Soil Fauna Communities Research Articles

Macrofauna amplify plant litter decomposition and stabilization in arctic soils in a warming climate

The soil organic carbon (SOC) pool of the Arctic region is currently protected by low temperatures, but is likely to decrease due to greater organic matter (OM) decomposition under a warmer climate. Negative feedback for climate warming can, however, be reversed by SOC accrual as climate warming leads to shifts in arctic vegetation (from grass to shrub) and soil faunal (introduction of macrofauna) communities affecting plant-soil C allocation. To decipher these contrasting effects, we performed a laboratory experiment with soils from dry tundra to test the interacting effects of plant litter quality (high-quality grass litter vs. the intermediate- and low-quality litter of shrubs) and soil fauna functional grouping (micro-, meso- and macrofauna [millipede]) on the processes of litter decomposition and OM stabilization.Our findings showed that macrofauna largely promoted decomposition of shrub litter, while soil micro- and mesofauna were mainly responsible for the decomposition of grass litter. Our study thus confirmed that, when introduced and established in a warmer Arctic, macrofauna may become an important agent in shrub litter decomposition. Our data also showed that with shrub litter, higher C content was stabilized as particulate OM (POM) in aggregates, whereas in grass litter and low-quality shrub litter, higher C content was stabilized as mineral-associated OM (MAOM). Both these effects were larger in the presence of macrofauna and with a higher abundance of fungi. This suggests that consequent shrub OM stabilization in occluded POM and MAOM fractions will be carried out jointly by macrofauna and fungi, which will probably lead to more efficient OM stabilization in Arctic soils than in the case of grass litter OM stabilization by micro- and mesofauna and bacteria. In conclusion, our study suggests that vegetation changes and the introduction of macrofauna in a warming climate will most probably lead to higher OM stabilization in Arctic soils.

Effects of wild boar grubbing on the soil nematode community subject to seasonal variation in a broad-leaved Korean pine forest in Northeast China

Soil disturbances caused by large animals impact soil biodiversity and potentially alter forest ecosystem functioning and productivity. However, most studies have focused on the effects of wild boar infestations on above-ground vegetation and soil physical and chemical properties. Little is known about the influence of wild boar grubbing on the soil faunal community within forested ecosystems. To address this knowledge gap, we conducted a long-term (10-year) exclosure experiment to investigate the responses of soil nematode communities to wild boar grubbing and seasonal variations in a broad-leaved Korean pine forest in Changbai Mountain, China. The results indicated that wild boar grubbing did not significantly impact soil nematode abundance, genus richness, diversity indices (Shannon-Wiener diversity index, Simpson index, and evenness index), and ecological indices (enrichment index, channel index, structural index, and basal index). However, we observed that grubbing reduced the relative abundance of plant parasites while increased that of bacterivores and the maturity index (MI), leading to changes in nematode community composition. Notably, the influence of grubbing was more pronounced in the spring than in the autumn. Although season itself did not significantly affect soil nematode genus richness and diversity indices, it did affect soil nematode relative abundance, bacterivores, omnivores-predators, plant parasites, K-strategistis, r-strategistis, MI, enrichment index, and channel index. Long-term wild boar grubbing appeared to mitigate seasonal effects on soil nematode communities, resulting in higher MI and increased stability in nematode community abundance. Our findings suggest that changes in soil parameters, such as soil NH4+, soil pH, and soil NO3–, likely mediate the observed impact of wild boars on the soil nematode community. In summary, our study demonstrated that wild boar grubbing altered the structure of soil nematode communities, albeit with seasonal variations, indicating that the effects of wild boar activity on forest soil ecosystems influence biogeochemical cycles through changes in nematode community composition rather than nematode genera richness.

Responses of soil hexapod communities to increasing nitrogen in a subarctic grassland

The warming of boreal ecosystems accelerates decomposition and increases nitrogen (N) availability. The impact of increased N on subarctic soil fauna communities, however, remains poorly understood. We investigated the response of soil hexapods to a N addition experiment in a subarctic grassland. We characterized the soil hexapod communities using environmental DNA metabarcoding and analyzed the levels of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), microbial carbon (Cmic), and microbial nitrogen (Nmic). N addition increased DON and Nmic, while DOC and Cmic pools remained unchanged. Furthermore, N addition caused shifts in soil hexapod community compositional diversity between control and N plots in herbivore and microbivore taxa. The levels of DON and Nmic strongly correlated with these shifts, explaining 54% and 45% of the compositional variability, respectively. This study demonstrates a clear link between N availability and shifts in soil hexapod communities, associated to changes in microbial and dissolved N pools in subarctic grasslands.

