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Background and aims Long-term nitrogen (N) addition can affect soil organic carbon (SOC) pool within different soil fractions with different turnover rates. However, the mechanisms of these effects, particularly in alpine grassland ecosystems, are not clear. Methods We studied the responses of SOC content in different soil fractions to N addition based on a six-year N addition field experiment in an alpine meadow ecosystem on the Tibetan Plateau. We measured soil chemical and microbial properties, and SOC content in bulk soil, particular organic matter (POM) and mineral-associated organic matter (MAOM) fractions in response to N addition. Results N addition increased soil N availability, decreased soil pH and microbial biomass, but had minimal effect on plant biomass, soil enzyme activity, and SOC content in bulk soil. With increasing levels of N addition, SOC in the POM fraction (POC) showed a significant negative trend, while SOC in the MAOM fraction (MAOC) did not change significantly. Conclusions As plant biomass input and soil enzyme activity were not significantly altered with N addition, the decline in POC was likely caused by changes in microbial physiology (carbon use efficiency), while the insignificant change in MAOC may be determined by the balance between input (from microbial necromass) and output (from microbial decomposition). Taken together, our study showed that the less-protected POC fraction is more vulnerable to N addition than the more-protected MAOC fraction in the alpine grassland. This finding may improve the prediction of soil C dynamics in response to N deposition in alpine grassland ecosystems on the Tibetan Plateau.

Immune checkpoint blockade (ICB) has significantly advanced cancer immunotherapy, yet its patient response rates are generally low. Vaccines, including immunostimulant‐adjuvanted peptide antigens, can improve ICB. The emerging neoantigens generated by cancer somatic mutations elicit cancer‐specific immunity for personalized immunotherapy; the novel cyclic dinucleotide (CDN) adjuvants activate stimulator of interferon genes (STING) for antitumor type I interferon (IFN‐I) responses. However, CDN/neoantigen vaccine development has been limited by the poor antigen/adjuvant codelivery. Here, pH‐responsive CDN/neoantigen codelivering nanovaccines (NVs) for ICB combination tumor immunotherapy are reported. pH‐responsive polymers are synthesized to be self‐assembled into multivesicular nanoparticles (NPs) at physiological pH and disassembled at acidic conditions. NPs with high CDN/antigen coloading are selected as NVs for CDN/antigen codelivery to antigen presenting cells (APCs) in immunomodulatory lymph nodes (LNs). In the acidic endosome of APCs, pH‐responsive NVs facilitate the vaccine release and escape into cytosol, where CDNs activate STING for IFN‐I responses and antigens are presented by major histocompatibility complex (MHC) for T‐cell priming. In mice, NVs elicit potent antigen‐specific CD8+ T‐cell responses with immune memory, and reduce multifaceted tumor immunosuppression. In syngeneic murine tumors, NVs show robust ICB combination therapeutic efficacy. Overall, these CDN/neoantigen‐codelivering NVs hold the potential for ICB combination tumor immunotherapy. Cancer neoantigens and cyclic dinucleotide (CDN) vaccines can improve immune checkpoint blockade (ICB) immunotherapy, but have poor codelivery. Here, pH‐responsive nanovaccines are reported that efficiently codeliver CDNs/antigens to the cytosol of lymph nodal antigen presenting cells, resulting in efficient STING activation, durable antigen presentation, potent CD8+ T‐cell responses with memory, reduced tumor immunosuppression, and robust ICB combination tumor therapy.

Island area and variations in climate (e.g., temperature and precipitation) are widely known to affect the insular‐dwelling soil bacterial and fungal communities. Such effects can be context‐dependent, and many factors can determine the diversity of soil microbes. For example, island area and climate factors can directly influence soil bacterial and fungal communities, as well as exert an indirect effect by altering plant communities and/or soil properties. However, we lack a comprehensive mechanistic understanding of the relative importance of these potential drivers. To explore the key factors affecting insular soil microbial community dynamics, we selected 20 representative tropical islands in the South China Sea and established two to eight permanently marked plots based on the island area. Then, we investigated the plant community composition and measured growth strategy‐related plant traits (i.e., specific leaf area and leaf dry matter content). Concurrently, we analyzed a series of soil properties (i.e., pH, salinity, organic carbon, total nitrogen, total phosphorus, total potassium, and carbon/nitrogen ratio) and the diversity of soil bacterial and fungal communities. For the soil bacterial community, based on structural equation modeling (SEM) analysis, we found an indirect effect of climate factors and island area on bacterial richness through their influence on plant richness, in addition to the direct effect of island area on bacterial richness. In contrast, for the soil fungal community, we found that the influences of temperature and precipitation are primarily indirect via changes in soil pH and the community‐weighted mean (CWM) value of plant leaf dry matter content. Overall, this study highlights that island‐dwelling soil bacterial and fungal communities are shaped by island‐specific plant community and soil pH, which may interplay with macroscopic threats like ongoing sea level rise and biological invasions, thus providing crucial insights into the dynamics of soil microorganisms under global change scenarios.

