Postpyrogenic transformation of soils under Pinus sibirica forests in the southern Lake Baikal basin

The results of experimental investigations of the postpyrogenic dynamics of the widespread rawhumus podzols under Pinus sibirica forests in the southern Lake Baikal basin are discussed. Ground fires transform the diagnostic surface organic soil horizons into organic pyrogenic horizons (Opir, OL/Opir, and AOpir). The adverse effect of ground fires of different intensities on the changes in the reserves, the fractional composition of the litters, and the chemical composition of the organic horizons is shown. The soils of dark coniferous forests are inclined to long-lasting restoration. The Pinus sibirica regrowth under the canopy of deciduous species serves as the basis for the restoration of native stands and the formation of the soils characteristic of the southern part of the Lake Baikal basin.     

Algological and Mycological Characterization of Soils under Pine and Birch Forests in the Pasvik Reserve

The structure of algological and mycological complexes in Al–Fe-humus podzols (Albic Podzols) under pine and birch forests of the Pasvik Reserve is characterized. The number of micromycetes is higher in more acid soils of the pine forest, while the species diversity is greater under the birch forest. The genus Penicillium includes the largest number of species. The greatest abundance and occurrence frequency are typical for Penicillium spinulosum, P. glabrum, and Trichoderma viride in pine forest and for Umbelopsis isabellina, Mucor sp., Mortierella alpinа, P. glabrum, Aspergillus ustus, Trichoderma viride, and T. koningii in birch forest. Cyanobacteria–algal cenoses of the investigated soils are predominated by green algae. Soils under birch forest are distinguished by a greater diversity of algal groups due to the presence of diatoms and xanthophytes. Species of frequent occurrence are represented by Pseudococcomyxa simplex and Parietochloris alveolaris in soils of the pine forest and by Tetracystis cf. aplanospora, Halochlorella rubescens, Pseudococcomyxa simplex, Fottea stichococcoides, Klebsormidium flaccidum, Hantzschia amphioxys, Microcoleus vaginatus, and Aphanocapsa sp. in soils under birch forest     

Variability of physicochemical characteristics of brown forest soils within the phytogenic fields of trees (the Southern Far East)

The variability of physicochemical characteristics was investigated in the surface horizons of brown forest soils within the phytogenic fields of Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) and Korean pine (Pinus Koraiensis Sieb. et Zucc.) growing in the southern Russian Far East. The relationships between the soil acidity, the type and content of humus, the optical parameters of the humic acids, and the phosphorus content were established as related to the orientation of the sectors of the phytogenic fields of trees and the distance of the sampling points from the trees. The heterogeneity of the soil conditions within the phytogenic fields of the tree species studied was assessed.     

Soil actinomycetes in the National Forest Park in northeastern China

The taxonomic and functional structure of actinomycete complexes in the litters and upper horizons of the soils under an artificial coniferous–broad-leaved forest located around the town of Chanchun (Tszilin province, PRС). The complex of actinomycetes included representatives of the Streptomyces, Micromonospora, Streptosporangium, and Streptoverticillium genera and oligosporous forms. In the actinomycete complexes, streptomycetes prevailed in the abundance (61–95%) and frequency of occurrence (100%). In the parcels of Korean pine (Pinus koraiensis) and Mongolian oak (Quercus mongolica), streptomycetes of 19 species from 8 series and 4 sections were isolated. The most representative, as in European forest biomes, was the Cinereus Achromogenes series. A distinguishing feature of the streptomycete complex in the biomes studied was the high participation of species from the Imperfectus series. The verification of the functional activity of natural isolates made it possible to reveal strains with high antagonistic and cellulolytic abilities. A high similarity of actinomycete complexes was found in Eurasian forest ecosystems remote from each other, probably due to the similarity of plant polymers decomposable by actinomycetes.     

Forest-growing properties of soils under young Siberian stone pine (<Emphasis Type="Italic">Pinus sibirica</Emphasis>) forests in Western Siberia

The results of studying the forest-growing properties of the iron-illuvial podzols under purposefully formed young Siberian stone pine (Pinus sibirica L.) forests are presented. The sufficient supply of these stands with moisture and the high content of nitrogen in the soils make the soils favorable for the regeneration, growth, and development of dark coniferous forests. The soils of the test objects exposed to sanitary cutting were compared to those under the control stand. The silvicultural procedures were shown to promote more efficient use of the soil resources by Siberian pine trees.     

