As one of the key soil invertebrates, earthworms can greatly impact soil processes, and thus was named as “ecosystem engineer”. Earthworm activities such as feeding, digestion, excretion, and burrowing, facilitate the formation of various drilosphere in their guts or soils around, through which they alter the biological, chemical and physical processes of the ecosystem. Earthworms act as consumer, decomposer and modulator in ecosystem. The ecological functions of earthworm include: (1) effects on key soil ecosystem processes such as decomposition of soil organic matters and nutrient cycling; (2) effects on soil chemical and physical properties; and (3) interaction with plants, microorganisms and other animals. Earthworm activities and their functions in ecosystem are determined by various factors such as ecological groups of earthworms, population size, vegetation, parent materials of soil, climate, time scale, and history of soil utilization. The development of earthworm ecology was constrained by the complex feature of soil, the scarce knowledge of natural history and biogeography of earthworms, and the low efficiency of approaches in field manipulation of earthworm community. We suggest that new technologies such as the C and N isotope technique for nu-trient cycling and the image analysis approaches for soil micro-structure should be applied on earthworm ecological research in order to better understand the functions of earthworms.

Soil health is important for the sustainable development of terrestrial ecosystem. In this review, we summarizes the relationship between soil quality and soil microbial characteristics such as soil microbial community structure, soil microbial biomass and soil enzymatic activity in order to illustrate the function of soil microbial characteristics as bio-indicators of soil health. Many studies have showed that the soil nutrient is correlated with the quantity or the composition of bacteria, fungi and actinomycetes in soils. In general, higher ratio of soil bacteria indicates better soil quality and higher soil nutrient content. Soil microbial bio-mass is closely correlated with soil organic carbon, and the ratios of soil microbial biomass carbon to soil or-ganic carbon(C_mic : C_org) and microbial metabolic quotient (qCO2) reflect the use efficiency of soil organic C. The activity of soil enzymes are positively correlated with soil microbial biomass carbon and nitrogen. Therefore, soil microbial characteristics reflect the changes of soil quality and thus can be used as bio-indicators of soil health.

The springtails are widespread small to tiny arthropods in soil ecosystem. They play important roles in the circulation of soil materials, development of soil, formation of soil micro-structure, improvement of soil physical and chemical properties, and the maintenance of soil living community. The diversity, community structure, and species composition of springtails in the soil reflect the status of soil quality and con-tamination. The important roles of springtails in the soil ecosystem, their potential values in the ecological practices and the recent advances and prospects are introduced in the present paper.

As increasing attention has been paid to below-ground ecosystems in recent years, the impact of exotic plant invasions on soil ecosystems has emerged as a central issue in invasion ecology. In this paper, effects of exotic plant invasions on soil biota and soil nutrient cycling processes are reviewed, and the mechanisms that underlie these impacts are discussed. The available literature suggests that no consistent pattern exists on the impacts of exotic plant invasions on soil microbes, soil animals, soil carbon cycling and nitrogen cycling. The mechanisms underlying the impacts of exotic plant invasions are also complex and diverse. The discrepancies most likely arise from the differences between invasive and native plants in a variety of physiological and ecological traits, such as litter quality and quantity, root distribution, and phenology. Future studies are recommended to (a) compare the impacts across multiple scales and multiple ecosystems; (b) intensify mechanical studies of the impacts; (c) link the impacts on biodiversity and ecosystem processes; and (d) explore the mutualistic interactions between soil ecosystems and exotic plants.

Rice is one of the most important crops in the Ningxia region of China, and rice planting helps to maintain ecosystem balance and prevent land desertification. Soil microbial diversity provides basic functions for rice field soil ecosystems. To better understand bacterial diversity and community composition in Ningxia paddy soil, the total bacterial DNA was extracted from paddy soil collected from a typical rice field of Ningxia using the culture independent method. A 16S ribosomal DNA (16S rDNA) clone library of soil bacteria was constructed. The 16S rDNA fragments were analyzed by PCR-RFLP. Further sequencing and cluster analysis were conducted to elucidate the bacterial diversity. Over 23 kb DNA fragments were obtained from the paddy soil and 74 MspI restriction endonuclease types were detected by PCR-RFLP analysis. Sequence analysis revealed that 77.3% of clone sequences were similar to those of uncultured bacteria in the environment, while only 22.7% clone sequences were most closely related to those of cultured bacteria in GenBank, suggesting great potential for undeveloped bacterial resources was available in paddy fields. Our phylogenetic analysis found that the sequenced clones fell into 12 major lineages within the domain bacteria. Among them, members of the Proteobacteria were the dominant group, accounting for 37.8%, including α-Proteobacteria (13.5%), γ-Proteobacteria (12.2%), δ-Proteobacteria (6.8%) and β-Proteobacteria (5.4%), followed by Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi and Planctomycetes division with 16.2%, 12.2%, 10.8%, 10.8%, 8.1%, respectively. Firmicutes, Gemmatimonadetes, and Verrucomicrobia were less well represented. Our study revealed an extensive diversity of soil bacteria in a paddy field in Ningxia.

