Applied Soil Ecology最新文献

Climate change is changing the elevational pattern of soil fauna in the mountain system, leading to their upward invasion process. Earthworm invasion activity contributes to greenhouse gas emissions and soil nutrients. However, the effect of earthworm invasion on gas emission, and the contributions of interaction with litter have not been clearly understood. In this study, we conducted a microcosm study of soil samples collected from four vegetation zones in Changbai Mountain to determine the effect of earthworms, litter, and their interactions on soil CO₂ and N₂O emissions. Soil samples were incubated in the laboratory at the average soil temperature in each vegetation zone during summer for 71 days. Our findings indicate that the CO₂ gas emission rate (RCO₂) first increased and then decreased, whereas the N₂O gas emission rate (RN₂O) decreased with increasing elevation. During the microcosm study, the addition of litter decelerated the rate of decline in earthworm biomass. Earthworm-, litter-, and the interactions-induced RCO₂ increased by 19.7–44.2 %, 72.8–96.3 %, and 104.1–131.6 %, respectively. Litter-induced (SL and SLE) RN₂O was higher (1.24–10 and 5.5–16 times) compared to S except in coniferous and broad-leaved forests, with SLE showing the highest values (0.11–1.23 μg kg⁻¹ h⁻¹). The impacts of earthworms and litter on greenhouse gases were not a simple additive effect. Environmental factors explained 35.34 % and 42.83 % of the total variations in RCO₂ and RN₂O emissions, respectively, in which NO₃⁻-N contributed the largest variations. Piecewise structural equation modeling (SEM) results underscored the interplay between elevation, earthworms, litter, and soil properties in affecting soil CO₂ and N₂O emissions. Earthworms, litter, and their interactions could affect CO₂ and N₂O emissions, and these variations were predominantly controlled by environmental factors. Our study provides valuable insights into how litter input and earthworm invasion influence soil carbon and nitrogen cycling. With the background of global climate change, the synergistic response of soil fauna invasion and greenhouse gas emissions to warming be an integral part of future risk assessment, and that to evaluate soil process, both the soil fauna and environmental factors must be taken into account.

Alien invasive plant species of the genus Carpobrotus pose a major threat to coastal dune ecosystems. These human-introduced species have quickly expanded throughout the Mediterranean basin and other regions due to their high reproduction rates and adaptability. Carpobrotus invasion alters soil properties due to necromass and the release of allelopathic compounds, hindering the regrowth of native flora, with anticipated impacts on the native vegetation-associated soil microbial communities. While some studies have described changes in microbial communities between native and Carpobrotus-impacted areas, none have specifically addressed the responses of microbial communities associated with single native species. In this light, the bacterial and fungal communities specifically associated with different native species in both natural and Carpobrotus-impacted plots were examined in three locations along the middle Tyrrhenian Italian coast. Microbial communities responses to the Carpobrotus invasion varied greatly depending on the native species and the edaphic characteristics of the study locations. Microbial communities associated with Pancratium maritimum were the most affected ones and those associated with Cakile maritima the less sensitive to the invasion, which may be correlated to the different characteristics of these plant species. Furthermore, fungal communities exhibited a greater degree of disruption compared to bacterial ones. In invaded plots, fungal species that comprise plant pathogens were notably more abundant. This suggests that patterns in microbial communities response to this invasion phenomenon cannot be generalized, and that recovery strategies should consider various local conditions and be adjusted for the various native vegetation species. Finally, the possible spread of fungal plant pathogens as a mechanism of defence of Carpobrotus should be considered.

Straw application is an effective and common measure to improve soil quality but generally increases greenhouse gas (GHG) emissions. The combined application of biochar and straw has been proposed to mitigate these emissions. However, the effects of the combined application of biochar and maize straw, particularly at different proportions, on GHG emissions remain inadequately understood. In this study, an incubation experiment was conducted with five treatments: soil only (CK), 1 % maize straw application (TS), 0.7 % maize straw +0.3 % biochar application (S7B3), 0.5 % maize straw +0.5 % biochar application (S5B5) and 0.3 % maize straw +0.7 % biochar application (S3B7). The study also considered the effect of 1 % biochar application (TB) from our previous study with the same soil type and incubation condition. Carbon isotope technology was utilized to trace CO₂ sources and assess the priming effects on soil organic carbon (SOC) mineralization. The results showed that TB reduced CO₂ emission, while TS increased CO₂ emission due to maize straw decomposition and its positive priming effect on native SOC mineralization. S7B3, S5B5 and S3B7 also increased CO₂ emissions, but with significantly lower emissions than TS, in the order of TS > S7B3 > S5B5 ≥ S3B7. The positive priming effects of S7B3, S5B5 and S3B7 on native SOC mineralization weakened over time and eventually turned negative. TB, TS and combined applications reduced N₂O emission due to decreased substrates (NH₄⁺ and NO₃⁻) for nitrification and denitrification, induced by promoting microbial fixation of inorganic nitrogen. The reduction effects on N₂O emission of combined applications were superior to those of TS and TB, with S5B5 demonstrating the best efficacy. TS increased CH₄ emission, while S7B3, S5B5 and S3B7 reduced CH₄ emission. The reduction effects of CH₄ emission with combined applications were superior to that of TB, and S5B5 exhibited the lowest CH₄ emission. Unlike soils with higher nitrogen content, where N₂O emission dominated the global warming potential (GWP), CO₂ emission dominated the GWP in this study, resulting in increased GWP in TS, S7B3, S5B5 and S3B7, but with significantly lower values for S7B3, S5B5 and S3B7 compared to TS. In conclusion, our study suggests that the combined application of biochar and maize straw, especially S5B5, could effectively mitigate GHG emissions promoted by maize straw application, especially in soils with higher nitrogen content.

