Litter and soil biodiversity jointly drive ecosystem functions

Nitrogen addition decouples the microbial necro-mass from soil organic carbon formation in a temperate grassland

Increasing anthropogenic nitrogen (N) inputs has profoundly altered soil microbial necro-mass carbon (MNC), which serves as a key source of soil organic carbon (SOC). Yet, the response pattern of MNC and its contribution to SOC across a wide range of N addition rates, remain elusive. In a temperate grassland with six years' consecutive N addition spanning seven rates (0-50 g N/(m2·year)) in Inner Mongolia, China, we explored the responses of soil MNC and its contribution to SOC. The soil MNC showed a hump-shaped pattern to increasing N addition rates, with the N saturation threshold at 18.07 g N/(m2·year). The soil MNC was driven by nematode abundance and the ratio of bacterial to fungal biomass below the N threshold, and by plant biomass allocation pattern and diversity above the N threshold. The contribution of soil MNC to SOC declined with increasing N addition rates, and was mainly regulated by the ratio of MNC to mineral-associated organic carbon and plant diversity and the ratio of bacterial to fungal biomass. In addition, the soil MNC and SOC differentially responded to N addition and were mediated by disparate biological and geochemical mechanisms, leading to the decoupled MNC production from SOC formation. Together, in this N-enriched temperate grassland, the soil microbial necro-mass production tends to be insufficient as a general explanation linking SOC formation. This study expands the mechanistic comprehension of the connections between external N input and soil carbon sequestration.

Land use impacts on plant diversity and soil C/N stocks in semi-arid grasslands of northern China

Grasslands play an indispensable role in global ecological balance. However, land utilization practices such as mowing, grazing, and mining have led to degradation, affecting plant diversity and reducing carbon (C) and nitrogen (N) stocks. Revealing these degradation mechanisms after various land utilization practices is essential for implementing effective management practices to restore and sustain degraded grasslands. This study examines the effects of different land use types-mowing, light grazing, heavy grazing, and mining-on plant community characteristics, biomass, soil C and N dynamics in the Hulunbuir Grassland of Inner Mongolia. Our results revealed that across 50 herbaceous species, dominant vegetation shifted significantly: light grazing favored native grasses like Cleistogenes squarrosa and Artemisia frigida, while heavy grazing and mining promoted invasive species (e.g., Taraxacum mongolicum). Plant diversity and biomass were highest under mowing, but mining reduced species richness by 35 % and biomass by 50 % compared to mowing. Soil organic carbon (SOC) and total nitrogen (STN) stocks varied significantly across land-use types and plant growth phases, peaking in mowing sites (SOC: 9.85 ± 1.45 g/kg; STN: 1.55 ± 0.05 g/kg at 0-20 cm depth) and declining sharply in mining areas (SOC: 3.44 ± 0.46 g/kg; STN: 0.76 ± 0.06 g/kg). Strong correlations linked plant diversity and root biomass to SOC and STN retention, whereas Asteraceae biomass showed minimal influence. Structural equation modeling demonstrated that land use influenced SOC and STN stocks primarily through indirect effects on plant, root, and litter biomass rather than direct impacts. These findings underscore the need for daptive, site-specific restoration frameworks to mitigate degradation, prevent invasive species encroachment in mining areas and grazing livestock for sustainable grassland restoration.

Litter alteration reduces ecosystem multifunctionality through divergent aboveground-belowground feedbacks in alpine grasslands

