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Air pollution causes serious problems in spring in northern China; therefore, studying the ability of different plants to accumulate particulate matter (PM) at the beginning of the growing season may benefit urban planners in their attempts to control air pollution. This study evaluated deposits of PM on the leaves and in the wax layer of 35 species (11 shrubs, 24 trees) in Beijing, China. Differences in the accumulation of PM were observed between species. Cephalotaxus sinensis, Euonymus japonicus, Broussonetia papyriferar, Koelreuteria paniculata and Quercus variabilis were all efficient in capturing small particles. The plants exhibiting high amounts of total PM accumulation (on leaf surfaces and/or in the wax layer), also showed comparatively high levels of PM accumulation across all particle sizes. A comparison of shrubs and trees did not reveal obvious differences in their ability to accumulate particles based on growth form; a combination of plantings with different growth forms can efficiently reduce airborne PM concentrations near the ground. To test the relationships between leaf traits and PM accumulation, leaf samples of selected species were observed using a scanning electron microscope. Growth forms with greater amounts of pubescence and increased roughness supported PM accumulation; the adaxial leaf surfaces collected more particles than the abaxial surfaces. The results of this study may inform the selection of species for urban green areas where the goal is to capture air pollutants and mitigate the adverse effects of air pollution on human health.

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We quantified the soil conservation service of ecosystems in China on a GIS platform using the Universal Soil Loss Equation (USLE) and revealed spatial patterns and impacts of this service. The results showed that the total amount and mean capacity of soil conservation service in China were 214.64 billion t a − 1 and 224.42 t ha −1 a −1 , respectively. South-east China generally displayed a much higher capacity than the north-west, and ecosystems with a capacity of N1000 t ha − 1 a − 1 were primarily located in mountain areas, including the Tsinling, Nanling, and Wuyi Mountains. Through comparisons, ecosystems located in the provinces of Fujian, Guangxi, Zhejiang, those in the basins of south-eastern rivers, the Pearl River, and the Yangtze River, and those at elevations of 200-1000 m all performed much better than others, from the erosion control perspective. As for the impacts, the spatial characteristics of soil conservation service in China were primarily controlled by climate and terrain at the national scale. In addition, population growth might not affect the soil conservation service directly, whereas land reclamation could impair this service and subsequently exacerbate soil erosion. Finally, the results of this study could contribute to soil erosion control and ecosystem protection in China.

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Abstract:The Plain Forestation Project is an important measure designed to alleviate air pollution in Beijing, the capital of China. Ten commonly cultivated forest types of the Plain Forestation Project were studied at three growth stages of leaves. The particulate matter (PM)2.5 concentrations and forest structures were surveyed to analyze the PM2.5 concentration differences between different forest types, and establish a linear relationship between forest structures and PM2.5 concentration differences. The results suggested that forest ecosystems can block and capture PM2.5 from the air. Forests with luxuriant foliage are most effective in removing PM2.5 from the air. The average PM2.5 mass concentration in the Leaf-on Period (LOP) was the lowest when compared with other periods. The PM2.5 concentrations in the forest usually were higher than the control. Correspondingly, PM2.5 concentration indexes were negative values during daytime, but this results were reversed at night. Forests can reduce the diffusion rate of PM2.5 leading to PM2.5 were detained in the forest during daytime, and play an important role in the adsorption or deposition of particulate matter at night. Forest structure was primary reason of the PM2.5 concentration difference between different forests. The PM2.5 concentration index was positively correlated to canopy density, leaf area index (LAI), and mean diameter at breast height (DBH), and negatively correlated to the average tree height (height), forestland area, grass coverage and height.

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