An essential ecosystem service is the dilution effect of biodiversity on disease severity, yet we do not fully understand how this relationship might change with continued climate warming and ecosystem degradation. We designed removal experiments in natural assemblages of Tibetan alpine meadow vegetation by manipulating plot‐level plant diversity to investigate the relationship between different plant biodiversity indices and foliar fungal pathogen infection, and how artificial fertilization and warming affect this relationship. Although pathogen group diversity increased with host species richness, disease severity decreased as host diversity rose (dilution effect). The dilution effect of phylogenetic diversity on disease held across different levels of host species richness (and equal abundances), meaning that the effect arises mainly in association with enhanced diversity itself rather than from shifting abundances. However, the dilution effect was weakened by fertilization. Among indices, phylogenetic diversity was the most parsimonious predictor of infection severity. Experimental warming and fertilization shifted species richness to the most supported predictor. Compared to planting experiments where artificial communities are constructed from scratch, our removal experiment in natural communities more realistically demonstrate that increasing perturbation adjusts natural community resistance to disease severity.

The artificial fertilization of soils can alter the structure of natural plant communities and exacerbate pathogen emergence and transmission. Although the direct effects of fertilization on disease resistance in plants have received some research attention, its indirect effects of altered community structure on the severity of fungal disease infection remain largely uninvestigated. We designed manipulation experiments in natural assemblages of Tibetan alpine meadow vegetation along a nitrogen-fertilization gradient over 5 years to compare the relative importance of direct and indirect effects of fertilization on foliar fungal infections at the community level. We found that species with lower proneness to pathogens were more likely to be extirpated following fertilization, such that community-level competence of disease, and thus community pathogen load, increased with the intensity of fertilization. The amount of nitrogen added (direct effect) and community disease competence (indirect effect) provided the most parsimonious combination of parameters explaining the variation in disease severity. Our experiment provides a mechanistic explanation for the dilution effect in fertilized, natural assemblages in a highly specific pathogen–host system, and thus insights into the consequences of human ecosystem modifications on the dynamics of infectious diseases.

Island biogeography theory posits that both island area and isolation significantly influence species distribution patterns and community structure. This study investigates the effects of island area and isolation on plant community structure, specifically focusing on the variation in species richness and abundance among different plant life forms (i.e., trees and shrubs) on tropical islands in the South China Sea. We surveyed woody plants and collected soil samples from 20 tropical islands in the South China Sea, analyzing how island area, isolation, climate and soil factors influence plant communities across different life forms (trees vs. shrubs). The results indicate that species richness increases with island area and decreases with isolation, which aligns with the classic predictions of island biogeography. However, plant abundance exhibits a more complex pattern: tree abundance is positively correlated with island area and negatively correlated with isolation, while shrub abundance shows the opposite trend. Furthermore, the relative tree richness and abundance are predominant on larger, less isolated islands, whereas shrubs are more prevalent on smaller, more remote islands. These contrasting patterns suggest that different life forms adopt distinct ecological strategies within island ecosystems. The structural equation model (SEM) revealed that island area, isolation, and climatic factors directly affect the richness and abundance of trees but not shrubs. Additionally, the indirect effect of soil pH has proven to be a crucial environmental factor in shaping plant community structure. Overall, this study highlights the multifaceted roles of geographic, climatic, and soil factors in determining the composition of island plant communities across different life forms. The findings have important implications for island conservation, as they provide a deeper understanding of how plant communities respond to spatial and environmental factors, aiding in the management of biodiversity on tropical islands.