Plant litter plays critical roles in altering biogeochemical processes and ecological functions in global grasslands. However, little is known about how plant litter alterations influence the multiple ecological functions in semi-humid alpine grasslands. A controlled experiment in field was carried out in alpine grassland, where different plant litter inputs levels were conducted to explore how plant litter manipulation affects the ecosystem multifunctionality (EMF). The results showed that plant litter removal tended to positively affect plant diversity and productivity but negatively affect soil nutrients. In contrast, plant litter addition had a trend to decrease plant diversity and productivity but increase soil nutrients. Both plant litter addition and removal had negative influences on the EMF index in semi-humid alpine grassland. Ecosystem multifunctionality (EMF) was significantly decreased under the L+100 % treatment (p < 0.01). However, we found that the above- and belowground ecological functions responded differently to plant litter manipulation. Plant litter addition had negative impacts on the aboveground ecosystem functioning but tended to positively affect the belowground ecosystem functioning. Aboveground ecosystem multifunctionality (AEMF) was significantly decreased under the L+50 % treatment (p < 0.05), while a significant decrease in AEMF was observed under the L+100 % treatment (p < 0.001). However, plant litter removal had a trend to increase the aboveground ecosystem functioning but significantly decreased the belowground ecosystem functioning. Belowground ecosystem multifunctionality (BEMF) was significantly decreased under the L-50 % treatment (p < 0.05), while a significant decrease in BEMF was observed under the L-100 % treatment (p < 0.001). In addition, the finding revealed that plant litter manipulation affected the ecosystem multiple functioning directly through regulating plant diversity and productivity as well as soil fertility. These results emphasize the significant role of climate change and grazing induced alterations in plant litter inputs in maintaining the ecological functions in alpine grasslands and indicate that such changes in litter inputs may alter the relative contribution of plant diversity to ecosystem functioning by mediating plant productivity and soil nutrient cycling.

Effects of simulated warming and litter removal on structure and function of semi-humid alpine grassland in the Qinghai-Tibet Plateau

Climate warming and human activities are modifying plant litter inputs in alpine grasslands, which is predicted to affect ecosystem structure and function. However, the effects of plant litter removal and warming as well as the combined impacts on the ecological functions of alpine grasslands are not well understood. A field experiment was conducted to investigate the effects of experimental warming, litter removal, and their interaction on ecosystem multifunctionality (EMF) of alpine grasslands. Our results demonstrated a significant decrease in plant diversity (p < 0.05) and vegetation cover (p < 0.01) under experimental warming treatment, whereas the richness index (R) and belowground biomass (BGB) significantly increased under litter removal treatment (p < 0.05). The interaction effect of experimental warming and litter removal results in a neutralizing effect on the ecological functions in alpine grasslands. Meanwhile, the EMF tended to increase under all treatments of experimental warming, litter removal, and experimental warming-litter removal. However, there are differences in the response of aboveground and belowground multifunctionality to experimental warming and litter removal. The aboveground ecosystem multifunctionality (AEMF) showed a decreasing trend, while belowground ecosystem multifunctionality (BEMF) increased significantly (p < 0.01) under the experimental warming treatment. In contrast, AEMF and BEMF showed an increasing trend in litter removal treatment. In addition, the study found that litter removal could alleviate the negative effect of experimental warming on multiple ecological functions. These research findings can serve as a reference for maintaining ecosystem functions in alpine grasslands under climate change conditions and provide effective measures to enhance the capacity of grassland ecosystems to respond to climate change. The application of appropriate litter management measures and other nature-based solutions (NbS) to improve ecosystem functions, aiming to adopt sustainable approaches to address environmental challenges, holds significant importance for ecological conservation.

Progressing towards eco-friendly agricultural management: Utilizing Ginkgo biloba leaf litter for potato common scab control

