Influence of Urban Forest Size and Form on PM2.5 and O3 Concentrations: A Perspective of Size Threshold

摘要

城市森林（UF）是缓解空气污染的有效途径。在PM2.5-O3复合污染普遍且UF扩张面临瓶颈的阶段，基于其面积大小优化UF形态成为更优的管理策略。然而，现有研究尚未充分探讨UF尺寸的阈值效应。本研究利用面板阈值回归模型，考察了2014年至2022年中国长江三角洲（YRD）305个县的空气污染与UF（尺寸和形态）之间的关系。结果表明：（1）UF尺寸在三个关系中表现出双重阈值效应：斑块密度（PD）与PM2.5之间，分裂指数（SPLIT）与PM2.5之间，以及SPLIT与O3之间。同时，在其他UF形态指标与污染物浓度关系中观察到UF尺寸的单一阈值效应。（2）当UF尺寸在UF形态与污染物浓度关系中起阈值作用时，其阈值通常在3%、14%和45%左右。UF形态指标与PM2.5的相关性通常与与O3的相关性相反。（3）当UF尺寸小于45%时，PM2.5的减排有利于复杂形状和分散的UF斑块，而O3的减排则受益于更规则和集中的UF斑块。一旦UF尺寸超过45%，连续的区域性UF网络就有可能解决PM2.5-O3复合污染问题。本研究旨在为大气治理和UF规划提供参考。

Abstract

Urban forest (UF) is an effective means of mitigating air pollution. At the stage where PM2.5-O3 composite pollution is prevalent and UF expansion reaches a bottleneck, optimizing UF form based on its area size becomes a superior management strategy. However, existing research has not fully explored the threshold effects of UF size. Using the panel threshold regression model, this study examines relationships between air pollution and UF (size and form) in 305 counties within the Yangtze River Delta (YRD) from 2014 to 2022. The results show (1) UF size exhibits a double threshold effect in three relationships: between patch density (PD) and PM2.5, between splitting index (SPLIT) and PM2.5, and between SPLIT and O3. Meanwhile, a single threshold effect of UF size is observed in relationships between other UF form metrics and pollutant concentrations. (2) When UF size plays the threshold effect in relationships between UF form and pollutant concentrations, its threshold values usually lie around 3%, 14%, and 45%. UF form metrics’ correlations with PM2.5 are generally opposite to those with O3. (3) When UF size is below 45%, PM2.5 reduction favors complex-shaped and dispersed UF patches, while O3 reduction benefits from more regular and concentrated UF patches. Once UF size exceeds 45%, a continuous regional UF network can potentially address PM2.5-O3 composite pollution. This study aims to provide insights into atmospheric governance and UF planning.

引用格式

@article{2025_aqah_forest_pm25_o3,
  title={Influence of urban forest size and form on PM2.5 and O3 concentrations: A perspective of size threshold},
  author={Xin Chen and 蔚芳},
  journal={Air Quality, Atmosphere & Health},
  year={2025},
  doi={10.1007/s11869-025-01722-7}
}