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.

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.

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.

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 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.

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.

In order to study the effect of plant community composition on soil microbial communities in a typical Inner Mongolian grassland, the abundance and community structure of bacteria and fungi in bulk soils under different plant functional groups and in soils from the rhizosphere of different grass species were analyzed using real-time PCR and automated ribosomal intergenic spacer analysis (ARISA) under plant functional group removal treatments. Our results indicated that changes in plant functional group affect bacterial abundance, but not fungal abundance or bacterial/fungal community structure in bulk soil. The abundance of bacteria and fungi in the rhizosphere soil varied with plant species. Cluster analysis revealed that community structure of bacteria and fungi also varied among plant species in the rhizosphere soil but not in the bulk soil. which was more evident for bacteria. Our results point to the ways in which plant species can influence soil microbial and fungal communities through the action of their roots.

Ectomycorrhiza (ECM) are symbionts formed between soil fungi and plant root systems, in which the fungus exchanges soil-derived nutrients for carbohydrates obtained from the host plant. As an important component of terrestrial ecosystems, ECM fungi can play an essential role in biodiversity maintenance and plant community succession. Understanding the distribution pattern and maintenance of ECM fungal diversity is therefore critical to the study of biodiversity and ecosystem functioning. An analysis of results of recent research indicates that ECM fungal diversity increases with increasing latitude, i.e. from tropical to subtropical and temperate regions. The role of dispersal in ECM fungal distribution is dependent on spatial scale. Thus, it has been found to be weak across global and local scales, but strong at regional and small scales. At the local scale, its influence has also been shown to be host-dominant dependent; thus, it is important in host non-dominant ecosystems, but not in host dominant ecosystems. Selection by plant, animal, microbe and abiotic factors can also affect the distribution pattern of ECM fungi, according to studies of temperate ecosystems. In contrast, studies of tropical ecosystems indicate that selection on ECM fungal distribution can be either strong or weak. ECM fungal diversity is also influenced by plant diversity and productivity. The plant diversity hypothesis at host genus-level fits well with ECM fungal diversity in temperate, subtropical and tropical forest ecosystems; in contrast, the productivity diversity hypothesis is only supported by some studies in temperate forest ecosystems. We propose that future studies should focus on the distribution pattern, maintenance mechanism and ecosystem function of ECM fungal diversity at a global scale, taking account of scenarios of global climate change.

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.

To determine the diversity of arbuscular mycorrhizal (AM) fungi in the rhizosphere of tea plant (Camellia sinensis) in Laoshan region, Shandong Province, we selected and sampled 12 representative tea gardens. Soil samples were collected from these gardens in September 2007. Spores of AM fungi were identified to reveal the species richness, frequency, spore density, relative abundance, importance value and Shannon-Wiener indices of AM fungi. Species diversity and composition of AM fungal community were also compared among the 12 tea gardens. A total of 22 species belonging to three genera were identified according to the morphological characteristics of the spores isolated from soil samples collected using wet-sieving techniques. The relative abundance of the genus Acaulosporawas the highest, followed by Glomus. Soil samples from Xiaowang Village Tea Garden showed the highest spore density, while Gaojia Village soils were the lowest. Species richness in soil samples from Changjiacun Village and Sangyuan Village Tea Garden was significantly higher than that in other tea gardens. Species diversity was highest in the Changjiacun Village Tea Garden. Acaulospora laeviswas the dominant species in Beilao Tea Garden, Wanglijiang Tea Garden, Yingshanchun Tea Garden, Wanlijiang Organic Tea Garden, Changjia Village, and Sangyuan Village Tea Garden, while Acaulospora undulata was the most common species in Gaojiacun Village and Wanlaike Tea Garden. Glomus occultum occurred most frequently in Yingshanchun Tea Garden, Xiaowang Village and Wanlaike Tea Garden. Relationships between environmental factors and AM fungi spore density in the Laoshan Tea region were determined using Canonical Correspondence Analysis, and their relative degree of impact on density was as follows: available phosphorus content>soil organic matter content>tree age>soil available nitrogen content>soil pH>soil available potassium content.

