Green space can effectively retain particles and improve air quality. However, most studies have focused on leaf-scale measurements or regional-scale model simulations, and few focus on individual trees. In this study, 176 urban park green spaces were selected within the 5th Ring Road in Beijing, and the i-Tree Eco model was used to estimate the PM_2.5 retention levels of individual trees and sample plots. The results show that the retention capacity varied according to tree species. The PM_2.5 retention of each sample plot was significantly affected by the tree coverage, species richness, mean tree height, mean crown width, and number of trees. The PM_2.5 retention of urban park green spaces in the study area was estimated to be about 6380 t·year⁻¹, and the air quality improvement rate was 1.62%. After structural optimizing, PM_2.5 retention of the mixed coniferous and broad-leaved green space was as high as 80,000 g·year⁻¹. This study studied the effects of trees on PM_2.5 retention at multiple scales to fill the gaps in existing research at the scales of individual trees and communities, and it can serve as a reliable reference for the design and construction of green spaces aimed at improving air quality.

Explaining community assembly mechanisms along elevational gradients dominated by deterministic processes or stochastic processes is a pressing challenge. Many studies suggest that phylogenetic and functional diversity are significant indicators of the process. In this study, we analyzed the structure and beta diversity of phylogenetic and functional traits along an elevational gradient and discussed the effects of environmental and spatial factors. We found that the phylogenetic and functional traits showed inconsistent changes, and their variations were closely related to the abiotic environment. The results suggested that the community assembly of woody plants was obviously affected by the combined effect of deterministic processes and the stochastic hypothesis (primarily by the latter). Phylogenetic and functional traits had a certain relationship but changed according to different rules. These results enhance our understanding of the assembly mechanism of forest communities by considering both phylogenetic and functional traits.

The treeline is a sensitive region of the terrestrial ecosystem responding to climate change. However, studies on the composition and formation mechanisms of soil fungal communities across the treeline are still lacking. In this study, we investigated the patterns of soil fungal community composition and interactions among functional guilds above and below the treeline using Illumina high-throughput sequencing and ecological network analysis. The results showed that there were significant differences in the soil environment and soil fungal community composition between the two ecosystems above and below the treeline. At the local scale of this study, geographic distance and environmental factors affected the composition of the soil fungal community. Soil temperature was an important environmental predictor of soil fungal community composition. Species in soil fungal communities in the subalpine meadow were more closely related to each other compared to those in the montane forest. Furthermore, the soil fungal community in montane forest was more stable. Our findings contribute to a better understanding of how mountain ecological functions respond to global climate change.

The diversity and spatial patterns of soil invertebrates are the cornerstones for understanding their ecological functions, which are crucial to maintaining nutrient cycling and soil health in forest ecosystems. Based on a continuous altitudinal gradient (1020–1770 m) composed of 119 plots, this study analyzed the spatial patterns of invertebrate communities in temperate mountain forest litter and soil using multi-scale ordination. The results indicate that along the altitudinal gradient, the invertebrate communities in both litter and soil layers exhibit “patches” at a scale of approximately 33 plots that are mainly composed of Mesostigmata and Apterogasterine oribatid mites. In the litter layer, at the 11-plot scale, an aggregation of Onychiuridae is also formed, while in the soil layer, there are “patches” represented by Diadocidiidae at the 33-plot scale. The positive–negative associations among invertebrate taxa also shift between the litter and soil layers, as well as among “patches”. Our study confirms that the richness of invertebrates in temperate-forest litter is higher and forms multi-scale assembly “patches” despite the higher abundance of invertebrates in the soil layer. Future studies should delve deeper into the aggregation mechanisms of these specific taxa and may require higher sampling densities to reveal the multi-scale spatial patterns of soil invertebrates.