Aim: Environmental and genetic factors are believed to be the main drivers of variation of plant function traits, which may further influence rhizosphere soil bacteria through root exudates. However, it still remains unclear whether the genetic differentiation would affect the diversity and community structure of nitrogen-fixing bacteria in the rhizosphere soil of plant species.

Method: A common garden experiment was established to examine the diversity and community structure of nitrogen-fixing bacteria in the rhizosphere soil of three Caragana from different provenances by using high-throughput sequencing techniques, which was subsequently correlated with the provenance climates and common garden soil properties to investigate how the environmental factor and genetic differentiation affect the rhizosphere nitrogen-fixing bacterial diversity and community structure.

Result: The present results demonstrated that the rhizosphere nitrogen-fixing bacteria of three Caragana species belonged to 6 phyla, 9 classes, 18 orders, 21 families, 33 genera and 72 species. Proteobacteria, Verrucomicrobia and Cyanobacteria were the main dominant phyla of the three Caragana species of nitrogen-fixing bacteria in the rhizosphere soil, and Mesorhizobium, Azohydromonas and Bradyrhizobium were the dominant genera. There were no significant differences in the diversity and community structure of rhizosphere nitrogen-fixing bacteria among the three Caragana species, but significant differences in the α diversity index between provenances were observed in C. liouana and C. roborovskyi (P < 0.05). The community structure between provenances of C. microphylla and C. roborovskyiwas also significant (P < 0.05). Furthermore, redundancy analysis showed that soil pH of the common garden and mean annual temperature (MAT) of provenance were the dominant factors respectively affecting the diversity and community of rhizosphere nitrogen-fixing bacteria of the three Caragana species.

Conclusion: In summary, our results indicate that the common garden environment and genetic differentiation jointly shape the diversity and community structure of nitrogen-fixing bacteria in the rhizosphere soil of Caragana species. This research can provide important theoretical basis and data support for the ecological adaptation mechanism and introduction and cultivation of Caragana.

Aims: Over the past 30 years, a range of ecological restoration measures such as aerial seeding and grazing prohibition have been conducted for desertification control in the Mu Us Desert, and significant vegetation greenness have been achieved in improving the regional ecological environment; however, the changes in soil multifunctionality after vegetation restoration are still unclear, in particular the influence of soil microorganisms on soil multifunctionality.

Methods: In this study, soils of shrublands established at the same time in the Mu Us Desert, and dominated by Artemisia ordosica, Salix psammophila, Caragana korshinskii, respecitively, were investigated. Soil microbial community structure was determined using high-throughput sequencing, and soil multifunctionality was calculated by the Z-score method.

Results: There were significant differences in soil organic carbon content, total nitrogen content, total phosphorus content, microbial biomass carbon content, and microbial biomass nitrogen content among three shrub soils (A. ordosica shrubland > S. psammophila shrubland > C. korshinskii shrubland). Soil invertase activity, alkaline phosphatase activity, and multifunctionality were significantly higher in A. ordosica and S. psammophila shrubland than that in C. korshinskii shrubland. Soil microbial Chao 1 index, observed species number and Shannon index in A. ordosica shrubland was significantly higher than that in C. korshinskii shrubland. The net relatedness index of soil microbes in C. korshinskii shrubland was significantly lower than that in the other two types of lands. Shannon index, Faith’s phylogenetic diversity and network topology properties (nodes, edges, linkage density) in the three shrublands and the net relatedness index in C. korshinskii shrubland were positively correlated with soil multifunctionality. Soil microbial network topological properties, species diversity, and phylogenetic diversity explained 24.46%, 19.72%, and 5.92% of the variation in soil multifunctionality, respectively. Structural equation modeling showed that soil microbial diversity increased soil multifunctionality indirectly by promoting network structure.

Conclusion: The results indicate that different shrub soils have different effects on soil microorganisms and multifunctionality, and soil microbial diversity influence soil ecosystem functions mainly through positive regulation of microbial interspecific relationships. The results of the study help to understand the effects of different vegetation restoration measures on soil functions from the perspective of soil microorganisms, and can provide a theoretical basis for the selection of plant species for desertification control.

Aim: The change of water table level has an obvious causative effect on the vegetation composition and diversity of peatlands, which may profoundly change the carbon sequestration potential of peatlands. However, the exact responses of the diversity of vegetation and soil organic carbon in peatland have to water table fluctuations are still controversial. In addition, there are few reports on the effects of water table level on plant diversity, biomass and soil organic carbon in oligotrophic peatlands in subtropical regions.

Methods: Soil organic carbon content, species diversity and vegetation biomass of different groundwater levels were compared by one-way ANOVA. Significant difference in species diversity and biomass of plant community were analyzed by LSD multiple comparison method (P = 0.05). Linear correlation analysis was used to compare the correlation among water level, oxygen content, Sphagnum moss and shrub biomass.

Results: (1) With a decrease in level of the water table, soil water content, soil organic carbon content and polyphenol content all decreased significantly, while dissolved oxygen increased significantly (P < 0.05). Moreover, soil organic carbon at the low-water table (-20 cm) was 72% of that at the high-water table (-4 cm). (2) Water table significantly changed the plant species composition of oligotrophic peatland in the Southwestern Hubei Province. With a decrease in level of the water table, the number of shrub species increased, and the shallow-rooted Ericaceae and Rosaceae were the dominant shrubs. (3) Overall, shrub diversity showed a significant increase with the decrease of water table (P < 0.05), while herbaceous diversity showed no significant change. (4) Water table had no significant effect on the total aboveground biomass of vegetation. However, with the decrease of water table, shrub biomass (P < 0.01) and herbaceous biomass (P < 0.05) significantly increased, while moss biomass decreased.

Conclusion: This study shows that a higher water table is a key factor to maintain soil organic carbon content in oligotrophic peatlands in the Southwestern Hubei Province, and the increase of vascular plant diversity does not increase the carbon sequestration potential of the peatlands.

Aims: Mineral elements are important determinants of soil nutrients and are related to forest community composition and nutrient cycling. There is high terrain heterogeneity in karst seasonal rainforest local scale, but there is still lack of research on how terrain and other abiotic and biotic factors affect the spatial distribution of soil mineral elements in karst area.

Methods: In this study, we set up 100 litter fall traps along the elevation gradient in the 15 ha northern tropical karst seasonal rainforest dynamics plot in Nonggang, southwestern Guangxi, and conducted soil sampling at the litter fall trap sites. We tested soil samples for the content of mineral elements such as K, Ca, Mg. We performed quantitative analysis of the association between ecological factors and soil K, Ca, Mg in karst seasonal rainforests based on methods such as spatial regression models and variation partitioning.

Results: Soil K, Ca and Mg in the study area were all spatially autocorrelated, with Ca significantly positively correlated with elevation and convexity (P < 0.05), mainly clustered in the hilltop; K significantly positively correlated with topographic wetness index, mainly clustered in low-lying land; Mg showed clustering characteristics in the hillside. Variation partitioning shows that ecological factors drove the spatial distribution of soil K, Ca and Mg more than spatial structure. Elevation was the highest predictor variable among the individual ecological factors, and abiotic factors were higher than biotic factors in general, and species richness was the highest among biotic factors, while the aggregation of Mg elements was accompanied by a higher level of species richness.

Conclusion: In this study, the soil K, Ca and Mg in the 15 ha northern tropical karst seasonal rainforest dynamics plot in Nonggang have spatial autocorrelation, and the spatial distribution of the three soil elements was significantly different. In the karst seasonal rainforest in southwestern Guangxi, ecological factors such as altitude have a strong driving effect on the spatial distribution of soil K, Ca and Mg. However, in terms of the accuracy of the analysis results, adding more ecological factors and expanding soil sampling points may further enhance the interpretation of ecological factors and spatial variables on the spatial distribution of soil elements.

Aims: Northeast black soil is one of the most important agricultural resources in China. Understanding the spatial distribution of nematode communities as well as their influcing factors is of great importance for ensuring food security in China.
Methods: In September 2018, 31 farmland sampling sites were selected across the black soil region within the bounds of 42°50°-49°08° N, and 93 soil samples were collected. Soil nematode communities were identified by morphological identification.
Results: A total of 47 nematode genera (relative abundance > 1%) were identified. Across all samples, the bacterivores nematode Acrobloides was the most abundant (relative abundance > 5%). Species richness and abundance of nematode communities increased with latitude, but only among bacterivores and omnivores/predators nematodes. Soil organic carbon was the most important environmental factor affecting richness and abundance of soil nematodes in a typical black soil region, followed by monthly mean temperature. Soil nematode community structure in this region was divided into two categories: south and north, with a boundary at 47° N separating the two groups. This division was attributed mainly to the differences in the relative abundance of plant parasitic and omnivorous/predatory nematodes between the two areas. Soil pH value and bulk density were the most important factors influencing community structure in the south and north, respectively.
Conclusion: This study clarifies the relationship between environmental factors and nematode community structure, as well the geographical distribution of nematode communities in a typical black soil region. As such, it provides basic data and reference for the mechanism driving the character of soil biota under agricultural interference.

