Biomass Of Soil Microorganisms Research Articles

Exploring polyphosphates in soil: presence, extractability, and contribution to microbial biomass phosphorus

Polyphosphates (Poly-P) are known to fulfil several important physiological functions. Many microorganisms can accumulate large amounts of Poly-P in their biomass. Regardless of these facts, systematic research on Poly-P in soil is missing, probably due to the absence of any method of direct Poly-P quantification. In this study, we attempted to unequivocally prove the presence of Poly-P in the biomass of soil microorganisms and quantify their extractability and contribution to microbial biomass phosphorus. To do so, we combined several approaches that can indicate Poly-P presence in soil microbial biomass indirectly, i.e. growth of soil inoculum on media without phosphorus, associated with measurement of changes in the microbial biomass stoichiometry, and the colour of the microbial suspension stained by the Neisser method. All soil microbial communities exhibited growth on media without phosphorus. As the growth on this media depleted Poly-P content, the biomass carbon to phosphorus and nitrogen to phosphorus ratio increased and the colour of the microbial suspension stained by the Neisser method changed predictively. The associated Poly-P addition experiment indicated that the recovery of added Poly-P from soil in form of soluble reactive phosphorus in sodium bicarbonate extract may reach up to 93% mainly due to abiotic depolymerization. Using a simple stoichiometric model applied to measured data, we calculated that the Poly-P content of microbial biomass in our soils may be up to 45 or 70% of total microbial biomass phosphorus depending on the assumptions applied regarding parameter values. We discuss the magnitude of error associated with the measurement of soil microbial phosphorus due to the high extractability of Poly-P.

Soil-Microbial CNP Content and Ecological Stoichiometry Characteristics of Typical Broad-Leaved Tree Communities in Fanjing Mountain in Spring

This study aims to investigate the impact of diverse forest stand types and soil depths on soil ecological stoichiometry characteristics, shedding light on nutrient limitations and cycling patterns within the mid-subtropical forest ecosystem in southwest China during spring. The research focused on four representative forest stands situated in Fanjing Mountain: Castanopsis fargesii (C. fargesii), Cyclobalanopsis multiervis (C. multiervis), Cyclobalanopsis argyrotricha (C. argyrotricha), and Rhododendron argyrophyllum Franch (R. argyrophyllum). Sample plots were established in these forest types, and soil samples were collected from the 0–20 cm and 20–40 cm soil layers in March, spring of 2023. Various soil parameters, including pH, soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), soil microbial biomass carbon (MBC), soil microbial nitrogen (MBN), and soil microbial phosphorus (MBP) were measured, and their stoichiometric ratios were calculated. The findings of the study were as follows: (1) In the 0–20 cm soil layer, C. argyrotricha exhibited the highest soil organic carbon, followed by C. fargesii, C. multiervis, and R. argyrophyllum with the lowest content. No significant differences in soil organic carbon were observed among the four forests in the 20–40 cm soil layer. Additionally, C. argyrotricha displayed a significantly higher soil C:N ratio compared to other forest types in different soil layers. In the typical broad-leaved forest area of Fanjing Mountain, the TP was classified as deficient. (2) In the 0–20 cm soil layer, the MBC of C. fargesii surpassed C. multiervis, C. argyrotricha, and R. argyrophyllum by 26.59%, 42.92%, and 24.67%, respectively. There were no significant differences in soil MBC:MBP ratio and MBN:MBP ratio, regardless of forest species and soil depths. The low availability of soil nitrogen in different forest stand types in Fanjing Mountain strongly limits soil microorganism biomass. (3) The correlation between SOC, TN, TP, and their stoichiometric ratios varied across different soil layers. Therefore, in managing the Fanjing Mountain forest area, attention should be paid to supplementing N and P in the soil.

