Soil Ecological Functions Research Articles

Influence of select bioenergy by-products on soil carbon and microbial activity: A laboratory study

Concerns about the negative impacts of crop biomass removal on soil ecological functions have led to questioning the long-term sustainability of bioenergy production. To offset this potential negative impact, use of organic C rich by-products from the bioenergy industries have been proposed as a means to replenish soil C in degraded soils. However, the impact of these by-products application on soil carbon dynamics is not fully understood. We measured biogeochemical changes in soil organic C following a three-year field application of two by-products, biochar (BC) and fermentation-by product (FBP), of bioenergy industry processes in an elephant grass [Pennisetum purpureum (L.) Schum.] field. There was a significant increase in overall soil organic C (SOC) observed in BC (270%) treated plots, however the higher labile SOC (51%) content was present in FBP treated plots. Solid-state 13C NMR spectroscopy further revealed increased aromatic and alkyl groups in BC amended soils which lend to its significantly higher hydrophobicity index, HI (2.13) compared with FBP amended soils (HI = 0.8). Initial biogeochemical responses of amended soils to drought conditions were also investigated during a short-term experiment with drying and rewetting of soils. Increased concentrations of extractable C and higher stimulation of microbial activities (respiration and enzyme activities) in FBP amended soils were measured. Overall, our results reveal different impacts of the two soil amendments, where FBP soil application can affect the labile SOC availability, and stimulate rapid microbial response in drought affected soils, and biochar soil application lowers the labile SOC and microbial stimulation facilitating C sequestration over time.

Bacterial community variations in paddy soils induced by application of veterinary antibiotics in plant-soil systems

Soil bacterial communities have complex regulatory networks, which are mainly associated with soil fertility and ecological functions, and are likely to be disturbed due to antibiotics applications. The impact of antibiotics, particularly in mixtures form, on bacterial communities in different paddy soils is poorly understood. Using pyrosequencing techniques of 16 S rRNA genes, this study investigated the synergistic effects of veterinary antibiotics (sulfadiazine, sulfamethoxazole, trimethoprim, florfenicol, and clarithromycin) on bacterial communities in a soil-bacteria-plant system. Rice was grown under controlled greenhouse conditions where unplanted and planted treatments were doped with 200 µg kg−1 of combined antibiotics over a period of 3 months. Bacterial richness remained unaltered, while a significant decline was observed in bacterial diversity due to antibiotics in the four paddy soils. Bacteroidetes and Acidobacteria were increased, while Actinobacteria and Firmicutes decreased under antibiotics exposure. Despite antibiotics perturbation, compositional variations were mainly attributed to the different paddy soils which harbor distinct bacterial communities. Haliangium and Gaiella were among the sensitive genera that were negatively correlated to antibiotics perturbation. Additionally, electrical conductivity, total organic carbon, and total nitrogen of soil solution were the key physiochemical indices which significantly influenced the structure of bacterial communities in the paddy soils. These findings expanded our knowledge of effects from synergistic antibiotics application and variations in bacterial communities among different paddy soils.

The Ecological Functions and Ecosystem Services of Urban and Technogenic Soils: from Theory to Practice (A Review)

A review of Russian and foreign approaches to analyze and assess the ecological and socioeconomic role of urban and technogenic soils is made in the context of the two popular concepts: the ecological functions of soils and ecosystem services. The modern definitions, classification, and evaluation of ecosystem services and their relationships with soil functions are considered both in general and in relation to urban and technogenic soils. Despite some methodological differences, the work shows that the concepts are closely related, and their joint use is highly promising. Three practical examples for the cities of Moscow, Hangzhou, and Hong Kong show a consistent transition from the analysis of soil properties and functions to the assessment of ecosystem services and decision making in engineering, urban improvement, and sustainable urban development.

Changes of Soil Microbiological Properties during Grass Litter Decomposition in Loess Hilly Region, China.