Preliminary Study on the Diversity of Soil Oribatid Mite (Acari: Oribatida) Community Reveals Both Longitudinal and Latitudinal Patterns in Paddy Fields along the Middle and Lower Reaches of Yangtze River, China

Soil biodiversity plays an important role in maintaining soil fertility and agricultural health. Exploring the patterns of soil fauna diversity across geographical gradients is a fundamental and crucial scientific topic for understanding the mechanisms of soil biodiversity in farmlands. However, the spatial pattern of soil fauna diversity across longitudinal gradients has received far less attention. In order to explore the longitudinal pattern (west to east) of the composition and diversity of the soil oribatid mite community in paddy fields along the middle and lower reaches of the Yangtze River (MLYR), an investigation was carried out in July 2021 at nine sites spanning a longitudinal range of 8.86° (906 km) in southeastern China. In total, 19 taxa and 2392 individuals were observed with a density of 1535.47/m2. Protoribates and Ceratozetes were the most dominant and widely distributed genera along MLYR. The distribution patterns of the richness, abundance, and diversity index were obvious across the longitudinal and latitudinal gradients. The longitudinal pattern showed a quadratic distribution of first increasing and then decreasing, while the latitudinal pattern showed an increasing pattern with the increase in latitude (unimodal pattern). The influence of latitude on the abundance of the soil oribatid mite community was greater than that of longitude, and the influence of longitude on richness and the corresponding diversity index was greater. The dominance index did not show a distribution pattern in the longitudinal and latitudinal directions, while the evenness index showed only the distribution pattern in the longitudinal direction, and the latitudinal pattern was not significant. The results of this study suggest that the diversity of the soil oribatid mite community along MLYR displays both longitudinal and latitudinal patterns in paddy fields. Moreover, we highlighted the importance of integrating longitudinal and latitudinal patterns into spatial patterns of the soil fauna community in farmlands at a regional scale.

Neutral effect of nitrogen addition and negative effect of precipitation reduction on the soil faunal community in a temperate forest

ABSTRACT Nitrogen deposition can promote belowground soil carbon pools, and precipitation reduction can eliminate this positive effect. Soil fauna play crucial roles in regulating the dynamics of organic matter and maintaining biodiversity in ecosystems. However, it is not clear whether belowground soil fauna have similar responses to changes after long-term nitrogen deposition and drought. We simulated nitrogen deposition by applying fertilizer, and simulated drought by excluding 30% of the ambient precipitation in a temperate forest from 2009. Our results showed that experimental precipitation reduction alone significantly changed the composition and decreased the abundance of the soil faunal community. Precipitation reduction could also promote the soil food web in a fungal-dominated pathway by decreasing trophic groups of Isotomidae abundance. In contrast, although nitrogen addition treatment increased soil available nitrogen content, it had a neutral effect on the soil faunal community. Soil faunal community showed strong temporal variations in response to both nitrogen deposition and precipitation reduction treatments. Notably, interactions between precipitation reduction, nitrogen addition, and sampling time were significant for specific trophic groups, including saprozoites and omnivores. Shannon-Weiner diversity was not sensitive to these global change factors. Our results suggest that soil water content and plant richness may, directly and indirectly, regulate the soil faunal community.

Community structure of soil fauna under different tree species in subtropical forests

