Needle litter chemistry and climate are major determinants of litter decomposition in forests, but their relative importance during the decomposition process remains largely unclear, particularly for single tree species. We synthesized rate-regulating factors for long-term (maximum six years) decomposition of local Norway spruce (Picea abies) needle litter in a 13-site climatic gradient with mean annual temperatures ranging from -1.7 to 7.2 °C. Analyses were made for acid-unhydrolyzable residue (AUR), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and manganese (Mn) in all samplings. We investigated annual mass loss, using five categories of the decomposing litters. Climate had a minor and decreasing influence (> 40

Per- and polyfluoroalkyl substances (PFAS), as persistent organic pollutants, accumulate in estuarine environments and pose serious threats to ecosystems and human health. This study compiled global data on PFAS contamination in estuarine waters and systematically analyzed their spatiotemporal distribution, temporal trends, socioeconomic drivers, and ecological risks. Results indicated that PFAS were ubiquitously detected in estuaries worldwide, with contamination hotspots identified in North America, Western Europe, and East Asia. Dominant compounds included perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), and perfluorobutanesulfonic acid (PFBS). Those PFAS, predominantly composed of traditional groups such as perfluorocarboxylic acids (PFCAs) and perfluoroalkyl sulfonate acids (PFSAs), exhibited an inverted U-shaped temporal trend in concentrations with a fitted peak around 2015-2017. Partial least-squares path modeling (PLS-PM) revealed that industrial activity was the primary driver of PFAS contamination, whereas effective environmental governance directly mitigated pollution and positively influenced public health outcomes and demographic structure. Additionally, PFOA and PFOS remained the major contributors to ecological risks, while emerging concerns were identified for short-chain alternatives, such as perfluorobutanoic acid (PFBA) and PFBS. These findings highlight the urgent need for coordinated global governance and targeted interventions to mitigate ongoing PFAS pollution and address the potential risks posed by both legacy and alternative PFAS.

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants of global concern, yet substantial uncertainty remains regarding their health and ecological risks, particularly at low exposure levels. This paper provides the first extensive evaluation of PFAS-induced hormetic dose responses across a wide range of ecological models, from bacteria to vertebrates, and, where available, examines the underlying mechanisms. Hormesis, characterized by low-dose stimulation and high-dose inhibition, is shown to be a common and evolutionarily conserved response to PFAS exposure. Evidence across diverse taxa—including zebrafish, invertebrates, insects, amphibians, and microbial systems—demonstrates consistent biphasic dose-response relationships affecting endpoints such as locomotion, immune function, reproduction, growth, and survival. Quantitative features of these responses generally align with established hormetic patterns, with stimulatory effects often occurring well below toxic thresholds. Mechanistically, PFAS-induced hormesis appears to involve adaptive processes such as modulation of oxidative stress, immune activation, and metabolic reprogramming. The findings highlight the generality of hormesis across biological systems and suggest that low-dose PFAS exposures may elicit adaptive or beneficial responses under certain conditions. These results challenge traditional toxicological assumptions and underscore the importance of incorporating hormetic dose-response models into ecological risk assessment frameworks.

This paper provides the first critical review of the capacity of per- and polyfluoroalkyl substances (PFAS) agents to induce hormetic effects in mammalian toxicological and biomedical cellular and animal models. PFAS induced hormetic responses were reported in primary cells and cell lines from multiple organ systems (e.g., liver, lung, colon, breast, prostate, immune, brain) from animal models and humans. While more limited, PFAS induced hormetic dose responses in experimental animals for short-term and chronic studies. Hormetic effects were induced by long and shorter carbon length alternative PFAS agents, with hormesis dose-response features being similar. The PFAS-induced hormetic dose responses are consistent with quantitative features of hormetic responses of other chemical and physical agents, including PFAS effects on plants and ecological animal models. These findings suggest ways to optimize study designs to assess the nature of the dose response in the low-dose zone, including dose selection, number of doses and dose spacing strategies. The findings present challenges for interpretations concerning what is an adverse effect as some effects presented here may be desirable while others potentially harmful. The introduction of the hormesis concept into the hazard assessment process creates novel risk assessment considerations making the process more scientifically robust, creating a range of new regulatory options. These findings and those shown with plants and ecological animal models indicate that the hormetic concept should become a fundamental feature of ecological and human risk assessment principles and practices by regulatory agencies.