Impacts of biostimulants on crop yield and biological activity under drought conditions

AbstractIntroductionBiostimulants are proposed to have a role in sustainable food production and are being increasingly used strategies to limit the negative effects of drought stress on crop yield and soil health. However, how different biostimulants used alone, or in combination with conventional management approaches affect soil health and crop yield under drought in different soils is not well understood. Here we conducted a glasshouse experiment to investigate this.Materials and MethodsTwo soil types from fields maintained under intensive (IM) and extensive (EM) management practices were used with two commercial biostimulants [Universal Natural Plant food (UNP) and Converte Seed Primer (CSP)] on soil microbial populations and crop yield (lettuce) under well‐watered and drought stressed conditions. We examined the activity and biomass of soil microorganisms as well as seed germination and root and shoot biomass to examine the effect of application of biostimulants on parameters of soil health and crop yield.ResultsBiostimulants generally increased crop yield, basal soil respiration and microbial biomass, with effects stronger in EM soils than in IM soils, but effects on soil enzyme activities were variable. The combined use of biostimulant and inorganic fertiliser negated the benefits of the biostimulant on soil biological properties in some cases. Nevertheless, effects of biostimulants had a positive impact on crop yield with the combined use of soil‐applied and seed applied biostimulants have the greatest impact on plant biomass and also conferring some resistance in both soil microbial communities and plant growth to drought.ConclusionsWhile biomass and activity of the microbial community and plant growth responses to biostimulant additions are both soil and biostimulant dependent, their combined use has potential to aid both plants and maintain promote microbial activity under of drought, compared to conventional fertiliser treatments in extensively managed soils.

Parallel successions of microbiomass and oribatid mites in the soil during the transformation of the forest ecosystem into an agrocenosis in the south of Western Siberia

The analysis of the state of the destructive block in gray forest soils in the Novosibirsk region was carried out. Forest, meadow under pasture and vegetable agrocenosis were selected as the objects of the study. Soil-zoological and soil-microbiological methods were used in the work. The biomass of soil microorganisms, basal respiration, metabolic coefficient, species richness and the total numbers of oribatid mites in soils were studied. Strong changes in the studied parameters in soils with different agricultural uses, compared with the soil under the forest, are demonstrated. With the deforestation and the transformation of the formed grass ecosystem to pasture, all the studied indicators decrease. When the grass ecosystem is plowed and the soil is used for a long time as an agrocenosis, a further decrease in microbiological and zoological indexes is observed. The conclusion is made about the possibility of applying the methods used in the practice of ecological monitoring of gray forest soils is made.

Soil-biological methods in monitoring the processes of turning the steppe into a meadow near lake ecosystems of Khakassia

The article analyzes the results of the study of microbiological and zoological components in the soils of lake territories in the steppe zone of the Khakassia Republic. It is shown that the transformation of the zoo-microbial complex of the southern chernozem in the process of turning the steppe into a meadow occurs along the way of reducing the biomass of soil microorganisms and a sharp increase in the total and specific metabolic activity of this biomass. At the same time, a sharp decrease in the number of oribatids occurs in the process of turning the steppe into a meadow, with the practical immutability of species richness. At the same time, the composition of the oribatid community is undergoing a radical transformation. These changes in the zoo-microbial complex are associated with changes in the level of soil moisture. The conducted research demonstrated that the identified features of the studied biological and soil indicators (microbiomass, respiration of biomass and metabolic coefficient, the number and species richness of oribatid mites) can be successfully used in the practice of monitoring the process of turning the steppe into a meadow on lake territories in the steppe zone of the Khakassia Republic.

Effects of Continuous Cropping of Dictyophora on Soil Physical and Chemical Properties, Microbial Biomass and Enzyme Activity

The continuous obstacle of Dictyophora indusiata has become the one of the main factors affecting the healthy development of D. indusiata industry. In order to study the effects of continuous cropping of D. indusiata on the soil environment, four treatments were used in this study: no planted (CK), planted for 1 years (1Y), continuous cropping for 2 years (2Y) and continuous cropping for 3 years (3Y), to determined of the yield of D. indusiata, soil physical and chemical properties, microbial content and enzyme activity. The results showed that the yield and soil pH value decreased with the increase of continuous cropping years, and the contents of organic matter, total nitrogen, total phosphorus and total potassium, C/N and C/P also increased with the increase of continuous cropping years. Soil availability decreased with the increase of continuous cropping years, the content of alkaline nitrogen, available phosphorus and available potassium decreased by 12.25%, 28.91% and 24.86% at 3Y compared with 1Y, respectively. The biomass of bacteria, actinomycetes and fungi and the total amount of microorganism in soil increased at 1Y compared with CK, but with the increase of continuous cropping years, the biomass of bacteria and actinomycetes and the total amount of microorganism decreased significantly, while the biomass of fungi increased significantly; the continuous cropping of D. indusiata also decreased the value of bacteria/fungi in soil. The enzyme activities of the soil were higher than those of the unplanted plots, however, the activities of urease, catalase, peroxidase, sucrase, phosphatase and protease decreased with the increase of continuous cropping years. In a word, with the increase of continuous cropping, the acidity of rhizosphere soil increased, the availability of soil nutrients and the activity of soil enzymes decreased, the biomass of soil microorganisms, bacteria and actinomycetes decreased. However, the increase of fungal biomass led to the decline of soil texture.