Crop residue serves as a vital source of energy and nutrients for microbial proliferation, ultimately contributing to the formation of soil organic carbon (SOC). Labile organic C pool (i.e., extractable organic C and microbial biomass C) not only represents a small part of SOC, but also is a sensitive indicator of soil biogeochemical process under agricultural management. However, the interaction between maize residue types and initial soil C status on the fate of residue C in labile organic C pools remains not very clear. Here, we added the ¹³C-labeled maize root, stem, and leaf residues into soils with low and high initial C status for 360 days of incubation and analyzed the contents of residue derived- salt-extractable organic C (SEOC) and microbial biomass C (MBC). The results showed that average 7.31 % and 6.46 % of SEOC was derived from maize residue C in the low and high C soil during the whole incubation, respectively. The contribution of MBC derived from residue C to total MBC in the high C soil was on average 13.36 % higher than that in the low C soil, which indicated that the high C soil could accelerate the transformation of residue C into microbial biomass by efficient anabolism pathway. The distribution percentage of leaf residue C to MBC was on average 1.73 % higher than those of root residue C and stem residue C to MBC in the low C soil, whereas more root residue C was entered to SEOC and MBC compared with stem residue C and leaf residue C in the high C soil, which demonstrated that the low-quality residue (i.e., maize root) tended to be more susceptible to microbial utilization, but it depended on the initial soil C status. Overall, these findings contribute to understanding the mechanisms of microbial-mediated C transformation processes, and provide insights into the capture and incorporation of plant residue C into labile organic C pools driven by initial soil C status and crop residue returning.

Accurately predicting soil-borne fungal diseases linked to plant diseases through the analysis of soil microbial communities is advantageous for early disease detection and monitoring. In this study, a meta-analysis was conducted to establish a classification model for two soil-borne plant fungal diseases, Fusarium and Verticillium wilt disease, based on soil microbiome datasets. The study integrated a scalable denoising method and an imbalanced data processing strategy for processing imbalanced data. The findings reveal a substantial enhancement in model performance when employing denoised and balanced datasets as opposed to the original dataset. Overall, the model based on bacterial ASV features outperformed the model based on fungal ASV features, achieving an accuracy of over 90 % in predicting Fusarium and Verticillium wilt disease on the independent test set. Some bacteria, such as those classified as the Chitinophagaceae, Nocardioides, and Sphingomonas, have been identified as biomarkers for distinguishing between healthy and diseased soils. Despite this achievement, the models exhibited suboptimal classification precision, underscoring the necessity for additional training sets or more comprehensive environmental information to augment disease prediction capabilities. Our analysis highlights the importance of microbiome-based deep learning (DL) models to make plant disease predictions based on microbiome characteristics.

Understanding the driving factors of ecosystem stability can help restore degraded ecosystems. Resistance is an important part of ecosystem stability, and soil microbial diversity and soil microbial community structure are key attributes of soil microorganisms. However, the effects of the two on soil community resistance are controversial. We used high-throughput sequencing data to analyze changes in soil bacterial diversity, community structure, and resistance along the aerial seeding restoration sequence from 1983 to 2017 in the Mu Us sandy land of China. We further analyzed the effects of soil bacterial diversity and community structure on community resistance. The results showed aerial seeding restoration increased soil bacterial diversity, changed soil bacterial community structure, and improved soil bacterial resistance. Soil bacterial diversity and soil bacterial community structure significantly correlated with resistance. The structural equation model showed that soil bacterial community structure contributed more to the impact of resistance than soil bacterial diversity. This study confirmed the crucial role of soil bacterial community structure in soil bacterial community resistance, deepened the theoretical understanding of the relationship between soil microbial community resistance, microbial diversity, and community structure in the process of ecosystem restoration threatened by desertification, and provided guidance for the improvement of soil community resistance during the aerial seeding restoration process.