Litter, the link between soil and plant, is an important part of nutrient return to soil. Deeply understanding the effect of litter decomposition on soil microbiological properties is important for the sustainable development of grasslands. Three plants (Thymus quinquecostatus Celak., Stipa bungeana Trin. and Artemisia sacrorum ledeb.) leaf litter were selected. A simulation experiment using the nylon bag method was conducted to measure the soil microbial biomass carbon and nitrogen, and soil enzyme activity during litter decomposition. The results showed that the decomposition of three leaf litter enhanced soil microbial carbon and nitrogen. The change rate of soil microbial carbon and nitrogen decreased as Ar.S > St.B > Th.Q. The activities of soil invertase, soil urease, and soil nitrate reductase were significantly improved by the coverage of leaf litter. After 741-day litter decomposition, the change rate of soil invertase was from 16.7% to 33.2%. The change rate of soil urease was highest in the Th.Q treatment; St.B treatment and Ar.S treatment followed, and lowest in the control. The change rates of soil nitrate reductase in the St.B and Ar.S treatment were >1000% higher than those of other treatments. The response of soil enzyme activity to litter decomposition “lagged” behind the change of soil microbial biomass. The significant increase of soil microbial biomass and enzyme activity demonstrated that litter decomposition played an important role in maintaining soil ecological function.

Genetic correlation network prediction of forest soil microbial functional organization

Soil ecological functions are largely determined by the activities of soil microorganisms, which, in turn, are regulated by relevant interactions between genes and their corresponding pathways. Therefore, the genetic network can theoretically elucidate the functional organization that supports complex microbial community functions, although this has not been previously attempted. We generated a genetic correlation network based on 5421 genes derived from metagenomes of forest soils, identifying 7191 positive and 123 negative correlation relationships. This network consisted of 27 clusters enriched with sets of genes within specific functions, represented with corresponding cluster hubs. The clusters revealed a hierarchical architecture, reflecting the functional organization in the soil metagenomes. Positive correlations mapped functional associations, whereas negative correlations often mapped regulatory processes. The potential functions of uncharacterized genes were predicted based on the functions of located clusters. The global genetic correlation network highlights the functional organization in soil metagenomes and provides a resource for predicting gene functions. We anticipate that the genetic correlation network may be exploited to comprehensively decipher soil microbial community functions.

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.

Converting ‘trade-offs’ to ‘trade-ons’ for greatly enhanced food security in Africa: multiple environmental, economic and social benefits from ‘socially modified crops’

To address the issues of food insecurity within the context of land degradation, extreme poverty and social deprivation, this review seeks first to understand the main constraints to food production on smallholder farms in Africa. It then proposes a highly-adaptable, yet generic, 3-step solution aimed at reversing the downward spiral which traps subsistence farmers in hunger and poverty. This has been found to be effective in greatly increasing the yields of staple food crops and reducing the ‘yield gap’. This solution includes the restoration of soil fertility and ecological functions, as well as the cultivation, domestication and commercialization of traditionally-important, highly nutritious, indigenous food products for income generation and business development. A participatory approach involving capacity building at the community-level, leads to the development of ‘socially modified crops’ which deliver multiple environmental, social and economic benefits, suggesting that increased agricultural production does not have to be detrimental to biodiversity, to agroecological function, and/or to climate change. These are outcomes unattainable by attempting to raise crop yields using conventional crop breeding or genetic modification. Likewise, the livelihoods of smallholder farmers can be released from the constraints creating spatial trade-offs between subsistence agriculture and (i) international policies and (ii) globalized trade.

Emission and Sink of Greenhouse Gases in Soils of Moscow

The first inventory and zoning of the emission and sink of methane and carbon dioxide in the urban structure of greenhouse gases from soils and surface technogenic formations (STFs) (Technosols) on technogenic, recrementogenic, and natural sediments have been performed with consideration for the global warming potential under conditions of different formation rate of these gases, underflooding, and sealing. From gas geochemical criteria and anthropogenic pedogenesis features, the main sources of greenhouse gases, their intensity, and mass emission were revealed. The mass fractions of emissions from the sectors of waste and land use in the inventories of greenhouse gas emissions have been determined. New sources of gas emission have been revealed in the first sector, the emissions from which add tens of percent to the literature and state reports. In the second sector, emissions exceed the available data in 70 times. Estimation criteria based on the degree of manifestation and chemical composition of soil-geochemical anomalies and barrier capacities have been proposed. The sink of greenhouse gases from the atmosphere and the internal (latent) sink of methane in soils and STFs have been determined. Ecological functions of soils and STFs have been shown, and the share of latent methane sink has been calculated. The bacterial oxidation of methane in soils and STFs exceeds its emission to the atmosphere in almost hundred times.