SOIL-MICROBIOLOGICAL METHODS IN MONITORING OF NEAR-LAKE ECOSYSTEMS OF THE WESTERN BAIKAL REGION

The article analyzes the main characteristics of the state and metabolic activity of the biomass of soil microorganisms in the ecosystems of the near-lake salt meadows and dry steppes of the Western Baikal region. It is shown that during the transition from semi-hydromorphic soils (lake salonchak) to automorphic soils (chestnut soils of dry steppes), the levels of moisture and salinity decrease. Changes in soil properties lead to a significant transformation of the soil microbiocenosis. The study demonstrated that such soil-microbiological indicators as the carbon content in the biomass of soil microorganisms, basal respiration and specific metabolic activity, estimated by the value of the metabolic coefficient, can be successfully used in the practice of environmental monitoring of the near lake areas of the Tazheran steppe.

FEATURES OF ECOLOGICAL MONITORING OF SALINE SOILS OF THE STEPPE ZONE IN KHAKASSIA

The article deals with the results of the study of the biomass of soil microorganisms and the community of oribatid mites in the soils of lake territories in the steppe zone of the Republic of Khakassia. It is shown that the transformation of the zoo-microbial complex of chernozem-meadow soils of lake ecosystems in the process of salinization occurs along the path of reducing the microbiomass and metabolic activity (the microbiological part of the complex), the number and species richness (the zoological part of the complex). This transformation is related to the level of saline groundwater occurrence. The study demonstrated that the identified features of the studied soil biological indicators (respiratory activity of microbiomass and its metabolic coefficient, the number and species richness of oribatid mites) can be successfully used in the practice of monitoring ecosystems and soils located in the lake territories in the steppe zone of the Republic of Khakassia.

<b>Comparison of methods to quantify soil microbial biomass carbon

Soil microorganism biomass is an important soil quality indicator. The microbial biomass of soil was determined by killing and lysing the soil microbes by fumigation with chloroform, irradiation with gamma rays, or irradiation with microwaves. Four soils with increasing carbon concentrations (5, 10, 15, and 30 g kg -1 ) were analyzed using four methods: the direct application of chloroform, chloroform fumigation, microwave irradiation, and gamma ray irradiation with radiation doses of 15, 25, 35, 45, and 60 KGy. The fungi and bacteria in the soil were quantified by plate counting. Microwave irradiation and gamma irradiation with doses equal to or above 25 KGy killed all the soil microorganisms, but the chloroform methods did not. The carbon liberation increased with higher gamma doses, while the microbe mortality rates were the same, indicating that carbon was liberated from organic matter sources other than microorganisms. The biomasses determined by the microwave method correlated with those determined by the fumigation and 25 KGy gamma irradiation methods, but their values differed among all methods for at least one soil type. Despite this discrepancy, all methods were consistent in ranking microbial biomasses in increasing order of soil carbon concentrations, which corresponds with decreasing land use intensities.

Soil Microbial Communities of Eastern Antarctica

Investigation of microbial communities of Antarctica soils is a very important field of research that expands our knowledge of microbial participation in primary soil formation and specific features of their communities in extreme habitats, and it is of considerable interest in directed search of for microorganisms as potential biotechnological objects. The results of long-term (2012–2017) complex studies on soil microbial communities of the Russian East Antarctica polar stations at Shirmakher oasis (Novolazarevskaya station), the Larsemann Hills (Progress station), and the Tala Hills (Molodezhnaya station) are presented in this review. The assessment of biomass of soil microorganisms by the methods of direct microscopy has been carried out for the first time for this region. The general amount of microbial biomass is small; the fungi dominate (77–99%). The unique features of Antarctic soils are the high content and morphological diversity of small forms of microorganisms: fungi are presented by mainly single-celled structures (small spores and yeasts), while bacteria by ultrafine (filtering) forms. At the same time, microorganisms can significantly contribute to such important ecological functions of soil as the emission of greenhouse gases, especially during the warm season with the stable positive temperatures of the soil. This should be considered during creation of models and forecasts of global warming. The use of various isolation techniques for the analysis of the soil microbial population, together with the succession approach, significantly expand the information about taxonomic diversity of cultivated fungi and bacteria in Antarctica soils.