Soil ecological degradation intensifies soil-borne crop diseases. Employing eco-friendly and economical strategies to restore soil health is imperative for managing soil diseases. Here, we focused on potato common scab (PCS), a worldwide soil-borne disease caused by Streptomyces spp., and evaluated the suppression effects of Ginkgo leaf litter (GL) and its extract (GE), while elucidating their mechanisms. The results showed that both GL and GE significantly reduced the PCS disease index, with GL achieving over 50 % suppression in both pot and field trials. Both treatments effectively antagonized the PCS pathogen, reducing its relative abundance in bulk soil and geocaulosphere soil. The soil bacterial community was significantly correlated with the disease index, with the bacterial community in bulk soil making a particularly notable contribution to disease suppression, accounting for 52 % of the effect. Furthermore, GL and GE enhanced the stochastic processes in bacterial community assembly, and increased the complexity of bacterial co-occurrence networks. Notably, the microbial community restructured by GE significantly inhibited the expression of the pathogen's toxin gene, txtAB, decreasing its level from 104.5 copies per gram of soil to 102.1 copies, marking a decline exceeding two orders of magnitude. ASV339 (Aeromicrobium) and ASV932 (Achromobacter) were identified as key microbes, and their respective strains, Aeromicrobium OH2-5 and Achromobacter YD1-3, were isolated. The growth curve and biomass of these strains were positively influenced by GE, demonstrating Ginkgo leaves' enriching effect on beneficial microorganisms. These strains exhibited potent antagonistic activity against the PCS pathogen. Additionally, GE alleviated reactive oxygen species stress and up-regulated the defense-related gene PR1 in potato plants. This study validates the potential of Ginkgo leaf litter as a soil amendment additive for suppressing PCS and reveals its multifaceted mechanisms.

Soil and litter microbiomes as joint drivers of ecosystem multifunctionality in a 60-year-old forest plantation

Afforestation is considered an effective strategy to mitigate a changing climate. However, it remains unclear how ecosystem multifunctionality (EMF) changes under long-term afforestation and the role of soil and litter microbiomes in this process. To address this, we studied a well-characterised 60-year-old plantation and analysed soil and litter microbial communities influencing EMF variations. We found that long-term plantations significantly enhance forest EMF, largely due to the joint contributions of soil and litter microbial communities. In older stands (60 years), the stability of microbial interaction networks increased, while the α (Shannon) diversity of soil bacteria and litter fungi significantly decreased during succession. This transition suggests that microbial communities shifted towards more stable interactions rather than increased diversity, a strategic adaptation that potentially allows microbes to effectively utilize the continuously increasing resource supply, ultimately enhancing forest EMF. Structural equation modelling revealed that biotic factors, including composition of soil and litter microbial communities and their network stability, coupled with abiotic factors such as soil and litter physicochemical properties, jointly explained 98 % of EMF variation. This study highlighted the role of both soil and litter microbes in enhancing EMF in long-term plantation forests, offering new insights into the ecosystem service functions of plantations.

Niche Conservatism and Community Assembly Reveal Microbial Community Divergent Succession Between Litter and Topsoil

Natural restoration is an effective approach for restoring degraded ecosystems, yet the successional patterns and assembly mechanisms of aboveground (litter layer) and belowground (topsoil) microbial communities remain poorly understood. We applied the niche conservatism framework to investigate niche partitioning, successional patterns and community assembly processes of microbial communities in the litter and topsoil layers during long-term vegetation restoration in southwestern China. The results showed that, during vegetation succession, the potential source communities of microbial communities in the litter layer gradually shifted from being dominated by the topsoil to being dominated by the litter. Fungal communities had a significantly higher proportion of external immigrants (> 80%) than bacteria (> 40%) and archaea (< 20%). During succession, bacterial and fungal communities in the litter and topsoil layers underwent niche differentiation, displaying a divergent succession pattern, while archaeal communities showed niche overlap, following a convergent pattern driven by stochastic processes. Additionally, the dispersal rate (m) and β-diversity turnover rate (slope) of bacterial and fungal species in the litter were significantly lower than in the topsoil, with community assembly being more influenced by deterministic processes in the litter. This study reveals that higher habitat specialisation in the litter imposes stronger filtering effects on the colonisation of most microbial groups, particularly fungal communities, highlighting the role of strategy differentiation in shaping microbial communities.

Vegetation types shape the soil micro-food web compositions and soil multifunctionality in Loess Plateau

Introduction

Vegetation degradation and soil erosion are severe problems in the Loess hilly region, rendering it one of the most ecologically vulnerable areas in China and globally. Vegetation restoration has been recognized as an effective approach to amending the fragile ecological environment and restoring degraded ecosystems.