Accumulation of polycyclic aromatic hydrocarbons in soils and plants of the tundra zone under the impact of coal-mining industry

Thirteen polycyclic aromatic hydrocarbon (PAH) compounds were identified in organic horizons of tundra surface-gleyed soils ( Histic Stagnosols (Gelistagnic) and plants. The total content of PAHs in contaminated soils exceeded the background values by three times. Concentrations of low-molecular weight hydrocarbons in soils at different distances from the coalmines were relatively stable. Concentrations of highmolecular weight hydrocarbons had a distinct maximum at a distance of about 0.5 km from the source of emission. The increased values of correlation coefficients were found between PAH concentrations in organic soil horizons, plants, and coal of the Vorkutinskaya mine. Mostly low-molecular weight structures predominated in the organic soil horizons and in the studied plant species. The maximum capacity for the biological accumulation of PAHs was displayed by Pleurozium schreberi and the minimum capacity was displayed by Vaccinium myrtillus. Mosses and lichens actively absorbed polyarenes from the surface; most of the PAHs were transported into the plants. This phenomenon was not observed for Vaccinium myrtillus Concentrations of PAHs on the surface and in plant tissues decreased with an increase in the distance from the mine. Distribution of polyarenes in plant organs was nonuniform. Insignificant excess of concentration of polyarenes was found in dead part of Pleurozium schreberi in comparison with its living part. The accumulation of polyarenes in the leaves of Vaccinium myrtillus was higher than that in its stems and roots.     

Biochar nutrient availability rather than its water holding capacity governs the growth of both C3 and C4 plants

Purpose

Biochar has been suggested as a soil conditioner to improve soil fertility and crop productivity while simultaneously mitigate global climate change by storing carbon in the soil. This study investigated the effect of pine (Pinus radiata) biochar application on soil water availability, nitrogen (N) and carbon (C) pools and growth of C3 and C4 plants.

Materials and methods

In a glasshouse pot trial, a pine biochar (untreated) and nutrient-enriched pine biochar were applied to a market garden soil with C3 (Spinacia oleracea L.) and C4 (Amaranthus paniculatus L.) plants at rates of 0, 1.0, 2.0, and 4.0 % (w/w). Plant biomass, soil pH, moisture content, water holding capacity (WHC), hot water extractable organic C (HWEOC), and total N (HWETN), total C and N, and their isotope compositions (δ ¹³C and δ ¹⁵N) of soils and plants were measured at the end of the experimentation.

Results and discussion

The soil moisture content increased while plant biomass decreased with increasing untreated biochar application rates. The addition of nutrient-enriched biochar significantly improved plant biomass in comparison to the untreated biochar addition at most application rates. Biochar application also increased the levels of labile organic C and N pools as indicated by HWEOC and HWETN.

Conclusions

The results suggested that the addition of pine biochar significantly improved soil water availability but not plant growth. The application of nutrient-enriched pine biochar demonstrated that the growth of C3 and C4 plants was governed by biochar nutrient availability rather than its water holding capacity under the pot trial condition.

     

Cartographic Assessment of Soil Diversity in Russia

The paper describes approaches assessing the diversity of soils in Russia, as well as algorithms for quantitatively assessing the differentiation of soil bodies and covers. To assess soil diversity (or the degree of differentiation of parent rock materials into soil bodies and soil covers), two indices have been introduced: the vertical differentiation index (Ird) and the spatial lateral differentiation index (Ild (red)). These indices were computed based on the soil cover structure shown on the Soil Map of the Russian Federation on a scale of 1: 2.5 M within the spatial framework of the Map of Soil-Ecological Zoning of the Russian Federation on a scale of 1: 2.5 M. Based on the data obtained, the most complex soil covers and soil profiles on plains were identified at the boundary of the Boreal and Subboreal geographical belts in the zones of soddy-podzolic soils (umbric albeluvisols/umbric podzols) of the southern taiga and gray forest soils (albic luvisols/luvic greyic phaeozems) of deciduous forests characterized by widespread occurrence of dynamically mature soils, as well as in mountainous soil provinces of the Altai and Caucasus.     

