Soil fungal communities play a critical role in the promotion of nutrient cycling and the stabilization of ecosystem functions in subtropical forests. Yet, clarifying the relationships between soil fungal diversity and microclimate variability along an elevational gradient, as well as understanding the driving mechanisms of their variations in subtropical forests, remains insufficiently understood. In this study, we recorded the composition and soil fungal diversity along an elevational gradient in Daiyun Mountain of China, aiming to elucidate the primary factors influencing the structure of the dominant soil fungal along an elevational gradient in subtropical forests. The results showed that (1) the dominant phylum of soil fungi at different elevations were Basidiomycota, Ascomycota (relative abundance > 10%) and Zygomycota (relative abundance > 1%). The Simpson index of soil fungi showed a clear upward trend along the elevational gradient, while no significant difference was observed in the other indices, and both overall reached their maximum value at the elevation of 1200 m. (2) The mean annual soil temperature and moisture, soil pH and available phosphorus were the main factors driving the dominant soil fungal along the elevational gradient. (3) Co–occurrence network analyses revealed a distinct modular structure of dominant soil fungal communities at different elevations, with Ascomycetes identified as the key taxa in fungi network relationships. Our research holds ecological significance in understanding the pivotal role of soil environmental factors in shaping the complex composition and interactions within soil fungal communities.

The investigation of taxonomic diversity within island plant communities stands as a central focus in the field of island biogeography. Phylogenetic diversity is crucial for unraveling the evolutionary history, ecological functions, and species combinations within island plant communities. Island effects (area and isolation effect) may shape species distribution patterns, habitat heterogeneity affects habitat diversity, and anthropogenic disturbances can lead to species extinction and habitat destruction, thus impacting both species diversity and phylogenetic diversity. To investigate how taxonomic and phylogenetic diversity in island natural plant communities respond to island effects, habitat heterogeneity, and anthropogenic disturbances, we took the main island of Haitan (a land-bridge island) and nine surrounding islands (oceanic islands) of varying sizes as the subjects of our study on the Pingtan islands. We aim to elucidate the influence of island effects, habitat heterogeneity, and anthropogenic disturbances on taxonomic and phylogenetic diversity. The results showed that, (1) Both the taxonomic and phylogenetic diversity of plants on the Pingtan islands followed the island area effect, indicating that as the island area increases, both taxonomic and phylogenetic diversity also increase. (2) Island effects and habitat heterogeneity were found to enhance taxonomic and phylogenetic diversity, whereas anthropogenic disturbances were associated with a decrease in both taxonomic and phylogenetic diversity. Furthermore, the synergistic influence of island effects, habitat heterogeneity, and anthropogenic disturbances collectively exerted a negative impact on both taxonomic and phylogenetic diversity. (3) The contribution of explanatory variables of anthropogenic disturbances for taxonomic and phylogenetic diversity was higher than that of island effects and habitat heterogeneity. Additionally, the contribution of the explanatory variables under the combined influence of island effects, habitat heterogeneity, and anthropogenic disturbances is higher than that of the individual variables for island effects and habitat heterogeneity. These findings suggest that anthropogenic disturbances emerged as the dominant factors influencing both taxonomic and phylogenetic diversity. These findings demonstrate the intricate interplay between island effects, habitat heterogeneity, and anthropogenic disturbances, highlighting their combined influence on both taxonomic and phylogenetic diversity on island.

Negative air ions (NAIs) are crucial for assessing the impact of forests on wellbeing and enhancing the physical and mental health of individuals. They serve as pivotal indicators for assessing air quality. Comprehensive research into the distribution patterns of NAI concentrations, especially the correlation between NAI concentrations and meteorological elements in tourist environments, necessitates the accumulation of additional long-term monitoring data. In this paper, long-term on-site monitoring of NAI concentrations, air temperature, relative humidity, and other factors was conducted in real time over 24 h, from April 2020 to May 2022, to explore the temporal dynamic patterns of NAIs and their influencing factors. The results showed that (1) the daily dynamics of NAI concentrations followed a U-shaped curve. The peak concentrations usually occurred in the early morning (4:30–8:00) and evening (19:10–22:00), and the lowest concentrations usually occurred at noon (12:50–14:45). (2) At the monthly scale, NAI concentrations were relatively high in February, August, and September and low in January, June, and December. At the seasonal scale, NAI concentrations were significantly higher in winter than in other seasons, with higher concentrations occurring in the summer and autumn. (3) Relative humidity, air temperature, and air quality index (AQI) were the primary factors that influenced NAI concentrations. Relative humidity showed a significant positive correlation with NAI concentrations, while air temperature and AQI both exhibited a significant negative correlation with NAI concentrations. Higher air quality corresponds to higher NAI concentrations. Our research provides new insights into NAI temporal dynamics patterns and their driving factors, and it will aid in scheduling outdoor recreation and forest health activities.

Silicon (Si) and calcium (Ca), as elements abundant in the Earth’s crust, are closely related to plant growth and stress resistance and have similar roles. Understanding the stoichiometry of Si and Ca can provide more insight into the mechanical and stress resistance of plants, as well as their preferences for the absorption and use of Si and Ca. Here, we measured the content of Si and Ca in the leaves of the dominant tree species located in the Mount Wuyi National Park, with an elevation ranging from 800 m to 1700 m, in an attempt to reveal changes in the Si and Ca content and ratio in the leaves along the altitude, as well as their possible relationships with environmental factors and phylogeny. The results indicated that the leaf Si and the leaf Si/Ca decreased, while the leaf Ca increased significantly with the increase in elevation. Changes in environmental factors induced by variations in elevation affected the silicon and calcium stoichiometry characteristics of the leaves, either directly or indirectly. Specifically, the mean annual precipitation, soil available silicon, soil organic matter, and soil bulk density accounted for most of the variations in leaf silicon and calcium. The leaf silicon and calcium stoichiometry was phylogenetically conservative, suggesting more similar characteristics among closely related tree species. Structural equation modeling and variation partitioning indicated that phylogeny might be more important than environmental factors in influencing leaf Si and Ca stoichiometry. Additionally, the shared effects of environmental factors and taxonomic levels indicated changes in the forest community, and the differential responses of different functional types due to elevation variation also affected the altitudinal patterns of leaf Si and Ca stoichiometry.

Excessive light intensity, often resulting from anthropogenic disturbances, poses a threat to light-sensitive Liquidambar formosana seedlings. This study examined the effects of five light intensity levels and three silicon (Si) application rates on photosynthetic performance, oxidative stress responses, and seedling growth. Results indicated that full sunlight significantly reduced ground diameter, chlorophyll content, specific leaf area, and stomatal conductance. Meanwhile, it increased the activities of superoxide dismutase and peroxidase, and led to higher accumulation of malondialdehyde (MDA). Application of Si enhanced seedling height, biomass accumulation, and antioxidant enzyme activity under high-light conditions, while reducing MDA content, stomatal CO₂ conductance, and transpiration rate, and maintaining a stable net photosynthetic rate. However, excessive Si (3000 mg·kg⁻¹) led to decreased catalase activity, chlorophyll content, and leaf area under intense light. These findings suggest that L. formosana seedlings perform best under moderate shade (11,000–46,000 lx) and moderate Si application (1000–2000 mg·kg⁻¹), which together mitigate photoinhibition damage. Optimal physiological responses thus require balanced Si concentrations. Further investigation is warranted to elucidate the mechanisms underlying the interactive effects of shading and Si application for improved seedling resilience.