Soil fauna play an important role in key functions of ecosystem such as material cycling. Litter quality and microenvironment of different tree species may regulate soil fauna community structure. In this study, we investigated soil fauna community structure, the differences of taxonomic and functional groups, and the regulatory factors under eight dominant tree species in August 2022. We captured 567 soil fauna (except for termites and ants), belonging to 3 phyla, 10 classes, 26 orders, and 99 families, with Achipteriidae, Trygoniidae, Poduridae, and Isotomidae as the dominant species. Tree species significantly affected soil fauna abundance, following an order: Michelia macclurei > Elaeocarpus decipiens > Castanopsis carlesii > Cunninghamia lanceolata > Lindera communis > Schima superba > Pinus massoniana > Liquidambar formosana. However, the richness, evenness, and diversity of soil fauna under different tree species were significantly different. Richness and diversity of M. macclurei, C. lanceolatas soil fauna were relatively high, while L. formosana, C. carlesii were relatively low. The evenness of meso-microfauna of L. formosana was the highest, which was significantly higher than that of M. macclureis and E. decipiens. The evenness of macrofauna and total soil fauna was not significantly different among the eight tree species. In addition, the abundance of omnivores and herbivores soil fauna was relatively high under M. macclurei, but relatively low under E. decipiens. The abundance of saprophages and predators soil fauna of E. decipiens, M. macclurei was higher than L. formosana, while saprophages was mainly meso-microfauna. Results of redundancy analysis showed that litter N, C:N, and K were the main factors affecting soil fauna community structure. The results indicated that the tree species with thicker litter layer and higher N and K contents may be conducive to enhancing the diversity of soil fauna community and affecting the distribution of different functional groups, thus contributing to the maintenance of forest biodiversity.

Research Progress on the Decomposition Process of Plant Litter in Wetlands: A Review

Wetland is a transitional area where terrestrial ecosystems and aquatic ecosystems interact and influence each other, and it is an important ecosystem on the Earth’s surface. Due to the special characteristics of wetland ecology, the decomposition of wetland plant litter is slightly different from litter in forests, grasslands, and meadows and other traditional areas. The role of litter mineralization in the wetland ecological C cycle and the functional role of plant litter have been neglected. This study analyzes the decomposition mechanism and decomposition model of wetland litter material and focuses on the effects of the decomposition process of wetland litter material on the structure of the soil fauna community, decomposition of soil organic matter, sediment properties, and the dynamic changes in the C cycle of the biological system by combining domestic and international studies from recent years. Finally, we propose that the direction of future research on wetland litter decomposition should be to reveal the mechanism of wetland biodiversity and ecology, as well as the ecological correlation between aboveground and belowground biodiversity, with a view to providing a decision-making basis for wetland phytoremediation and wetland wastewater treatment.

Collembola community contains larger species in frequently flooded soil

Climate change is increasingly affecting biotic communities, including soil fauna. Extreme weather events such as the incidence of heavy rainfall or prolonged drought can cause strong fluctuations in soil moisture. In river floodplains such extreme events determine the flooding intensity of the river bank grassland soils, and their communities. The diversity and distribution of many soil fauna groups depends on soil moisture content, so changes in inundation frequency and duration will impact soil fauna communities. We used the natural fluctuations in water levels of large Dutch rivers to investigate the effect of flooding intensity on the composition and traits of Collembola species, a key group of the soil fauna community. At five locations along large rivers in The Netherlands, we sampled Collembola communities at six levels of decreasing elevation and increasing flooding intensity. We identified all Collembola to species level and calculated species richness, composition and abundance values. Moreover, to understand the observed taxonomic changes across elevation we used the traits body size and life form to explain the change in Collembola community composition. Our results show that high flooding intensity favors larger Collembola species in the community. We hypothesize that high soil moisture in frequently flooded soil favors larger Collembola, which tolerate flooding. Life form, i.e. the preferred depth in the soil column, was significantly correlated with flooding intensity. There is an optimum in species richness and abundance at intermediate flooding intensity. These results can help predict the impact of climate change on soil fauna.

Nitrogen-fixing tree species rather than tree species diversity shape soil nematode communities in subtropical plantations

Positive relationships between tree species diversity and soil communities are reported in many studies. However, the effects of tree species richness and nitrogen (N)-fixing tree species on soil fauna communities are not yet fully understood. Here, we conducted a field experiment to investigate changes in soil nematode communities under a gradient of tree species richness (e.g., 1, 2, 4 and 6 tree species) with N-fixing tree species (absence or presence). We found that N-fixing tree species strongly affected soil nematode trophic groups, and significantly increased the abundance of omnivore-predators and structure index via promoting more trophic links and multi-trophic interactions, leading to a more stable and complex soil food web. In the presence of N-fixing tree species, tree species richness significantly increased the abundance and relative abundance of fungivores and the channel index, with the shift in soil energy channel through increased the C/N ratio of leaf litter. In contrast, tree species richness detrimentally affected the abundance of plant parasites due to the decline of leaf litter N content under the presence of N-fixing tree species. The results revealed that the bottom-up effects of N-fixing tree species on soil nematode community structure were crucial drivers in shaping nematode communities in subtropical plantations. Our study suggests that N-fixing tree species is more important than tree species richness to regulate soil nematode community structure and soil energy channel, and therefore, should be preferentially considered in multispecies forest plantations.