Soil microorganisms are important components of soil ecosystem and play central roles in biogeochemical cycling such as organic matter decomposition, mineral nutrient release, and energy transformation. Along with the intensive comprehension of the importance of biodiversity and the rapid development of methodology, more and more studies have focused on soil microbial diversity. This review introduces the current development of methodology and affecting factors of soil microbial diversity. We also discussed the directions of future research on soil microbial diversity.

Soil management techniques such as mulching and intercropping have important effects on soil quality, and soil microbes are sensitive indicators of soil quality. We investigated the effects of fertilizer treatments on the functional diversity of soil microbial communities in tea plantations using the Biolog technique. Six treatments were designed, and the change rates of AWCD (average well color development, slope) ranked as follows: caky fertilizer + intercropping with white clover>NPK fertilizer + straw mulching>caky fertilizer+PK fertilizer+straw mulching>caky fertilizer+PK fertilizer+tillage>NPK fertilizer+intercropping with white clover>NPK fertilizer+tillage, indicating that intercropping and organic matter (caky) fertilizer improved the abundance and diversity of soil microbes to a certain extent. Biodiversity indices showed that neither straw mulching nor intercropping with white clover influenced microorganism species composition, but decreased the evenness of microbial communities. Our results also showed that both carbohydrate and carboxylic acid played important roles in the differentiation of carbon sources.

Soil microbial diversity provides basic function of a soil ecosystem. In this study, the total DNA of microorganisms was extracted by an indirect method from a typical garden soil of Taihu region, Jiangsu Province. The 16S rDNAs of the extracted DNA were amplified using bacterial universal primers 27F and 1492R. PCR products were ligated into the pMD 18-T Vector and transformed into Escherichia coli DH5α to construct a 16S rDNA clone library of the soil microbes. A total of 173 clones from the library were screened and their 16S rDNA fragments were reamplified. The PCR products were digested by Rsa I and Hha I, re-spectively, and their fingerprints were analyzed. The results indicated that the library includes 63 Hha I and Rsa I restriction endonuclease types and the coverage (C value) of the clone library is 76.30%. The number of genotypes digested either by Hha I or Rsa I is only 40 and 27 although it has a high coverage. There were two main restriction types accounting for 16% and 12% of the total 16S rDNA clones, respectively. Phy-logenetic analysis suggests that the dominant bacteria in this garden soil belong to α-proteobacteria and γ-proteobacteria.

This paper introduces the species diversity and the functions of soil nematodes. Nematodes are ubiquitous with diverse feeding behaviors and life strategies. The diversity of feeding behaviors and some intrinsic properties result in the complex biotic interaction between soil nematodes and other soil biota, which greatly affects the ecosystem functions. However, the research on the species diversity of soil nematodes and their ecosystem functions is still inadequate. To understand the role of soil nematodes in the ecosystem requires: (1) the combination of laboratory microcosm study and field mesocosm experiments; and (2) the combination of biodiversity survey and functional analysis of different groups.

The ecological functions of soil fauna have attracted widespread interest from ecologists during the past two decades. A growing number of evidences show that the soil fauna interact with microorganisms and play important roles in regulating soil ecosystem processes and plant growth. This review addresses the issue of how bacterial- and fungal-feeding nematodes influence soil microorganisms, nitrogen mineralization and plant growth. Most studies suggest that bacterial- and fungal-feeding nematodes stimulated soil nitrogen mineralization and promoted plant growth. The mechanisms underlying these effects are the impact of nematode grazing on microorganisms and the release of nutrients from consumed microbial biomass. How-ever, these effects vary with different nematode species, microorganism species, plant species and C/N ratios of substrates, and are influenced by complex interactions between different trophic groups of nematodes as well as other soil fauna. Future studies should (1) enhance our understanding about the mechanistic basis of the interaction of nematodes, microorganisms and plants; (2) address more complex interactions between different trophic groups of nematodes and other soil fauna; (3) examine the ecological roles of soil nematodes at a longer temporal scale; (4) compare different ecosystems to understand the ecological roles of soil nematodes at a broader spatial scale; and (5) predict the responses and feedbacks of soil nematodes to atmospheric drivers of global changes.