A long-standing issue in ecotoxicology is the arbitrarily chosen and ambiguous definition of “environmentally relevant” concentrations, which undermines research comparability and hampers risk characterization. Here, we propose a probabilistic framework that anchors exposure levels to percentiles of environmental concentration distributions, defining low (<5th percentile), typical (5th to 95th percentiles), and high (>95th percentile) concentrations, as well as worst-case scenarios (e.g., the 99th percentile) for specific contexts. This framework transforms test concentration selection from a subjective assertion into a statistically justified practice, where each concentration corresponds to an explicit occurrence probability. Using global monitoring data, we demonstrate that environmental concentrations reliably follow cumulative probability distributions, validating the fundamental assumption. Crucially, the framework offers a statistical solution for designing proof-of-relevance and proof-of-concept studies. Collectively, this work provides an empirically grounded, immediately usable template for designing ecotoxicological experiments that bridge environmental monitoring, laboratory testing, and regulatory decision-making.

Micro/Nanoplastics (MNPs) and per- and polyfluoroalkyl substances (PFASs) are emerging environmental contaminants of global concern. This study assessed the acute and multigenerational toxicity of perfluorooctanoic acid (PFOA) and its alternative, hexafluoropropylene oxide dimer acid (HFPO-DA, also commercially known as GenX), in the marine rotifer Brachionus plicatilis, in the presence of 80 nm and 5 μm MNPs. Acute toxicity tests demonstrated that MNPs enhanced the lethality and reproductive toxicity of both PFOA and GenX in a size-dependent manner. At the population level, MNPs exacerbated the inhibitory effects of these compounds on population growth. In multigenerational assays, fecundity was identified as the most sensitive life-history trait, exhibiting cumulative multigenerational impairments that were more pronounced in the presence of NPs. This trend aligned with the expression patterns of reproduction-related genes. Transcriptomic analysis further showed that co-exposure to NPs increased the number of differentially expressed genes, particularly those involved in metabolic and steroid biosynthesis pathways, suggesting elevated energy demands and reproductive toxicity. Collectively, these findings highlight the necessity of incorporating mixture toxicity and multigenerational effects into risk assessment frameworks to achieve more realistic chemical risk characterization and management.

Soil fertility and nutrient cycling can be enhanced with application of biosolids; however, it can also pose risks associated with introduction of heavy metals. The balance between these beneficial and adverse effects in influencing soil health and multifunctionality remains unclear. Further, eco-friendly strategies to alleviate heavy metal accumulation in biosolids-applied soils are undetermined. With this objective, we sampled soil from an agricultural field that had been applied with biosolids for 16 years at rates of 0 t ha(-1) (Control), 4.5 t ha(-1) (SW1), 9 t ha(-1) (SW2), 18 t ha(-1) (SW3), and 36 t ha(-1) (SW4). Bacterial, fungal and arbuscular mycorrhizal (AM) fungal communities were determined, and soil health index (SHI) and multifunctionality (SMF) quantified. Field experiment showed that optimal biosolids application significantly increased SHI and SMF by 3-20 % and 3-75 %, respectively, compared to the Control treatment. Bacterial and AM fungal keystone taxa abundances were positively correlated to SHI and SMF. Additionally, to corroborate these results, pot experiments were conducted to test the effect of AM fungal inoculation on soil microbial diversity and multifunctionality, and its mitigatory effect on heavy metal accumulation. AM fungal inoculation significantly increased SMF by 42-61 %, and reduced Cu and Zn contents by 7-10 % and 4-6 %, respectively. Metagenomic analyses showed that AM fungal inoculation significantly increased soil carbon, nitrogen, phosphorus and sulfur gene abundance, positively correlated to SMF. Overall, the findings underscore the benefits of judicious biosolids application combined with AM fungal bioaugmentation as a viable strategy for mitigation of heavy metal accumulation for sustainable agriculture.

Rapid climate change is reshaping forests globally, yet its impacts vary along environmental gradients, complicating predictions of forest responses. Using four decades of satellite NDVI and gridded climate data, we examined patterns of larch forest changes in Northeast China, an area experiencing a rapid warming-drying trend, along latitudinal and elevational gradients. Larch forests of this region showed an overall greening trend, but the pattern was highly structured. Weak greening and localized browning were concentrated in low-latitude, low-elevation sectors, whereas mid- to high-elevation areas and higher latitudes were characterized by stability and patchy greening. The rate of NDVI change increased with elevation at mid- and high latitudes but declined with elevation at lower latitudes. Latitudinal patterns of NDVI change were strongly elevation-dependent, with the weakest trends occurring at intermediate latitudes in low-elevation areas, a steady northward increase at mid elevations, and the strongest positive responses at intermediate-to-high latitudes in high-elevation areas. In lower latitudes and elevations, NDVI was primarily associated with temperature seasonality, growing-season maximum temperature and annual precipitation. In higher latitudes and elevations, vapour pressure deficit, precipitation seasonality and solar radiation showed the strongest influences with greening maintained within a narrow window of moderate atmospheric demand. These findings suggest that the observed spatial patterns are consistent with shifts in hydrothermal constraints along climatic gradients, alleviating energy limitation in colder environments while intensifying atmospheric and hydrological stress in warmer conditions. By identifying spatially varying climate threshold-like patterns and climate-sensitive zones, this study provides an important basis for informing climate-adaptive forest management.