Pesticide effects on soil fauna communities—A meta‐analysis

Abstract Soil invertebrate communities represent a significant fraction of global biodiversity and play crucial roles in ecosystems. A number of human activities threaten soil communities, in particular intensive agricultural practices such as pesticide use. However, there is currently no quantitative synthesis of the impacts of pesticides on soil fauna communities. Here, using a meta‐analysis of 54 studies and 294 observations, we quantify pesticide effects on the abundance, biomass, richness and diversity of natural soil fauna communities across a wide range of environmental contexts. We also identify scenarios with the most detrimental effects on soil fauna communities by analysing the effects of different pesticides (herbicides, fungicides, insecticides, broad‐spectrum substances and multiple substances), different application rates and temporal extents (short‐ or long‐term), as well as the response of different functional groups of soil animals (body size categories, presence of exoskeleton). Pesticides overall decreased the abundance and diversity of soil fauna communities across studies (Grand mean effect size (Hedge's g) = −0.30 +/− 0.16) and had stronger effects on soil fauna diversity than abundance. The most detrimental scenarios involved multiple substances, broad‐spectrum substances and insecticides, which significantly decreased soil fauna diversity even at recommended rates. We found no evidence that pesticide effects dampen over time, as short‐term and long‐term studies exhibited similar mean effect sizes. Policy implications: Our study highlights that pesticide use has significant detrimental non‐target effects on soil biodiversity, eroding a substantial part of global biodiversity and threatening ecosystem health. This provides crucial evidence supporting recent policies, such as the European Green Deal, that aim to reduce pesticide use in agriculture to conserve biodiversity. The detrimental effects of multiple substances revealed here are particularly concerning because realistic pesticide use often combines several substances targeting different pests and diseases over the crop season. We suggest that future guidelines for pesticide registration, restrictions and banning should rely on data able to fully capture the long‐term consequences of multiple substances for multiple non‐target species in realistic conditions.

Soil fauna community characteristics and driving factors of Pinus tabuliformis in the loess region of northern Shaanxi

This study aimed to examine the characteristics and regulatory mechanisms of the soil fauna community in Pinus tabuliformis plantations at different restoration ages. The study was conducted on the soil fauna of Pinus tabuliformis in different restoration ages (6a, 11a, 18a, and 22a) in Wuqi County. Soil fauna, soil samples, understory herb biomass were collected in the spring, summer, autumn and winter of 2021. The relationship between the soil fauna community characteristics and environmental factors were studied. The results are as follows: (1) The density increased and the number of species decreased in the soil fauna community with an increase in restoration ages, and the composition and structure of the soil fauna community were significantly different at different restoration ages. (2) The diversity of the soil fauna community was highest and the soil food web was the most stable in 6-year-old Pinus tabuliformis plantations. Followed by a 22-year-old Pinus tabuliformis plantation. The lowest soil fauna diversity and the least stable food webs were found at 11- and 18-years-old of Pinus tabuliformis plantations. (3) The understory herb community had the greatest impact on the composition and structure of soil fauna community. SOM, NCP and NHS were the main factors affecting the composition of the soil fauna community. (4) During the restoration of Pinus tabuliformis plantations, the soil fauna community is mainly controlled by the top-down food resources, and the understory herb community driven the evolution process of the soil fauna community, thereby regulating the soil food web. Our research results emphasize the importance of sub-forest herbaceous vegetation to soil animals, which is essential for the formulation of sustainable biodiversity conservation policies for planted forest ecosystems.