Plant–soil interaction affects the mineralization of soil organic carbon: evidence from 73-year-old plantations with three coniferous tree species in subtropical Australia

Purpose

Plantation is an important strategy for forest restoration and carbon (C) storage. Plantations with different tree species could significantly affect soil properties, including soil pH, soil nutrient content, soil microbial activities, and soil dissolved organic C. Changes in these abiotic and biotic factors could regulate mineralization of soil organic C (SOC). However, it remains unclear to what extent these factors affect the mineralization of SOC under different tree species plantations.

Materials and methods

Soil was collected at 0–10 cm depth from plantations with Pinus elliottii Engelm. var. elliottii, Araucaria cunninghamii, and Agathis australis, respectively, in southeast Queensland, Australia. Soil samples were assayed for soil organic C; organic N and mineralization of SOC; soil particle size; total C, N, and P; and pH. In addition, a 42-day laboratory incubation with substrate additions was done to examine the influence of different substrates and their combinations on bio-available organic C.

Results and discussion

Our results suggested that SOC mineralization was mainly determined by soil pH and soil C content among plantations with different tree species, whereas SOC mineralization was not correlated with soil N and P contents. These results were further confirmed by the substrate addition experiments. SOC mineralization of soils from slash pine showed greater response to C (glucose) addition than soils from other two plantations, which suggested significant differences in SOC mineralization among plantations with different tree species. However, neither N addition nor P addition had significant effects on SOC mineralization.

Conclusions

Our results indicated that plantations with different tree species substantially affect the mineralization and stability of soil organic C pool mainly by soil pH and soil C content.

     

Soil carbon dynamics in successional and plantation forests in subtropical China

Purpose

The purpose of this study was to better understand how both the content and flux of soil carbon respond to forest succession and anthropogenic management practices in forests in subtropical China.

Materials and methods

We assembled from the literature information on soil organic carbon (SOC) and soil respiration (Rs) covering the forest successional chronosequence from pioneer masson pine (Pinus massoniana) forest (MPF) to medium broadleaf and needleleaf mixed forest (BNMF) and the climax evergreen broadleaf forest (EBF), along with the two major forest plantation types found in subtropical China, Chinese fir (Cunninghamia lanceolata) forest (CFF) and Moso bamboo (Phyllostachys pubescens) forest (MBF).

Results and discussion

Both SOC and Rs increased along the forest successional gradient with the climax EBF having both the highest SOC content of 33.1?±?4.9 g C kg^?1(mean?±?standard error) and the highest Rs rate of 46.8?±?3.0 t CO₂?ha^?1 year^?1. It can be inferred that when EBF is converted to any of the other forest types, especially to MPF or CFF, both SOC content and Rs are likely to decline. Stand age did not significantly impact the SOC content or Rs rate in either types of plantation.

Conclusions

Forest succession generally increases SOC content and Rs, and the conversion of natural forests to plantations decreases SOC content and Rs in subtropical China.

     

Effect of <Emphasis Type="Italic">Eucalyptus</Emphasis> forests on understory vegetation and soil quality

Purpose

Eucalyptus forest plantations are normally devoid of understory vegetation that is often assumed to be associated with Eucalyptus allelopathic effects. The objective of this study was to determine the influence of high soil compaction and low soil moisture content on inhibition of the germination of understory seeds in Eucalyptus forests and thus would result in the scarcity of understory vegetation.

Materials and methods

The soil water content above the depth of 1 m of six major understory vegetation types was analyzed to determine if there was a correlation between soil water content and understory vegetation. The effects of soil treatment (soil-loosening vs. no soil-loosening) and water supply amount (2500, 2000, 1500, 1000, 500, 250, or 0 ml of water per day) on the seed germination rate of Stylosanthes sp. were explored using an artificial climate chamber experiment. Influence of soil source (five Eucalyptus forest soils vs. two non-Eucalyptus forest soils) and water supply (0, 50, 150, 200, or 400 ml of water every day) on the germination rate of five types of seed were assessed using a three-factor analysis of variance (ANOVA).

Results and discussion

Soil-loosening and water supply significantly (P?<?0.05) increased seed germination rate with the contribution rates of 26.14 and 42.93 %, respectively. Analysis of variance for three-factor experiments revealed a significant (P?<?0.05) effect of water supply and vegetation seed type on the germination rate of plant seeds. No significant effect of soil type was observed on germination rate, indicating that germination rate was not affected by soils in Eucalyptus forest.