Methods

The effects of different vegetation types: Caragana korshinskii, Prunus armeniaca L., Pinus tabuliformis Carrière, Medicago sativa L., and the control vegetation Stipa bungeana on soil micro-food webs and soil multifunctionality, as well as their response mechanisms to soil environmental drivers, were investigated using High-throughput sequencing technology.

Results

C. korshinskii significantly enhanced soil physicochemical properties and soil enzyme activities by facilitating the stability of the soil micro-food web structure driven by soil bacteria and fungi and increasing the soil multifunctionality in contrast to S. bungeana. Prunus armeniaca also improved soil multifunctionality by promoting soil organic carbon and alkaline phosphatase activity. However, the stability of the soil micro-food web structure and soil multifunctionality were suboptimal in P. tabuliformis and M. sativa. Soil pH, along with carbon, nitrogen, and phosphorus cycling nutrients and enzymes, profoundly influences the structure of the soil micro-food web and soil multifunctionality; among these factors, those related to the carbon and phosphorus cycles are identified as key influencing factors.

Discussion

Therefore, a vegetation restoration strategy prioritizing C. korshinskii as the dominant vegetation type, supplemented by P. armeniaca, significantly impacts restoring soil multifunctionality and stabilizing the soil micro-food web in Loess hill regions and comparable ecological areas.

Polyethylene microplastics distinctly affect soil microbial community and carbon and nitrogen cycling during plant litter decomposition

Plant litter is an important input source of carbon and nitrogen in soil. While microplastics (MPs) and plant litter are ubiquitously present in soil, their combined impact on soil biogeochemical processes remains poorly understood. To address this gap, we examined the soil changes resulting from the coexistence of plant litter (Alfalfa) and polyethylene microplastics (PE). The soil changes included physicochemical properties, composition of soil dissolved organic matter, and structure of the soil microbial community. The results showed that the addition of polyethylene (PE) inhibited the degradation of humus-like substances and decreased the quantity of humic acid-like compounds in soil dissolved organic matter (DOM). PE negatively impacted plant litter decomposition, disrupted soil organic carbon (SOC) breakdown, interfered with the nitrogen cycle, and significantly altered microbial community structures during the process. By day 35, SOC and total nitrogen (TN) levels were reduced by 39.8% and 10.1%, respectively, in the presence of PE. Furthermore, PE significantly decreased the abundance of nitrogen-fixing microbes, including Streptomyces (43.1%) and Bacillus (45.9%), which play key roles in nitrate reduction to ammonium. This study highlights the environmental effects of MPs on plant litter decomposition and their potential implications for soil biogeochemical processes.

Exploring Fungal Biodiversity in Crop Rotation Systems: Impact of Soil Fertility and Winter Wheat Cropping

This study investigated soil fungal biodiversity in wheat-based crop rotation systems on Chernozem soil within the Pannonian Basin, focusing on the effects of tillage, crop rotation, and soil properties. Over three years, soil samples from ten plots were analyzed, revealing significant fungal diversity with Shannon-Wiener diversity indices ranging from 1.90 in monoculture systems to 2.38 in a fertilized two-year crop rotation. Dominant fungi, including Fusarium oxysporum, Penicillium sp., and Aspergillus sp., showed distinct preferences for soil conditions such as pH and organic matter (OM). Conservation tillage significantly enhanced fungal diversity and richness, with the highest diversity observed in a three-year crop rotation system incorporating cover crops, which achieved an average winter wheat yield of 7.0 t ha-1-47% higher than unfertilized monoculture systems. Increased OM and nitrogen levels in these systems correlated with greater fungal abundance and diversity. Canonical correspondence analysis revealed strong relationships between fungal communities and soil properties, particularly pH and calcium carbonate content. These findings highlight the importance of tailored crop rotation and tillage strategies to improve soil health, enhance microbial biodiversity, and boost agricultural sustainability in temperate climates, providing valuable insights for mitigating the impacts of intensive farming and climate change.