Mapping of Soil-Ecological Conditions of a Medium-Size Industrial City (Birobidzhan City, Jewish Autonomous Oblast, FarEast of Russia as an Example)

The authors analyze soil relations with other elements of the city ecosystem (the position in the landscape, soil-forming rocks and lithology, vegetation and its state) to develop the legend and map of soils in the City of Birobidzhan (scale 1:25 000). The focus of study is the morphological structure of urban soils with different degree of disturbance of these relations under the impact of technical effects, economic and recreational activities of the city population. The soil cover structure is composed of four large ecological groups of soils: natural untransformed, natural with a disturbed surface, anthropogenic soils and technogenic surface formations. Using cartometry of the mapped soil contours the authors created the scheme of soil-ecological city zoning, which in a general way depicts the state of soil ecological functions in the city as well as identified zones of soils with preserved, partially and fully distured ecological functions and zones of local geochemical anomalies at the initial formation stage (environmental risk zones).

Use of soil biota in the assessment of the ecological potential of urban soils

In assessing the ecological conditions and classification of urban soils, data about soil biota should be taken into account. The environment of urban territories is characterized by significant changes compared to their surrounding environments. It is established that the algal flora of urban soils lose their zonal features and features associated with the edification influence of higher plants. Specific biotopes with a definite species structure are formed in urboecosystems. Fifty 50 algae species have been recorded in the soils of the Henichesk urboecosystems (Kherson region, Ukraine): Cyanoprocaryota – 21, Chlorophyta – 13, Charophyta – 2, Eustigmatophyta – 1, Xanthophyta – 11, Bacillariophyta – 2. Among dominant and subdominant species were Cyanoprocaryota and Chlorophyta. The other phyla were represented by Klebsormidium dissectum, K. flaccidum, Hantzschia amphioxys, Eustigmatos magnus, Botrydiopsis eriensis. Compared with the surrounding environment, the urbanized flora of Henichesk has a low species richness, and is characterized by prevalence of Cyanoprocaryota and Chlorophyta species. The coefficient that takes into account the percentage of preservation of species richness in a particular urban area compared to the background indicators of species richness can be used to evaluate the urban transformation of soil biota. The degree of degradatory changes in the composition of living organisms and the direction of these changes depends on the specificity and intensity of exploitation of the territory of the urban ecosystem. The most diverse composition of algae species within the the city of Henichesk was noted in the recreational, residential, and transport zones, in comparison with the industrial zone and the zone of special use. Different functional areas of the city are distinguished not only by the algae species richness, but also by the composition of dominants. Among the dominants and subdominants of the recreational and transport zones were species of different phyla. The dominants and subdominants of the residential and industrial zones were Cyanoprocaryota species, in the zone of special use – representatives of Chlorophyta. The distribution of species richness of algae along the soil profile in the city acquires an atypical character. The species richness increases not in the most superficial layers of soil, but in the lower, aphotic parts of the soil profile. The soil biota, on the one hand, depends on the ecological conditions of soil, and on the other as a result of its life activity, changes the ecological functions of the soil, strengthening or weakening them. The reduction in the species richness of the soil algae of the urboecosystem Henichesk shows the limitations of ecological functions of urban soils. It is established that changes in the composition of algae in soils of urban ecosystems are one of the indicators of the presence and severity of transformation processes. These processes occur with the soil biota and soil as a whole under the conditions of urban ecosystems and can be used as indicators in the environmental assessment of urban soils, in the development and subsequent examination of ways to reduce negative expression of urbanization.

Основные направления внутреннего агроэкологического аудита на сельскохозяйственных предприятиях

In this paper we investigate the question of loss of fertility of the soil cover, ecological functions of soils. Th e main purpose of the article is to study the mechanisms of control over the preservation of land in agricultural production.