In this paper, the effect of soil management practices and environmental factors on soil microbial diversity are reviewed and the methods for studying soil microbial diversity are briefly introduced. Soil microbial diversity includes microbial species diversity, genetic diversity and ecological diversity. Culturing techniques using a variety of culture media are used traditionally to analyze soil microbial communities, but only a small fraction of soil microbial community has been cultured and isolated. Recently several modern methods including Biolog analysis, phospholipid fatty acid analysis and nucleic acid-based analysis have been utilized internationally to study and characterize soil microbial diversity. Soil microbial diversity is affected by many factors including management practices. Application of pesticides usually causes declines in soil microbial diversity or changes in its structure and function. Organic manures are commonly reported to maintain soil microbial diversity and activities, but reports on the effects of inorganic fertilizers have been contradictory. Generally speaking, microbial diversity is higher and biomass is larger in agricultural soils cultivated with reduced tillage and crop rotation than in those soils cultivated with conservation tillage and monoculture. Soil microbial diversity may also be influenced by soil organic matter, vegetation, seasonal change, and usually suffer from stresses such as drought, overgrazing, and nutrient deficiencies.

Soil biodiversity has been one of the foci in the soil ecological research field. Soil biota can change the physical, chemical and biological characters of soil in different ways. In farmland ecosystems, soil organisms are main regulators in the decomposition, nutrient mineralization and other ecological processes of soil. Soil nematodes are the most abundant metazoan, which have various types of life-history and feeding habits, and play a key role in soil food web. This paper introduces the main factors influencing soil nematode diversity in farmland ecosystems, reviews the present situation in the nematode diversity research field and presents the research prospect of nematode diversity in the future. We propose to integrate the life strategy approach and trophic group classification to obtain a better understanding of nematode diversity and their functions, so as to use nematodes as effective bioindicators in farmland ecosystems.

In order to understand the distribution pattern of the resources of arbuscular mycorrhizal (AM) fungi in arid zones in northwestern China, we investigated AM fungal diversity in five vegetation types: desert, grassland, forest, meadow, and oasis farmland. Forty AM fungal species belonging to six genera were identified from the rhizospheres of 60 plant species. Of these fungi, 35 were identified to species and five were identified to genus. Glomus claroideum was the dominant species throughout the sampling area, but the occurrence and distribution pattern of AM fungi in the five vegetation types were quite different. Entrophospora was only observed in desert while Paraglomus was found in oasis farmland and desert, Archaeospora existed in grassland, desert and oasis farmland, and Scutellospora existed in meadow, forest and grassland. The biodiversity index in oasis farmland and meadow were higher than other vegetation types, indicating soil moisture may be the most important factor affecting the distribution of AM fungi in arid zones.

In this paper, the soil biodiversity and its functioning in ecosystem were briefly summarized, and the history and development of the discipline of soil biology were also reviewed. Meanwhile, I pointed out some issues on soil biology to be addressed for a few years to come. Due to the importance of soil biodiversity to the maintenance of ecosystem functions but inadequate study on soil biota in China, a series of articles on soil biota were collectively published in this issue of Biodiversity Science. The objectives of this issue were to enable the Chinese scientists to better understand the functions of soil biodiversity and to stimulate the interest of young scholars in the discipline of soil biology. The ultimate goal was to push forward the research and development of soil biology in China and to apply the knowledge and techniques of soil biology in the development of national economy.

In order to understand the relationship between soil arthropod community structure and floor litter at different successional stages of tropical forests, we surveyed the floor litter and the soil arthropods in a 23-year secondary forest, a 35-year secondary forest and a primary seasonal rainforest of Xishuangbanna, SW China in September 2001. Soil arthropods were extracted from the litter by Tullgren funnel method. The results showed that both the quantity and quality (N and C/N) of litter in the 35-year secondary forest were higher than those of the 23-year secondary forest and the seasonal rainforest. Acari and Collembola were dominant groups (> 80%), while ants, Coleoptera, Diptera, and Archaeognatha were common groups in the three forests. A higher individual density and relative individual density of soil arthropods were found in the 35-year secondary forest (10,067 ind./m2 and 22.72 ind./g dry litter) compared to the seasonal rainforest (5,654 ind./m2 and 18.44 ind./g dry litter) and 23-year secondary forest (2,881 ind./m2 and 5,818 ind./g dry litter). Pielou and Shannon-Wiener index of soil arthropod community were significantly higher in the 23-year secondary forest, while the richness (Margalef index) peaked in seasonal rainforest, and the domi-nance index (Simpson index) in 35-year secondary forest was the highest. The soil arthropod community composition was similar among the three forests. The individual density (ind./m2) of soil arthropods were positively correlated with floor litter mass in three forests, and they were correlated with the standing stock of N of the floor litter in 23-year secondary forest, and the standing stock of N of the floor woody detritus in seasonal rainforest. We conclude that the development of soil arthropod community in tropical forests is closely related to vegetation succession, and the soil arthropod community structure can be regulated through plant litter during the forest succession process, but other environmental effects including predator effect and human disturbance should not be ignored.