ПРОСТРАНСТВЕННОЕ ВАРЬИРОВАНИЕ СОДЕРЖАНИЯ ВТОРИЧНЫХ МЕТАБОЛИТОВ, УГЛЕРОДА И АЗОТА В ПОДСТИЛКАХ СЕВЕРОТАЕЖНЫХ ЕЛЬНИКОВ*, "Лесоведение"

ПРОСТРАНСТВЕННОЕ ВАРЬИРОВАНИЕ СОДЕРЖАНИЯ ВТОРИЧНЫХ МЕТАБОЛИТОВ, УГЛЕРОДА И АЗОТА В ПОДСТИЛКАХ СЕВЕРОТАЕЖНЫХ ЕЛЬНИКОВ*, "Лесоведение"

Influence of root components of celery on pyrene bioaccessibility, soil enzymes and microbial communities in pyrene and pyrene-diesel spiked soils

Though phytoremediation is deemed as a promising approach to restore polycyclic aromatic hydrocarbon (PAHs) contaminated sites, studies about how the biodegradation of PAHs is enhanced still remains incomprehensive. Effects of root components on pyrene bioaccessibility, soil enzymes and microbial communities were explored in the paper, and their interactions in simulated pyrene and pyrene-diesel spiked microcosms were tried to give a reasonable explanation. Results indicated that root components enhanced the pyrene removal of bioaccessible and adsorbed fractions by 16.10 and 1.80mgkg−1, respectively, in pyrene-spiked soils at the end of the experiment. By contrast, root components increased the degradation of bioaccessible fraction by only 3.3mgkg−1 in pyrene-diesel spiked soils. Although the bound fractions of pyrene increased over time in treatments without root components, they remained relatively stable, ranging from 0.02 to 0.03mgkg−1, in root components amended treatments. Activities of soil enzymes (polyphenol oxidase, catalase, invertase, urease and alkaline phosphatase) varied differently in response to pollutants and root components. Analysis of phospholipid fatty acids revealed that root components increased the biomass of soil microorganisms and altered the microbial structure. Pearson correlation analysis proved positive correlations between all the microbial subgroups and pyrene removal in pyrene-spiked soils, but the degradation of bioaccessible pyrene was only positively related with microorganisms confirmed by monounsaturated fatty acids in pyrene-diesel spiked soils.

Tidal flooding diminishes the effects of livestock grazing on soil micro-food webs in a coastal saltmarsh

Livestock grazing not only has a direct impact on plant productivity but also exerts an indirect influence on soil biota via various pathways. However, little is known about the effects of livestock grazing on soil food webs in saltmarsh ecosystems that are subject to regular tidal inundation stress. By exclosure experiments established at a frequently inundated middle marsh and a less inundated high marsh of Chongming Island (China), the responses of soil micro-food web components (microorganisms, protozoa, and nematodes) to cattle grazing in intertidal marshes were investigated. In the high marsh, cattle grazing significantly increased the biomass of soil microorganisms, protozoa, and the abundance of total nematodes by 30.0%, 97.3% and 76.2%, respectively, but did not significantly affect their biomass or abundance in the middle marsh. For low-trophic-level nematodes, the abundance of bacterial-feeding and algal-feeding nematodes increased more in the high marsh than in the middle marsh, and that of plant-feeding nematodes decreased more in the high marsh than in the middle marsh under grazing. In contrast, carnivorous and omnivorous nematodes at high trophic levels did not respond to cattle grazing along an elevational gradient. The nematode maturity index and structure index based on nematode functional guilds significantly decreased under grazing along the elevational gradient, suggesting that cattle grazing caused a more simplified and unstable soil micro-food web structure. Overall, low trophic levels in soil micro-food webs were most vulnerable under grazing and the response was strongest in the less inundated high marsh. Thus, cattle grazing leads to different changes in soil ecosystem processes at different elevations. These results indicate that the strength of the biotic grazing effect on soil micro-food webs and ecological functions might also depend on local abiotic disturbance such as tidal inundations in the saltmarsh.