Comparative Genomics of Fungi in Nectriaceae Reveals Their Environmental Adaptation and Conservation Strategies

This study presents the first genome assembly of the freshwater saprobe fungus Neonectria lugdunensis and a comprehensive phylogenomics analysis of the Nectriaceae family, examining genomic traits according to fungal lifestyles. The Nectriaceae family, one of the largest in Hypocreales, includes fungi with significant ecological roles and economic importance as plant pathogens, endophytes, and saprobes. The phylogenomics analysis identified 2684 single-copy orthologs, providing a robust evolutionary framework for the Nectriaceae family. We analyzed the genomic characteristics of 17 Nectriaceae genomes, focusing on their carbohydrate-active enzymes (CAZymes), biosynthetic gene clusters (BGCs), and adaptations to environmental temperatures. Our results highlight the adaptation mechanisms of N. lugdunensis, emphasizing its capabilities for plant litter degradation and enzyme activity in varying temperatures. The comparative genomics of different Nectriaceae lifestyles revealed significant differences in genome size, gene content, repetitive elements, and secondary metabolite production. Endophytes exhibited larger genomes, more effector proteins, and BGCs, while plant pathogens had higher thermo-adapted protein counts, suggesting greater resilience to global warming. In contrast, the freshwater saprobe shows less adaptation to warmer temperatures and is important for conservation goals. This study underscores the importance of understanding fungal genomic adaptations to predict ecosystem impacts and conservation targets in the face of climate change.

Warming enhances the negative effects of shrub removal on phosphorus mineralization potential

Shrubs have developed various mechanisms for soil phosphorus utilization. Shrub encroachment caused by climate warming alters organic phosphorus mineralization capability by promoting available phosphorus absorption and mediating root exudates. However, few studies have explored how warming regulates the effects of dominant shrubs on soil organic phosphorus mineralization capability. We provide insights into warming, dominant shrub removal, and their interactive effects on the soil organic phosphorus mineralization potential in the Qinghai-Tibetan Plateau. Real-time polymerase chain reaction was used to quantify the soil microbial phosphatase genes (phoC and phoD), which can characterize the soil organic phosphate mineralization potential. We found that warming had no significant effect on the soil organic phosphate-mineralized components (total phosphate, organic phosphate, and available phosphate), genes (phoC and phoD), or enzymes (acid and alkaline phosphatases). Shrub removal negatively influenced the organic phosphate-mineralized components and genes. It significantly decreased soil organic phosphate mineralization gene copy numbers only under warming conditions. Warming increased fungal richness and buffered the effects of shrub removal on bacterial richness and gene copy numbers. However, the change in the microbial community was not the main factor affecting organic phosphate mineralization. We found only phoC copy number had significant correlation to AP. Structural equation modelling revealed that shrub removal and the interaction between warming and shrub removal had a negative direct effect on phoC copy numbers. We concluded that warming increases the negative effect of shrub removal on phosphorus mineralization potential, providing a theoretical basis for shrub encroachment on soil phosphate mineralization under warming conditions.

Keystone taxa enhance the stability of soil bacterial communities and multifunctionality under steelworks disturbance