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.

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.

In order to understand the effects of seasonal freeze-thaw on the structure of soil macro-faunal community, we conducted a field experiment in three representative fir (Abies faxoniana) forests at different elevations in the subalpine/alpine forests of western Sichuan. The composition, abundance, and diversity of soil macro-faunal community were investigated in winter (including onset of soil freezing period, soil frozen period, and soil thawing period) and growing season of vegetation from November 2008 to October 2009. A total of 10,763 individuals were collected and, according to preliminary identification, they belonged to 91 families. There were obvious differences in soil macro-faunal community structure between winter and growing season. The dominant groups in winter consisted of Hesperinidae and Sciaridae, while the ordinary groups consisted of Tipulidae, Scydmaenidae and Ceratopogonidae. However, the dominant groups in growing season consisted of Formicidae, Staphylinidae, Hesperinidae and Spirostreptida, and the ordinary groups consisted of Lithobiomorpha, Projapygidae and Muscidae. Moreover, individual density, number of taxonomic groups, and Shannon-Wiener index of soil macro-faunal community tended to decrease and then increase to a distinct peak in the soil thawing period as seasonal freeze-thaw proceeded in winter. In addition, saprozoic species dominated the functional groups in winter, and the proportion of predatory and phytophagous soil macro-faunal species increased in late soil thawing (April 25) and early growing season (May 25). Our results suggest that seasonal freeze-thaw and freezing events significantly influence the structure of soil faunal community, and that changes in the soil faunal community during the transitional period between late soil thawing and the early growing season may have important influences on ecological processes.

In order to understand the diversity of cultivable rhizobacteria associated with Dongxiang wild rice at different growth stages and to discover new species and strains of plant growth-promoting rhizobacteria (PGPR), we isolated 118 bacteria strains with different colony morphology using the dilution plate counting method and tested their plant growth promoting activities (PGPA) in May, August and November 2009. Phylogenetic analysis based on partial 16S rRNA sequences indicated that 118 strains clustered into 11 genera, and the dominant bacteria genera were Bacillus, Pantoea and Sphingomonas. The rhizobacteria displayed a high diversity with Shannon-Wiener indices of 2.037-2.741. PGPA analyses indicated that most strains displayed PGPR effects, including nitrogen-fixation, phosphorus-solubilization, IAA-production and siderophore-secretion, and that the dominant PGPR was Pantoea. Additionally, we found that the total amount and PGPA of cultivable rhizobacteria began to increase gradually at seedling stage of Dongxiang wild rice, and reached its peak at heading stage, then decreased at grain filling stage. Our results show that the diversity of bacterial communities in the rhizosphere soil of Dongxiang wild rice is abundant, and that the rich rhizobacteria may be a fascinating PGPR reservoir.

Soil fauna were very important for the ecological reconstruction of mine tailings. We investigated community characteristics of soil fauna at two sites, including reclamated copper-mine-tailings (RCMT) and suburb forest land of reclamated copper-mine-tailings (SFL) in Tongling City to test and illustrate the value of soil fauna for mitigating the impacts of heavy metal pollution. In the spring of 2011, we established four transects (150 m) at the two sites and collected soil samples of macro-, meso- and micro- soil fauna from four depths (0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm) at 13 30 cm× 30 cm sampling quadrats. Our results showed that at RCMT, the Acarina, Collembola and Nematoda were dominant groups; the Formicidae, Coleoptera larvae, Oligochaeta, Diptera larvae and Diplura were frequent groups; and the additional 16 groups were less commonly encountered. While at SFL the Collembola and Acarina were dominant groups and the Nematoda and Oligochaeta were frequent groups. Overall abundance of soil fauna at RCMT were significantly less than that of SFL (F=20.65, P<0.01), and number of faunal groups were lower at RCMT (F=5.88, P<0.05). We did not find a significant difference between the density of macro-soil fauna at RCMT and SFL, but found that the density of meso- and micro- soil fauna at RCMT was significantly lower than that of SFL (F=29.99, P<0.01). The Shannon-Wiener diversity index (H) at RCMT was higher than that of SFL (F=24.06, P<0.01), but DG diversity index was lower at RCMT compared to SFL (F=4.75, P<0.05). There was evident surface aggregation of soil fauna at RCMT, especially in the differences between the first layer and the other layers of the soil profile (F_ind.=17.80, F_gro.=33.33, P<0.01). Redundancy analysis indicated that soil macro-, dry-type, wet-type meso- and micro-fauna at different habitats were differentially affected by various environmental factors. At reclaimed land with higher copper concentrations, we found a higher greater number of Formicidae and Coleoptera and lower numbers of Collembola and Acarina adults. Our study suggests that the key of soil fauna recovery at reclaimed lands is to reduce the content of Cu and improve the microhabitat conditions.