Effect of poultry manure in combination with straw on the biological properties of soddy-podzolic soil and the yielding capacity of grain crops

Effect of the double application of high doses of poultry manure in combination with straw on the biological state, nitrogen status, and organic matter of sandy loamy soddy-podzolic soil and the yield of grain crops has been studied in a field experiment. It has been found that the application of poultry manure with straw favors the increase in the abundance, activity, and biomass of soil microorganisms; the decrease in the excessive accumulation of mineral nitrogen due to its biological immobilization without reducing the yield of grain crops; and the accumulation of organic nitrogen and carbon in the plow layer of soil.

Do microorganism stoichiometric alterations affect carbon sequestration in paddy soil subjected to phosphorus input?

Ecological stoichiometry provides a powerful tool for integrating microbial biomass stoichiometry with ecosystem processes, opening far-reaching possibilities for linking microbial dynamics to soil carbon (C) metabolism in response to agricultural nutrient management. Despite its importance to crop yield, the role of phosphorus (P) with respect to ecological stoichiometry and soil C sequestration in paddy fields remains poorly understood, which limits our ability to predict nutrient-related soil C cycling. Here, we collected soil samples from a paddy field experiment after seven years of superphosphate application along a gradient of 0, 30, 60, and 90 (P-0 through P-90, respectively) kg.ha-1.yr-1 in order to evaluate the role of exogenous P on soil C sequestration through regulating microbial stoichiometry. P fertilization increased soil total organic C and labile organic C by 1-14% and 4-96%, respectively, while rice yield is a function of the activities of soil β-1,4-glucosidase (BG), acid phosphatase (AP), and the level of available soil P through a stepwise linear regression model. P input induced C limitation, as reflected by decreases in the ratios of C:P in soil and microbial biomass. An eco-enzymatic ratio indicating microbial investment in C vs. P acquisition, i.e., ln(BG): ln(AP), changed the ecological function of microbial C acquisition, and was stoichiometrically related to P input. This mechanism drove a shift in soil resource availability by increasing bacterial community richness and diversity, and stimulated soil C sequestration in the paddy field by enhancing C-degradation-related bacteria for the breakdown of plant-derived carbon sources. Therefore, the decline in the C:P stoichiometric ratio of soil microorganism biomass under P input was beneficial for soil C sequestration, which offered a "win-win" relationship for the maximum balance point between C sequestration and P availability for rice production in the face of climate change.

Microorganisms in Small Patterned Ground Features and Adjacent Vegetated Soils along Topographic and Climatic Gradients in the High Arctic, Canada

In this study, we determine differences in total biomass of soil microorganisms and community structure (using the most probable number of bacteria (MPN) and the number of fungal genera) in patterned ground features (PGF) and adjacent vegetated soils (AVS) in mesic sites from three High Arctic islands in order to characterize microbial dynamics as affected by cryoturbation, and a broad bioclimatic gradient. We also characterize total biomass of soil microorganisms and the most probable number of bacteria along a topographic gradient within each bioclimatic subzone to evaluate whether differences in topography lead to differences in microbial dynamics at a smaller scale. We found total microbial biomass C, the most probable number of heterotrophic bacteria, and fungal genera vary along this bioclimatic gradient. Microbial biomass C decreased with increasing latitude. Overall, microbial biomass C, MPN and the number of fungal isolates were higher in AVS than in PGFs. The effects which topographic position had on microbial biomass C varied across the bioclimatic gradient as there was no effect of topographic position in Isachsen (subzone A) and Mould Bay (subzone B), when compared to Green Cabin (subzone C, warmer site).There was no effect of topographic position on MPN counts at Mould Bay and Green Cabin. However, in Isachsen, MPN counts were highest in the wet topographic position as compared to the mesic and dry. In conclusion, PGFs seem to decouple the effect climate that might have on the total biomass of soil microorganisms along the bioclimatic gradient; and influence gets ameliorated as latitude increases. Similarly, the effect of topography on the total microbial biomass is significant at the warmest bioclimatic zone of the gradient. Thus, climate and topographic effects on total microbial biomass increase with warmer climate.

Characterisation of actinomycetes community from the heavy metals-polluted soil

The isolation of actinomycetes was performed from soil samples influenced by car-traffic. The acute toxicity of soil leaches was tested by the help of Microtox®bioassay testing system which uses freeze dried luminescent bacteriaPhotobacterium phosphoreumas the test organisms. The content of heavy metals in biomass of soil microorganisms and in whole soil samples was determinate. 115 strains of actinomycetes were isolated and their total numbers in soil samples were estimated. The acute toxicity of soil influenced the total numbers of actinomycetes. By the help of DNA-DNA reassociation procedure the generic diversity of bacteria was estimated. The identification and differentiation of streptomycetes from the total isolated actinomycetes was made using specific morphological criteria and the gas chromatography-fatty acid methyl ester (GC-FAME) analysis. FAME method is adequate only for differentiation of members of genusStreptomycesfrom other actinomycetes because of their characteristical profile of fatty acids.