Root decomposition is a key process driving belowground carbon (C) and nitrogen (N) cycling. However, how decomposition and nutrient turnover vary across the full gradient of ten root orders, and which traits that regulate these patterns, remains unclear. We conducted a four-year in situ decomposition experiment across ten branch orders of Fraxinus mandshurica to examine how root traits influence mass loss and N dynamics. In fine roots (1st-5th orders), initial decomposition rates (ka) increased with order and showed positive associations with non-structural carbohydrate (NSC) concentrations but negative correlations with condensed tannins (CT) concentrations. In contrast, coarse roots (6th-10th) showed decreasing ka, associated with low NSC concentrations, high C:N ratios, and greater structural resistance. Asymptotic residue (A) declined with order in both groups, but through distinct mechanisms-chemical recalcitrance in fine roots and physical fragmentation in coarse roots. Nitrogen release also diverged-fine roots showed continuous net loss (47%), whereas coarse roots showed immobilization (32% net loss). Across all orders, both N retention and A were strongly correlated with N content and stoichiometric traits. Together, these findings supported a root-order continuum model in which functional traits mediate decomposition and N cycling, improving our capacity to predict soil C and N fluxes in temperate forests.

Urban communities exhibit complex thermal behaviors driven by interactions among buildings, vegetation, and shadows, yet their combined effects remain insufficiently understood. This study analyzed 309 communities within Beijing's core urban area to quantify how green space ratio (GR), vegetation spatial configuration (ENN_MN), building density, and shadow ratio influence land surface temperature (LST). Using multi-source remote sensing data, Gradient Boosted Regression Trees (GBRT), and SHAP interpretation, we found that building density is the dominant driver of community-scale thermal patterns (43.7%), followed by shadows (35.9%) and green spaces (20.4%). Building density and shadow ratio exhibited clear threshold effects, with building density above 50% intensifying warming and shadow ratios below 10% failing to provide adequate cooling. Similar GR levels corresponded to varied cooling effects, demonstrating the strong interactions between community elements. These findings highlight the necessity of integrated planning that coordinates building form, shading, and vegetation structure to improve community thermal environments. The study provides actionable quantitative thresholds and configuration guidelines for designing climate-resilient urban communities.

The global phase-out of legacy brominated flame retardants (BFRs) has coincided with the increasing detection of novel BFRs in the environment, creating a complex scenario of coexisting legacy and novel pollutants. Aquatic systems serve as major sinks for BFRs, making it imperative to assess the potential ecological risks posed by BFRs to aquatic animals. This study synthesized 8009 valid data points from 137 publications using meta-analysis, machine learning, and the Geodetector model. Meta-analysis revealed that biological factors (life stage and ecological niche) are important determinants of species sensitivity to BFRs, with early life stages, adults and benthic animals exhibiting stronger responses. Exposure conditions (BFR type, exposure time and concentration) were also important factors driving toxicity, particularly the significant effects induced by banned BFRs, high concentration exposure (> 1000 μg/L) and chronic exposure (> 14 days). A non-monotonic dose-response relationship was observed, indicating that the toxic effects did not follow a simple linear concentration‑dependent pattern. Toxicological endpoint analysis identified cytotoxicity and endocrine disruption as dominant effects. Machine learning and Geodetector model identified endpoint and BFR type as the most important factors, with widespread interactive enhancement effects among the factors. Notably, decabromodiphenyl ethane (DBDPE), a primary alternative to decabromodiphenyl ether (BDE-209), exhibited effect magnitudes comparable to or even greater than those of BDE‑209 for certain endpoints (e.g., programmed cell death and thyroid endocrine). Its toxicity was also more susceptible to modulation by exposure conditions. These findings challenge the perceived safety of DBDPE as a "safer alternative" and underscore its non‑negligible ecological risk. Mechanistically, comparative analysis of ecological niches across species indicated that the same BFR could trigger divergent adverse outcome pathways in different species, attributable to species-specific molecular initiating events.