Impacts of long-term organic production on soil fauna in boreal dairy and cereal farming

Intensified arable farming results in fewer functional groups of soil biota with decreased biodiversity. Organic farming with slurry fertilization and long crop rotation cycles favors soil fauna diversity under tropical and temperate conditions. Faunal responses to agricultural practices in northern latitudes may, however, differ from those in southern latitudes due to different soil types, climatic conditions, and intensity of management. We investigated the abundance and diversity of soil fauna communities (nematodes, microarthropods, enchytraeids and earthworms) in a boreal sandy soil in replicated organically and conventionally cultivated field blocks that simulated cultivation in a cereal farm and in a forage producing dairy farm. In addition to traditional methods, we investigated nematode diversity using DNA metabarcoding. The results show that organic production system did not unequivocally result in higher abundance and diversity of soil fauna compared with conventional production systems, neither in the cereal nor the dairy farming type. Instead, abundances of all soil fauna groups were typically higher in the dairy than in the cereal farming type irrespective of production system. This holds up for all functional groups of nematodes except omnivores, all four orders of Acari present, two out of the six families of Collembola, the total number of enchytraeids and density of earthworms. Nematode diversity, measured as average ZOTU number, was in conventionally cultivated cereal farming type an order of magnitude lower than in other production and farming type combinations. Of the various differences between farming types, the crop species was the most important one as it defines the management practice and thus the soil conditions where soil biota lives. Our findings underline that when comparing soil faunal communities under organic and conventional cultivation, the differences between farming types need to be considered in addition to the production system as they can have an overriding importance across the food web.

Diversity of medium and small-sized soil fauna community in different urban-rural green spaces and its influencing factors in Nanchang, China.

Urbanization is one of the important factors leading to biodiversity loss and habitat fragmentation. As an important component of urban ecosystem, soil fauna community plays a key role in improving soil structure and fertility, and promoting material circulation of urban ecosystem. To investigate the distribution characteristics of medium and small-sized soil fauna community in green space and the mechanisms underlying their responses to environmental change during urbanization, we selected 27 green space plots with a gradient of urban, suburban, and rural areas in Nanchang City as study objects, and measured plant parameters, soil physicochemical properties, and distribution characteristics of soil fauna community in these plots. The results showed that a total of 1755 soil fauna individuals were captured, belonging to 2 phyla, 11 classes, and 16 orders. The dominant groups were Collembola, Parasiformes, and Acariformes, which accounting for 81.9% of total soil fauna community. The density, Shannon diversity index, and Simpson dominance index of soil fauna community were significantly higher in suburban area than those in rural area. In the green space of the urban-rural gradient, there were large structure variations in different trophic levels of medium and small-sized soil fauna community. Herbivores and macro-predators occupied the largest proportion in rural area, and less in other areas. Results of the redundancy analysis showed the crown diameter, forest density, soil total phosphorus contents were the main environmental factors affecting soil fauna community distribution, with interpretation rate of 55.9%, 14.0% and 9.7%, respectively. Results of the non-metric multidimensional scale analysis showed that there were variations in soil fauna community characteristics in green space of the urban-rural gradient, and that the aboveground vegetation was the dominant factor for this change. This study improved our understanding of urban ecosystem biodiversity in Nanchang, and provided basis for maintaining soil biodiversity and urban green space construction.

Responses of soil fauna community under changing environmental conditions

Soil faunas account for 23% of known animal species and play a crucial role in ecosystem processes such as mineralizing nutrients, regulating microbial community composition, forming soil aggregates, and enhancing primary productivity. However, due to global climate change, population density, community composition, and distribution patterns of soil fauna vary. Understanding the responses of soil fauna to major environmental change facilitate the conservation of biodiversity. Therefore, a review work of recent researches for analysing the effects of key environmental factors on soil fauna, such as warming, drought, food quality, and soil physical-chemical properties was studied. For most species, warming may exert a positive effect on their abundance and population development, however, it can inhibit the survival and reproduction of hibernating species. Drought leads to low soil porosity and water holding capacity, which reduces soil fauna population and changes their community composition. Drought also can reduce the coverage of flora and alter microclimate of the soil surface, which in turn indirectly reduces fauna abundance. Climate warming and elevated atmospheric carbon dioxide can reduce litter quality, which will force soil fauna to change their dietary choices (from higher-quality foods to poor quality foods) and reduce reproduction for survival. However, it is still predicted that enhanced species richness of plant (or litter) mixtures will positively affect soil fauna diversity. Habitat loss caused by the deterioration of soil physical-chemical property is primary factor affecting soil fauna. We mainly discuss the threats of increased salinity (a major factor in arid land) to soil fauna and their potential responses to anthropogenic disturbance in saline soils. The increase in soil salinity can override other factors that favour habitat specialists, leading to negative effects on soil fauna. Moreover, we find that more studies are needed to explore the responses of soil fauna in saline soils to human activities. And the relationship of important ecological processes with soil fauna density, community structure, and diversity needs to be redefined.