Island ecosystems, due to their geographical isolation and unique environmental conditions, often serve as natural laboratories for ecological research and are also sensitive to global climate change and biodiversity loss. The allometric relationship between plant height-diameter reflects the adaptive growth strategy of plants under different environmental conditions, particularly in response to biomechanical constraints (e.g., wind resistance) and resource availability. This study aims to explore the key driving factors of the height-diameter allometry of island plants, focusing on how island area, soil properties, and climatic factors (e.g., wind speed, temperature, and precipitation) affect plant growth strategy. We analyzed plant data from 20 tropical islands, using SMA regression to calculate the allometric exponent and intercept for each island's plants, and evaluated the effects of island area, soil properties, and climatic factors (wind speed, temperature, and precipitation) on the height-diameter allometric relationship. The results show that island area has no significant effect on plant allometry, while climatic factors, particularly wind speed, and soil properties significantly influence the allometric exponent and intercept, respectively. Specifically, wind speed is the primary driver of the height-diameter allometric exponent, regulating plant growth proportions through mechanical stress and canopy limitation. In contrast, soil properties predominantly govern changes in the allometric intercept, reflecting their critical role in determining baseline growth conditions, such as resource allocation and initial morphological adaptation. The effects of temperature and precipitation are relatively weak, likely due to the buffering effects of the tropical climate and marine moisture supplementation. Overall, this study highlights the key roles of wind speed and soil in shaping the allometry of island plants, providing new insights into the adaptive strategies of island plants under resource limitations and climatic pressures, as well as offering important scientific evidence for island ecological conservation and restoration.

Rheumatoid arthritis (RA) is a systemic autoimmune disease with pathogenic inflammation caused partly by excessive cell‐free DNA (cfDNA). Specifically, cfDNA is internalized into immune cells, such as macrophages in lymphoid tissues and joints, and activates pattern recognition receptors, including cyclic guanosine monophosphate–adenosine monophosphate synthase (cGAS), resulting in overly strong proinflammation. Here, nanomedicine‐in‐hydrogel (NiH) is reported that co‐delivers cGAS inhibitor RU.521 (RU) and cfDNA‐scavenging cationic nanoparticles (cNPs) to draining lymph nodes (LNs) for systemic immunosuppression in RA therapy. Upon subcutaneous injection, NiH prolongs LN retention of RU and cNPs, which pharmacologically inhibit cGAS and scavenged cfDNA, respectively, to inhibit proinflammation. NiH elicits systemic immunosuppression, repolarizes macrophages, increases fractions of immunosuppressive cells, and decreases fractions of CD4 + T cells and T helper 17 cells. Such skewed immune milieu allows NiH to significantly inhibit RA progression in collagen‐induced arthritis mice. These studies underscore the great potential of NiH for RA immunotherapy.

Plant nitrogen (N) uptake is a critical ecosystem function, especially when terrestrial ecosystems are threatened worldwide by increasing anthropogenic N deposition. However, the mechanisms by which biotic factors mediate the effects of increases in N addition on community N uptake remain unknown. Here, we determine how inter- and intraspecific differences contribute to this response by decomposing N uptake in a specific community in a 7-year NH4NO3 addition experiment in a Tibetan alpine meadow using variance partitioning approach. We measured both plant N uptake from ammonium and nitrate of 25 common species in control plots and community-level uptake along a N addition gradient, using short-term in situ 15N labeling. Plant community composition, soil properties (soil ammonium and nitrate, pH, Al3+ and base cations), soil microbial biomass carbon and nitrogen were measured and recorded. We found that N addition increased community-level N uptake by significantly increasing individual species’ variability of N uptake (that is, positive intraspecific variability), although with limited effect of community composition shift. The significantly positive intraspecific variability from ammonium and nitrate along the N addition gradient was caused by increased soil available N and soil acidification with N addition. The limited effect of community composition shift means that N addition increased community-level N uptake with only limited species filtering. Our results provide a novel insight into the mechanism of how N addition affects community-level N uptake, by linking physiological, community and ecosystem function, and highlight the important role that intraspecific variability of N uptake plays.

Global environmental change is causing a decline in biodiversity with profound implications for ecosystem functioning and stability. It remains unclear how global change factors interact to influence the effects of biodiversity on ecosystem functioning and stability. Here, using data from a 24-year experiment, we investigate the impacts of nitrogen (N) addition, enriched CO 2 (eCO 2 ), and their interactions on the biodiversity-ecosystem functioning relationship (complementarity effects and selection effects), the biodiversity-ecosystem stability relationship (species asynchrony and species stability), and their connections. We show that biodiversity remains positively related to both ecosystem productivity (functioning) and its stability under N addition and eCO 2 . However, the combination of N addition and eCO 2 diminishes the effects of biodiversity on complementarity and selection effects. In contrast, N addition and eCO 2 do not alter the relationship between biodiversity and either species asynchrony or species stability. Under ambient conditions, both complementarity and selection effects are negatively related to species asynchrony, but neither are related to species stability; these links persist under N addition and eCO 2 . Our study offers insights into the underlying processes that sustain functioning and stability of biodiverse ecosystems in the face of global change. This study reveals that nitrogen addition and elevated CO₂ diminish the effects of biodiversity on complementarity and selection effects, but do not alter the relationship between biodiversity and either species asynchrony or species stability.