Greenhouse gas emissions from a Cu-contaminated soil remediated by in situ stabilization and phytomanaged by a mixed stand of poplar, willows, and false indigo-bush

ABSTRACTPhytomanagement of trace element-contaminated soils can reduce soil toxicity and restore soil ecological functions, including the soil gas exchange with the atmosphere. We studied the emission rate of the greenhouse gases (GHGs) CO2, CH4, and N2O; the potential CH4 oxidation; denitrification enzyme activity (DEA), and glucose mineralization of a Cu-contaminated soil amended with dolomitic limestone and compost, alone or in combination, after a 2-year phytomanagement with a mixed stand of Populus nigra, Salix viminalis, S. caprea, and Amorpha fruticosa. Soil microbial biomass and microbial community composition after analysis of the phospholipid fatty acids (PLFA) profile were determined. Phytomanagement significantly reduced Cu availability and soil toxicity, increased soil microbial biomass and glucose mineralization capacity, changed the composition of soil microbial communities, and increased the CO2 and N2O emission rates and DEA. Despite such increases, microbial communities were evolving toward less GHG emission per unit of microbial biomass than in untreated soils. Overall, the aided phytostabilization option would allow methanotrophic populations to establish in the remediated soils due to decreased soil toxicity and increased nutrient availability.

Allometric equations for estimating fresh biomass of five soil macroinvertebrate species from neotropical agroecosystems

Accurate estimation of soil macroinvertebrate fresh biomass is crucial to link macroinvertebrate community to ecosystem functions, but remains a challenging task under field conditions. Here, we present allometric equations to estimate the fresh biomass of three diplopods (Rhinocricidae), one earthworm (Glossoscolescidae) and one earwig species (Anisolabididae) that are abundant in soil communities and potentially important for the provision of soil ecological functions in tropical agroecosystems. Body length, body width, and body volume, were measured using a novel method of image analysis, and then used to estimate the fresh biomass. Our results show that length-biomass allometric relationships provide reliable estimation of fresh biomass for diplopods (r2 = 0.98) and earwigs (r2 = 0.97). However, the biomass of earthworms was not as accurately predicted by body length (r2 = 0.82). The use of body volume, estimated with body length and width, allowed to increase the predictive power for earthworms. Furthermore, a general allometric equation based on body volume, including all taxa considered in this study, was found to predict 96% of the observed body weight variability, suggesting that this equation could be generalizable to a large range of soil macroinvertebrates. Therefore, we conclude that using body volume could provide a better accuracy in estimating soil macroinvertebrate biomass. Although the estimation of body volume on each individual requires an additional measure, the use of image analysis software renders this step feasible for a large number of individuals. By improving the feasibility of trait measurements, this method may facilitate field surveys and foster trait-based studies on soil macroinvertebrates.

The influence of e-waste recycling on the molecular ecological network of soil microbial communities in Pakistan and China

Primitive electronic waste (e-waste) recycling releases large amounts of organic pollutants and heavy metals into the environment. As crucial moderators of geochemical cycling processes and pollutant remediation, soil microbes may be affected by these contaminants. We collected soil samples heavily contaminated by e-waste recycling in China and Pakistan, and analyzed the indigenous microbial communities. The results of this work revealed that the microbial community composition and diversity, at both whole and core community levels, were affected significantly by polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and heavy metals (e.g., Cu, Zn, and Pb). The geographical distance showed limited impacts on microbial communities compared with geochemical factors. The constructed ecological network of soil microbial communities illustrated microbial co-occurrence, competition and antagonism across soils, revealing the response of microbes to soil properties and pollutants. Two of the three main modules constructed with core operational taxonomic units (OTUs) were sensitive to nutrition (total organic carbon and total nitrogen) and pollutants. Five key OTUs assigned to Acidobacteria, Proteobacteria, and Nitrospirae in ecological network were identified. This is the first study to report the effects of e-waste pollutants on soil microbial network, providing a deeper understanding of the ecological influence of crude e-waste recycling activities on soil ecological functions.