Background & Aims: Urbanization threatens biodiversity on local to global scales, and soil fauna is an essential component of soil biodiversity and play a vital role in the maintenance of soil health and ecosystem functions in cities. In recent years, many studies previously focused on the structure and diversity of urban soil fauna communities that have made significant progress to understand their complex relationships. However, systematic summaries and discussions are still limited.
Progress: This review advances our knowledge in these areas by drawing upon current urban soil biodiversity studies with relevant broader research on soil fauna. From these works, we summarize the major pathways by which urbanization affects the community composition and diversity of soil fauna and highlight ecological processes that potentially threaten the persistence of soil fauna in cities.
Prospects: We recommend that future studies should focus on (1) the impact of urbanization on gut microbiomes of soil fauna and how it relates to changes in soil fauna functions, (2) the environmental determinants to the structures and functions of soil food webs in urban ecosystems, and (3) the role of soil fauna in the regulation of human pathogens. Ultimately, our review provides a relevant scientific basis for biodiversity protection and maintenance of soil health and ecosystem stability in cities.

Aims: (1) To study effects of mean annual precipitation (MAP) on the diversity and community assembly of bacterial communities in the Gurbantunggut Desert; (2) Further our understanding of how bacterial communities respond to desertification.

Methods: We conducted the high-throughput sequencing data of bacterial communities from 30 soil samples (0-10 cm depth) collected from the Gurbantunggut Desert, where the MAP ranges from180 mm to 230 mm. We investigated the effect of MAP on the diversity of three defined categories of bacterial communities (whole, abundant and rare), and compared the compositions of the bacterial communities. Finally, we assessed the relative importance of deterministic and stochastic processes of the bacterial community assembly using the null model method.

Results: The results showed that MAP had no significant influence on the richness and Shannon index of whole and abundant bacterial taxa (P > 0.05). However, the indices of richness and Shannon diversity of rare bacterial taxa were significantly decreased with MAP reduction (P < 0.05). Moreover, MAP had a noticeable effect on the community composition of the whole, abundant and rare bacterial communities, with the rare bacterial taxa having the highest levels of community variation and spatial turnover followed by whole and abundant bacterial communities, respectively. The results indicated that the whole, abundant, and rare bacterial taxa in the Gurbantunggut Desert responded differently to MAP. Rare bacterial taxa showed strong sensitivity to regional precipitation differences, whereas whole and abundant bacterial taxa were resistant to MAP variation. The null model analysis showed that dispersal limitation dominated the bacterial community assembly process in the Gurbantunggut Desert (> 73.0%). In contrast, the rare desert bacterial taxa were subject to heterogeneous selection (43.0%), indicating that the desert precipitation differences enhanced the environmental selection or species competition of the rare bacterial taxa. In addition, spatial distance and MAP determined the whole bacterial community construction, and the abundant and rare taxa respectively. Particularly, MAP played an essential role in balancing the relative importance between deterministic and stochastic processes of the rare bacterial taxa.

Conclusion: Small-scale MAP differences in the Gurbantunggut Desert significantly alter the composition and assembly processes of the bacterial community. The community composition and turnover of rare bacterial taxa were affected strongly by MAP, which help mitigate the lag in the response of desert bacteria to environmental changes. Dispersal limitation isa stronger determinant of β diversity for whole and abundant bacterial taxa than for rare bacterial taxa, indicating that geographic distance explained more species turnover for desert whole and abundant bacterial taxa than for rare bacterial taxa, while the diversity distribution and ecological niche preference of desert rare bacteria were more precipitation-dependent than spatial geographic scale.

Aims: Soil fauna as the key component of terrestrial ecosystems, playing an important role in decomposition of animal dung, mineralization of organic matter and turnover of soil nutrients. Many studies have been done on the soil fauna’s effects on plant litter’s decomposition. Still, less information is available on their impact on the decomposition of animal dung.
Methods: Here we conducted a field experiment in a temperate semi-arid steppe ecosystem to investigate the effect of the different soil fauna groups with different body sizes on the decomposition of horse and cattle dung pats on the soil surface over a one-year period. The experiment had five treatments: CK, soil only, no dung nor soil fauna; T0, dung pat covered with a wire-mesh-cage of 0.425 mm holes (excluding dung beetles and soil meso-fauna); T1, dung pat covered with a wire-mesh-cage of 1 mm holes (excluding dung beetles); T2, dung pat covered with a wire-mesh-cage of 2 mm holes (excluding tunneler dung beetle); T3, exposed dung (with no exclusion of soil fauna).
Results: We found that (1) compared with dung only (excluding dung beetles and soil meso-fauna) treatment (T0), the presence of soil fauna (T1, T2 and T3) did not enhance the dry mass loss of livestock dung during the first 60 days of the experiment; in contrast, in the presence of all soil fauna (T3) significantly increased the dry mass loss of cattle dung but decreased that of horse dung at the end of the experiment (at day 360). (2) Soil fauna also enhanced the decline rate of carbon and nitrogen content in dung during the first 60 days of the experiment. (3) Dung addition increased the soil microbial respiration, and the increase was most obvious in the presence of soil fauna (T3) on days 15 and 30 of the experiment. (4) Compared to the soil with no dung (CK), the soil with horse dung had higher contents of soil available N, soil organic carbon and soil moisture, and the contents were higher in the presence of soil fauna (T2 and T3); whereas the soil with cattle dung had no changes.
Conclusion: We conclude that the feeding and activities of dung beetle in the early stage of dung decomposition alter the physicochemical properties of dung, which indirectly affect the role of soil biota in the decomposition in the later stage.

Background & Aims: Earthworms, which are known as the ecosystem engineers of the soil, are highly diverse and distributed worldwide. They are used as indicators of soil health. They are highly adaptable to their environment, and their genomes have evolved through the process of adaptation. In this paper, recent research progress of the whole genome and mitochondrial genome of the earthworms are reviewed.
Progresses: The sequencing, assembly and analysis of earthworm genome lay a foundation for the study of earthworm ecology, molecular toxicity mechanism of pollutants to earthworm, molecular mechanism of immune defense, earthworm regeneration and so on. The mitochondrial genome is mostly used in the study of molecular phylogeny of earthworms. Currently, various types of earthworm species have been identified based on mitochondrial genome sequencing.
Prospects: This paper highlights the following aspects of research that should be focused in future studies: (1) Carry out the studies on comparative genomics, evolutionary genomics and functional genomics using the existing whole genome sequencing results of the four species earthworms; (2) Improve the gene libraries and expressed sequence tags of different species of earthworms; (3) Strengthen the association analysis between mitochondrial genome and whole genome with the species diversity of earthworm.

Aims: Global environmental change leads to increasing biodiversity loss, and soil animal communities are among the most species-rich components of terrestrial ecosystems. One of the most important biodiversity-ecosystem functioning experiments was designed in subtropical China (referred to as BEF-China). Here, we investigate the change of oribatid mite community structures in different tree species forests (site A and site B) of BEF-China.
Methods: Soil samples from BEF-China were collected from September 2019 to April 2022. The abundance, diversity, community structure, and ecological indices of oribatid mite communities as well as environmental factors were analyzed and compared between forests with different tree compositions.
Results: We found that, (1) the community structure of oribatid mites in each forest was significantly different. The relative abundance of Oppiidae, Lohmanniidae, Oribatulidae, and Microzetidae was higher in site A than site B; and the relative abundance of Scheloribatidae, Tectocepheidae, and Trhypochthoniidae was higher in site B than site A. (2) There were different seasonal dynamics of oribatid mite communities among the four seasons. In site A, the abundance, species richness, and Shannon diversity of oribatid mites in summer and autumn were markedly lower than those in spring and winter. However, the diversity of oribatid mites in spring and autumn were similar in site B. (3) There were distinct correlations between oribatid mite communities and environmental factors. And yet, different oribatid mite species have varied responses to indicated factors.
Conclusion: The results highlight that oribatid mite community structures are impacted by aboveground plants. This research provides a reference for future researchers to help understand the biotic interactions between soil oribatid mites and plants.