重度火烧迹地微地形对土壤微生物特性的影响——以坡度和坡向为例

It is well known that the Great Xingan Mountain forest region is one of the most important parts of the northeast forest region.Not only does it serve as an important resource for lumber,it also is an important ecological regulator that keeps balance in this area.Fires are common disturbances in this area.Severe fires can cause enormous losses,and can significantly change the structure of the forest ecosystem and disturb its succession process.In order to help the forest recover from such disturbances,it is necessary to study the restoration of soil quality,which can directly affect the forest restoration process.Soil microorganisms,which are common residents in soil,can interact with soil environment during the process of soil quality restoration.They are very sensitive to the changes in soil quality,thus serving as very useful indicators of soil quality.Among many environmental factors,topographic factors,such as slope and aspect,are very important to the restoration of forest soil quality.They affect the distribution of other environmental factors(such as light,heat,water,soil,etc.),and further affect ecological processes in various degrees.In this study we focused on the response of microbial populations to changes in the soil environment of different topographic factors(such as slope and aspect) in recently severe burned areas in the Great Xingan Mountain,where the restoration was at the early regeneration stage.The purpose of this study was to examine the effects of slope and aspect on soil microbial biomass distribution,soil microbial community structure,and soil microbial functional diversity in these areas.Soil samples were collected from severly burned forest sites(2003 fires) with different slopes and aspects.Standard experimental methods were used to measure typical physical and chemical indicators,such as total nitrogen(TN),total carbon(TC),soil organic carbon(SOC),soil moisture(SM),soil available nitrogen(AN),and electrical conductance(EC).Fumigation,extraction,and Biolog methods were used to detect soil microbial biomass,soil microbial community structure,and soil microbial functional diversity,respectively.Our results showed that soil microorganism biomass carbon(MBC) on flat land is higher than that on sloped lands.The ratio between soil microorganism biomass carbon and microorganism biomass nitrogen(MBN) has the same pattern,with the flat land having a significantly higher value(9.49) than that of the sloped land(6.76).Soil microorganism metabolic activities and carbon use capacities of microorganism community,which are assessed by average well-color development(AWCD),however,showed different patterns.That is,the value of AWCD on flat land was significantly lower than that on the sloped land,with values of 0.39 and 1.21 on the flat land and sloped land,respectively.Four types of carbon source use capacities and the Shannon-Weiner index of diversity(H') of microorganism community exhibited a pattern similar to AWCD.AWCD and H' values were higher on west(facing) slopes than those on south slopes,but data analysis showed that AWCD and H' have no significant correlations with soil nutrition,pH or electricity conductance(EC),which suggests that aspect might not be closely related with soil microorganism metabolic activities and diversity of microorganism community.Soil microorganism community structures on these two aspects showed similarity.Slope influenced the soil nutrition and water supply condition of different areas,which can affect soil microorganism biomass,soil microbial community structure,and soil microbial functional diversity in these areas.In the early restoration stages of severely burned areas,MBC values on the flat land were higher than those on slope land,and those on west slopes were higher than those on south slopes.Differences in MBC are not significant among these areas after rehabilitation for 6 years.However,soil microbial community structure and soil microbial functional diversity are still significantly different which might due to different soil water content caused by different slope.