A preliminary study on the diversity of soil invertebrate communities was conducted at Yushan Hill, Changshu, Jiangsu Province. Twenty-six taxa of invertebrates were identified, belonging to 10 classes and five phyla, of which Acarina，Collembola and Nematoda were dominant, accounting for 88.2% of the total individuals. Vegetations at Yushan Hill were grouped into three categories: pine-broad-leaf mixed forest, tea garden and bamboo forest. Pine-broad-leaf mixed forest ranked the highest in taxon and individual numbers of invertebrates, H′ index, DG index and DIC index. The lowest was in the bamboo forest. Evenness (J) of invertebrates in the three categories showed a complex pattern of variation: the highest value was observed in tea garden and the lowest in bamboo forest. The invertebrate community in bamboo forest had the highest Simpson index　(C) compared with the other two forests. The results also showed that the similarity (q) of soil invertebrates among these three forests was moderate (q>0.5) in all communities. The numbers of groups in soil decrease rapidly with increase in depth of soil layer.

We have attempted to use the SRAP (sequence-related amplified polymorphism) markers, a new molecular technology, to study genetic diversity in soil microbes. We sampled rhizosphere soil microbes from 20 plant species and employed 22 SRAP primer combinations. A total of 237 scorable fragments were identified, of which 221 (93.2%) were polymorphic loci. The average percentage of polymorphic loci (PPL), polymorphism information content (PIC), allele haplotype (Ah), and expected heterozygosity (He) for each primer combination were 93.78%, 0.94, 18.05 and 0.92, respectively. Our results revealed rich genetic diversity in rhizosphere soil microbes and the high ability of SRAP to resolve samples based on their genetic basis. Differences in genetic distance for rice rhizosphere microbes between two locations, and that among four different developmental stages were both significant at 0.01 level, but the difference was not significant between two varieties. Shannon diversity indices indicated that the genetic diversity of rhizosphere soil microbes was lowest in rice and highest in lettuce. The rhizosphere soil microbes from 20 plant species could be clustered into three groups at the 0.454 (GD) level based on UPGMA, in which the first group was from rice, while the second group was from celery planted in plastic green house, and the third group was from 18 other plant species cultivated in dry lands. Our results suggest that SRAP is an efficient method for analyzing the genetic diversity in rhizosphere soil microbes.

In the search for mineral potassium-solubilizing bacterial strains with multiple activities that may be relevant for a beneficial plant-microbe interaction–potassium solubilization, indoleacetic acids (IAA) and siderophore production, a total of 23 heterotrophic eugenic strains were isolated from rhizospheric soil in Shandong Province using a medium with feldspar as the sole K source. All strains produced IAA or their derivatives, and 43.5% of the strains displayed a very high level of siderophores. Seventeen percent of the strains showed better growth on feldspar and effects on solubilization of K in liquid cultures, suggesting that they were a valuable pool for discovering plant growth-promoting bacteria. Two bacterial strains, AFM2 and AC2, exhibited greater K release efficiency than other isolates. Amplified rDNA restriction analysis (ARDRA) revealed that all isolates could be divided into 11 groups at the similarity level of 60%. Most strains exhibited a unique 16S rDNA restriction pattern even when strains were isolated from the same soil type or plant species. Strains AC2 and AHZ1 of group XI were highly related toBacillus mucilaginosus, strain AFM2 of group IV shared 99% sequence homology with Agrobacterium tumefaciens.

The objective of this study was to investigate soil nematode communities associated with three naturally-distributed plant species (Artemisia ordosica, Caragana korshinskii and Cynanchum Komarovii) in Mu Us sandy land in the Ordos Plateau, Inner Mongolia. Total abundance of nematodes was 6,098, mean individual abundance was 169 per 100 g dry soil, represented by 43 genera from 19 families. Acrobeles, Aphelenchus, Rotylenchus and Dorylaimus were the most dominant genera in bacterivores, fungivores, plant-parasites and predators-omnivores, respectively. No differences in the diversity, richness, evenness and the total abundances of soil nematode community were observed among three plant species (P > 0.05). Structure index was significantly (P < 0.05) different among three plant species whereas channel index and enrichment index were not. Plant species not only modified abundance of plant-feeding, omnivorous and predatory nematodes, but also percentage of each trophic group. Bacterivorous and fungivorous nematodes were affected most by the differences in plant species. Results presented here indicated that plant species modified nematode community structure in arid ecosystems.