Conclusions

The conservation of soil characteristics, such as water content and compaction, during the development of a Eucalyptus forest plantation may be an effective strategy for encouraging the growth of understory vegetation. This study highlights the importance that in dry areas or areas prone to long-term drought, it would be preferable to retain native vegetation.

     

Land use change exerts a strong impact on deep soil C stabilization in subtropical forests

Purpose

It has been widely recognized that land use changes can cause significant alterations of soil organic matter (SOM) of various ecosystems. Forest conversion, a common land use change, and its effects on SOM have been a hot research topic during the past two decades. However, the mechanisms of the effects of forest conversion on SOM dynamics, particularly in deep soils, largely remain uncertain. This study aimed to examine the impacts of forest conversion on SOM stabilization through the analysis of soil aggregate and density fractionation, microbial composition, and functions in deep soils.

Materials and methods

Soil C and microbes were sampled in soil layers of 0–20 and 60–80 cm under broadleaved secondary forest and two coniferous plantations (Cunninghamia lanceolata and Pinus massoniana). Aggregate and density fractionation techniques were used to analyze C accumulation in non-protected, physically, chemically, and biochemically protected C fractions. A 90-day laboratory mineralization incubation experiment with and without 400-mg C kg^?1 soil glucose and phenol was conducted to determine the potential mineralizable C, utilization of substrate capacity, and metabolic quotient (qCO₂).

Results and discussion

Conversion of secondary forests into coniferous plantations significantly decreased bulk soil C, especially in the deep soils. Forest conversion significantly decreased non-protected, physically, and chemically protected C fractions in both topsoil and deep soil and biochemically protected C fraction in deep soils. The soil organic carbon (SOC) of topsoils was dominated by non-protected fraction while in deep soil which was dominated by protected fraction. Compared with the topsoils, soil microbes in the deep soils tend to preferentially use labile soil organic matter with lower substrate use efficiency (higher values of qCO₂), which indicates that a r-strategy dominates of microbes. The increased respiration rate in the deep soils caused by forest conversion, when normalized to soil C, indicates that deep SOM may be more prone to decomposition and destabilization than top SOM.

Conclusions

Forest conversion can cause a significant alteration of SOC stabilization through the changes of physically, chemically, and biochemically protected SOC fractions. The mechanisms for the changes in non-protected or/and protected SOC fractions may be associated with the redistribution of r-strategy- and K-strategy-dominated microbes due to changes in litter inputs and priming effects.

     

Stoichiometric responses of soil microflora to nutrient additions for two temperate forest soils

The ratios of soil carbon (C) to nitrogen (N) and C to phosphorus (P) are much higher in Chinese temperate forest soils than in other forest soils, implying that N and P might limit microbial growth and activities. The objective of this study was to assess stoichiometric responses of microbial biomass, enzyme activities, and respiration to N and P additions. We conducted a nutrient (N, P, and N + P) addition experiment in two temperate soils under Korean pine (Pinus koraiensis) plantation and natural broadleaf forest in Northeast China and measured the microbial biomass C, N, P; the activities of β-glucosidase (BG), N-acetyl-β-glucosaminidase (NAG), and acid and alkaline phosphomonoesterase (AP); and the microbial respiration in the two soils. Nitrogen addition increased microbial biomass N and decreased microbial biomass C-to-N ratio and microbial respiration in the two soils. Nitrogen addition decreased NAG activity to microbial biomass N ratio, P addition decreased AP activity to microbial biomass P ratio, and N, P, and N + P additions all increased BG activity to microbial biomass C ratio. These results suggest that microbial stoichiometry is not strictly homeostatic in response to nutrient additions, especially for N addition. The responses of enzyme activities to nutrient additions support the resource allocation theory. The N addition induced a decline in microbial respiration, implying that atmospheric N deposition may reduce microbial respiration, and consequently increase soil C sequestration in the temperate region.     