Aims: Soil invertebrate communities are of extremely high diversity but still poorly studied in DNA-based diversity assessments. Since traditional morphological identifications have trouble in completing thousands of taxonomy assignments accurately with limited time, more and more biodiversity surveys turn to molecular taxonomy assignments. To promote biodiversity surveys on soil invertebrates, we made a comprehensive comparison for five popular taxonomy assignment tools (VSEARCH, HS-BLASTN, EPA-NG, RAPPAS and APPLES) targeting on different molecular markers (COI, 16S and 18S). Four soil invertebrate groups (Collembola, Acari, Clitellata and Chromadorea) were selected in the comparison representing three representative phyla of varied body-sizes.
Methods: The databases of four soil invertebrate groups using three molecular markers were built with a filtering step. The commands of five taxonomy assignment tools were integrated into a script which would finally output the taxonomic information of query sequences. All of assignment accuracy, running speed and memory usage of five tools were estimated and compared.
Results: Our results indicated that EPA-NG performed best in accuracy for most cases, especially for COI. VSEARCH and HS-BLASTN remained high accuracy and showed similar accuracy performance when utilizing 16S and 18S markers. Moreover, shorter running time and lower memory usage made VSEARCH more popular applying in 16S and 18S than EPA-NG. RAPPAS and APPLES showed unstable performances in accuracy and were often too conservative to identify some species at generic or familial levels.
Conclusion: This study concluded that molecular taxonomy assignment could accomplish identifications of soil invertebrates in an accurate and efficient manner. COI marker is the most recommended marker applied in molecular taxonomy assignment for soil invertebrates because of its abundant repositories of reference sequences reflected in all of species, genus and family levels. When COI is utilized as marker, EPA-NG is the most recommended tool unless the reference database is too large. When 16S or 18S is utilized as marker, VSEARCH is most highly recommended.

Background & Aims: Protists are widely distributed in soil and throughout different habitats with high abundance and diversity. They play important roles in nutrient cycling and the energy flow of ecosystems, as well as maintaining soil and plant health. Compared with other microorganisms and fauna in soil, protists have received little attention until recently, and the study on their classification and molecular detection are largely challenged due to their complex taxonomy systems and ecological types.
Progresses: This review systematically summarized and sorted out previous research on soil protists. The research progress on the taxonomic systems of protists, properties of different trophic functional groups, the distribution pattern, and the influencing factors of soil protists were summarized. Then the ecological functions of protistan communities in participating in soil nutrient cycling and maintaining soil health were further highlighted. The main factors that drive the construction of protistan community was clarified, and the prospect and application prospect were further put forward.
Prospects: The future perspectives and research efforts towards taxonomic classification, biodiversity, ecological function, and applications of soil protists need to be explored.

Aims: The establishment of national parks is crucial in protecting the integrity of natural ecosystems and biodiversity. As one of the first ten pilots, the Qianjiangyuan National Park system pilot (hereafter referred to as Qianjiangyuan) has developed the easement-inspired adaptive management and achieved remarkable outcomes. However, it remains unclear how this creative management might influence the soil microorganisms and systematic evaluation is in need.

Methods: We took Qianjiangyuan as the study area and collected surface soils from rice paddies in the different districts and under different management types. Four management types were included, namely, reformed land within the park, abandoned land within the park, unreformed land within the park, and unreformed land outside the park. We employed high-throughput sequencing techniques to characterize the community composition and structure of both bacteria and fungi. We then analyzed the driving forces behind the spatial patterns of bacterial and fungal communities.

Results: Compared to the other three types of lands, contents of soil nitrogen and phosphorus and heavy metals were relatively low in the abandoned land, but they were similar in the other three types. The bacterial communities were dominated by Proteobacteria (48.57%) and Acidobacteria (31.62%), while the fungal communities were dominated by Ascomycota (78.31%) and Basidiomycota (16.28%). Bacterial communities varied largely in lands under different management types, with significant difference between abandoned land and other three types, while the other three types were similar. Fungal communities showed slight variation, with significant difference being identified only between abandoned land and outside unreformed land. We found significant correlation between soil environmental factors and spatial variation of bacterial communities. The most important five factors driving bacterial spatial patterns were pH, chromium, total nitrogen, available phosphorus, and organic matter. However, no significant correlation was detected between fungal communities and soil environmental factors. Analysis of neutral community models found that neutral processes played an important role in the spatial distribution of both bacterial and fungal communities.

Conclusion: Based on these findings, we conservatively conclude that no significant impacts have been produced by land reforming policy so far. In contrast, the abandoned land may have begun rewilding. Therefore, long-term monitoring is needed to comprehensively assess whether and how ecological protection easement will impact the recovery of rice soils.

Aims: Using an agricultural soil permanent plot, we wanted to reveal the spatial distribution patterns of soil organisms and functional diversity, as these are important metrics for maintaining soil organism diversity and improving agricultural soil quality.
Methods: In October 2020, 210 soil samples were collected from a large permanent farmland soil plot (9 ha) in Shangqiu, Henan Province. Soil mites were extracted by Tullgren’s funnel method in the laboratory. The soil mites were identified to species and their body length and width were measured to illustrate both the spatial distribution pattern of species diversity as well as body size of soil mites in wheat-maize rotation farmland.
Results: (1) A total of 17,256 adult mite individuals were captured, of which oribatid mites were the dominant group (94.67%). Results of MGP analysis showed that the oribatid mite community belonged to P-type, indicating that it was strongly affected by human factors. Niche breadth and overlap analysis showed that for higher degrees of evolution, niche width of oribatid mites increased, and for closer degrees of evolution, oribatid mites experienced greater competition. (2) Values of Moran’s I index showed that from 20 m to 100 m, the individuals of dominant soil mite community were significantly positively correlated with body length and body width; yet from 220 m to 300 m, individuals of soil mite community and four dominant species had a negative spatial autocorrelation. A semi-variance function showed that the spatial variation of species, individual number, body length and width of oribatid mites were mainly affected by deterministic processes, while the spatial variation of mesostigmatid mites was affected by both deterministic and stochastic processes. (3) There was a weak negative correlation between the individual number of soil mites and body length and body width, which generally exists in each community and dominant species of soil mites.
Conclusion: This study suggests that the spatial pattern of species and functional diversity represented by mite body length and width should be considered when evaluating maintenance mechanisms of soil mite community and for protecting the diversity of soil mites.

Aims: Soil microorganisms play an irreplaceable role in the energy flow and material cycle of forest ecosystems. Larix gmelinii is the dominant tree species in the Greater Khingan Mountains of China, and the Aershan area is the southernmost point of its distribution in China, which is significantly affected by climate warming. Exploring the soil microbial community structure under L. gmelinii forest is of great significance to understand and maintain the stability of forest ecosystem in Northeast China.

Method: In this study, we collected soil samples from Bailang Town and Tianchi Town in the Aershan area and used high-throughput sequencing technique to analyze the soil bacterial and fungal communities in two forest stands.

Results: The results showed that (1) 5,163 bacterial operational taxonomic units (OTUs) and 2,439 fungal OTUs were obtained according to a 97% sequence similarity level. The diversity of bacteria was higher in the Tianchi area than in the Bailang area, but no significant difference in fungal diversity between the two sites. (2) The dominant phyla of bacteria were Actinobacteriota, Proteobacteria, Verrucomicrobiota, Chloroflexi, and Acidobacteriota, and the dominant phyla of fungi were Basidiomycota and Ascomycota. The dominant bacterial genus was Candidatus_Udaeobacter, and the dominant genera of fungi were Inocybe, Sebacina, Piloderma and Tomentella. (3) The correlation analysis indicated that soil pH and cation exchange capacity were the main factors driving soil bacterial species diversity, and soil total nitrogen and organic carbon were the main factors driving fungal species diversity. (4) Soil total nitrogen, organic carbon, available phosphorus and cation exchange capacity were important factors affecting soil bacterial community composition, while fungal community composition was not significantly affected by the physical and chemical properties of the soil. (5) The relative abundance of Chloroflexi was significantly correlated with pH; the relative abundance of Basidiomycota was significantly correlated with soil total nitrogen and organic carbon, while that of Ascomycota was significantly correlated with soil total nitrogen, organic carbon and cation exchange capacity.

Conclusion: The results of this study indicate that soil physicochemical properties have a significant impact on the soil microbial community structure in L. gmelinii forest within the Aershan area, and the diversity of bacterial and fungal communities also plays an integral role in maintaining the soil ecology and functional environment in this area.