To understand the response of soil nematode communities to vegetation restoration, we surveyed soil nema-todes in a wasteland (Wj), a natural broad-leaved forest (Cc), a conifer-broadleaved mixed forest (Clc), and a coniferous forest (Pm) in northern Fujian from September 2003 to August 2004. A total of 142,005 nematode individuals were collected, belonging to two classes, four orders, 10 families and 24 genera. The results indicated that the number of soil nematode varied significantly (P<0.01) in response to different restoration stages of vegetation, ranking Wj > Cc > Clc > Pm. Nematode numbers also fluctuated with season. Both genera number and individual density ranked spring > winter > autumn > summer. Richness and DG indices ranked Cc >Wj > Clc > Pm, while Shannon-Wiener index Wj >Cc > Clc > Pm. Root biomass and soil physical and chemical characters were different at the four restoration stages. Nematode numbers were positively correlated with root biomass, soil water, soil porosity, organic matter, total N, and available P. We conclude that the dynamics of nematodes are an important biological indicator for vegetation restoration.

In order to evaluate the process of ecological restoration in Dongting Lake region, we surveyed the community structure and diversity of soil animals in October 2005. A total of 8,484 individuals, belonging to five phyla and 11 classes, were obtained from three typical habitat types, i.e., wetland restored from farm-land, farmland, and original wetland. Twenty-six species were obtained from wetland restored from farmland, of which Nematode and Acarina accounted for 66.97%, while 28 species were collected from farmland, of which Nematode and Araneae occupied 61.79%. However, only 13 species were found in the original wet-land, of which Gastropoda was the absolutely dominant group, accounting for 79.89%. The results analyzed using diversity indices (H′, E, C, D, C_j) indicated that: (1) Complexity index (C_j ) is manifested better than H' in representing the complexity and the diversity of animal communities; (2) Community diversity index (H′), had a closer relationship with evenness index (E) (P<0.05); (3) Wetland restored from farmland and the farmland were richer in soil animal taxa than the original wetland (P<0.01). In terms of soil animal individu-als, there were far more in the farmland than in the original wetland (P<0.01), whereas no significant differ-ence (P>0.05) was found between the wetland restored from farmland and in the original wetland. The results indicated that the ecological restoration process in Dongting Lake region was fairly slow and inefficient.

Much attention has been paid to the studies of aboveground biological processes in terrestrial ecosystems. Mutual feedbacks between above- and belowground processes have recently become a central interest of ecologists. Soil biota, the most active portion in belowground systems, play crucial roles in processes such as nutrient cycling and energy transformation in terrestrial ecosystems. Soil biota, driven by resource heterogeneity, nutrient availability, and abiotic conditions, could impose direct or indirect and positive or negative feedbacks on aboveground biology by altering rates of nutrient mineralization and the spatial distribution of nutrient availability, rhizospheric hormones and the soil environment. We analyze spatial and temporal variations in soil functional diversity, soil foodweb structure, and the above- and belowground interactions across a wide range of terrestrial ecosystems. These analyses will improve our understanding of belowground ecological processes, and inform the management of ecosystem stability and biodiversity conservation in response to global changes.

In order to characterize arbuscular mycorrhizal (AM) fungal resources in the rhizosphere of tree-peony (Paeonia suffruticosa), we collected soil and root samples, and isolated 35 species in five genera of AM fungi from the main tree-peony cultivation areas, Heze and Luoyang of China. Glomus showed the highest relative abundance, followed by Acaulospora. There were differences in species richness, spore density and species diversity of AM fungi between the two regions. Spore density in the rhizospheric soil of tree-peony grown in Heze Zhaolou Tree-peony Garden was highest, while in soil of the Luoyang Cuoli Tree-peony Nursery it was lowest. The species richness in Heze Zhaolou Tree-peony Garden was lowest. Species diversity in the rhizospheric soil of tree-peony grown in Heze Tree-peony Nursery was significantly higher than in other sam-pling sites. Glomus geosporum was the dominant species in Heze Zhaolou Tree-peony Garden and Luoyang Wangcheng Garden, while G. constrictum was the dominant species in Heze Tree-peony Nursery, Heze Zhaolou Tree-peony Garden, Luoyang Tuqiao Seedling Nursery and Luoyang Tree-peony Garden. The results suggest that AM fungal diversity is rich in the main tree-peony cultivation areas.

To find out the relationship between the abundance and diversity of soil animals and soil characteristics in industrial zones, we investigated soil animals in litters of different functional zones in Baoshan Steel Plant. A total of 52,070 soil animals were collected using Tullgren funnel, belonging to three phyla, 10 classes and 19 orders. The dominant groups were Arcarina and Collembola, accounting for 90.60% of the total in terms of individual numbers. The common groups were Lepidoptera and Oligochaeta plesiopora. The results indicated that different functional zones had similar dominant groups but different common groups. Soil animal reduced along a gradient of production zone, transition zone, office zone. Similarity index showed that the five indices were different in different functional zones. The density-group index (DG) showed the following pattern: production zone > transition zone >office zone. The seasonal change of the total number of soil animals were ranked as: winter>autumn>summer>spring, while the number of soil animal groups were ranked as: winter=autumn>summer=spring. The pH, TOC, TN and TP of litters in different functional zones were different, which might have impacts on the distribution of soil animals.