Indica-japonica hybrid rice (IJHR) integrates the superior traits of indica rice and japonica rice (JR), with advantages in yield, Nitrogen (N) use efficiency (NUE), and root carbon (C) input. To assess its sustainability, a 9year field experiment was conducted comparing the IJHR and JR under equivalent N applications. IJHR achieved higher grain yield and NUE and lower apparent N surplus than did JR. Compared with JR, IJHR increased soil organic matter (SOM) by 15.8 %, dissolved organic C and N by 37.0 % and 66.0 %, respectively, and microbial biomass C by 26.8 %. The activities of C- and N-cycling enzymes increased by up to 106 %. These enhancements contributed to a 129.8 % improvement in the soil quality index (SQI) compared to that of the JR. Random forest analysis identified aboveground biomass, NUE, and dissolved organic C as the main yield drivers. SQI improvements were attributed mainly to SOM accumulation and root-derived C inputs, reinforced by enzymemediated C and N cycling. A higher SQI further enhanced the yield. Partial least squares path modeling demonstrated that IJHR achieves a higher yield primarily through an increase in the number of spikelets per panicle, mediated by root-driven improvements in soil quality. NUE enhancement was driven mainly by greater plant N uptake. These findings provide a process-based framework linking root traits, soil biochemical functioning, yield formation and NUE in rice systems. Here, we highlight the dual benefits of IJHR in boosting grain production and soil quality, providing a promising pathway for reconciling food security and sustainability.

Emerging contaminants in natural waters, typically present at low concentrations, pose largely unrecognized hazards and exhibit a concealed risk profile. Recently, low-dose contaminant-induced hormesis has been identified as a significant contributor to bacterial resistance and harmful algal blooms, often described as a “phantom menace”. However, the widely observed hormesis are greatly marginalized in current ecological risk assessment (ERA) guidelines, resulting in missed opportunities for proactive risk management and timely intervention during early contamination stage. To address this gap, the present work reveals the mismatch between laboratory designs and realistic scenarios, highlights the overlooked subthreshold hormesis, and reframes the dose-response relationship at low exposure levels. Building on these findings, we propose and further empirically validate a conceptual framework for integrating hormesis into conventional ERA. This framework enables the derivation of low-concentration risk thresholds grounded in the concept of hormesis. Consequently, a paradigm shift from the traditional single-threshold approach for risk identification and decision-making to a multi-threshold strategy is achieved. This advancement facilitates more precise risk profiling of emerging contaminants across low to high concentrations and calls on the scientific and regulatory communities to critically reassess existing risk assessment guidelines and water quality standards.

Nitrogen deposition, which is typically composed of various forms of nitrogen compounds, has become increasingly severe over recent decades, particularly in countries or regions with rapid economic growth, such as China. However, the long-term impacts of chronic nitrogen input on forest ecosystems and the potential differential effects between various nitrogen forms remain largely unclear. A 14-year (2010 to 2023) nitrogen addition experiment, involving three nitrogen treatments at the same total nitrogen application rate, i.e., inorganic (ammonium nitrate [NH4NO3]), organic (urea [CH4N2O] and glycine [C2H5NO2]) and mixed inorganic-organic (NH4NO3, CH4N2O and C2H5NO2) nitrogen fertilizers, was conducted on a Larix gmelinii plantation in northeastern China. Multiple tree-ring parameters (tree-ring width, earlywood width, and latewood width) were used to examine the long-term stem growth dynamics in response to these treatments. We found that separate additions of inorganic and organic nitrogen fertilizers had not stimulated Larix gmelinii stem growth in ten years but afterwards exerted increasing negative effects. In contrast, addition of mixed inorganic-organic nitrogen fertilizers enhanced obviously tree growth and the positive effects continued over the fertilization phase, which was especially pronounced in earlywood growth. However, the Larix gmelinii trees with elevated earlywood growth were susceptible to increased growth variability and decreased resilience to potential external disturbances, as indicated by obvious increases in both coefficient of variation and first-order autocorrelation coefficient of earlywood width with the mixed inorganic and organic nitrogen fertilization relative to the control. This study identified the varying effects on Larix gmelinii stem growth among different forms of nitrogen input and revealed an increase in growth instability underlying growth enhancement caused by elevated nitrogen.

Unraveling how organic fertilization affects microbial diversity, community stability, and network complexity and how these changes affect soil multifunctionality is essential for sustainable agriculture development, however, knowledge of which still has not been fully elucidated. Here, the associations between microbial diversity, community stability and network complexity with soil multifunctionality were assessed using a long−term field experiment. The following four fertilization treatments were selected: (1) without fertilization (Control), (2) chemical fertilizer only (NPK), (3) chemical fertilizer combined with cattle manure (NPKCM), and (4) chemical fertilizer combined with rice straw (NPKRS). Our results indicated that organic residues addition, particularly cattle manure input, increased microbial diversity, stability, and network complexity, along with soil multifunctionality compared with no fertilization and chemical fertilizer only. Significant positive relationships were detected between diversity, stability, and complexity and soil multifunctionality. However, random forest analysis performed that network complexity was a more influential driver of soil multifunctionality. Importantly, partial least squares path model (PLSPM) analysis demonstrated that network complexity, rather than microbial diversity or community stability, predicted the dynamics of soil multifunctionality. Therefore, the return of organic residues provided comprehensive soil function. Our study highlights the importance of network in regulating soil multifunctionality under long−term organic residues application.