Aims: Many mining activities can lead to heavy metal pollution in soils near mining areas, leading to negative consequences to the native soil biota. In particular, mercury, thallium, and other heavy metals are highly toxic, but the related ecological risks are rarely studied. As an indicator of soil environmental change, collembola species can be used to assess soil quality.
Method: The study was conducted in an agricultural field near a mercury-thallium mining area in Guizhou Province. Four sampling areas were established according to different pollution levels and crop types, with two crops in each area and three sampling plots for each crop, in order to study the community structure and diversity of soil collembola and its influencing factors.
Results: The mean density of collembola across sampling areas was 12,000 ind./m². The closer a sampling area was to the mining area, the higher level of soil heavy metal pollution and the higher comprehensive pollution index. Generally, collembola species richness, density, and the diversity and richness index initially increased, but then decreased thereafter. Analysis of environmental factors showed that mercury, thallium, and arsenic had a significant negative effect on the community structure of collembola species: Folsomides americanus, Isotomiella minor and Protaphorura encarpatus.
Conclusion: High organic matter content could mitigate the effects of heavy metals on soil collembola. However, in this study there was no significant difference between maize and coix seed on soil collembola community structure. The results of this study indicate that soil organic matter could mitigate the effects of heavy metal pollution on the soil collembola community.

Aims: Harvest ant nests are an important microhabitat in gobi ecosystems that greatly affect the distribution and diversity of animals and plants by enhancing litter and improving the soil environment. This study analyzed the distribution pattern and influencing factors of soil macrofauna diversity between ant nest and adjacent bare ground microhabitats.
Methods: We investigated the assemblage of soil macrofauna in gobi Messor desertus ant nests and adjacent bare ground microhabitats using pitfall traps in May, June, and October 2020.
Results: (1) The community composition of soil macrofauna differed between ant nest and adjacent bare ground microhabitats and showed obvious seasonal variations. Soil macrofauna communities of ant nests and adjacent bare ground differed significantly in October, with an average dissimilarity of 62.9%. Slight differences were also observed in May and June, with 34.8% and 39.3% average dissimilarity, respectively. (2) The activity density and groups richness of soil macrofauna were significantly higher in ant nests than in adjacent bare ground microhabitats in June; the groups richness and diversity index of soil macrofauna communities were also higher in ant nests in October, and the evenness index of soil macrofauna communities was significantly lower in ant nests than bare ground microhabitats in May. (3) Ant nests significantly increased the activity density and groups richness, which increased the interactions between predatory and non-predatory soil macrofauna and altered the interactions between Messor desertus and some soil macrofauna groups. (4) pRDA showed that soil electrical conductivity, total nitrogen, and silt content were the main soil factors driving the distribution of soil macrofauna communities between ant nest and adjacent bare ground microhabitats.
Conclusion: Messor desertus ant nests increased the diversity of soil macrofauna communities and altered the trophic and non-trophic relationship among soil macrofauna groups, which affects the trophic structure and ecological function of soil macrofauna communities.

Aims: Understanding the distribution and drivers of soil fauna diversity as well as their ecological functions have become areas of cutting-edge research in modern geoscience and ecology. Here, we briefly introduce the latest progress in this field, discuss present research limitations and uncertainties, and offer promising research directions in future studies of soil fauna.
Progresses: Many studies have described the global distribution of representative soil fauna taxa diversity and abundance, such as that of earthworms. Research on soil fauna distribution and ecological function in China has also flourished with many large scale, intensive sampling studies in the past 10 years (especially for earthworms and nematodes). Based on a literature review, we observed that there were two main distribution patterns of soil fauna diversity across latitudes. Diversity was found to be highest either at low-latitude tropical zones or at mid-latitude temperate zones; while changes in soil fauna abundance and diversity can be consistent, non-related, totally different, and even opposite. Precipitation, plant productivity and soil organic matter were the critical drivers of soil fauna distribution, but their influences varied with soil faunal taxon. The major ecological functions of soil fauna include improving soil physical structure, facilitating nutrient cycling and organic carbon stabilization, and enhancing plant health. The concept of multifunctionality of soil fauna has been proposed by soil ecologist to fully measure these multi-dimensional ecological functions, but it still faces many challenges.
Prospect: The drivers of soil fauna distribution are not simply predicted from the variation pattern of soil faunal community characteristics across latitudes, longitudes or altitudes. Rather, we suggest that drivers of the soil fauna distribution should be explored within a multi-dimensional spatial-temporal framework based on a combination of geological and ecological history as well as “latitude & longitude-altitude-distance to coast”. The distribution pattern of soil fauna may critically influence their potential ecological functions; however, the prediction and simulation of soil fauna distribution mainly relied on data-driven empirical models, and the results were not conclusive. Thus, the application of theories such as metabolic ecology deserves more attention. Research on the relationship between soil fauna diversity and function is in the preliminary stages; focusing on functional diversity and exploring the redundancy mechanism of taxonomic diversity could link soil fauna diversity and function. We propose to understand soil fauna diversity and function under specific condition of space and time, as well as the context of the whole soil food web and its connection with plants. There are two promising directions for further research: (1) illustrating the large uncertainties that human activity and climate change may bring to soil fauna studies; (2) developing precision manipulation approaches of soil fauna community to ultimately link soil fauna multifunctionality with human well-being.

Aims: Soil nematodes are abundant in agroecosystems and are sensitive to edaphic environmental changes, they can be used to assess soil health under different field management conditions. This study aims to investigate the effects of long-term fertilization and soil aggregation patterns on nematode community distribution and functional diversity in purple soil.
Methods: Five fertilization treatments were established: no fertilizer (control, CK), chemical fertilizer alone (NPK), biochar + chemical fertilizer (BCNPK), commercial pig manure + chemical fertilizer (OMNPK) and straw + chemical fertilizer (RSDNPK). Soil particle sizes were categorized as: bulk soil, large macroaggregates (> 2 mm) and small macroaggregates (0.25-2 mm).
Results: Fertilization increased the number of soil nematodes compared to the CK with a minimum increase of 66% under the NPK treatment group. Soil treated with a combination of organic and chemical fertilizers exhibited an increase in nematode abundance of 206%. The relative abundance of nematode groups was consistent across treatments: bacterivores > omnivores/predators > plant parasites > fungivores. However, omnivores/predators and bacterivores populations in small macroaggregates were smaller and larger, respectively, than populations associated with other soil particle categories. Community structure and enrichment index values increased in the RSDNPK group, and the nematodes’ functional footprint varied across treatments.
Conclusions: The application of a combination of organic and chemical fertilizers (especially RSDNPK) can increase soil nutrient supply capacity and help establish stable and healthy soil ecosystems, supporting the development of sustainable local agriculture.

Aim: The managements in farmland in lower reaches of Liaohe Plain, such as long-term cultivation, fertilizer and agrochemicals application on cropland have led to soil degradation, environmental pollution and the decline of productivity, which inevitably have an impact on soil biological health. Therefore, we investigated the seasonal variations of soil nematode community composition to explore the effects of field artificial management measures on the abundance and diversity of soil nematode community.
Methods: Soils from cropland and abandoned cropland (as controls) were collected in the National Field Observation and Research Station of Shenyang Agroecosystems in the spring (May), summer (July), autumn (September) and winter (November) of 2019. Soil nematodes were identified and the corresponding ecological indices were analyzed.
Results: The results showed that the total abundance of soil nematodes was significantly higher in abandoned cropland than that in cropland soils, but no significant differences were observed among four seasons. Seasonal variation mainly influenced the abundance of soil free-living nematode individuals, with the highest abundance occurring in September. Seasonal variation also significantly affected the number of soil nematode genera, which was the lowest in November (non-growing season). Compared to the abandoned cropland, farmland management significantly reduced the abundance of soil nematodes including omnivores-predators and fungivores.
Conclusions: In cropland, the soil food web was relatively stable, whereas abandoned cropland was more susceptible to seasonal variations, and its soil food web was moderately disturbed.

Background & Aims: Soil nematode diversity is one of the hot topic in soil ecology research. However, in-depth studies on soil nematode community composition and diversity are limited by the established taxonomy and methodology. At present, the development of molecular biological techniques has elevated our understanding of the diversity of soil nematodes, but it also included set-backs. This paper summarizes the research progress in molecular biology technology, including denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (T-RFLP), quantitative real-time PCR (qPCR) and high-throughput sequencing (HTS) technology, and the advantages and disadvantages of high-throughput sequencing in nematode research. We elaborate these techniques based on the extraction of soil nematode DNA, the selection of primers and reference databases, as well as the comparison between high-throughput sequencing and morphological identification analysis.
Prospects: The selections of soil nematode DNA extraction methods, in combination with proper primers and reference databases remain the key point to study nematode diversity. When focusing on nematode classification, we recommend DNA extraction after enrichment of nematodes suspension. Conclusively, researchers can then select the optimal combination to conduct experiments according to their research objectives.