The diversity , component and dist ribution of bacterial hysiological groups and microbial flora in eight soil types of the Tiantai Mountain were studied. The results indicated that the amount of bacteria , fungi and actinomyces is the highest in the soil of Pinus taiwanensis forest , bamboo forest , Rhododendron fortunei forest , and the smallest in Cryptomeria fort une forest soil , which is co-related to the content s of organic matter , net nit rogen , net phosphorus and the litter in soil. The ratios of the bacteria , fungi , actinomyces to the total of microorganisms are as follows : bacteria amount is the most common , actinomyces amount is the next , and fungi is the smallest . Different dist ribution patterns of bacteria physiological groups are recognized. The ratios of aerobic cellulose-decomposing bacteria , aerobic nitrogen-fixing bacteria , ammoniation bacteria , organic phosphorus-decomposing bacteria ,inorganic phosphorus-decomposing bacteria to the net amount of soil bacteria physiological groups are the dominant bacteria groups. The ratios of anti-nitrify bacteria and anti-vulcanization bacteria to the soil bacteria physiological groups net amount are the next in eight soil types of the Tiantai Mountain. The Simpson index and Shannon-Wiener index of the bacteria physiological groups are smaller in soil of the Heptacodium miconioides forest , bamboo forest , Rhododendron fortunei forest and Chamaecyparis pisifera forest , that of the bacteria physiological groups are relatively larger in the soil of Cryptomeria fortune forest , tea plantatio forest ,Pseudolarix amabilis forest , and Pinus taiwanensis forest .

Salix psammophila is an excellent sand-fixation plant that can not only thrive in arid desert environment, but also can fix sand and promote desert management by maintaining the balance and stability of desert ecosystems. To understand the species diversity and ecological distribution of AM fungi associated with S. psammophila, we collected soil samples (0-50 cm deep) from the rhizosphere of S. psammophila at three different sites (Heichengzi, Zhenglanqi and Yuanshangdu) in Inner Mongolia in May, August and October 2009. A total of 37 AM fungal species belonging to four genera were isolated. Of these, 23 species belong to Glomus, 10 to Acaulospora, 3 to Scutellospora, and 1 to Gigaspora. Glomus reticulatum was the dominant species at all three sites, Scutellospora was found only in Heichengzi and Zhenglanqi, and Gigaspora decipiens only in Zhenglanqi. Generally, species richness, evenness, Shannon diversity and Simpson diversity indices showed the following trend across sites: Zhenglanqi > Heichengzi > Yuanshangdu. Species diversity of AM fungi in Yuanshangdu was significantly lower than that at the other sites. Species richness and Shannon diversity index of AM fungi were higher in August and October than in May. Species richness, evenness, and diversity indices first increased and then decreased with increasing levels of soil available N. Our results suggest that the subtle complexities present in the symbiotic relationship between S. psammophila and AM fungi in desert ecosystems.

The effects of chemical fertilizer on nematode community composition and diversity were investigated in a field throughout the corn-growing season in the Black Soil Region , Northeast China. 14 families and 16 genera were observed. Cephalobidae , Rhabditidae , A phelenchus , and Tylenchus were found to be the dominant families/ genera. Significant differences were found between sampling dates ( p < 0. 01) and between treatments ( p < 0. 01) in the total number of nematodes during the study period. Ecological indices of diversity , evenness , richness and dominance and the dynamics of the nematode community were compared between the t reatment and the cont rol plot . Shannon index and richness were found to be more sensitive indicators than other ecological indices for assessing the response of nematode communities to the application of chemical fertilizer.

In 2008, an ice storm caused extensive damage to the montane evergreen broadleaved forest in Chebaling National Nature Reserve, Guangdong Province, China. To assess the response of soil arthropod diversity and distribution to a gradient of canopy openness following the ice storm, 17 plots, each 400 m², were selected within a 2-ha permanent plot. Canopy openness was estimated with hemispherical photography in each plot. We sampled the litter layer and two soil layers (0-10 cm and 10-20 cm) to measure arthropod diversity and soil properties. We used two-way cluster analysis to group sites based on arthropod abundance in the litter layer. We also utilized canonical correspondence analysis to reveal relationships between soil arthropods in the 0-10 cm layer and four environmental variables, i.e., canopy openness (CO), soil organic matter (SOM), electric conductivity (EC), and natural moisture content (NMC). Results showed that abundance, richness and diversity of arthropod communities decreased with depth. A negative association was found between canopy openness and the number of arthropod groups in the litter layer; some arthropod taxa, such as the Oribatida, Prostigmata and Mesostigmata, were found in a wide range of light conditions, whereas the Hymenoptera, Symphyla, Pseudoscorpiones and Lepidoptera larvae may be photophobic. The distribution of arthropods in the 0-10 cm soil layer was closely related to CO, SOM, EC, and NMC on the first and second canonical axes. Hence, a series of changes in canopy structure and soil factors following the ice storm appeared to have affected the composition and distribution of soil arthropod communities. Findings from the present study also indicated that arthropod communities could serve as indicators to characterize the ecosystems they inhabit, thus being particularly suitable for monitoring forest regeneration and successional dynamics following ice storms.

