD and sand (R2 = 0.35 and 0.53) or silt (R2 = 0.43), but not with clay (R2 = 0.06 and 0.16). The spatial variability of the ECa-based predictions (CV = 3.26 to 27.61) of soil properties was lower than the measured values (CV = 5.56 to 41.77). These results inferred that the temporal stability of ECa might be a suitable proxy to understand the spatial variability of soil physical and hydraulic properties in agricultural podzols. [ABSTRACT FROM AUTHOR]

The main aim of the study was to examine the biochar efficiency in copper (Cu) ion removal from Haplic (Luvisol, Podzol) soils. In other words, the most effective biochar dose and the most favorable environment pH value were proposed. The copper removal was carried out based on the adsorption process. The results of kinetics measurements were modeled using Richie equation, whereas the adsorption isotherms using Langmuir–Freundlich and Dubinin–Radushkevich equations. The copper removal is a strongly pH-dependent process which is associated with variability of chemical Cu forms and various reactivities of organic molecules. The Cu adsorption amount was higher on silty Haplic Luvisol than on sandy Haplic Podzol mainly due to higher content of organic carbon, functional groups, clay and silt fractions as well as larger surface area. Moreover, the biochar addition increased linearly the soil surface charge and contributed to higher copper adsorption in the whole range of investigated ion concentrations. The higher the biochar dose added, the more Cu ions were adsorbed. [ABSTRACT FROM AUTHOR]

Actinomycetic complexes of soils and plant substrates from tundra and taiga zones of Russia and Finland have been studied. A molecular cytogenetic technique—fluorescence in situ hybridization (FISH) method—has been applied to estimate the metabolically active component in the representatives of the Actinobacteria. In the prokaryotic microbial communities of studied plant substrates, the biomass of metabolically active psychrotolerant representatives of Actinobacteria was determined upon incubation at 5°C reached 34% of the total bacterial biomass; at the incubation temperature of 20°C, it increased to 56%. Under conditions of low temperature, psychrotolerant actinomycetes displayed active growth with the development of both substrate and aerial mycelium. The abundance of psychrotolerant actinomycetes reached thousands and tens of thousands CFU/g for taiga mosses in Finland and increased to millions CFU/g for tundra flowering plants in the Taimyr Peninsula of Russia. It decreased in the sequence: peat soil > plants > moss cushions > litter horizons. The length of actinomycetic mycelium in tundra plants varied from 98 m/g at 5°C to 291 m/g at 20°C; in taiga mosses, it varied from 120 to 180 m/g, respectively. The complex of psychrotolerant actinomycetes was mainly composed of colorless species of the Streptomyces genus possessing specific ecophysiological features, such as the change in the color of substrate and aerial mycelium, the appearance of pigmentation, and the increase in the growth rate upon higher incubation temperatures. More than 60% of actinomycetes isolated from taiga mosses of Finland were represented by psychrotolerant species of Micromonospora genus. [ABSTRACT FROM AUTHOR]

Purpose: Biochar is one of the most widely used ameliorants for soil amendment, which is known as factor which rises crop yields and levels of soil biological activity. Nowadays, it is under investigated how biochar application affects the dynamics of the humic components and whole soil organic matter (SOM) and the processes of its alteration. This investigation is aimed to evaluate the influence of biochar on the content, composition, and transformation of humic acids (HAs) as the main component of the SOM. Materials and methods: The incubation experiment was carried out on three Podzol Antric soils, with varying amounts of initial total organic carbon. The incubation time was 90 days, using biochar gravimetric doses of 0.1 and 1.0%. The biochar was produced by fast pyrolysis of birch and aspen wood at 550 °С. Humus composition was analyzed for the organic matter fractions extracted with 0.1 M NaOH (containing HAs 1 + fulvic acids (FAs) 1) and 0.1 M Na4P2O7 (containing HAs 1 + FAs 1 + HAs 2 + FAs 2). Isolated HAs were characterized for their elemental composition (C, N, H, and S) and molecular composition with the use of solid-state 13C nuclear magnetic resonance (13C-NMR) techniques. Results and discussion: We found that 0.1% of biochar amendment does not influence SOM mineralization, but 1.0% of biochar increases the mineralization by 15–18%. This process is accompanied by changes in the composition and properties of the HS. The increased proportion of HA aromatic fragments in biochar indicates an increasing of their stability. However, in soils with high humus content and a significant amount of insoluble matter, the processes of mineralization and the growth of HAs are taking place simultaneously. The replenishment of HAs could be the outcome of both the intensification of the transformation processes (mineralization and humification) of the more sustainable insoluble matter compounds and the humification of the biochar itself. Conclusions: The influence of biochar on humification in Podzol Antric soils was revealed on the basis of incubation experiment. Both negative and positive changes under biochar in HS system were demonstrated. The active decrease of humus total contents and also the labile HS ought to qualify as negative changes. The increase of HA chemical maturity that leads to the stability of humus in whole as well as the intensive new HA formation thought to qualify as positive changes. [ABSTRACT FROM AUTHOR]