Litter decomposition is an important ecosystem function, and is an indispensable process for carbon and nutrient cycling. Litter decomposition is influenced by many factors, especially soil microbial communities, which are subject to their corresponding plant communities. It is necessary to study changes in soil microbial communities during litter decomposition and how these changes respond to plant diversity in corresponding forest communities to understand the mechanisms of decomposition. In the present study, we investigated these changes and responses using a litter bag method. Our results showed: (1) After 183 days of litter bag placement, microbial diversity decreased, and there was a negative correlation between plant species diversity and microbial diversity; (2) Soil microbial communities varied before and after the placement of plant litter bags. In particular the PLFAs of fungi and bacteria after the placement of litter bags were much higher than those before the placement of litter bags; (3) Topography was the most important factor correlated with the soil microbial community, and explained 29.55% of the variation of microbial communities. In contrast, litter quality and plant diversity explained 15.39% and 8.45%, respectively, and the interaction of the three factors explained 2.97% of the variation of the microbial communities. In conclusion, we find plant diversity plays a less important role than topography in determining soil microbial diversity, and litter quality influences soil microbial communities during litter decomposition.

Artificial plantations were set up by irrigating saline ground water (salt content 4～5 g/ L ) in extremely arid areas in the center of Taklimakan Desert . Soil microorganisms were detected in the drift sand dunes and afforestation plots in March and J une 1998. The result showed that : 1) after the establishment of artificial vegetation , the quantity of microorganisms increased greatly with ages ; 2) soil microbial taxa varied with plant species in the plots of same age ; 3) bacteria were predominant , accounting for 90 % of the total , actinomyces the next and fungi the least ; and 4) there are more microorganisms in the topsoil (0～10 cm deep) of afforested sand dunes than in the subsoil layers (10～50 cm deep) . The changes in quantities of soil microorganisms showed that the drift sand was developing into more fertilized soil.

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.

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 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 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.

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.

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.

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.

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.

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.

The properties of red soil may change over time when paddy fields are developed on what was previously dry land. The effect of rice cultivation duration on soil invertebrates is unknown. Five chronosequences of rice cultivation (1, 10, 20, 50 and 100 years) were selected to investigate the temporal changes of soil microbiological properties and nematode assemblages. The results showed that soil microbial properties (microbial biomass C, microbial biomass N, basal respiration), nutrient availability (mineral N and P), nematode abundance and richness of nematode genera generally increased with the duration of rice cultivation. Notably, most soil measurements peaked after 50 years of cultivation (P<0.05) and decreased slightly after 100 years. As the period of rice cultivation increased, the proportion of nematode herbivores rose significantly (P< 0.05), while that of predators/omnivores slightly declined. Nematode Channel Ratio (NCR) also increased with cultivation duration (P< 0.05), indicating that the bacterial energy channel was more dominant in old rice fields when compared to those cultivated for a shorter period. Other ecological indices of nematode assemblage such as maturity index and structure index, did not reveal consistent trends with an increased period of rice cultivation. In summary, a change in land use from dry land to paddy fields promotes soil microbial properties and nematode assemblages in the first few decades, which then become stable after 50 years of cultivation.