Profile analysis of microbiomes in soils of solonetz complex in the Caspian Lowland

The taxonomic structure of the microbiota in two associated soils—solonetz on a microhigh and meadow-chestnut soil in a microlow—was studied in the semidesert of the Caspian Lowland. A highthroughput sequencing of the 16S rRNA gene was used for the soil samples from genetic horizons. A considerable reduction in the bacterial diversity was found in the lower horizons of the solonetz and compact solonetzic horizon with a high content of exchangeable sodium. In the meadow-chestnut soil, the microbial diversity little decreased with the depth. In both soils, a portion of archaea from the Thaumarchaeota group also decreased in the deeper horizons. In the soil horizons with the lower total bacterial diversity, a share of proteobacteria of the Enterobacteriaceae, Pseudomonadaceae, and Sphingomonadaceae families became higher. The difference between the structure of the microbial population in the solonetz and meadow- chestnut soil can be first explained by the different water regimes and soil consistence.     

Quantifying soil macropore networks in different forest communities using industrial computed tomography in a mountainous area of North China

Purpose

Macropores have important effects on the movement of soil water, air, and chemical substances. However, the quantitative relationship between complex 3D soil macropore networks and forest communities remains unclear in the northern mountainous area in China. The objectives of this study were to (1) use industrial computed tomography (CT) scanning and image analysis to quantitatively analyze macropore networks in intact soil columns and (2) identify characteristics of soil macropore networks in different forest communities.

Materials and methods

Intact soil columns (100-mm diameter, 300 mm long) were taken from six local forest communities with three replicates for a total of 18 samples. Industrial X-ray CT was used to scan soil samples; then, the scanned images were used to obtain the 3D images of rock fragments and macropore structures. Next, the macropore structure was quantified, including volume, diameter, surface area, length, angle, tortuosity, and number of macropores. This technique provided an accurate method to quantify the structure of macropores.

Results and discussion

The analysis and results revealed that different forest communities influence soil macropore 3D structure significantly and in different ways. Macropores in mixed Pinus tabulaeformis, Castanea mollissima, and Ulmus pumila forest had the largest diameter, surface area, network density, and length density of macropores as well as the smallest mean tortuosity of soil macropores. This is caused by the fact that mixed forest soils had more complex root systems, better soil structure, and more biotic activity. Within the soils of a single forest community, macropore porosity, network density, surface area density, and length of macropores decreased with increased soil depth, because more roots and more biological activity were present in the surface soil.

Conclusions

Advanced industrial CT technology can allow an accurate quantification of soil macropore structure. This is important because this type of structure has significant effects on soil water, air, and chemical transport. The results suggest that mixed forest is the best afforestation model in the northern mountainous area in China because of its ability to improve soil structure.

     

Restoration of Vegetation in Relation to Soil Properties of Spoil Heap Heavily Contaminated with Heavy Metals

The main objectives of our study were to evaluate soil contamination on a zinc-lead spoil heap in the Upper Silesian Industrial Region in southern Poland using pollution indices, and to investigate the relation between soil properties and the natural succession of vegetation. Organic carbon and nitrogen, pH, soil texture, base cations, and heavy metal content were analyzed in soil samples at depths of 0–15 cm below the organic horizon over a regular grid of 14 sampling plots. The contents of Zn, Pb, and Cd exceeded by several times the acceptable thresholds. Measurements of soil enzyme activity were used to evaluate the progress of vegetation development in relation to soil chemical properties. The results indicate that heavy metals had a significant impact on soil enzyme activity and the development of vegetation cover. High contents of Pb and Cd reduced enzyme activity, while this activity increased with increasing amounts of soil organic matter. Further, the accumulative capacities of heavy metals in needles of Scots pine (Pinus sylvestris L.) and aboveground biomass of bladder campion (Silene vulgaris (Moench) Garcke) were examined. A high accumulation of Zn, Pb, and Cd in the aboveground tissues of S. vulgaris indicated an unusual tolerance of this species to heavy metals and the possibility of using this species in phytoremediation of post-industrial sites.     