Abstract Fe(III) oxides stabilize soil organic matter by forming Fe organo-mineral associations (Fe-OMA). Under anoxic conditions, Fe-OMA may be destabilized by microbial dissimilatory iron reduction that releases aqueous Fe(II) and also possibly adsorbed or co-precipitated organic matter. Soil spodic horizons that accumulate Fe-OMA are ideal natural materials to study such impact. Here, we study three spodic horizons from pedons (P) of increasing age: P-270 yrs, P-330 yrs and P-530 yrs. Their contents of total carbon and short range ordered (SRO) Fe oxides increase with soil age from, respectively, 1486 to 3618 and 13 to 249 μmol g−1. The samples were incubated for 96 h under anoxic conditions, with and without Shewanella putrefaciens (a model dissimilatory Fe(III)-reducing bacteria) in a minimal medium devoid of any pH buffer and external electron donor. The concentration of dissolved Fe(II), total Fe and organic C was monitored at 9 time steps. With increasing age, both the rate and extent of microbial Fe(III) reduction increased after S. putrefaciens addition. In P-270 yrs, P-330 yrs and P-530 yrs, respectively, the microbial reduction rates were 0.004, 0.026 and 0.114 fmol Fe(II) h−1 cell−1 while the amounts of released Fe(II) were 0.23, 0.32 and 1.98 μmol Fe(II) g−1, both being strongly correlated with SRO Fe oxides content. Dissolved organic carbon (DOC) was released with or without S. putrefaciens in all samples (up to 73 μmol OC g−1 after 96 h in P-530 yrs). Adding S. putrefaciens significantly increased DOC release, but only in P-270 yrs. Podzol development thus increases the impact of anoxia on Fe(II) release since organic matter accumulation impedes Fe oxide crystallization, thereby amplifying Fe availability for Fe reducing microbes. The evolution of Fe oxide content and crystallinity thus affects the fate of both C and Fe in soils. Highlights • Microbial Fe reduction correlates with short range ordered Fe oxides content. • Microbial Fe reduction did not lead to a significant OM release in solution. • OM impact on Fe oxide crystallinity probably affected microbial Fe reduction. [ABSTRACT FROM AUTHOR]

Digestates and compost are used as valuable fertilizers in agriculture because of their benefits for plant nutrition and carbon sequestration potential. These amendments are also suspected to interfere negatively with the soil. To compare their relevance for priming effect and hydrophobicity of soils, two amounts of digestate or compost, respectively, were mixed with a homogenized cambic Luvisol and a Podzol. The basal respiration rate (BAS), the repellency index (RI) and organic carbon content (Corg) of pre-dried mixtures were investigated. The podsolic mixture showed quantitative reduction of Corg and increased BAS (this effect was not statistically significant) due to priming effect through microbial stimulation. As a result of enhanced organic substance (OS) protection in the cambic Luvisol mixture, constant amounts of Corg and declined BAS could be detected. The wettability was reduced in both soils: either directly by the supply of amphiphilic components or indirectly by increased incorporation of microbial exudates. This reduction was not statistically significant. Higher contents of available organic compounds in digestates and higher amounts of hydrophobic humic acids in the compost could be assumed to be decisive for generation of hydrophobicity. Also the soil texture controlled the microbial decomposition by higher incorporation of OS in finer pores and contributed to the protection against microbial decay. [ABSTRACT FROM AUTHOR]

