Sampling ozone exposure of Canadian forests at different scales: some case studies

Area of Science:

• Environmental Science
• Forest Ecology
• Atmospheric Chemistry

Background:

• Forest health monitoring relies on understanding pollutant exposure.
• Ozone (O3) is a significant phytotoxic air pollutant impacting forest ecosystems.
• Traditional monitoring methods may not capture fine-scale exposure variations.

Purpose of the Study:

• To evaluate the efficacy of passive samplers for monitoring forest ozone exposure.
• To assess the spatial and temporal variability of ozone exposure in forest plots.
• To investigate the influence of topography and canopy characteristics on ozone exposure.

Main Methods:

• Deployment of passive samplers in national forest health monitoring plots.
• Comparison of passive sampler data with continuous monitoring data.
• Analysis of ozone exposure gradients along air pollution deposition gradients.
• Investigation of vertical profiles and edge effects within forest stands.

Main Results:

• Passive samplers accurately determined spatial and temporal differences in ozone exposure.
• Significant variation in accumulated ozone exposure was observed along pollution gradients.
• Sampler data showed weak correlation with distant continuous monitors but strong correlation with co-located samplers.
• Elevation and tree canopy characteristics were identified as crucial factors influencing regional ozone exposure.

Conclusions:

• Passive samplers are effective tools for in situ forest canopy ozone exposure monitoring.
• Topography and canopy structure play vital roles in determining plant exposure to ozone.
• Passive sampling facilitates the development of spatial models for ozone exposure assessment at various scales.