Background & Aims: The impact of urbanization on biodiversity is one of the hotspot issues of ecology, which has attracted extensive attention. Soil microorganisms are the key driver of ecosystem process, which is very important in the exertion of ecosystem function and the provision of ecosystem services. Soil microbial diversity as an important part of urban biodiversity play vital roles in maintaining the health and stability of urban ecosystem. In recent years, studies have focused on the structure and diversity of urban soil microbial community and addressed some key questions, but the related systematic summary and discussion remains limited.

Progresses: Here we analyzed the impact of urbanization on soil microbial characteristics, community composition, function and diversity. Then we summarized the main factors affecting urban soil microbial diversity. We found that urbanization has changed the community composition and function of soil microorganisms, and had different impacts on bacterial and fungal diversities. Urban environmental factors affected soil microbial diversity through direct and indirect effects.

Prospects: We discussed the maintaining mechanisms and protection of urban soil microbial diversity. Finally we highlighted the questions needing attention in the future research of urban soil microorganisms. We recommend that future researches need focus on (1) influence mechanism of urbanization on soil microbial diversity in urban green space; (2) effects of microbial diversity change in urban soil on ecosystem multi-function; and (3) relationship between soil microbial diversity and human health. This could provide guidance for the protection of urban soil biodiversity.

Aims: This study was conducted to analyze the soil multifunctionality (SMF) pattern and their driving factors of the Junggar Desert. We tested that whether climate factors (temperature, precipitation and Aridity), soil environment (soil water content, soil temperature and pH) and vegetation factors would be the main driving factors of the spatial variability of SMF in the Junggar Desert.

Methods: The data of the sampling were collected from 79 sample sites of the Junggar Desert. The SMF indices were calculated by mean method and factor analysis method. The spatial characteristics of SMF in the Junggar Desert were obtained by using Kriging interpolation method in ArcGIS. Correlation analysis between single soil function and SMF was performed in R language software, and the best-fit model was used to fit the environmental factors and SMF of the 79 sample sites. The best-fit model was selected applied on the R² and the AIC value of the model. Structural equation model (SEM) analysis was performed using the “Lavaan” package in R language. Direct and indirect effects of different variables on SMF were identified, and the driving factors of spatial variability of the SMF in the Junggar Desert were determined.

Results: Overall, the SMF in the Junggar Desert showed large heterogeneity in spatial distribution, with an increasing trend of SMF from west to east, and trend of increasing first and then decreasing from south to north of the desert. The best-fit model showed that SMF had a significant quadratic function with MAP (mean annual precipitation) and MAT (mean annual temperature), and showed a decreasing first and then increasing trend of with the increase in MAP and MAT. The SMF had a significant primary function with pH and EVI (enhanced vegetation index). Specially, SMF had a trend of significant decreasing along with the increase in pH, and a significant increasing trend along with the increase in EVI. The SMF and Aridity (drought) showed both quadratic and linear (R² was the same for both) relationship, with SMF decreasing with the increase in Aridity. The results of structural equation modeling (SEM) indicated that, SWC was the most important driver of SMF change, followed by EVI. Soil pH, SWC (soil water content), MAT, Aridity and EVI had significant direct effects on SMF in the desert area, with SWC and EVI having significant positive effects and the others having negative effects. MAP, Lon (longitude), Lat (latitude) and Alt (altitude) had indirect effects on SMF by affecting factors such as MAT.

Conclusion: The results of this study indicate that the changes in SMF are caused by the combined effect of multiple environmental conditions. The results are important for the in-depth understanding of the spatial pattern and driving factors of the SMF in the Junggar Desert, which will be beneficial for the assessment of the effects of environmental changes on the multifunctionality and for the ecosystem managements of the desert ecosystems.

Aims: Oribatid mites, with large numbers and rich diversity, are one of the three main groups of soil animals. Up to 2020, the recorded oribatid mite species in China represented only 7.6% of all known species in the world. However, the species diversity has generally not been scientifically evaluated, highlighting a big gap between known species and its actual number. To commemorate the 100th anniversary for the birth of Chinese Oribatology, this study aims to summarize the new taxa of Oribatida worldwide from 2020 to 2021, and new species in China from 2007 to 2021.
Methods: We catalogued new Oribatida taxa in the world from 2020 to 2021, and new species of Chinese oribatid mites from 2007 to 2021 based on the described taxa and published literature. We also analyzed the biodiversity information provided by those new taxa, such as geographical distribution, author contributions and publications.
Results: From 2020 to 2021, a total of 238 new taxa of Oribatida were described globally, including 21 new genera and new subgenera, and 217 new species. Hotspots for new taxa discovery were in the Ethiopian, Oriental and Neotropical realms. The new taxa described were contributed by 27 authors, most of whom were non-Chinese scholars. All papers were published in non-Chinese journals, with most publications in the journal Systematic and Applied Acarology. From 2007 to 2021, a total of 183 new species of oribatid mites were described in China, but no new family and new genus were published. The hotspots for new species discovery were in the southeast, southwest and adjacent areas. The new species described were contributed by 24 authors most of whom were Chinese authors. Papers were mainly published in international journals, with Systematic and Applied Acarology and Zootaxa being the main journal.
Conclusions: Based on the above results, it shows the limited research power studying on Oribatida, and highly uneven distribution of newly discovered species among families and regions. Opportunities and challenges will continue to coexist in the development of classical taxonomy.

Aims: Due to global climate change, precipitation regimes in arid and semi-arid regions are exhibiting a trend of increase in rainfall intensity with a reduction in frequency. These changes in precipitation patterns can affect belowground communities and ecosystem functions. However, previous studies mainly focused on the effects of precipitation amounts on soil micro-food web, the changes of precipitation intensity and frequency on soil micro-food web were relatively few, especially in ecosystem function.
Methods: We performed a field experiment initiated in 2012 to examine the effects of changes in the precipitation regime (i.e. precipitation intensity: 2 mm, 5 mm, 10 mm, 20 mm, and 40 mm). Microbial communities were determined by phospholipid fatty acid (PLFA) and high throughput sequencing (16S and ITS). The composition and structure of the nematode community was determined by morphological identification.
Results: Different precipitation intensities significantly affected soil fungal PLFA, which was highest under the 20 mm treatment. Furthermore, fungal diversity had different responses to precipitation intensity treatment. The abundance of nematodes in each trophic group responded differently to precipitation intensity, and the abundance of bacterivores increased monotonically with the increase in precipitation intensity (P = 0.012). The abundance of fungivores (P < 0.001) and plant parasites (P = 0.046) were both significantly higher in medium (10 mm), high (20 mm) and extrem precipitation intensities (40 mm) than in low precipitation intensities (2 mm and 5 mm). Different precipitation intensities significantly affected soil nematode diversity. All the diversity indices were the highest under medium and high-intensity precipitation (10 mm or 20 mm). The soil nematode community composition was similar between moderate precipitation intensity (10 mm) and extreme precipitation intensity (40 mm). Changes in precipitation patterns increased soil water content, fungal PLFA, and fungivore diversity, thus improving ecosystem multifunction.
Conclusion: High precipitation intensity promoted fungal PLFA in the northern temperate steppe, while moderate precipitation intensity promoted microbial diversity. The abundance of nematodes increased with precipitation intensity, and the diversity of nematodes was highest under moderate and high precipitation intensity. The changes in soil micro-food web further affected ecosystem multifunction, mainly through increasing fungal biomass, abundance of fungivores nematodes, and nematode diversity.

Aims: Fungus-feeding Phlaeothripidae species are important components of soil invertebrates. They will contribute to the studies of biodiversity conservation and utilization, plant protection and zoogeography. Current studies on the taxonomic diversity of these species in China are insufficient, and on influence factors of distribution patterns in large scale are still unclear. Based on the extensive field surveys from China and the taxonomic studies about specimens deposited in some collections of research institutions at home and abroad, we generated a Chinese checklist of known fungus-feeding Phlaeothripidae species with their geographical distribution, summarized the current status and brief history of the taxonomy, analyzed the distribution patterns of species diversity and their drivers.
Progress: A total of 237 species of fungus-feeding Phlaeothripidae thrips were recorded in China, including 156 species from 39 genera in subfamily Phlaeothripinae and 81 species from 22 genera in subfamily Idolothripinae. Four genera were the dominant with each more than 10 species, including Bamboosiella, Psalidothrips, Apelaunothrips and Holothrips. Of these 73 species were endemic to China. More than 60 species were recorded from each province of Guangdong, Taiwan, Hainan and Yunnan, where had both tropical and subtropical humid monsoon climate characteristics and were suitable for survival of these organisms. Relative abundance analysis indicated that they were a common group of soil animals in forest litter layer of tropical and subtropical areas. Annual average temperature, precipitation and foods were the main factors for restricting the geographical distribution of these thrips.
Prospects: The results provide evidences on broadening the research field of soil biodiversity and explaining the position and large-scale spatiotemporal pattern of fungus-feeding thrips.