Bacterial traits and quality contribute to the diet choice and survival of bacterial-feeding nematodes

The dietary choices of bacterial-feeding nematodes could control the structure and ecological functions of soil bacterial communities. However, the physiological basis for the selection of particular bacterial species as food, and the consequences of these dietary choices for the survival of bacterial-feeding nematodes, is poorly understood. The objectives of this study were (1) to determine how nematode feeding preference was related to bacterial traits (cell size, gram stain and growth rate) and quality (water content, carbohydrate content, protein content and metabolite concentration), and (2) to evaluate how dietary choices affected the reproduction and lifespan of two soil-dwelling bacterial-feeding nematodes of the species Mesorhabditis and Acrobeloides. Their food sources included one model bacterium, Escherichia coli OP50, and four soil-dwelling bacterial species: Bacillus amyloliquefaciens, Bacillus megaterium, Variovorax paradoxus and Pseudomonas fluorescens. Both nematode species exhibited a similar hierarchy of diet choice, with P. fluorescens and E. coli OP50 being the most preferred food, whereas B. megaterium was the least preferred bacteria. Nematode feeding preference was strongly related to the water content, growth rate and metabolite concentration of bacterial cells, which explained 63–75% of the variation in the feeding preference index (PI, which indicates the number of nematodes attracted to specific bacteria), and the rest of the variation was attributed to bacterial cell size, gram stain, carbohydrate content and protein content. We propose two physiological mechanisms to explain dietary choices of bacterial-feeding nematodes: 1) chemical attraction to higher carbon dioxide levels around rapidly-growing bacteria or repulsion to volatile organic molecules released from bacterial cells, and 2) selective ingestion of bacterial cells with preferred characteristics (e.g., high water content in cells). Nematodes feeding on preferred bacteria always had higher reproduction, but dietary choices were not a good predictor of their lifespan. For example, Acrobeloides feeding on their preferred food P. fluorescens had the largest brood size but a moderate survival time. However, when Acrobeloides consumed their least-preferred food B. megaterium, they produced the smallest brood size and had the shortest survival time. This may be due to the fact that dietary resources are allocated first towards reproduction, and second to prolong the lifespan of bacterial-feeding nematodes. Our findings suggest that dietary choices are important for the survival of bacterial-feeding nematodes, and their ability to find and selectively ingest preferred bacterial species may have implications for soil bacterial community structure and ecological functions.

Evaluation of carbon stocks in the soils of Lena River Delta on the basis of application of “dry combustion” and Tyurin’s methods of carbon determination

The aim of this paper is evaluation of carbon stocks in the soils of the Lena River Delta by two methods: “dry combustion” and Tyurin’s methods, as well as their comparison. This work presents methodical aspect and data on the estimation of organic carbon stocks in the soils of the Lena River Delta. Here we show that the data on the content of organic carbon based on dichromate oxidation by Tyurin’s method differed significantly from the actual carbon content of organic substances, derived from application of “dry combustion” method based on direct accounting of emitted CO2 from soils it uses of chromatography techniques. Due to this difference, the application of Tyurin’s method can lead to incorrect estimate of carbon stocks in the soil. This knowledge is very important for correct estimation of soil ecological functions related to stabilization of organic matter.

Biophysical processes supporting the diversity of microbial life in soil.

Soil, the living terrestrial skin of the Earth, plays a central role in supporting life and is home to an unimaginable diversity of microorganisms. This review explores key drivers for microbial life in soils under different climates and land-use practices at scales ranging from soil pores to landscapes. We delineate special features of soil as a microbial habitat (focusing on bacteria) and the consequences for microbial communities. This review covers recent modeling advances that link soil physical processes with microbial life (termed biophysical processes). Readers are introduced to concepts governing water organization in soil pores and associated transport properties and microbial dispersion ranges often determined by the spatial organization of a highly dynamic soil aqueous phase. The narrow hydrological windows of wetting and aqueous phase connectedness are crucial for resource distribution and longer range transport of microorganisms. Feedbacks between microbial activity and their immediate environment are responsible for emergence and stabilization of soil structure—the scaffolding for soil ecological functioning. We synthesize insights from historical and contemporary studies to provide an outlook for the challenges and opportunities for developing a quantitative ecological framework to delineate and predict the microbial component of soil functioning.