This paper provides the first comprehensive documentation and assessment of the capacity of per- and polyfluoroalkyl substances (PFAS) agents, including PFAS-based pesticides, to induce hormetic effects in plants, including agricultural crops, aquatic algae, seaweed and riparian species, as well as cyanobacteria and fungi. PFAS-induced-hormetic responses in plants were generally associated with their capacity to enhance growth processes, chlorophyll production and the upregulation of antioxidant enzymes to counter PFAS-induced oxidative stress. The findings show that PFAS induced-hormetic effects in highly diverse plant species is a reasonable biological expectation, showing considerable generality. Recognition that PFAS regularly induces hormetic effects in highly diverse plant species should help guide future PFAS research on plants with respect to study design strategies, dose selection, number of doses, dose spacing and temporal aspects of such studies.

Understanding how biotic interactions shape forest communities along environmental gradients remains a central challenge in ecology as the mechanisms regulating plant species richness and abundance are highly variable. Here, we examine how mycorrhizal composition and species dominance jointly shape species richness and abundance across the tree, shrub, and herb layers. Species richness peaks at intermediate levels of mycorrhizal dominance, especially in the tree layer, supporting the mycorrhizal mixture hypothesis. In contrast, strong species dominance generally reduces species richness but increases abundance across all vegetation layers, consistent with the relaxation of conspecific negative density dependence. Canopy mycorrhizal composition exerts cross-layer effects on shrubs and herbs, with arbuscular mycorrhizal dominated canopies facilitating higher understory richness but lower abundance than ectomycorrhizal dominated canopies. Environmental gradients primarily influence forest communities indirectly by regulating the prevalence of mycorrhizal strategies and species dominance. We provide an alternative mechanism involving mycorrhizal symbiosis and interspecific competition that reconciles the divergent patterns of species richness and abundance observed in temperate and boreal forests. Plant species richness peaks at intermediate mycorrhizal dominance, while strong species dominance reduces richness but increases abundance across trees, shrubs, and herbs, with canopy mycorrhizal type shaping understory dynamics, according to an analysis of 1,917 forest inventory plots.

Ensuring equitable access to urban green space (UGS) is essential for sustainable and just urban development. However, current assessments of UGS availability typically rely on a single spatial boundary, conflating internal community green space and external public green space despite their distinct functions and allocation mechanisms. To address this gap, this study developed a novel method based on the Constant Elasticity of Substitution (CES) production function to integrate internal (GSSin) and external (GSSout) green space supply into a composite Green Space Availability (GSA) index. Applying this method to 8677 communities across 31 Chinese provincial capitals, we revealed systematically opposing spatial gradients: GSSin predominantly increases toward urban peripheries, while GSSout concentrates in urban centers, creating a vital compensatory mechanism. Importantly, incorporating external public green space improved spatial equity only when they were spatially matched with internal green space deficits; otherwise, they exacerbated inequality. Furthermore, external public green space effectively mitigated the North-South regional disparities driven by climate but struggle to bridge East-West gaps rooted in economic differences. Machine learning analysis (GBRT and SHAP) uncovered dual allocation logics: internal greenery acts as a "passive residual" constrained by building density, whereas external public green space reflect "proactive provision" driven by municipal economic capacity and topography. This dual-source method provided a diagnostic tool for targeted urban planning, emphasizing that spatial matching, rather than aggregate supply, is the key to achieving environmental justice.

The decomposition of needle litter is governed by a complex interplay between climatic conditions and substrate chemical properties, yet how their relative influence shifts during decomposition remains poorly resolved. We synthesized rate-regulating factors for long-term decomposition of Scots pine (Pinus sylvestris) needle litter across a 15-site boreal-to-temperate climatic gradient (mean annual temperature − 0.7 to 6.3 °C). Annual mass loss was analyzed across four decomposition categories, alongside concurrent measurements of acid-unhydrolyzable residue (AUR) and nitrogen, phosphorus, potassium, calcium, magnesium, and manganese in all samplings. We found that mean annual mass loss declined significantly with increasing decomposition stage, from 30.2