喀斯特峰丛洼地土壤剖面微生物特性对植被和坡位的响应

选取广西环江县喀斯特峰丛洼地:草丛(T)、灌丛(S)、原生林(PF)(中坡位)不同植被类型,原生林上、中、下不同坡位,按土壤发生层采集淋溶层(A 层,0-10 cm)、过渡层(AB层,20-30 cm,草丛和灌丛;30-50 cm,原生林)、淀积层 (B层,70-100 cm)样品,研究土壤微生物量碳、氮(Soil microbial biomass carbon (SMBC)、soil microbial biomass nitrogen (SMBN))、微生物碳熵、氮熵(ratio of SMBC to soil organic carbon (<em>q</em>MBC)、ratio of SMBN to soil total nitrogen (<em>q</em>MBN))、土壤基础呼吸 (soil basic respiration (SBR))以及代谢熵 (microbial metabolic quotient (<em>q</em>CO₂))的剖面分异特征及其影响因素。结果表明,植被、土层深度显著影响土壤微生物量及基础呼吸,随植被恢复,SMBC、SMBN、SBR由草丛、灌丛、原生林依次上升,并随土壤发生层位的加深逐渐减少,<em>q</em>CO₂在3种植被类型间差异显著:T>PF>S;原生林A层SMBC, SMBN在各坡位间均显著高于AB层、B层, SBR在A层由下坡位至上坡位递减,而在AB和B层的上、下坡位间无显著差异,<em>q</em>CO₂坡位间无显著差异(<em>P</em>>0.05);SMBC与SMBN之间存在显著正相关(<em>r</em>=0.825,<em>P</em><0.01, <em>n</em>=45),且SMBC、SMBN、SBR分别与有机碳、全氮、碱解氮均呈显著正相关。因此,随植被恢复,土壤质量明显改善,且坡位对A层土壤的影响较AB层和B层更显著,对于维持土壤微生物调节的土壤养分循环功能,调控土壤氮素营养与土壤有机质同等重要,这为合理制订喀斯特生态恢复措施提供了理论依据。;Closed-forest type land coverage is an important measure for the restoration of degraded karst ecosystems, and soil microorganisms are one of the most useful indicators of soil quality; however, little is known about the effects of the vegetation pattern and slope on microbial characteristics within the soil profile. In this study, soil samples derived from three different genetic layers along the profile-leaching layer (A, 0-10 cm); transition layer (AB, 20-30 cm, tussock (T) and shrub (S); 30-50 cm, primary forest (PF)); and deposited layer (B, 70-100 cm)-were collected from the middle slope position of three ecosystems-tussock (T), shrub (S), and primary forest (PF)and in addition, from the upper and lower slope positions of primary forest (PF). The study determined soil microbial biomass carbon (SMBC), nitrogen (SMBN), ratio of SMBC to soil organic carbon (<em>q</em>MBC), ratio of SMBN to soil total nitrogen (<em>q</em>MBN), basic respiration (SBR), microbial metabolic quotient (<em>q</em>CO₂) and certain physico-chemical characteristics in order to identify changes in the microbial characteristics along the soil profile in response to the typical vegetation pattern and slope position, and the relationships between the soil microbial- and physico-chemical characteristics. Our results showed that the vegetation pattern and the type of soil genetic layer significantly affected soil microbial biomass and basic respiration, whereas no consistent effect on the slope position was observed. The values of soil microorganism biomass carbon along the soil profile from tussock (T) and shrub (S) ecosystems were 56.7-367 and 161-640 mg/kg, respectively, which were significantly lower than the 532-1217 mg/kg value for the primary forest (PF) ecosystem. The same trend (T<S<PF) was observed for soil microbial biomass nitrogen and soil basic respiration, but a different trend (T>PF>S) was observed for the microbial metabolic quotient. SMBC, SMBN, qMBC, and SBR declined for each progressive soil genetic layer, and the effect of slope position on these indicators was more significant within the leaching layer (A) than in the transition (AB) and deposited layers (B). In contrast, for SBR, two-way ANOVA showed that the slope position had no significant influence on <em>q</em>CO₂. A significant positive correlation was observed between SMBC and SMBN (<em>r</em>=0.825, <em>P </em>< 0.01, <em>n</em>=45). Further, there were significant differences in soil nutrients (TN, SOM, AN) along the profile between different vegetation patterns and slope positions; and SMBC, SMBN, and SBR were also correlated with organic carbon, total nitrogen, and available nitrogen. As a result, vegetation restoration had positive effects on the physico-chemical and microbial characteristics, and these changes were more prominent in surface soil than in deep soil. Soil nitrogen nutrition and soil organic matter were equally important for the maintenance of the soil microbial community and its ecological function. These findings should help facilitate preservation and revegetation activities in karst regions.

Biomass of microorganisms in the alas soil of the territory between the Lena and Vilyuy Rivers

We studied peculiar features of profile distribution of the biomass of soil microorganisms and the total and specific metabolic activity of this biomass in the cryogenic soils of Central Yakutia. The peculiarities of changes in microbiological characteristics during the evolution of alas ecosystems and soils were analyzed. The effect of a complex of factors on the studied characteristics at different stages of long-term alas succession was estimated.