PM2.5 Concentration Differences between Various Forest Types and Its Correlation with Forest Structure

Abstract

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.

Individual and Interactive Influences of Anthropogenic and Ecological Factors on Forest PM2.5 Concentrations at an Urban Scale

“…The variations in particulate retention among tree species in this study were consistent with those found by Liu [12] and Yang [45] and may be explained by variations in morphological characteristics that enable plants to trap particulates (e.g., canopy structure, leaf density, leaf surface roughness, and wax) [16]. The three-dimensional structure of tree canopies encourages turbulent air movement and the more complex the canopy structure, the more particulates are deposited onto leaf surfaces [46].…”

“…For instance, Jin [11] measured canopy density and LAI with a laser dust monitor and applied a mixed-effect model to quantitatively analyze the effect of particulates on vegetation. Similarly, Liu [12] used a TH-150C particulate sampler to obtain PM 2.5 concentrations in sample plots and applied a multiple regression model to analyze the relationship between PM 2.5 concentrations and NDVI and LAI. Although particle collectors can accurately capture PM 2.5 concentrations in real time, these instruments are expensive to operate.…”

Effects of Particle Matters on Plant: A Review

“…These studies are based on the comparison of leaf shape (linear, lanceolate, obovate, palmate, needle-like, tip-like, broad-leaved or elliptic) and leaf arrangement (opposite, alternate or whorled). As a result, the ability of the plants to capture and accumulate PM differs significantly among foliage with different morphological features [40][41][42][43][44][45]. But Daresta had different results: the arrangement of leaves had no effect on particle matters adsorption, perhaps because other characteristics of leaves had more significant effects than the leaves arrangement [46].…”

Retention of Atmospheric Particles by Local Plant Leaves in the Mount Wutai Scenic Area, China

“…Research by Wang et al showed that particles were more easily retained if there were 1-2 µm ridged grooves on leaf surfaces or rough blade surfaces far from the rachis in broad-leaved plants [11]. Factors including leaf shape, leaf size, tree trunk and crown density explained the different capacities of PM 2.5 retention in forests [12].…”