Applied Soil Ecology最新文献

Earthworm communities within urban environments remain an intriguing subject. This study aims to unravel the intricate relationship between these communities and the heterogeneous urban soils they inhabit. Urban soils, shaped by past and present human activities, harbor a rich diversity of earthworms, yet the specific factors influencing these communities remain poorly understood.

Earthworm communities were sampled across 13 urban parks of Montpellier, a Mediterranean city in France. The effect of four variables at two scales were assessed: (i) landscape attributes within a 100-meter radius surrounding each sampling point and (ii) site-specific factors, including soil properties such as organic carbon content and pH levels, soil age, and management practices. Variation partitioning was employed through partial canonical correspondence analysis in order to disentangle the effects of these variables on earthworm community composition.

A total of 16 species were identified out of 1270 individuals collected. Most are ubiquist, with a limited number being endemic to the Mediterranean region, potentially indicating biotic homogenization due to urbanization. In addition, multivariate analyses emphasized the substantial influence of landscape characteristics, composed by the rate of green spaces and the number of patches. These landscape-level attributes and especially the connectivity of green spaces emerged as primary drivers, surpassing the influence of management practices, soil age and soil properties.

Thus, this research underscores the importance of considering diverse scales, and particularly landscape-level factors, in comprehending and restoring soil fauna such as earthworm communities within Mediterranean urban parks.

Climate change causes temperature increase and alteration of precipitation patterns with frequent droughts. These are known to influence soil microorganisms leading to community shifts and physiological adaptations, with consequences for biogeochemical cycles. However, whether soil microbial communities evolved at different average temperature differ in their response to drought is not well understood. Therefore, we collected ten soil samples per site (0–30 cm soil depth) from a walnut-fruit forest at 1000, 1300 and 1600 m above sea level with similar vegetation which represent average temperature differences of 1.3 °C between sites, mimicking potential climate change. We incubated these for 70 days at 22 °C either at (i) constant moisture of 50 % soil water holding capacity, or subjected them to (ii) two or (iii) three drying-rewetting (DRW) cycles. Respiration was measured during the incubation; microbial and chemical properties were determined at the end. No elevation specific or interactive effects with DRW were detected, except for fungal gene abundance, where values were highest at the intermediate elevation level. This reveals that soil microbial communities evolved at different average temperature regimes do not differ in their response to drought. Therefore, data were pooled across all sites and analyzed for the main effects of DRW. Microbial activity increased with DRW as reflected by enhanced net‑nitrogen mineralization and basal respiration. However, microbial biomass carbon and ergosterol were reduced by 20 and 25 % and bacterial gene abundance between 20 and 40 %. This reflects the strong osmotic pressure of DRW causing death of microbial cells. The higher maintenance requirements for cell adjustment to osmotic pressure of surviving microorganisms was revealed by an increase of the metabolic quotient qCO₂ by 60 % and accumulation of potassium in the microbial biomass. Fungi cope better with DRW as shown by higher fungal gene abundance as well as their ratio to ergosterol after DRW, reflecting shifts in cell volume due to community shifts or morphological adaptations. Our findings highlight that soil microbial communities evolved under different average temperature regimes respond similarly to DRW, but overall shift towards fungi as this taxon can potentially physiologically better adapt to osmotic pressure. Consequently, DRW may cause higher organic matter turnover and nutrient release due to higher microbial maintenance costs for osmotic cell adjustments.

Wildfire represents a significant natural disturbance factor in forest ecosystems expected to further increase in importance due to global climate change. It has a detrimental short-term impact on soil biota, but much less is known about its long-term effects, especially on soil mesofauna. Our study compared oribatid assemblages of the forest floor in moderately-burned forest sites along a post-fire chronosequence (8 fire history classes covering 0–110 years since fire) with near-by reference sites without fire history. All sites were situated on acidic soils in the Central European Elbe Sandstone Mountains (Bohemian Switzerland National Park, NW Czechia), mostly covered by pine and spruce forests. Data were analysed using linear mixed-effect models. We found a substantial impact of fire on oribatid assemblages. Whereas lower densities were observed for the first few years after a fire only, changes in assemblage feeding guilds persisted over at least four decades. Shifts towards smaller body size, parthenogenesis and fungivory at burned sites compared to larger body size, sexual reproduction and detritivory in unburned controls implied changes in assemblage functioning. The changes in functional traits, which correspond to previous research findings on the recovery of oribatid mites after clear-cutting, underscore a more universal pattern of post-disturbance development.