Continuous discharge of wastewater, emissions, and solid wastes from steelworks poses environmental risks to ecosystems. However, the role of keystone taxa in maintaining multifunctional stability during environmental disturbances remains poorly understood. To address this, we investigated the community diversity, assembly mechanisms, and soil multifunctionality of soils collected from within the steelworks (I), within 2.5 km radius from the steelworks (E), and from an undisturbed area (CK) in Jiangsu Province, China, via 16 S rRNA sequencing. Significant differences were found in the Chao1 and the richness indexes of the total taxa (p < 0.05), while the diversity of keystone taxa was not significant at each site (p > 0.05). The deterministic processes for total taxa were 42.9%, 61.9% and 47.7% in CK, E, and I, respectively. Steelworks stress increased the deterministicity of keystone taxa from 52.3% in CK to 61.9% in E and I soils. The average multifunctionality indices were 0.518, 0.506 and 0.513 for CK, E and I, respectively. Although the soil multifunctionality was positive correlated with α diversity of both the total and keystone taxa, the average degree of keystone taxa in functional network increased significantly (79.96 and 65.58, respectively), while the average degree of total taxa decreased (44.59 and 51.25, respectively) in the E and I. This suggests keystone taxa contribute to promoting the stability of ecosystems. With increasing disturbance, keystone taxa shift their function from basic metabolism (ribosome biogenesis) to detoxification (xenobiotics biodegradation, metabolism, and benzoate degradation). Here we show that keystone taxa are the most important factor in maintaining stable microbial communities and functions, providing new insights for mitigating pollution stress and soil health protection.

Interguild fungal competition in litter and soil inversely modulate microbial necromass accumulation during Loess Plateau forest succession

Microbial interactions determine ecosystem carbon (C) and nutrient cycling, yet it remains unclear how interguild fungal interactions modulate microbial residue contribution to soil C pools (SOC) during forest succession. Here, we present a region-wide investigation of the relative dominance of saprophytic versus symbiotic fungi in litter and soil compartments, exploring their linkages to soil microbial residue pools and potential drivers along a chronosequence of secondary Chinese pine (Pinus tabulaeformis) forests on the Loess Plateau. Despite minor changes in C and nitrogen (N) stocks in the litter or soil layers across successional stages, we found significantly lower soil phosphorus (P) stocks, higher ratios of soil C: N, soil N: P and soil C: P but lower ratios of litter C: N and litter C: P in old (>75 years) than young stands (<30 years). Pine stand development altered the saprotroph: symbiotroph ratios of fungal communities to favor the soil symbiotrophs versus the litter saprotrophs. The dominance of saprotrophs in litter is positively related to microbial necromass contribution to SOC, which is negatively related to the dominance of symbiotrophs in soils. Antagonistic interguild fungal competition in litter and soil layers, in conjunction with increased fungal but decreased bacterial necromass contribution to SOC, jointly contribute to unchanged total necromass contribution to SOC with stand development. The saprotroph: symbiotroph ratios in litter and soil layers are mainly driven by soil P stocks and stand parameters (e.g., stand age and slope), respectively, while substrate stoichiometries primarily regulate microbial necromass accumulation and fungal: bacterial necromass ratios. These results provide novel insights into how microbial interactions at local spatial scales modulate temporal changes in SOC pools, with management implications for mitigating regional land degradation.

Trophic interactions in soil micro-food webs drive ecosystem multifunctionality along tree species richness

Rapid biodiversity losses under global climate change threaten forest ecosystem functions. However, our understanding of the patterns and drivers of multiple ecosystem functions across biodiversity gradients remains equivocal. To address this important knowledge gap, we measured simultaneous responses of multiple ecosystem functions (nutrient cycling, soil carbon stocks, organic matter decomposition, plant productivity) to a tree species richness gradient of 1, 4, 8, 16, and 32 species in a young subtropical forest. We found that tree species richness had negligible effects on nutrient cycling, organic matter decomposition, and plant productivity, but soil carbon stocks and ecosystem multifunctionality significantly increased with tree species richness. Linear mixed-effect models showed that soil organisms, particularly arbuscular mycorrhizal fungi (AMF) and soil nematodes, elicited the greatest relative effects on ecosystem multifunctionality. Structural equation models revealed indirect effects of tree species richness on ecosystem multifunctionality mediated by trophic interactions in soil micro-food webs. Specifically, we found a significant negative effect of gram-positive bacteria on soil nematode abundance (a top-down effect), and a significant positive effect of AMF biomass on soil nematode abundance (a bottom-up effect). Overall, our study emphasizes the significance of a multitrophic perspective in elucidating biodiversity-multifunctionality relationships and highlights the conservation of functioning soil micro-food webs to maintain multiple ecosystem functions.