The maintenance of biodiversity of organisms, especially microbes in the soil, plays a key role for a healthy and sustainable agroecosystem. Agricultural activities including farming systemsaffect significantly the structure and ecological functions of soil-borne plant-associated microorganisms. As a new biotic component of the ecosystem, released genetically engineered crops initiate a change in the biotic community, the health and the stability of an agricultural ecosystem. This paper focuses on the behavior of gene products released from the roots of transgenic pest and disease-resistant crops (TPDRC) and the decomposition of TPDRC residue, and their effects on various organisms in the rhizosphere and surrounding crop residues in the soil. It is concluded that gene expression products have a long-term effect and lead to complex changes. It is suggested that a long-term study on ecological impacts of various released TPDRC is necessary. The emphasis should be focused on the following three aspects: (1) behavior of various products from different transgenic plants and their biotic activity in agroecosystems; (2) influence of transgenic plants on community composition of soil borne microorganisms and (3) influence of various isolated and purified gene expression products on microorganism functional groups in container culture conditions.

Arbuscular mycorrhizal (AM) fungi in the rhizosphere of five dominant plants Tamari xchinensis , Phragmites communis , Suaeda glauca , Ael uropuslit toralis var. sinensis and Cirsium setosum grown in saline-alkaline soil of the Yellow River Delta were investigated on fixed sample sites from March 2000 to February 2001. AM fungi in the rhizosphere of the five plants were isolated. The result indicated that the diversity of AM fungi in saline-alkaline soil was quite low , especially in winter. Species richness and spore density were decreased by 18.0 % and 61.6 % , respectively , relative to those in summer. Differences were also observed in the dist ribution of AM fungi in different layers of soil.

Cold-adapted bacteria and archaea are widely distributed in cold environments on Earth, such as permafrost, cold soils and deserts, glaciers, lakes, sea ice in the Arctic, Antarctic and high mountains, as well as the deep sea, ice caves and the atmospheric stratosphere etc. Cold-adapted organisms inhabiting these environments exhibit rich diversity. Studies on the biogeography of psychrophiles will enable us to understand their biodiversity, distribution and origins. Due to long-term living in cold regions, cold-adapted bacteria and archeae have developed specific physiological mechanisms of adaptation to cold environments. These mechanisms include: regulating the fluidity of the cytoplasmic membrane through adjusting the composition of membrane lipids; achieving low-temperature protection through compatibility solute, antifreeze proteins, ice-binding proteins, ice-nucleation proteins and anti-nucleating proteins; production of heat-shock and cold- shock proteins, cold acclimation protein and DEAD-box RNA helicase at low temperatures; production of cold-active enzymes; increasing energy generation and conservation. With the rapid development of sequencing technology, various omics-based approaches have been used to reveal cold-adaptive mechanisms of psychrophiles at the genomic level.

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 .

We examined the dynamics and community structure of soil mesomicroarthropods during litter decomposition in tropical rain forests of Xishuangbanna, SW China between May, 2000 and April, 2001.? The experiment was carried out in three plots of tropical seasonal rain forest located within a distance of 15 km. Mixed-species litterbags were constructed and placed in the field for one year. Soil meso-microarthropods were extracted from the litterbags by the Tullgren method each month during litter decomposition. The densities of soil meso-microarthropod groups and individuals were calculated per gram of dry litter (relative density). The data showed that Collembola and Acari were the most abundant groups of arthropods in the tropical seasonal rain forests (above 30%). Diversity indices, numbers of groups and number of individuals of soil meso-microarthropod were all higher in the middle stage of decomposition than in the early and end stages of decomposition. Variation of soil mesomicroarthropod communities, including abundance of some groups, was correlated with litter quantity and quality. Relative density of soil meso-microarthropod reflects the dynamic relationship between litter quality and number of groups and individuals of soil meso-microarthropods during the decomposition process. The differences of diversity and abundance of soil meso-microarthropods among three different plots were higher in the end stage of decomposition than ?in the early stage of decomposition, but litter weight loss did not differ among the three different study site plots.