Fertilizer application is key for plant yield promotion, but also has side effects on microbes, organic carbon storage and aggregate size distributions. However, links between these factors and especially how different amounts of organic and mineral fertilizers affect microbial-driven CO₂ release at the aggregate scale remains largely unknown. We quantified carbon decomposition gene abundance and diversity, microbial residual carbon and CO₂ release from the labile or stable carbon pools in three soil aggregate size fractions in organic and mineral fertilized soil. Compared to mineral fertilizer, organic fertilizer increased abundances of carbon decomposition genes, extracellular enzyme activities, microbial residual carbon and CO₂ released from the labile carbon pool, but decreased CO₂ released from the stable carbon pool in microaggregates. Likewise, organic fertilizer increased the proportion of macroaggregates, microbial residual carbon and CO₂ released from the labile carbon pool, but had no effect on carbon degradation gene abundance and extracellular carbon enzyme activity. Taken together, we illustrate that organic fertilizer application decreases CO₂ release via increasing the proportion of macroaggregates, leading to increased carbon storage that can provide a means to lessening atmospheric carbon.

Rhizodeposition plays a crucial role in the soil carbon (C) cycle, yet a comprehensive understanding of global research trends and directions related to rhizodeposition remains elusive. To provide a global perspective, this study employs bibliometric analysis to systematically review research on the Soil C cycle-rhizodeposition (SCC-Rhizo) publication characteristics, topic trends, and knowledge domains over the past decades. The SCC-Rhizo documents (2598) from 1966 to 2023 in the Web of Science Core Collection and Scopus were analyzed using VOSviewer, CiteSpace software and ‘bibliometrix’ package of R. A significant rise in annual publications and international scientific collaboration has been observed over the past years, indicating substantial growth potential and a dynamic research landscape. The study topics varied and flourished over time. The research scope expands from small-scale lab simulations to encompass large-scale ecosystem studies in diverse environments (i.e. grasslands, forests and paddy fields). The composition of rhizodeposition has been scrutinized from general compounds to specific materials (such as organic acids), while interactions between rhizodeposition and soil are currently being explored at the molecular level, which is expected to be a focal point of future research. Beyond bacteria, investigations now encompass fungi, microbial activity, and microbial communities. Isotope labeling and metagenomics sequencing are increasingly prevalent technology in SCC-Rhizo research. The results provide a global, objective perspective for understanding SCC-Rhizo research over the past decades. This research underscores the necessity for future studies to accurately quantify the rates and composition of rhizodeposition at the ecosystem level, explore the interactions with soil components, and develop predictive models.

Stoichiometric imbalances between soil resource availability and soil microbial biomass cause nutrient limitation for microbial activity, ultimately affecting soil carbon (C), nitrogen (N), and phosphorus (P) cycling. Little is known about how land use change, such as the conversion of primary natural broadleaf forests (BF) to monoculture plantations (PF) and regenerated secondary forests (SF), impacts stoichiometric imbalances and soil microbial communities. We measured soil available nutrients, microbial biomass, and potential activities of C-, N- and P-acquiring enzymes, and investigated the diversity and structure of soil microbial communities in BF, SF, and PF in subtropics. Forest conversion of BF to PF, but not to SF, increased dissolved organic carbon (DOC): available nitrogen (AN) ratio and slightly decreased microbial biomass C:P and N:P ratios, resulting in increasing C:P and N:P imbalances between soil resource availability and soil microbes. We found microbial communities to maintain stoichiometric homeostasis by increasing the threshold elements ratio of C:N (TER_C:N) and altering the stoichiometry of C-, N-, and P-acquiring enzymes in order to store scarce nutrients such as P. Higher stoichiometric imbalances of C:P and N:P in PF soils were associated with the decreases in fungal richness, α-diversity and bacterial β-diversity. Bacterial communities shifted from copiotrophs (Actinobacteria) to oligotrophs (Chloroflexi and Verrucomicrobia) with the conversion of BF to PF. This study suggests that the response of soil available nutrients (especially soil P) and soil microbial biomass to forest conversion, and associated changes in stoichiometric imbalances substantially regulate soil microbial community structure and enzyme activities with forest conversion.

Winter mulching is a periodic short-term warming measure commonly used in agroforestry production, that has a fluctuating impact on the soil microenvironment. However, We know little about the response of fungal communities and their trophic patterns to short-term mulching. In this study, soil fungal communities in Lei bamboo (Phyllostachys praecox) forests were explored under a 4-month winter mulching period (from Month 0 to 4). Three kinds of organic compounds that can be fermented to produce similar high temperatures were used as mulch. With the extension of the mulching period, alpha diversity of the three mulching-type treatments followed a similar trend, with the values peaking in Month 1 and then decreasing sharply. Fungal community composition was clustered according to mulching time rather than mulching type. The majority of the soil fungi were Trechispora, Penicillium, and Trichoderma species before mulching, while Archaeorhizomyces became the most abundant genus, followed by Trechispora and Penicillium after mulching. Redundancy analysis strongly suggested that compositional shifts were related to dynamic alterations in the soil microenvironment, mainly soil temperature and the contents of available nutrients. The co-occurrence patterns of the fungal community were different in the three post hoc groups, with variation in keystone taxa and module populations. Wood saprotrophs were the most abundant functional guild before mulching, while soil saprotrophs were increased after mulching. These results indicated that winter mulching resulted a strong interference with soil fungal communities and that the effects of short-term agricultural disturbance on soil biodiversity cannot be ignored.