Arbuscular mycorrhizal (AM) fungi are obligate symbiotic endophytes which have not been cultured in vitro. The life cycle of AM fungi can be completed only when the mycorrhiza forms between the fungi and plant roots. There are more than 200 genetically-diverse species of AM fungi belonging to Glomeromycota in the Kingdom Fungi. It is well documented that surprisingly high genetic variability exists between and within species, and even in a single spore of AM fungi. We summarize recent advances in the study of AM fungal diversity, discuss some related problems, and introduce present and future research trends.

To elucidate the diversity of arbuscular mycorrhizal (AM) fungi associated with the common desert plant Artemisia ordosica, we sampled, in April 2007, the following four representative sites in the Mu Us Sandland and Tengger Desert regions: Yulin Psammophyte Garden (Yulin), Yanchi Desert Shrub Garden (Yanchi), Ordos Sandland Ecological Research Station (Research Station), and Shapotou Desert Research and Experiment Station (Shapotou). We collected soil samples from the rhizosphere ofA. ordosica and divided them into five depth intervals, each 10 cm, to 50 cm depth. A total of 28 AM fungal species from four genera were isolated. Of these, 16 species belonged to Glomus, 7 to Acaulospora, 4 to Scutellospora and 1 toDiversispora. Glomus mosseae was the dominant species. Acaulospora bireticulata andG. reticulatum were common species (>25% frequency of occurence) andG. constrictum was rare species (≤25% frequency of occurence) at the four sampling sites.Glomus geosporum was found only in Yanchi, G. melanosporum only in Yulin and A. mellea, A. lacunosa, G. coremioides and G. magnicaule occurred only in Research Station. Richness of AM species was highest in Yanchi and Research Station and spore density was highest in Yulin. Species richness and spore density were the lowest in Shapotou. Generally, spore density, isolation frequency, relative abundance and importance value followed the trend Glomus > Acaulospora > Paraglomus > Diversispora. Our results are the first to assess the considerable diversity of arbuscular mycorrhizal fungi found in association with Artemisia ordosica. Further research should concentrate on understanding the dynamics of these relationships.

In order to provide scientific evidence of soil health for city planning, the diversity and composition of the soil animal community of the site of World Exposition Shanghai China 2010 were investigated. A total of 10,765 soil animal individuals belonging to 23 groups of soil animals were collected, of which Acarina was the dominant group of soil meso- and micro-fauna, and Collembola was the secondary one. As for soil macrofauna, Oligochaeta was the dominant group, while Isopoda, Coleoptera, and Gastropoda were the secondary ones. The results indicated that soil animals were abundant at this site. The soil animals reduced along with the increasing soil depth, and their distribution varied significantly at different sampling sites.

The seasonal and vertical distribution of soil nematode communities under three contrasting land uses, i.e., cropland, abandoned cropland and woodland, was conducted in an aquic brown soil. The results showed that land-use types affected the spatio-temporal distribution of soil nematodes and their dominant genera, and different dominant genera showed different responses to land uses. In the abandoned cropland and woodland, most dominant genera were present in the 0–20 cm layers and Chiloplacus was mainly distributed in the 5–30 cm layers, while in the cropland Pratylenchus exhibited an even distribution from the 0–5 to the 40–50 cm depths. Soil environmental parameters under different land uses could influence soil nematodes; soil porosity, total organic C, total N and the C/N ratio were found to positively influence the abundance of some dominant genera in the present study. The faunal profiles revealed that the environmental stability and the homeostasis of the abandoned cropland and woodland lead to higher levels of community structure and the soil food web tend to succeed to maturity. Nematode faunal analyses were found to be a useful method for interpreting the stress or/and nutrient conditions under different land uses.