Aims: Woody debris provides essential habitat and food resources for macroinvertebrate communities and greatly impacts soil macrofauna biodiversity. Little is known about how features of woody debris are associated with soil macroinvertebrate communities, especially for subtropical forests. This study aims to investigate the effects of tree species, diameter classes, and decomposition stages of woody debris on the composition and structure of macroinvertebrate communities.
Methods: We sampled the woody debris of three tree species (Sassafras tzumu, Fagus lucida, and Cryptomeria fortunei), crossed with two size classes (10 ± 2 cm and 4 ± 2 cm in diameter) at different decomposition stages in the subtropical forests of the Badagongshan National Nature Reserve, Hunan, China, from October to November 2020. Then, macroinvertebrates in the sampled woody debris (i.e., taxonomical groups and number of individual) were inventoried for community composition.
Results: (1) A total number of 2,558 individuals belonging to 4 phyla, 10 classes, and 23 orders were found throughout the study. The dominant groups, common groups, and rare groups of macroinvertebrates differed in preferred tree species. (2) The individual density of macroinvertebrates in the woody debris of Fagus lucida was significantly higher than that in Cryptomeria fortunei and Sassafras tzumu. For Fagus lucida and Sassafras tzumu, the Shannon-Wiener diversity index of macroinvertebrates was significantly higher in large-diameter woody debris than that in small-diameter debris. The number of total groups and specialist groups of invertebrates in large-diameter wood debris were more than those in small-diameter woody debris. The Shannon-Wiener diversity index, Simpson dominance index, and Pielou evenness index of macroinvertebrates in woody debris were significantly and negatively correlated with wood density, indicating shifted macroinvertebrates communities in woody debris with the progress of decomposition. (3) The physical and chemical properties of woody debris (e.g., relative moisture content, total nitrogen, total carbon, and carbon nitrogen ratio), soil temperature and soil humidity were significantly correlated with the characteristics of macroinvertebrate communities in woody debris.
Conclusion: Our results highlight that the characteristics of macroinvertebrate community are different depending on the effect of tree species, diameter classes, and decomposition stages of woody debris. Preserving woody debris of both large and small diameter classes and those of different tree species in the subtropical forest can increase the biodiversity of macroinvertebrates.

Aim: Soil microorganisms are the main drivers of material cycling in urban park ecosystems, but there are few studies on the structure and function of forest soil bacterial communities in semi-arid urban parks.
Methods: In this study, three typical forest parks, Olympic Park (AL), Laodong Park (LD) and Aerding Botanical Garden (ZW) in Baotou City were selected, and the bacterial 16S rRNA V4-V5 regions were sequenced using Illumina high-throughput sequencing techniques to analyze the diversity, community composition and the mechanism underlying community assembly of bacteria. The metabolic functions of the bacterial community were also analyzed using Tax4Fun.
Results: The results showed that soil bacterial richness index were LD (2,443.00 ± 9.37) > ZW (2,392.90 ± 8.23) > AL (2,305.57 ± 17.48). Actinobacteriota, Proteobacteria, Acidobacteriota, Chloroflexi, and Gemmatimonadota were the dominant phyla. Bacterial community composition differed significantly among the three parks, and linear discriminant analysis effect size (LEfSe) results indicated that all parks harbored significant opertational taxonomic units in abundance. The neutral community model (NCM), normalized stochasticity ratio (NST), and the infer community assembly mechanisms by phylogenetic-bin-based null model analysis (iCAMP) showed that community assembly of bacteria in urban forests was determined by the combination of stochastic and deterministic processes, with drift and homogeneous selection being the dominant ecological processes. The results of Tax4Fun functional prediction indicated that metabolism involving membrane transport, carbohydrate metabolism, amino acid metabolism, energy metabolism and signal transduction were the main metabolic functions of soil bacteria in these urban parks, and further analysis showed that the metabolic functions of microbial communities differed across parks.
Conclusion: Our study investigated preliminarily the diversities, community assembly mechanisms and functions of bacteria in the semi-arid urban parks, which could provide basic data and scientific basis for urban park green space construction and ecological improvement.

Aims: The succession of southern subtropical forests can alter the composition of vegetation and soil environment, thus exerting a profound influence on soil biota. Consequentially, the changes in soil biota can then in turn influence the succession progress of the forest ecosystem. To date, the specifics related to the dynamics of soil biota during the succession of subtropical forests are not well understood. Here, we investigated the diversity and structural dynamics of the soil nematode community and associated it with environmental factors during the succession of forests (i.e., Pinus massoniana forest (PF)-mixed pine and broadleaf forest (MF)-monsoon evergreen broadleaf forest (MEBF)) in Dinghushan, Guangdong.
Methods: Soil samples from each forest were collected. The abundance, diversity, community composition, and ecological indices of soil nematode community as well as soil properties were analyzed and compared amongst different forests.
Results: (1) With the succession of southern subtropical forests, the α diversity of soil nematodes was significantly higher in MF and MEBF than that in PF; however, there were no significant changes in the total abundance of soil nematodes or the relative abundance of different trophic groups. (2) The enrichment index of soil nematodes in MF was significantly higher than that in PF, thus indicating higher soil fertility in MF, while the higher structural index in MEBF indicated a decreased disturbance degree of the ecosystem. (3) The soil moisture content and soil properties (excluding soil phosphorus levels) in MF were at the same level as that in MEBF while the soil pH was significantly lower than that in PF. The soil pH and soil moisture content were the predominant factors for the dynamics of the soil nematode community.
Conclusion: The responses of soil nematodes to vegetation succession are different in the abundance, diversity, and community composition, and the convergence of soil environment in the process of succession can explain the observed similarities in the nematode community between MF and MEBF.

Aims Extreme drought exacerbates the expansion of desert areas around the world. Microbial diversity is associated with multiple ecosystem functions in the desert. Evaluating the response of fungal communities to extreme drought is essential for our understanding of regional desertification caused by drought in a temperate desert.

Methods Based on three-year (D3) and ten-year (D10) drought plots established in the Gurbantunggut Desert, we investigated the effect of extreme drought on the diversity and ecological network of fungal communities.

Results Our results demonstrated that in both the D3 and D10 plots, the droughts had no significant influence on the Chao1 and Shannon diversity indexes of the whole and abundant fungi, while the rare fungal Shannon diversity index significantly increased. Both extreme drought treatments had a noticeable effect on community composition of whole, abundant and rare fungi, with stronger effect on rare fungi (ANOSIM, R = 0.378-0.595, P < 0.01) than that on the abundant fungi (ANOSIM, R = 0.282-0.555, P < 0.01), suggesting that abundant fungi were more resistant to drought than rare taxa. Moreover, beta-diversity of the whole, abundant, and rare fungi decreased significantly in D3 and D10 treatments, suggesting that extreme drought served as an ecological filter on fungal community assembly. Molecular ecological network analysis revealed that in both the D3 and D10 plots there was a reduced fungal network complexity, suggesting that extreme drought reduced the interactions among fungal communities. In addition, abundant fungi had higher node topological parameters (P < 0.05), indicating that abundant fungi were important for maintaining fungal species interactions under extreme drought conditions.

Conclusion Extreme drought significantly altered fungal community composition and weakened the interactions among fungal communities in a temperate desert. Furthermore, rare fungi were sensitive to extreme drought, contributing to reducing the lag in the response to fungal communities, and abundant fungi, as the core microflora in fungal networks, were crucial to sustaining the stability of fungal communities and interactions among species under extreme drought conditions.

Aims Glomalin related soil protein (GRSP) is a type of glycoprotein produced by arbuscular mycorrhizal fungi, playing a vital role in the regulation of soil physical structure and soil carbon stability. Previous studies have demonstrated the effects of soil physico-chemical properties on GRSP accumulation. To date, there is a lack of systematic research on how plant species composition of diversity and dominance affecting GRSP accumulation.