The method of component integration was tested in the course of studies in typical biogeocenoses of the north of Western Siberia. This method as applied for separate horizons made it possible not only to estimate the contribution of different sources to the total efflux of CO2 from soils but also to evaluate the participation of horizons in soil respiration. Root respiration contributed to about 14 ± 3% of the CO2 efflux from the permafrost-affected peat soil (Hemic Cryic Histosol) and to about 29 ± 6% of the CO2 efflux from the tonguing podzol (Glossic Albic Rustic Podzol (Arenic)). Histosol was characterized by a higher storage of total (organic and inorganic) carbon (26 kg C/m2), extractable carbon (Cextr) (32 g C/m2), and microbial carbon (Cmic) (43 g C/m2). Its upper horizon (TO) contained about 50% of the total soil storage of Cmic and 100% of the total storage of roots (up to 300 g/m2). It had the maximum activity of microbiota and contributed to more than 70% of the total efflux of CO2 from the active layer (on average, 35 cm in thickness) of Cryic Histosol. Podzol was characterized by the low storage of total carbon (6 kg C/m2), considerable storage of Cmic (38 g C/m2), and much higher microbial activity. This circumstance, together with a tenfold higher storage of the roots (up to 3000 g C/m2) and favorable temperature regime specified high values of the gross production of CO2 and its emission from the Podzol surface exceeding the corresponding values for the Cryic Histosol by three–five times. The mineral profile of Podzol contributed to about 20% of the total efflux of CO2 from this soil (on average, about 38 cm in thickness). [ABSTRACT FROM AUTHOR]

Under climate change and local and global food security pressures conversion to agricultural lands on Podzols developed under boreal forests is accelerating across the global north. After conversion Podzols, acid and sandy, are infertile requiring significant management to allow economic production. Biochar, while less useful on fertile soils, may accelerate fertility gains on such marginal lands; it is already considered or land-applied by local farmers, under minimal guidance. A multi-year experiment assessed the utility of single or split application of biochar (BC), and of BC doses, for beet yields and nutrient uptake on newly converted Podzols. Time and rate-dependent progression of yields, macro- and micro-nutrients uptake, all parameters identified of interest by northern farmers, were evaluated. Kiln-derived hardwood biochar was added at 0, 10, 20, 40 or 80 Mg BC-C ha−1 (BC 0 to 80) either as single or as double application. Beet yields and elemental compositions were assessed over 4 years after biochar application. Work was done on a private farm in Labrador, Canada, under a scenario relevant to the boreal north. BC 0 could not sustain significant crop growth, suggesting that post-conversion mineralization of residual soil organic matter cannot support plant growth. In the first one to three years after application of biochar yields increased above the control, but statistically independent of application rates. A statistically significant positive biochar-rate to yield dependency was verifiable only in year 4. Nevertheless, biochar's positive effect on yields declined with time after application: e.g., BC 10 matched BC 0 yields in year 4. For the first three years, root nitrogen (N) concentrations were inversely correlated to yields and plant N% declined with biochar rate. In year 4 plant N% was directly correlated to plant biomass. In general, partitioning of nutrients between beet leaves and roots was not discernibly affected by the rate of biochar; an exception was boron whose preferential accumulation in leaves was directly related to the rate of biochar, indicating a role for the biochar for its mobilization. Biochar had an immediate positive effect on the beet yields and affected plant stoichiometry. Initially this was independent of the biochar rate. Biochar's utility declined with time at a rate inversely related to its application rate. Biochar is a recommendable fertility management tool for infertile, newly converted boreal Podzols; rates in the range of 10 Mg BC-C ha-1 may be repeated annually or every few years as practically feasible. Long term utilization requires further monitoring of micronutrients availability and uptake to inform any necessary management adjustments. Fertilizer management must consider the time since biochar's addition to soil. • Unmanaged Podzols on freshly converted boreal forest are infertile. • Biochar addition increases beet yield and yield quality, initially rate-independent. • A rate-dependent impact of biochar on yields and yield quality was noted in year 4. • Biochar's benefit fades over time at a rate inverse to its application rate. • Repeated, small biochar doses are recommendable over large single applications. [ABSTRACT FROM AUTHOR]