Crop diversification tends to favor the soil fauna community, soil aggregation, and consequently soil organic carbon (SOC) stock. Understanding the association between these attributes can help in understanding the dynamics of physical protection of soil organic matter. In this context, our study aimed to answer: (1) how does the edaphic macrofauna community and soil carbon and aggregate classes respond to two types of coffee agroforestry systems (coffee with Grevillea robusta and coffee with banana) and how these responses differ from native ecosystem; (2) how and to what extent are soil aggregation regulated by the complex structural interactions of plant residue input, SOC, and the soil faunal community? The work was conducted in the municipality of Planalto, state of Bahia, Brazil. Three systems were evaluated: agroforestry system of Coffee arabica L. with Grevillea robusta (CG); agroforestry system of Coffee arabica with Musa spp. (CB); and native forest (NF). Four plots were delimited in each system, in which dry fractionation of the soil was performed to obtain aggregates of classes >6, 6–4, 4–2 and < 2 mm. The macrofauna was sampled using the Tropical Soil Biology and Fertility Program method. The labile and total carbon of the soil and aggregates were determined and the carbon management indices were calculated. The CG and CB presented a greater amount of larger size aggregates (> 6, 6–4 and 4–2 mm) than the NF. The CB system provided more favorable conditions for the soil macrofauna. Despite this, both coffee agroforestry systems favored the occurrence of Oligochaeta. The CG was more favorable to maintain labile fractions of organic matter than the CB. The edaphic fauna show a close relationship with the formation of carbon aggregates and stabilization which was directly influenced by continuous input of plant residues in diverse coffee growing systems.

Litter input is crucial for enhancing carbon sequestration in karst ecosystems. While previous studies have linked litter input to carbon storage in karst soils, the unique conditions of southwest China’s karst regions, characterized by high precipitation and rapid groundwater dynamics, pose challenges to understanding dissolved organic carbon (DOC) migration under litter cover. This study investigated how different litter types from karst-adapted vegetation affect DOC migration and loss in karst soils, addressing the gaps in carbon sequestration evaluations during vegetation restoration. Artificial soil columns were used to monitor the natural rainfall over one hydrological year. The results indicated that litter cover increased the soil carbon dioxide (CO₂) concentration and enhanced DOC leaching and migration, with the highest DOC loss observed in the tree litter treatment (2614.50 mg) and the lowest in the shrub litter treatment (1844.13 mg). These differences were attributed to the synergistic interaction between rainfall and litter characteristics, which accounted for 29.94 % of the variation in soil DOC leaching after litter input. Regression analyses indicated that DOC leaching under litter cover was mainly affected by the soil CO₂ concentration, temperature, humidity, rainfall, and litter decomposition duration. In summary, litter cover significantly intensified DOC migration and loss in karst soils. This study provides valuable insights into vegetation restoration and reconstruction, particularly in karst regions.

Soil-dwelling invertebrates, found worldwide, are essential for decomposition of plant litter and other soil processes, requiring adaptations to changes in the climate. The microbiota associated with these animals profoundly impacts their health and fitness. While seasonal changes have been shown to shape vertebrate microbiota, the microbiota of arthropods adapted to winter remains unknown. In this study, we investigated microbiota of two Collembola species with different overwintering strategies, Tomocerus cf. jilinensis and Tomocerus nigrus, in summer and three different periods in winter (early, mid, and late winter) using 16S rRNA gene amplicon sequencing. The results reveal pronounced alterations in microbial diversity and composition of the Collembola driven by seasonal variations and temperatures. Collembola associated microbiota exhibited higher Shannon diversity during mid and late winter. Furthermore, early, mid, and late winter periods were characterized by an enrichment of representatives from Hungateiclostridiaceae, Pseudomonas, and Pedobacter, respectively. Distinct seasonal patterns in microbiota were observed across different Collembola species. Bacterial community networks in winter Collembola were predominatly marked by positive interactions. Ground temperature exhibited a negative correlation with the Shannon index of Collembola-associated bacteria and the relative abundance of Comamonadaceae, Renibacterium, Mycobacterium, Sphingomonas, and Aeromicrobium. Our study indicates that season alters Collembola associated microbiota and these microbial changes could facilitate Collembola activity in low temperatures. Overall, our study extends our knowledge of symbiotic relationships between winter-adapted animals and their microbiota.