Large-scale experimental warming reduces soil faunal biodiversity through peatland drying

Boreal peatlands are important ecosystems for carbon cycling because they store 1/3 of the world’s terrestrial carbon in only ∼3% of the global landmass. This high carbon storage capacity makes them a key potential mitigation strategy for increased carbon emissions induced by global climate warming. In high-carbon storage systems like peatlands, soil faunal communities are responsible for secondary decomposition of organic matter and nutrient cycling, which suggests they play an important role in the carbon cycle. Experiments have shown that warming can affect plant and microbial communities in ways that potentially shift peatlands from carbon sinks to sources. Although previous studies have found variable effects of climate change manipulations on soil communities, warming is expected to affect soil community composition mainly through reductions in moisture content, whereas elevated CO2 atmospheric concentrations are expected to only indirectly and weakly do so. In this study we used a large-scale peatland field-based experiment to test how soil microarthropod (oribatid and mesostigmatid mite, and collembolan species abundance, richness and community composition) respond to a range of experimental warming temperatures (between 0°C and +9°C) crossed with elevated CO2 conditions over 4 years in the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment. Here we found that warming significantly decreased surface peat moisture, which in turn decreased species microarthropod richness and abundance. Specifically, oribatid and mesostigmatid mite, collembolan, and overall microarthropod richness significantly decreased under lower moisture levels. Also, the abundance of microarthropods increased under higher moisture levels. Neither warming nor elevated [CO2] affected microarthropods when analysed together or separate, except for the richness of mesostigmatids that significantly increased under warming. At the community level, communities varied significantly over time (except collembolans), and moisture was an important driver explaining community species composition. While we expect that the cumulative and interactive effects of the SPRUCE experimental treatments on soil faunal biodiversity will continue to emerge, our results already suggest effects are becoming more observable over time. Taken together, the changes belowground indicate potential changes on carbon and nitrogen cycles, as microarthropods are important players of soil food webs.

Soil fauna effects on litter decomposition are better predicted by fauna communities within litterbags than by ambient soil fauna communities

Soil fauna effects on litter decomposition are better predicted by fauna communities within litterbags than by ambient soil fauna communities

Fertilization alters the abundance but not the diversity of soil fauna: A meta‐analysis

AbstractAimSoil fauna, a functionally important group of soil organisms, are greatly affected by fertilization. However, it is still debated whether and how fertilization affects the soil faunal community. Here, we aimed to synthesize the global patterns of soil fauna communities in response to fertilization in terrestrial ecosystems.LocationGlobal.Time period1997–2021.Major taxa studiedSoil fauna.MethodsWe examined the effects of fertilization on the abundance, number of groups and Shannon diversity of soil fauna by synthesizing 1218 observations based on 39 published studies. We also explored the associations between fertilization‐induced changes in the soil faunal community and changes in soil and microbial properties.ResultsFertilization increased the abundance of soil fauna by 56.3%, without significantly affecting the number of groups and the Shannon index. The type of fertilizer affected the responses of soil faunal abundance, and the effects of fertilizer type were altered by climate zones, ecosystem types and soil depths. Both organic and organic–mineral fertilizer treatments significantly increased the abundance of soil fauna in most climate zones, ecosystem types and soil depths, whereas mineral fertilizer treatment had no such effect. Additionally, we found inconsistent responses of soil fauna to fertilization among different taxonomic groups, not only at the order level but also at the class level, providing evidence for the idiosyncratic nature of the effects of fertilization on soil fauna. Furthermore, our regression analysis showed that changes in food resources, including soil nutrients and microbes, were crucial controls for the response of soil faunal abundance to fertilization.Main conclusionsFertilization generally increased soil faunal abundance at the global scale by affecting food resources, and the effects of fertilization were dependent on the specific soil fauna and type of fertilizer. We suggest the use of organic or organic–mineral fertilizers, rather than mineral fertilizers, to increase the benefits on specific soil fauna.