In podzols important environmental issues converge, including dissolved organic matter (DOM) transport, DOM-metal binding, and carbon storage in the subsoil. Therefore, it is important to understand the formation and degradation of podzols in relation to (changes in) environmental conditions. For this purpose a Holocene barrier island with coastal sand dunes (Ilha Comprida, SE Brazil) was chosen as study area. The island is build-up of five geomorphic units that have different age (from >5000 to 325 y BP), vegetation ( restinga ecosystems), soil hydrology (flat units or units with ridges and swales) and drainage (poorly drained, well-drained, and improved drainage). Representative profiles were studied for each geomorphic unit, resulting in 100 samples from A, E, B, and C horizons, from which soil organic matter (SOM) was isolated by alkaline extraction. To better understand carbon sources and dynamics, we additionally sampled litter from different vegetation types and DOM from various sources. The molecular composition of SOM, DOM and litter was analyzed with pyrolysis gas chromatography mass spectrometry (pyrolysis-GC/MS). Comparing the pyrolysates of all samples (DOM, SOM and litter) factor analysis demonstrated that the major difference in molecular composition (factor 1) was related to the contribution from DOM (phenol, acetic acid, benzofurans, pyridine, benzene and naphthalene) or in-situ root material (straight chain aliphatics and methoxyphenols from the biomacromolecules suberan and lignin, respectively). The contribution from DOM or roots was characteristic for a profile i.e. without much change with depth. Factor 2 reflected decomposition processes, and showed that the predominantly DOM-derived B horizons were relatively enriched in aromatics compared to DOM, indicating selective decay and/or selective precipitation. In geomorphic units with swales and ridges that received DOM via groundwater flow from the catchment area, the B horizon was predominantly DOM-derived; these profiles showed large differences in the contribution from black carbon (BC; (poly)aromatics), with the younger profiles showing a larger contribution from BC in precipitated DOM. B horizons with a relatively large contribution from in-situ root materials were found in well-drained soils and in some of the poorly drained soils without lateral groundwater flow from the catchment area, i.e., the flat geomorphic unit without ridges and swales. Microbial material (N-containing compounds and sugars) was associated with relatively recent SOM and with well-drained conditions at present. i.e., well-drained profiles, and profiles with improved drainage. [ABSTRACT FROM AUTHOR]

Transformation of water-soluble organic substances entering mineral horizons of podzol from the forest litter was studied in a model column experiment. The concentration of organic matter in the solution after its interaction with the E horizon increased by 10-44% due to the release of native soluble organic matter. This was accompanied by changes in the quality of water-soluble organic matter: the portion of hydrophobic components increased, the coefficients of extinction at 254-280 nm decreased, and the portion of low-molecular-weight compounds slightly decreased with a corresponding increase in the portion of high-molecular-weight compounds. Upon the interaction of water-soluble organic substances with the E horizon, the pH values first decreased and then slightly increased, which could be due to sequential desorption of organic acids of different strengths. Dissolved organic substances from the E horizon were partly sorbed in the BF horizon at the rate of about 65 mg С/100 g, or 22% of Corg in the BF horizon. The sorption resulted in the removal of mainly hydrophobic medium- and high-molecular-weight (>7000 Da) organic substances from the solution. As judged from the coefficients of extinction in the UV area, the sorbed substances were characterized by a higher aromaticity in comparison with the substances remaining in the solution. The sorption of organic substances in the BF horizon was accompanied by the rise in the pH of the solution, which corresponded to binding of organic anions on the surface of iron hydroxides according to the mechanism of ligand exchange with OH ions. [ABSTRACT FROM AUTHOR]