Investigating rhizosphere communities in saline soils is crucial for identifying the taxonomic groups that play significant roles in halophyte adaptation. However, how the microbiome is structured under different saline conditions remains unclear. This study aimed to analyze bacterial communities in the rhizospheres of halophyte species in different saline environments. Five rhizospheres were analyzed using high-throughput sequencing of the 16S rRNA gene: S1, Salicornia fruticosa from a hypersaline tidal plain; S2, Sporobolus virginicus; S3, Cyperus ligularis from a hypersaline lagoon; S4, Salicornia fruticosa and S5, Blutaparon portulacoides from an abandoned salt pan. Bacterial communities in the S4 and S5 rhizospheres were influenced by P and K content, suggesting that specific nutrients can foster unique microbial structures, potentially assisting in adaptation to saline soils. The unique ASV (Amplicon Sequence Variant), richness, diversity, and microbial core of the S1 system, along with its similarities to S2 and S3, suggest common halophyte adaptation strategies across different saline environments, aiding targeted survival efforts. Identifying keystone species such as Thermoleophilia in S1, Alphaproteobacteria in S2 and S3, multiple species in S4, and the presence of Clostridia and Bacilli in S5 shed light on the roles these bacteria play in halophyte survival. Metagenomic prediction analysis demonstrated that chemoheterotrophy and aerobic chemoheterotrophy were the main prediction functions. In summary, this study revealed the intricate microbial structures in halophyte rhizospheres, enriching our understanding of saline ecosystems.

Legumes in cropping sequence can strongly moderate soil biodiversity and its biochemical status, which could influence soil fertility and productivity. However, their impact on soil microbes and their relationships with soil chemical variables during the subsequent crop growth is not understood enough. In this study, we analyzed the changes in bacterial and fungal communities structure through 16S rRNA and ITS amplicon sequencing, respectively, across crop rotation with faba bean (faba bean-wheat-triticale, F) and without faba bean (wheat-wheat-triticale, W). Rhizosphere and bulk soil samples were taken during the triticale growth stages (stem elongation and maturity). Soil enzymatic activity and chemical properties were also determined. Study factors (crop rotation, soil compartment, growth stage) affected N, C, and P transformations, as indicated by the activity of soil enzymes, and F was more beneficial than W for protease, urease, and acid phosphomonoesterase activities, as opposed to cellulase activity. Changes in the chemical properties led to the shift in soil microbial communities with different bacterial and fungal communities' responses. F treatment enhanced the abundance of the bacterial genera representatives such as Streptomyces and Candidatus Udaeobacter while suppressing the abundance of Jatrophihabitans and Terrabacter. Crop rotation significantly influenced fungal genera and a greater abundance of Helgardia, Pseudogymnoascus, Monocillium, Fusarium, Chaetomium, and Vishniacozyma under F than W was noted and the adverse situation was noted for Peziza and Rhizopus. Rotation type significantly affected the alfa-diversity of the fungal, but not bacterial community. Beta-diversity analyses (nMDS, cluster) indicated that the main factor grouping samples were soil compartment and growth stage for the bacterial and fungal microbiome, respectively. The PERMANOVA results revealed significant effects of all factors on bacterial and fungal microbiomes. Different soil chemical variables governed bacterial and fungal communities. C_org, pH, P, Mg, and C_org, pH were the most important soil factors regulating bacterial and fungal community structure by crop rotation, respectively. Bacterial and fungal communities were more related to the content of N_tot in rotation with than without faba bean. The findings of this study contribute to a deeper insight into the relation between the faba bean in cropping sequence and soil microbiome, and modulation crucial soil conditions for the productivity of the successive crop.