Methods A total of 72 plots in Harbin Experimental Forest Farm of Northeast Forestry University were surveyed in this study. The soil profile at 1 m depth was divided into five layers for soil sampling. Tree species diversity indices (Richness, Shannon-Wiener index, Simpson index, and evenness index) were calculated. The importance values (IVs) were calculated for dominant tree species according to the relative abundance, species frequency, and cross-area ratio to total stem cross-area. Soil physico-chemical properties were measured, including soil organic carbon (SOC), total nitrogen (TN), soil moisture content (MC), electrical conductivity (EC), and pH. All soil samples were assayed for easily extractable GRSP (EEG), total GRSP (TG), EEG/TG, EEG-C/SOC, and TG-C/SOC. The association between GRSP traits and soil physicochemical properties, IVs of dominant trees, and tree species diversity were ordinated using redundancy ordination (RDA) and variation partitioning analysis.

Results (1) TG and EEG correlated positively with SOC throughout the entire soil profile. The same was true with TN and MC at some soil depths, but the correlation was negative with EC and pH values. (2) In most soil layers, the greater EEG accumulation with higher EEG-C/SOC (proportion of C in EEG to SOC) and EEG/TG accompanied with the higher IV for Pinus tabulaeformisvar. mukdensis, but smaller IVs for Phellodendron amurense and Ulmus pumila. In contrast, the greater TG accumulation aligned with the higher IVs in Juglans mandshurica, P. amurense, and U. pumila but lower IVs in P. tabulaeformis var. mukdensis, Larix gmelinii and Pinus sylvestris var. mongolica. (3) The plant Simpson index, Shannon-Wiener index, and species richness correlated negatively (P < 0.05) with EEG-C/SOC, EEG-N/TN (proportion of N in EEG to TN), TG-C/SOC (proportion of C in TG to SOC), and TG-N/TN (proportion of N in TG to TN), and these indices had no relationship with EEG, TG, and EEG/TG. In addition, EEG/TG and EEG-N/TN correlated positively (P < 0.05) with plant evenness. These trends were similar across different soil layers in the 1 m profile. (4) RDA ordination and variation partitioning showed that biotic factors (plant diversity, IV of dominant species) explained 20.2% of GRSP variation, and soil factors explained 7.8%. Of the biotic factors, the IVs of the dominant plant species accounted for 16.4%, while species diversity only explained 0.4%. The evergreen coniferous species (eg, P. tabulaeformis var. mukdensisand P. sylvestris var. mongolica), rather than the broad-leaved species, usually accompanied the higher GRSP accumulation and contribution to SOC and TN (P < 0.01). The underlying mechanism contributing this difference possibly related to mycorrhizal symbiosis of trees, i.e., TG related negatively to ectomycorrhizal tree IVs, but related positively to arbuscular mycorrhizal tree IVs.

Conclusion Our findings highlighted that GRSP amounts and its contribution to soil carbon and nitrogen are mainly regulated by tree dominance rather than their diversity traits. This data underscored that GRSP-oriented soil management and evaluation can be promoted by adjusting the dominant species, a much simple indicator than species diversity indices.

Aims: The soil ecosystem includes a lot of animals with representatives from almost all major taxa of terrestrial animals and may stand for one quarter of all currently described biodiversity. Nevertheless, biodiversity loss of soil animals has become a serious problem for agricultural ecosystems globally, especially in China. Though many solutions have been proposed, this problem has not been effectively tackled. Constructing permanent plots and monitoring them long-term has been regarded as an important and effective method for solving the challenge of soil animal biodiversity loss. However, we still know little about the implementation protocol of scientific investigation and monitoring of a permanent plot of agricultural soil animals, until now.

Methods: We propose the implementation protocol for scientific investigation and monitoring of permanent plots of agricultural soil animals in this study. The plot establishment and field investigation design are conducted according to the field protocol of the 50-ha Forest Dynamics Plot on Barro Colorado Island (BCI), Panama. The field investigation and long-term monitoring are carried out according to prior research of forest and farmland utilizing large permanent plots of soil animal in China.

Results: First, we must confirm which scientific questions need to be solved and decide the basic principles to be observed for scientific investigation and monitoring in permanent plots of agricultural soil animals. Eighteen scientific questions have been proposed from a basic theory and practical application standpoint, and four basic principles have been proposed: integrating the needs and ideas of scientific research and agricultural practice, scientific setting and selecting monitoring indices, concerning spatio-temporal heterogeneity and detection probability of monitoring indices, and emphasizing the effects of agricultural productions and human activities. Second, we need to standardize the terminology for long-term investigation and monitoring, such as site, plot, square, sample and specimen. Sites and plots should be selected according to research objectives and study area, and priority should be given to sites that are representative of typical agricultural activities and regional climatic characteristics. Then, the large permanent plot of agricultural soil animal can be established in terms of BCI 50-ha field protocols. Third, focusing on soil animal biodiversity and its effects on agricultural ecosystem health and function, we need to carry out long-term monitoring for four-class and twenty-seven-item scientific indices. Moreover, the field investigation and laboratory experiment should be performed based on a unified and standardized workflow. For field investigation, the working processes include drawing detailed sampling point map, training all investigators, looking for and locating the permanent plot of agricultural soil animals in the field using GPS or other instruments, labeling the sampling points in the permanent plot, and collecting samples. For laboratory experiment, different extracting methods for soil animals should be used according to different taxa characteristics and research objectives. Finally, we need to identify, describe, and preserve specimens scientifically. Researching and developing database and management information system that encompass the characteristics of soil animal are recommended. This process will help with data invoking, checking, analyzing, and mining later.

Conclusion: This study systematically puts forward the implementation protocol of scientific investigation and long-term monitoring of permanent plots of agricultural soil animals. The implementation protocol can be widely applied to almost agricultural ecosystems in China and can be used effectively to investigate and monitor all taxa of soil animals. The results of this study will promote standardized plot construction and network monitoring in China, and globally, as well as provide reliable long-term scientific data support for the assessment and protection of agricultural soil animals in China.

Aims: Soil invertebrates have the potential to modify plant responses to drought stress. For example, some functional groups improve soil conditions via resource provision and water retention, potentially alleviating drought stress. This study was designed in order to mechanistically understand the functional roles of soil fauna in ecosystem services.
Methods: A pot experiment using tomatoes (Lycopersicon esculentum) was conducted in a greenhouse. This study adopted a complete factorial design that manipulated earthworm (Metaphire guillelmi) abundance and drought stress level.
Results: Our results indicate that earthworms promote plant drought resistance under high drought stress, which significantly up-regulated gene expression (NCED, NSY, OPR, AOS and LOX) of abscisic acid and jasmonic acid biosynthesis, promoted the accumulation of abscisic acid and jasmonic acid by 43.2% and 33.6%, up-regulated transcription factor expression, and increased the activities of catalase, peroxidase and superoxide dismutase by 12.9%, 8.4% and 47.3% in tomato shoots, respectively. However, under low drought stress, earthworms up-regulated jasmonic acid synthesis pathway gene expression, but reduced abscisic acid content, and had no significant effect on the expression of transcription factors ABF4 and MYC2 genes or plant antioxidant capacity.
Conclusion: The effects of earthworms on plant resistance depends on drought level. This study confirms the importance of soil invertebrates in plant drought resistance including the potential impact of earthworms on plant hormone synthesis, signal transduction, and antioxidant capacity.

Background & Aim: Since the Janzen-Connell (J-C) hypothesis was proposed half a century ago, a mounting number of studies have been conducted to test the hypothesis in tropical and subtropical forests. These studies have since greatly improved our understanding of how high biodiversity is maintained. In particular, the pathogenic fungi-induced J-C effect, a type of negative plant-soil feedback (PSF), has been well-recognized as a mechanism to maintain biodiversity and structure community composition, though the overall contribution of PSF to the persistence of a large number of rare species in nature remains controversial. As predicted by the modern species coexistence theory, the “invasion criterion” should be met for rare species to co-exist with other species such that one species will increase in abundance when rare. However, previous studies show results contrary to the prediction of such theory and have thus sparked debates on the mechanism underlying rare species maintenance.
Progresses: In this work, we review PSF and the potential factors associated with PSF, including mycorrhizal fungi, soil nutrient content, and fine root functional traits. We discuss their contributions in maintaining rare species and determining species abundance via PSF. In addition to PSF, some other perspectives about rare species maintenance are also covered in this review.
Prospects: We propose that the advantages in maintaining the long persistence of rare species and the limitations in restricting population expansion of rare species may be of equal importance for rare species. The combination of modern species coexistence theory and new techniques and methodologies provide promising future directions to fully understand rare species and to better conserve rare species in the future.