Native soil organic matter as a decisive factor to determine the arbuscular mycorrhizal fungal community structure in contaminated soils

The present study of arbuscular mycorrhizal (AM) fungi is focused on the identification of AM ecotypes associated with different plants species (Poa annua, Medicago polymorpha, and Malva sylvestris) growing in three contaminated soils with different organic matter, phosphorus, and trace element (TE; Cu, Cd, Mn, and Zn) contents. Soils were amended with biosolid and alperujo compost. Shifts in AM fungal community structure, diversity, richness, root colonization, and plant TE uptake were evaluated. Soil properties and plant species had a significant effect on AM fungal community composition as well as on root colonization. However, AM fungal diversity and richness were only affected by soil properties and especially by soil organic matter that was a major driver of AM fungal community. As soil quality increased, Glomeraceae decreased in favor of Claroideoglomeraceae in the community, AM fungal diversity and richness increased, and root colonization decreased. No effect due to amendment (exogenous organic matter) addition was found either in AM fungal parameters measured or TE plant uptake. Our results revealed that the role of TE contamination was secondary for the fungal community behavior, being the native organic matter content the most significant factor.     

Ecological evaluation of oil-contaminated soils (Sakhalin) using enchytraeidae

The ecological status of oil-contaminated soils of Sakhalin and their background analogues has been evaluated with the use of soil invertebrates. The survival rates of Enchytraeus albidus in soils with different textures and the contents of organic carbon and nutrients have been compared. The indicative role of soil mesofauna (Enchytraeus albidus) for the ecological evaluation of oil-contaminated soils with due account for their properties has been shown. The permissible residual concentration of oil hydrocarbons in some soils of Sakhalin—acid brown forest soils (Umbrisols), high-moor peat soils (Histosols), acid meadow alluvial soils (Fluvisols), cultivated meadow soddy soils (Anthrosols), and mucky-podzolic surface-gleyed soils (Gleysols)— has been determined from data on the response of Enchytraeus albidus to different levels of the soil contamination with oil hydrocarbons.     

Rainfall/runoff/erosion relationships and soil properties survey in abandoned shallow soils of NE Spain

Purpose

Shallow soils previously cultivated under terraced systems may change their properties after agricultural release and spontaneous plant colonization. Investigations were conducted in terraced fields (NE Spain) to prove that vegetation installed after the abandonment may generally improve soil properties by the formation of stable organic horizons. However, restriction in plant species along the natural vegetation succession and intensification of erosion processes may occur after abandonment depending on fire frequency and soil use history.

Materials and methods

Ten environments with different plant covers under a Lithic Xerorthent were selected and erosion plots (Gerlach type) installed providing their best adaptability at the terrace scale. Selected soil environments represented the sequence of abandonment: from current poorly cultivated soils, soils under pasture, soils under shrubs, and soils under stands of pine and cork trees. Relevant rainfall events producing runoff and erosion were recorded from November 2011 to May 2012. Erosion rates and erosion components were analysed in sediments and water in order to monitor carbon, nitrogen and other nutrient removal by overland flow. Similarly, the physical and chemical properties of the soil environments under study were determined at the same time interval of runoff erosion.

Results and discussion

Soils under pasture, vines and recently burnt pine forest produced the highest runoff followed by soils under shrubs and forest. However, eroded soil yields and nutrient removal were much higher in cultivated soils and soils in recently burnt sites, which had shown poorer soil properties with respect to soils abandoned for longer and preserved by fire. Fire-affected soil environments also showed a thinner organic horizon and reduced water retention. Although erosion rates and nutrient depletion were low in all environments with respect to other areas of Spain, higher splash than water erosion was an early warning indicator of the high susceptibility to degradation of these shallow soils.

Conclusions

Results outlined that the renaturalization dynamics after agricultural abandonment are complex biophysical processes involving the parent material, depth to bedrock and other soil properties as well as the succession of vegetative cover and plant associations responsible for building a new soil mantle contrasting with erosion processes. Planning for management of land abandonment is strongly recommended.

     

Changes in soil algal communities in spruce phytocenoses under the influence of aerotechnogenic pollution

The regularities of the development of algal communities in podzolic soils under coniferous forests were studied in areas differing in their technogenic pollution intensity. In the unpolluted soils under spruce forests, 80 alga species of 6 divisions were found; in the soils under the coniferous forests located in the zone exposed to the technogenic pollution, 59 alga species of 5 divisions were found. The algal groups in the soils of the spruce forests included 14–48 taxa. Chlamydomonas gloeogama, C. reinhardtii, Chlorella vulgaris, Klebsormidium nitens, and Stichococcus bacillaris were resistant to different anthropogenic impacts. The results obtained may be used for monitoring of the state of the soil biota in the soils under the boreal forests of protected areas and also in spruce forests exposed to intense aerial technogenic pollution.