The effects of continuous planting on the growth of Casuarina equisetifolia (C. equisetifolia) have severely restricted the sustainable development of the industry. In this study, we investigated the diversity and functional changes of bacteria and fungi in the rhizosphere soil of continuously planted C. equisetifolia and their effects on soil nutrient transformation and C. equisetifolia growth. The results showed that after continuous planting, C. equisetifolia growth was significantly inhibited, the activities of nutrient transformation-related enzymes in rhizosphere soil were reduced, available nutrient content of the soil decreased, and soil bacterial diversity decreased, while fungi diversity increased. After continuous planting, 9 genera of significantly altered characteristic bacteria in the rhizosphere soil of C. equisetifolia were functionally enriched in animal parasites or symbionts, aromatic compound degradation, and nitrate reduction, with contributions mainly from the 3 characterisic bacteria such as Planctopirus, Bacillus, and Acinetobacter. After continuous planting, 7 genera of significantly altered characteristic fungi in the rhizosphere soil of C. equisetifolia were functionally enriched in soil saprotroph, lichen parasite, undefined saprotroph, endophyte, animal pathogen, wood saprotroph, litter saprotroph and plant pathogen, with contributions mainly from the 6 characteristic fungi such as Aspergillu, Fusarium, Saitozyma, Tolypocladium, Mortierella, and Funneliformis. Functional analysis and PLS-SEM equation analysis showed that the growth inhibition of C. equisetifolia due to continuous planting was the result of the joint action of the characteristic bacteria and fungi, but there was a difference between the functions of the two. The function of characteristic bacteria was mainly to provide conditions for the propagation of pathogenic organisms, which reduced soil nutrient content and hindered nutrient uptake by C. equisetifolia. The function of characteristic fungi was primarily to damage soil texture, nourish pathogenic bacteria to infest C. equisetifolia, and damage the root system to inhibit nutrient uptake. Characteristic bacteria and fungi together accelerated the effect of continuous planting on the growth of C. equisetifolia. This study provides an important reference for the cultivation regulation of continuously planted C. equisetifolia.

In an agricultural context, the use of conventional low-density polyethylene (LDPE) and biodegradable plastic mulch film has been actively promoted, however, the effects on physical and biochemical soil properties, crop growth dynamics, yield, and nutrient cycling of conventional and biodegradable mulch film use in a temperate climate remain largely undetermined. Here, we conducted a field experiment, exploring the effects of no mulch (control), conventional (LDPE), and biodegradable (PLA/PBAT) plastic mulch film on soil and crop (Zea mays L.) nitrogen (N) partitioning after application of ¹⁵N-labelled ammonium-nitrate fertiliser. Further, we also investigated the treatment effects on soil physical and biochemical properties (e.g., microbial diversity, compound-specific microbial ¹⁵N incorporation, N dynamics), plant development, as well as monitoring the biotic and abiotic degradation of the plastic mulch films. We found that conventional mulch film increased crop yield by 25 % and ¹⁵N uptake by 34 % compared to the control, simultaneously reducing ¹⁵N retention by 40 % in the topsoil (0–10 cm), but not affecting microbial N use efficiency and N transformation and incorporation into the protein pool. Biodegradable film application resulted in similar biomass (306 ± 14 g plant⁻¹) to both control (275 ± 14 g plant⁻¹) and conventional mulch (344 ± 20 g plant⁻¹) treatments, but significantly reduced ¹⁵N crop uptake by 63 % compared to the conventional mulch film. We ascribe this to the accelerated mechanical breakdown and faster degradation of the biodegradable mulch film during the growing season. These findings suggest that current biodegradable plastic mulch film polymer blends may not be a suitable alternative to conventional mulch film in terms of short-term productivity and N use efficiency in a temperate climate for maize production.