To better understand the role that fertilization systems play in soil fertility buildup and evolution, we employed denaturing gradient gel electrophoresis (DGGE) and restriction fragment length polymorphism (RFLP) to determine the influence of different fertilization treatments on archaeal community structure in calcareous purplish paddy soil under rice/wheat rotations. The eight fertilization treatments were as follows: manure only (M), nitrogen plus manure (NM), nitrogen and phosphorus plus manure (NPM), nitrogen, phosphorus and potassium plus manure (NPKM), without fertilization (CK), mineral nitrogen (N), nitrogen-phosphorus (NP) and nitrogen, and phosphorus and potassium (NPK). Our results showed that long-term fertilization significantly affected soil archaeal community structure; the richness and diversity of archaeal community under NM, NP and NPKM were lower than those under the other fertilization treatments (M, NPM, CK, N, and NPK). Based on the DGGE patterns, two soil DNA samples isolated from the NPK-amended soil were used for RFLP analysis of archaea. Phylogenetic analyses showed that archaea in the calcareous purplish paddy soil was highly diverse, and the sequences were closely related to those archaeal sequences isolated from various soils and water environment. Cluster analysis of the DGGE profiles showed that archaeal communities under the eight fertilization treatments clustered into three groups. In soil from paddies currently under rice cultivation, the archaeal communities in the soil amended with M and NPK grouped into the first cluster, while NP was in the second group, and NPKM, NM, CK, N and NPM were in the third. In the soil with wheat cultivation, NP-treated archaeal communities clustered into a cluster, NPKM and M were in the second cluster, and N, NPK, NM, NPM and CK soil communities comprised the third cluster. The cluster analysis showed that crop type impacts the community structure of soil archaea.

Soil biota is an important gene library and forms a major part of global biodiversity. Soil biota drive the cycling of soil C and N biogeochemistry and influence trace gases metabolism. Soil microorganisms exercise direct effects on trace gases metabolism. Fungi, methanogens, CH₄-oxidizing bacteria, nitrifiers, and denitrifiers are the key types of communities regulating trace gases metabolism. Fungi often dominate degradation activities in litter due to their large individual body and strong enzyme chemical degradation abilities. “Oxic-anoxic” interfaces are active habitats for microorganisms and easily influence trace gases metabolism. “Organic-inorganic” layers, the rhizosphere of hydrophytes, and soil faunal intestines are the typical interfaces for trace gases metabolism. Soil fauna are pioneers for litter degradation and show indirect effects on trace gases metabolism, and these effects are very important. Arthropods (e.g.termites) and annelid (e.g.earthworms) metabolise CH₄ and N₂O, respectively. Since the soil ecosystem is complicated, it is necessary to develop an integrated technique comprising microbiology, stable isotope and molecular biology for studying soil biodiversity and its effects on trace gases metabolism. Research on soil biodiversity and its relationship to trace gases metabolism urgently needs to be developed in China.

Soil biodiversity is an ignored study field , a lot of researches should be conducted urgently , which include : (1) field investigation of soil biodiversity ( the types , composition , distribution and data base of soil organisms) ; (2) study on functions and physio2ecological processes ; (3) the loss mechanism and restoration of soil biodiversity ; (4) study on the conservation and exploitation of soil biodiversity. Moreover , promising for it is utilization sustainable of the resource of living organisms in soils including edible animals , natural enemy organisms , rhizosphere microbes , biofertilizers and indicator organisms for environment pollution.

We used generic number, individual density, biodiversity, and functional group index to analyze the effect of mowing practice on soil nematode community in alkalinized grasslands of Leymus chinensis in Songnen Plain, Northeast China. A total of 8,335 soil nematode individuals were collected, belonging to two classes, seven orders, 23 families, and 40 genera. The results indicated that the generic number and individual density of soil nematodes were significantly lower in the land under mowing practice (MP) treatment than that under fencing enclosure (FE) treatment, whereas the diversity index showed no significant difference between the two treatments. The results also suggested that PPI/MI was sensitive to mowing practice, which changed the composition of functional groups of soil nematodes, especially that of free-living soil nematodes.

Sphaerophysa salsula is a highly nutritive and drought-tolerant perennial grass distributed in mid-Asia and northwestern China. This legume plant is highly prized for the revegetation of drought and high alkali soils. Our objective was to better understand the diversity and phylogeny of rhizobia collected from nodules of Sphaerophsa salsula in different regions of northwestern China. We estimated genetic diversity using 16S rDNA PCR-RFLP and 16S rDNA sequencing. Nine genotypes were tested from 57 strains. 16S rDNA sequencing revealed that these rhizobial strains belonged to the following genera: Mesorhizobium, Rhizobium, Sinorhizobium, Agrobacterium, Phyllobacterium and Shinella kummerowiae. The Jaccard similarity coefficient of the strains from Yinchuan was low while the strains isolated from Minle and Linze had rich diversity, with Simpson indices of 0.826 and 0.710, respectively, and Shannon-Wiener indices of 1.831 and 1.530, respectively. This study provides basic information for the phylogeny of rhizobia in northwestern China.