Structural defects of kaolinite could be associated with its genetic (weathering, pedogenetic, and hydrothermal) processes. Kaolinite crystallinity indices were evaluated in the context of pedogenetic processes associated with a representative Amazonian Ferralsol-Podzol soil system. This soil system, which is comprised of various types of kaolinitic materials and has a soil dynamics characterized by the progressive replacement of Ferralsols by Podzols, has been evaluated by Hinckley ( HI ), Aparicio-Galán-Ferrell ( AGFI ), Liètard ( R2 ), and Amigó ( A 001 ) “crystallinity indices” and the “expert system” of Plançon and Zacharie ( PZ ). The results indicate that the complexity of the kaolinite population, which is due to pedogenetic processes, makes it difficult to interpret the usual kaolinite crystallinity indices. In areas where kaolinites are formed under low aggressive conditions (higher pH and lower dissolved organic carbon, DOC) and in equilibrium with the soil solutions, low-defect phase becomes dominant and there is a good consistency between the “crystallinities” provided by each index. However, in areas where kaolinites are formed under highly aggressive conditions (lower pH and higher DOC), the proportion of low-defect phase decreases. This induces changes in the values of the indices, which do not have the same weight from one index to another. [ABSTRACT FROM AUTHOR]

A new methodological approach is described for estimating Ca, Mg and K fluxes from soil mineral weathering. This method combines Na flux in surface waters in the Hermine watershed with base cation (BC) concentrations to Na molar ratios from the soil weatherable pool obtained using sequential extraction method. Comparison of BC:Na molar ratios of the weatherable pool with those from other compartments of the watershed suggests possible accumulation of base cations in some areas of the watershed, while losses or minimal changes are observed in others. On average, present day Na weathering rates estimated using the watershed input-output budget method was 0.26 (range 0.16-0.36) kmolc ha−1 yearr−1, over the period of 1995-2006. For Ca, Mg and K, present day weathering rates estimated with the new methodological approach averaged 0.44 (range 0.27-0.60), 0.11 (range 0.07-0.15) and 0.02 (range 0.01-0.02) kmolc ha−1 year−1, respectively. These values are within the range of present day rates previously calculated for the same site and for forested soils from similar granitic environments using other methods. Candidate models for predicting BC weathering rates on individual annual observations were developed using Akaike’s information criterion. The best model includes the number of frost days (inverse relationship) and explained 51% of the variation in total BC weathering rates. The newly developed method may be applicable to other watersheds, providing yearly estimates of nutrient BC at the watershed scale. [ABSTRACT FROM AUTHOR]

The layering of the soil profile can influence the accumulation of infiltrated water and the way in which subsurface runoff is formed. This paper examines a mountain podzol characterized by clearly developed soil horizons. After these horizons had been identified, distinct soil layers were defined (the eluvial horizon, the spodic horizon (undifferentiated), and weathered bedrock). Saturated hydraulic conductivity (Ks), particle size distribution and bulk density were measured in these layers. A visualization of the distribution of infiltrated water in the podzolic profile was performed using a dye tracer experiment. The accumulation of dyed water and a distinct lateral flow were detected in the eluvial layer. Only limited entry of water into the spodic layer was observed. These effects were caused by changes in soil hydraulic properties (SHP) among the investigated layers. For the spodic horizons, the measured Ks value (crucial SHP) was significantly lower than the Ks values for the other tested horizons. The probable reason for the lower Ks was an accumulation of fine particles and various substances in the spodic horizons, and corresponding changes in the porous system. The observed effects of layering indicate that water can be accumulated and subsurface runoff can be formed over the spodic layer during intensive rain or snow melting. [ABSTRACT FROM AUTHOR]