Aims Nematodes are considered as an important part of the soil food web, and their community characteristics are an effective indicator of soil health and ecosystem restoration. The accurate measurement of soil nematode communities is necessary to better understand their ecological function. Historically, comparisons in nematode morphology has been used to understand nematode community characteristics. In recent years, the use of high-throughput sequencing (HTS) methods has become more popular. However, relatively little is known about how these two methods compare when analyzing soil nematode communities.
Methods Here, we used morphological identification and HTS methods to simultaneously analyze soil nematode abundance, community composition and structure, and ecological indexes, under different vegetation restoration approaches (cropland, naturally restored grassland, Caragana korshinskiiplantation and Medicago sativaartificial grassland) in the mountain area of southern Ningxia in the Loess Plateau region.
Result We found that morphological identification is a more accurate method to determine the absolute abundance of soil nematodes, while HTS can only obtain relative abundance data. In our study, the morphological method showed higher abundance of soil nematodes in the sites under vegetation restoration, especially in the naturally restored grassland and C. korshinskiiplantation. The HTS method, on the other hand, detected more nematode genera (42 genera belonging to 3 classes, 4 orders, and 26 families) than morphological method (27 genera belonging to 2 classes, 3 orders, and 18 families). However, only 15 genera were simultaneously identified with both methods, because the HTS method detected more plant-parasitic nematode genera (22) but fewer genera of bacterial-feeding nematodes and omnivores-predators than the morphological method. One major result indicated by both methods showed that the relative abundance of microbial-feeding nematodes greatly decreased, while those of plant parasites and omnivores-predators substantially increased, in all the sites under vegetation restoration when compared with nematodes in the farmland. This was especially the case in the naturally restored grassland and C. korshinskiiplantation, accompanied with the increases of maturity index (MI) and plant-parasitic index (PPI) and a decrease in the Wasilewska index (WI). When compared with the morphological method, the HTS method could detect more abundant and diverse plant parasites. Therefore, more significant differences were found in the composition, structure and ecological indexes of soil nematode communities when the HTS method was applied.
Conclusion Overall, the characteristics of soil nematode communities and their response patterns to vegetation restoration highly depended on the applied methodology, which greatly influences the understanding and evaluation of how vegetation restoration impacts the soil ecosystem.

Aim: This study aims to clarify the response of soil bacterial species composition, pattern, and functional structure to a range of grassland degradation in alpine meadows.
Methods: Degraded alpine meadows at five stages (including non-degraded, light-degraded, moderate-degraded, severe-degraded, and extreme-degraded) were selected in 2017 by the classification standard in the Three-River-Source. Four different plots at each degraded stages were set as replications, and the area of each plot is about 80 m². Soil microbial characteristics were analyzed by high-throughput gene detection, and the soil physical and chemical properties were analyzed by conventional methods.
Results: Acidobacteria, Actinobacteria, Planctomycetes, Proteobacteria and Verrucomicrobia were the dominant bacteria in alpine meadow soil, accounting for 16%‒18%、9%‒12%、12%‒14%、23%‒29% and 11%‒12%of the total soil bacteria abundance, respectively. The soil bacterial species compositions changed substantially with increasing grassland degradation: Proteobacteria abundance decreased, while Acidobacteria and Planctomycetes abundance increased significantly with increasing degradation. Furthermore, the number of taxa (at the family level) differed across the diverse soil layers in degraded alpine meadows. Grassland degradation had no effect on bacterial diversity, as measured by the Chao1 index, but alpine medow that were lightly degraded increased bacterial diversity, as measured by the Simpson index. Soil bacterial diversity, as measured by the Shannon-Wiener index, was greatest in severe-degraded grasslands. The Faprotax functions were mainly composed by the processes of Chemoheterotrophy, nitrification, nitrite oxidation, and sulfur metabolism. Grassland degradation altered the carbon, nitrogen, sulfur, iron and manganese cycles, which were mediated by microorganisms. Severe and extreme degradation increased the bacterial ammonia-oxidizing function, and decreased the functions of sulfide, nitrite oxidation, and ureolysis. Across the gradient of grassland degradation, the bacteriological Chemoheterotrophy, aromatic compounds degradation, and the denitrification functions all initially decreased before subsequently increasing; moderate stages of degradation stage represented turning points of the bacterial community in terms of ecological functional structure changes.
Conclusion: Alpine meadow degradation altered the soil bacterial community and functional structures. The main driving factors for differences in soil bacterial community and functional structures were soil moisture content, pH, total organic carbon, total nitrogen, total potassium, and the ratio of available nitrogen and phosphorus.

Aims: Biological soil crusts (Biocrusts) are complex assemblages of lichens, bryophytes, cyanobacteria, fungi, and heterotrophic microbial organisms in the top few centimetres of desert soils. Biocrusts perform important ecological roles in the nitrogen cycle of desert ecosystems. In desert ecosystems, water sources are vital, and the seasonal melting snow in early spring resurrects biocrusts in the Gurbantunggut desert and begins nitrogen fixation. However, little is known about how biocrusts impact nitrifier distributions across the landscape, specifically ammonia oxidation archaea (AOA) and ammonia oxidation bacteria (AOB).
Methods: We used fluorescent quantative PCR (qPCR) methods to characterize AOA and AOB amoA gene abundances at different soil depths (0-2, 2-5, 5-10 and 10-20 cm) in biocrust and biocrust-removal soils. Desert nitrification potential and soil physicochemical parameters were researched to understand biocrust impacts on the desert soil nitrogen cycle.
Results: The AOA amoA gene abundance was remarkably larger than that of AOB across all soil samples. ANOVA results showed that biocrusts significantly affected AOA and AOB amoA gene abundance (P < 0.01) while PNR results indicated that biocrust removal significantly reduced soil nitrification potential (P < 0.001), which confirmed that biocrusts play an important role in regulating nitrogen transformation in the Gurbantunggut desert. A redundancy analysis confirmed that soil moisture and NH₄ ⁺-N were the key environmental factors affecting niche separation of AOA and AOB in desert soil.
Conclusion: Biocrusts coupled with oil moisture and NH₄⁺-N affected differential distribution of ammonia oxidizing microorganisms in the temperate desert in the early spring.

The effects of global climate change are a worldwide concern. Inner Mongolian grasslands which are sensitive to global climate change are not only the important foundation of livestock and forage products, but also have irreplaceable ecosystem functions. Soil microorganisms comprise a large proportion of Earth’s biodiversity and play vital roles in various ecosystem process including carbon and nitrogen cycles. Due to technological limitation and complicated community structure, soil microbial ecology research is currently at the descriptive stage and its theoretical research is still inadequate. Hence it is crucial to use molecular technologies, in particular the next-generation sequencing technology, to study the maintaining mechanism of soil microorganisms systematically in the Inner Mongolia grassland of China. Here we first review recent studies that compared the relative effects of different climate change factors on soil microbial community in Inner Mongolia grasslands. We then analyze the physiochemical and ecological mechanisms for the effects of different environmental changes on soil microorganisms. Finally, we highlight open questions for future research on soil microbial diversity under global change in Inner Mongolia grasslands. We recommend that future researches focus on (1) effects of multiple global change factors on soil microbial diversity; (2) ecological mechanisms that maintain soil microbial diversity; (3) relationships between aboveground and belowground biodiversity; and (4) integration research of multiple ecosystems globally.

Soil nematodes are key components in the soil food web, playing a crucial role in the regulation of nutrient cycling and energy flow. Many studies have documented the importance of the soil environment in regulating variation in taxonomic diversity over space and time, though little is known about how soil environment influences the functional diversity of soil nematodes. We investigated soil nematode communities in alpine meadows distributed on contrasting environmental regimes (valley floor, northern slope, southern slope, and ridge top) at each of three sites on the Tibetan Plateau. We examined the association between soil environmental factors and the functional diversity of soil nematodes using the community-weighted mean of body-size (CWM) and the Rao functional diversity of body-size (FD_Rao). Our results showed that the taxonomic diversity of soil nematodes increased significantly with soil pH while the functional diversity of soil nematodes is associated with soil fertility (i.e. CWM and FD_Rao are positively correlated with soil organic matter and nitrogen content while negatively with soil total phosphorus). Results also revealed that the abundance of bacterivores and fungivores are significantly greater in valley floor plots. The abundance of herbivores and omnivore-predators are lesser at ridge top plots, with abundance of most functional groups positively correlated with soil phosphorous content, but negatively with plant species richness. Our study suggests that soil nematode taxonomic and functional diversity exhibit a decoupled response to soil environmental factors, providing new insight into our understanding of biodiversity assembly in soil animals in Tibetan alpine meadows.