城市森林冠层降水再分配及其对重金属沉降的影响—以广州帽峰山为例

理解全球变化与人类活动背景下城市森林冠层对降水输入和大气重金属沉降的影响，是当前生态水文学和环境科学领域所共同关注的热点问题之一，然而，目前城市森林冠层降水再分配过程对重金属沉降的影响机理仍不清楚。本项目以广州市帽峰山森林为例，选择3种典型森林类型（常绿阔叶林、针阔混交林和人工恢复林）建立实验观测样地，通过林冠调查并结合激光扫描技术构建林冠三维结构模型，辨识不同林种林冠结构特征差异性，基于野外高频水文过程监测与样品分析，研究林冠降水再分配过程及其主要影响因素，揭示不同林种穿透水和树干茎流中溶解态/颗粒态重金属通量及季节变化规律，阐明林冠穿透水量/率和树干茎流量/率与重金属含量间的定量关系，探讨城市森林冠层降水再分配对重金属沉降的影响机理。本研究将为城市森林减污抗污树种遴选与区域大气重金属污染防治提供科学指导。

Due to global change and human activities, the role of urban forest on modulating precipitation input and associated heavy metal deposition is a critical focus in ecohydrology and environmental sciences. However, the mechanism linkage between precipitation partitioning and heavy metal deposition in urban forest remains unclear. This project focuses on three typical forest types (evergreen broad leaved, coniferous and artificial restoration forest) in Maofeng Mountain, Guangzhou city with the aid of observing stations. Through high frequency sampling combined with 3-dimensional laser scanning and hydrological process monitoring, we aim to (1) identify the differences of canopy structure in different forest species and enhance the understanding of main influencing factors for the process of precipitation partitioning; (2) elucidate the seasonal variations in dissolved/granular heavy metals flux in throughfall and stemflow across different forest species; (3) clarify the quantitative relationship between precipitation partitioning process and heavy metal flux; (4) discuss the impact mechanism of precipitation partitioning on atmospheric heavy metal deposition in different forest species. These findings would provide valuable scientific guidance for the selection of pollution-reducing tree species for urban forest and the control of heavy metal pollutants in regional atmosphere.