Mineralization of water-soluble organic substances in forest litters of different compositions under conditions of their pollution with heavy metals from aerogenic emissions is considered. Water-soluble organic substances of the pine forest litters are shown to be less stable than that under the spruce forests irrespective of their pollution; the portion of mineralized at 20°C carbon for a month reached 40%. In the spruce litters, mineralizable amounts of carbon are related to their pollution: in the technogenic areas, compared to the background ones, carbon losses from the litters are twice greater. In the course of decomposition, in the spruce and pine litters, phenol compounds accumulate among the water-soluble organic compounds, and this process is more intense in the contaminated areas. After the decomposition of all the litters, irrespectively of their composition and the distance from the pollution sources, the water-soluble organic substances are characterized by higher indices of humification (HIX), more intense fluorescence, and greater coefficients of specific extinction (E260). In the ultraviolet spectra, bands appear in the region of aromatic amines absorption. These changes indicate the transformation of water-soluble organic substances: the degrees of their condensation and aromaticity increase and nitrogen-containing aromatic compounds are formed. [ABSTRACT FROM AUTHOR]

The spatial distribution of soil constituents at the micrometer scale is of great importance to understand processes controlling the formation of micro-aggregates and the stabilization of organic carbon. Here, the spatial distribution of organic and mineral constituents in Podzol horizons is studied by concerted measurements of (i) the content of various forms of Fe, Al, Si and C determined by selective extraction in the fine earth fraction of soil (f < 2 mm); (ii) the elemental composition of the clay fraction (f < 2 μm) with lateral resolution using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and with surface selectivity using X-ray photoelectron spectroscopy (XPS); (iii) the specific surface area (SSA) of fine earth and clay fractions by krypton physisorption. The SSA of the fine earth in illuvial horizons is predominantly due to finely divided Fe oxides, including goethite, characterized by an equivalent particle size of about 10 nm. Kaolinite platelets of about 2 μm size account for a large volume proportion in the clay fraction but have a minor contribution to SSA. Fe oxides and organic matter (OM) are intimately associated. Heterogeneity at the μm scale is created by local variations in the relative amounts of kaolinite and Fe-OM associations. These two kinds of physical entities are in random mixture. Moreover, variation of C/Fe atomic ratios reveals sub-μm scale heterogeneity. The latter is due to variation in the relative proportion of organic compounds and Fe oxides, indicating that aggregation of nanoparticles, and not only mere adsorption or pore filling, plays a role in these associations. In this regard, our results highlight that OM associated with Fe protects Fe oxides against physical displacement and that part of this associated OM is oxidizable by NaOCl treatment. These findings demonstrate that the concept of OM stabilization through association with Fe must be revisited when considering the sub-μm scale level because fine Fe oxide particles can be easily dispersed during oxidation of associated carbon. Combination of physical fractionation and microanalysis (e.g. SEM-EDS, vibrational spectroscopy) offer promising perspectives to clarify the relationship between chemical composition and sub-μm scale architecture, and to better understand soil processes. [ABSTRACT FROM AUTHOR]

Data on soddy-podzolic soils with the second humus horizon in the southwestern part of Kirov oblast are discussed. These soils were first studied by the authors on mantle calcareous loams of the Yarano- Kokshagskaya Plain in the eastern part of the Central Russian southern-taiga province of medium-humus soddy-podzolic soils of European Russia. The aim of this study is to reconstruct the history of the development of soil properties and soil cover in automorphic landscapes of this region. Morphology, substantive properties of mineral and organic components, soil genesis and evolution are analyzed using a set of physical, chemical, physicochemical, biochemical, and geochronological methods. The results of our study attest to the relict character of second the humus horizon and polygenetic nature of the studied soils. These soils have passed through two essentially different evolutionary stages in the Holocene: the accumulative stage in the first half of the Holocene and the accumulative-eluvial stage of erasing evolution with preservation of some inherited features in the second half of the Holocene. According to their properties, the studied soils are analogous to the earlier studied southern-taiga Vyatka-Kama province of high-humus soddy-podzolic soils of the northeast. At present, plowing of these soils leads to a partial or complete destruction of the second humus horizon; thus, spontaneous degradation processes are complemented by the human-induced soil degradation. A tendency for a gradual disappearance of these soils from the soil cover under the influence of natural and anthropogenic factors has been noted. The materials presented in this paper may be useful for organization of specially protected soil areas in the southwestern part of the Vyatka River basin. [ABSTRACT FROM AUTHOR]