An investigation on weed species biodiversity and host plants of vesicular arbuscular mycorrhiza fungi (VAMF) within weed communities in new developed f ruit gardens was conducted. Phosphorus content in various weed rhizospheric soils was analysed. There were 96 species belonging to 27 families in the weed community ,among which 39 species were tested to identify VAMF colonies. It was found that all the species tested were colonized by VAMF , but the percentage of colonization and the colonizing intensity were very different among the families and species. Correlation analyses showed that no significant correlation exists between phosphorus content in rhizospheric soil and VAMF colonization. VAMF colonization mainly depends on the characteristics of host plants and the selection of VAMF. This suggests that conservation of weed diversity in upland ecosystems will be favorable for conserving VAMF activities and diversity.

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.

The quantity and diversity of soil microbe were studied in different vegetation types in Gaoligong Mountain,Yunnan.The quantities of microbes,diverstity of fungi,and the amount of nutritions were examined in 12 soil samples,which were collected from different habitats with the elevation ranging from 1000 to 3000 meters,The result showed that the quantities of bacteria,fungi,actinomyces,and diversity of fungi varied with elevation.The highest values occurred at the elevation of about 2000 meters,and they decreased as the elevation increased of decreased.The lowest values appeared at bottom of the Mountains.The correlations between soil microbes and the ccological factors varied.The quantities and diversity of soil microbes were significantly correlated with temperature and organic matter except that there were to significant correlations between the quantity of bacteria and temperature,as well as between quantity of fungi and organic matter.In contrast,they correlated less with effective nitrogen and soil moisture content,much less with quick acting phosphorus and quick acting potassium.The results indicate that the main exoloical factors influencing the quantity and diversity of soil microbes were temperature,organic matter,effective nitrogen,and soil moisture content.

Up to now , there have been no special reports regarding soil animals in warm2temperate zone at home and abroad. From April 1993 to January 1994 ,by means of commonly- used quantitative and qualitative method , we carried out monthly sample collections in five plots in the Xiaolongmen Forestry Research Stations , Beijing. A total of 35 294 specimens were collected , belonging to five phyla , six classes , 54 orders , 176 families , 252 genera and 356 species. Among them , 822 individuals were large size soil animals ( Gastropoda , Arachnida , Myriapoda , Hymenoptera etc. ) , 3129 were small size animals (mainly ticks and mites) , 31 227 were wet land living soil animals (mainly nematods) , and annual mean occurrence of individuals per gram of dry soil of Protozoan (mainly Amoebae and Flagellates) was 789 238. The tendency of population fluctuation of dry soil animals showed evident seasonal variations and comparatively obvious fauna characteristics. There are similarities and differences regarding species composition compared with other areas in China and neighbouring countries.

The change in st ructure and diversity of soil arthropod communities of secondary forest after the simulated process of slash-and-burn was studied in Xishuangbanna. The results showed that colonies and individuals of soil arthropod communities declined from 14 colonies , 564 individuals in secondary forest to 7 colonies , 164 individuals in slash-and-burn fields one week after burning. The composition of soil arthropod communities was also changed. The proportion of individuals of Hymenoptera (ants) in burned remnants was greatly increased on the first day after burning , and this was obviously the dominant group in the soil arthropod community. The proportion of individuals of Acari was greatly increased during the first week after burning , and it was the only dominant group of the soil arthropod community in the field. The diversity of the soil arthropod community was decreased and the verticalst ructure of the community was disrupted by slash-and-burn. After the slash-and-burn process , there were many more colonies and individuals of soil arthropod in the lower soil than in the surface soil. The dest ruction by slash-and-burn of soil arthropod communities was reduced to a certain extent in deeper soil layers. Some soil arthropods can keep their numbers and species by moving lower in the soil during the slash-and-burn process.