The Legislative Background of the Application of Fermentation Residues to Agricultural Lands in Hungary

The broad presence of biogas plants – facilities using organic wastes and by-products to generate energy – now seems to warrant urgent attention to the land application of by-products (fermentation residues) from biogas plants. In Hungary, this activity can be carried out under statutory conditions, subject to official licensing. The protection provided by law is necessary because an adaptable and sustainable agriculture based on effects and interactions also requires such attention, since the most important natural resource of agriculture is soil, which, by nature, is a conditionally renewable natural resource [1] [2]. Protection of soil means primarily protection of quality: sustainable and adaptable agriculture contributes to retain the ecological functions of soil and its role in the ecosystem [3]. This publication analyses the possibilities and challenges of natural resource management by studying the agricultural use of fermentation residues from biogas plants. In order to be used in agriculture, fermentation residue should be classified according to its character and nutritional value, namely as harmless waste from non-agricultural sources. This substance may have the properties of slurry, and in certain cases it may be classified as a substance with characteristics of waste water/sewage sludge or sewage sludge compost.
 Main elements of the preparation of the soil protection plan: detailed laboratory tests of the fermentation residue according to standards and regulations; classification of the fermentation residue on the basis of the measured parameters and the field tests corresponding to the character of fermentation residue according to the relevant legislation. Soil protection plan is prepared by expert based on on-site investigation and laboratory reports. This is the basis of the licensing process.
 Land application of fermentation residues therefore requires expert analysis to ensure that the ecological functions of soil are not damaged. This, however, requires that the regulations governing the framework for the conditions of such application are carefully studied and interpreted.

Spatial variability of soil carbon to nitrogen ratio and its driving factors in Ili River valley, Xinjiang, Northwest China

Soil carbon to nitrogen (C/N) ratio is one of the most important variables reflecting soil quality and ecological function, and an indicator for assessing carbon and nitrogen nutrition balance of soils. Its variation reflects the carbon and nitrogen cycling of soils. In order to explore the spatial variability of soil C/N ratio and its controlling factors of the Ili River valley in Xinjiang Uygur Autonomous Region, Northwest China, the traditional statistical methods, including correlation analysis, geostatistic alanalys and multiple regression analysis were used. The statistical results showed that the soil C/N ratio varied from 7.00 to 23.11, with a mean value of 10.92, and the coefficient of variation was 31.3%. Correlation analysis showed that longitude, altitude, precipitation, soil water, organic carbon, and total nitrogen were positively correlated with the soil C/N ratio (P grass land > forest land > garden. Multiple regression analysis showed that geographical and climatic factors, and soil physical and chemical properties could independently explain 26.8%and 55.4% of the spatial features of soil C/N ratio, while human activities could independently explain 5.4% of the spatial features only. The spatial distribution of soil C/N ratio in the study has important reference value for managing soil carbon and nitrogen, and for improving ecological function to similar regions.

Effects of canopy density on the functional group of soil macro fauna in Pinus massoniana plantations

In order to understand the effects of canopy density on the functional group characteristics of soil macrofauna in Pinus massoniana plantations, we divided the captured soil fauna into five types including xylophages, predators, saprophages, omnivores and fungal feeders. The results showed that 1) Saprozoic feeders had the highest percentage of total individuals, and the omnivores and xylophages occupied higher percentages of total taxa. 2) The individual and group number of the predators, and the group number of xylophages did not change significantly under 0.5-0.6 and then decreased significantly under 0.6-0.9 canopy density. 3) With the increasing canopy density, the individual an dgroup number of predators in litter layer decreased significantly, the saprozoic individual number in 5-10 cm soil layer represented irregular trends. The individual number of xylophage increased with the depth of soil, and the group number in litter layer, the individual and group number in 5-10 cm soil layer decreased significantly. 4) Pielou evenness of xylophage had no significant changes with the canopy density, all the other diversity index of xylophage and saprophage were various with the increasing canopy density. The predatory Simpson index was stable under 0.5-0.8, and then decreased significantly under 0.8-0.9 canopy density. 5) The CCA (canonical correlation analysis) indicated that soil bulk density and moisture content were the main environmental factors affecting functional groups of soil macro fauna. Moisture content greatly impacted on the number of saprophagous individuals. But xylophage and predators were mostly affected by soil bulk density, and the predatory Simpson index was mainly affected by soil pH value and total phosphorus. Our research indicated that the structure of soil macro faunal functional group under 0.7 canopy density was comparatively stable, which would facilitate the maintenance of soil fertility and ecological function in Pinus massoniana plantation.