Specific features of the transformation of humic substances in particle-size fractions of drained soddy-podzolic soils were studied on a field (12 ha) of the Experimental and Educational Center of Lomonosov Moscow State University in Moscow oblast. The field had a clearly pronounced microtopography. Surface-gleyed soddy-podzolic soils (Albic Stagnic Glossic Retisols (Loamic, Aric, Ochric)) of microdepressions with excessive surface moistening and nongleyed soddy-podzolic soils (Albic Glossic Retisols (Loamic, Aric, Ochric)) of elevated positions were examined. These soils were studied before the field drainage and during 25 years after drainage works in the periods differing in conditions of humification and with due account for not only drainage works but also other factors, such as topography and agrotechnology and their joint action. The specificity of transformation of humic substances in the soils and their particle-size fractions was analyzed in the basis of data on the organic carbon content, group and fractional composition of humus, the intensity of individual stages of humification (the neoformation of humic acids and the formation of humates), and the optical density of the fractions of humic acids. The results of the study of these properties in the fine soil fractions (<50 μm) made it possible to assess the response of the clay (<1 μm) and silt (1-5, 5-10, 10-50 μm) fractions to changes in the ecological situation and the role of separate particle-size fractions in the degradation of humus under adverse impacts. Overall, a clear tendency toward worsening of the humus quality was observed in both soils during the 25-year-long period, which is related to the long-term (20 years) agricultural use of the reclaimed field without application of agrochemicals. The features of humus degradation were mainly manifested in the finest (<10 μm) fractions with a general decrease in the humus content, slowing down of the formation of humic acids and humates, and considerable loss of humic acids, including their agronomically valuable fractions HA1 and HA2. The degradation of humus quality in the clay fraction was largely due to the impact of the reclamation (drainage) factor; the degradation of humus quality in the fine and medium silt fractions was mainly due to the negative changes in the agricultural background. Among negative consequences of the worsening humus quality, the lowering of soil fertility, ecological sustainability, and productivity of agrocenoses should be noted. [ABSTRACT FROM AUTHOR]

The seasonal changes in the contents and compositions of n-alkanes and n-methyl ketones have been studied in typical soddy-podzolic soils (Albic Retisols (Ochric)) under lime forests in the Losiny Ostrov National Park, Moscow. In the humus horizons, the reserves (about 370 mg/m2) of odd n-alkanes with the chain length of C25-C35—the biomarkers of terrestrial vegetation—are 4-5 times below their amount entering with the leaf falloff in autumn. A noticeable contribution of microbial biomass hydrocarbons to the lipid fraction in the AY and AYel horizons manifests itself in the increased fraction of odd and medium-chain (

Statistical analysis of a vast body of data collected during five field seasons (2011-2015) was performed to characterize the biological activity of soils in the northern taiga ecosystems of Western Siberia. Automorphic forest soils, hydromorphic (oligotrophic bog) soils, and semihydromorphic (flat-topped and large peat mounds) soils were characterized. Statistically significant differences of average levels of CO2 emission from the soils were identified at the ecosystem level. The CO2 emission from podzols of automorphic forest ecosystems at the peak of the growing season (205 ± 30 to 410 ± 40 mg CO2/(m2 h)) was significantly higher than the emission from semihydromorphic soils of peat mounds (70 ± 20 to 116 ± 10 mg CO2/(m2 h)). The presence and depth of permafrost was a significant factor that affected ecosystem diversity and biological activity of northern taiga soils. Statistically significant differences in the total, labile, and microbial carbon pools were observed for the studied soils. Labile and microbial carbon pools in the organic layer (10 cm) of forest podzols amounted to 0.19 and 0.66 t/ha, respectively; those in the organic layer (40 cm) of peat cryozems of flat-topped peat mounds reached 1.24 and 3.20 t/ha, and those in the oligotrophic peat soils (50 cm) of large peat mounds were 2.76 and 1.35 t/ha, respectively. The portion of microbial carbon in the total carbon pool (Cmicr/Ctot, %) varied significantly; according to the values of this index, the soils were arranged into the following sequence: oligotrophic peat soil < peat cryozem < podzol. [ABSTRACT FROM AUTHOR]