Environmental Effects on Taxonomic Turnover in Soil Fauna across Multiple Forest Ecosystems in East Asia.

The large-scale spatial variation in and causes of biotic turnover of soil fauna remain poorly understood. Analyses were conducted based on published data from 14 independent sampling sites across five forest ecosystems in East Asia. Jaccard and Sørensen's indices were used to measure turnover rates in soil fauna orders. A redundancy analysis was used to investigate multiple environmental controls of the composition of soil fauna communities. The results showed that both Jaccard's and Sørensen's index increased significantly with increasing latitude difference. The environment explained 54.1%, 50.6%, 57.3% and 50.9% of the total variance, and spatial factors explained 13.8%, 15.9%, 21.0% and 12.6% of the total variance in the orders' composition regarding overall, phytophagous, predatory and saprophagous fauna, respectively. In addition, climate factors in environmental processes were observed to have a stronger effect than soil factors on the orders' turnover rates. Our results support the hypothesis that the effect of environment factors on soil animal taxa turnover is more important than the effect of spatial factors. Climatic factors explained more variation in the turnover of phytophagic fauna, but soil and environment factors equally explained the variation in the turnover of predatory fauna. This study provides evidence to support both environmental filtering and dispersal limitation hypotheses at the regional and population scales.

Soil faunal communities in mass outbreak areas of the great web-spinning sawfly Acantholyda posticalis (Mats.) are impoverished compared to pest-free Scots pine forests

Mass outbreaks of pests defoliating Scots pine monocultures are of constant concern to foresters, and the increase in their frequency under conditions of a warming climate is expected. Repeated mass outbreaks usually involve the same areas, which suggests that predispositions to pest attack are shaped by certain stand characteristics or their habitat conditions. The aim of the study was to examine whether the soil invertebrate communities of pine forests with A. posticalis mass outbreaks differ from those of stands with no mass occurrence of this pest, despite analogous stand-habitat conditions and close proximity. Pine monocultures in two regions of Poland differing in the timing of the pest's mass occurrence were selected for the study. The soils of the studied monocultures, both in outbreak areas and reference tree stands, were characterized by strong acidity and low nutrient status. A lower (soil invertebrate communities) and a higher (Collembola communities) taxonomic resolution were used to assess the differences between the soil fauna of infected and reference stands. We show that soil invertebrate communities of the mass outbreak areas were characterized by impoverishment compared to those of reference forests. However, both invertebrate and Collembola communities, which in outbreak areas consisted of fewer taxa, did not differ significantly in density from reference tree stands. Nonmetric multidimensional scaling (NMDS) ordination of the collembolan communities revealed that not only their composition but also their structure in the mass outbreak areas differed significantly from those of uninfected tree stands. Further research is needed to clarify whether the depletion of soil invertebrates is a result of foliar insect feeding, or is rather a manifestation of weakened stands increasing their predisposition to attacks by pest insects.

Land-Use Types Influence the Community Composition of Soil Mesofauna in the Coastal Zones of Bohai Bay, China

Soil faunal communities play key roles in maintaining soil nutrient cycling. Affected by different land-use types, soil environment and soil faunal communities change significantly. However, few studies have focused on the aforementioned observations in coastal zones, which provide suitable habitats for many species of concern. Here, we investigated the changes in soil mesofaunal communities under different land-use types, including cotton fields, jujube trees, ash trees, a saline meadow, and wetlands. The variations in land-use types affected the community composition and diversity of soil mesofauna in the coastal zones. The taxa of soil mesofauna had different responses to land-use types in the coastal zones. Isotomidae was regarded as an indicator taxon of the coastal cropland regions. Entomobryidae was considered to be an indicator taxon of coastal artificial trees. Meanwhile, Onychiuridae and three taxa (Brachycera, Armadillidiidae, and Gammaridae) were indicator taxa of the coastal terrestrial ecosystem and the coastal wetland ecosystem, respectively. Thus, we suggested that specific soil mesofaunal taxa were considered to be appropriate bioindicators for land-use types in the coastal zones. The results of this study were helpful to develop guidelines for coastal biodiversity and ecosystem conservation in the future.