Ozone Effects on Plant Physiology and Ecosystem Dynamics

Ground-level ozone, formed by photochemical reactions of precursor gases, represents a pervasive phytotoxic stressor with profound implications for plant function and ecosystem processes. At the leaf level, ozone enters through stomatal apertures and generates reactive oxygen species, impairing photosynthetic machinery, disrupting carbon assimilation and altering water relations through modified stomatal control. Chronic exposure induces visible foliar symptoms, accelerates cellular ageing and compromises growth, thereby reducing net primary productivity and lowering ecosystem carbon sequestration. Beyond individual plants, ozone influences species composition, nutrient cycling and soil-microbial interactions, with cascading effects on biodiversity and ecosystem resilience. Modelling studies reveal that ozone interactions with other environmental drivers—such as drought, elevated CO₂ and nitrogen deposition—can amplify or mitigate overall impacts. Through feedbacks to atmospheric chemistry and surface energy balance, ozone-induced physiological alterations feed back into regional climate and air quality. Together, these insights underscore the need for integrated assessments to inform air-pollution control and forest management strategies aimed at safeguarding global vegetation health and carbon dynamics.

Research from Nature Portfolio

Recent field experiments in tropical forests have quantified species-specific ozone sensitivities and integrated these data into dynamic vegetation models, revealing a 10–20 % reduction in annual net primary productivity across major tropical regions and a cumulative loss of roughly 0.3 Pg C yr⁻¹ in carbon drawdown since 2000. This work highlights that both intact and regenerating forests are disproportionately affected by elevated ozone, with implications for global carbon budgets under differing socioeconomic pathways.

A multi-model assessment of fire-related air pollution has disentangled the opposing roles of ozone and aerosols on global productivity. Fire-emitted ozone is shown to reduce gross primary productivity by nearly 1 Pg C yr⁻¹, while concurrently produced aerosols enhance diffuse radiation and stimulate photosynthesis; the net effect is a substantial decline in terrestrial productivity, emphasising the combined significance of oxidant and particulate emissions.

Detailed process-based simulations of temperate deciduous forests have incorporated ozone-induced stomatal sluggishness into coupled photosynthesis-stomatal models by adjusting a minimum conductance parameter. Results indicate that delayed stomatal responses under ozone stress can diminish water-use efficiency by up to 20 %, compared with only 5 % when sluggishness is neglected, thereby altering both carbon and hydrological balances at ecosystem scales.

Ozone Effects on Plant Physiology and Ecosystem Dynamics publication trend

The graph below shows the total number of articles in ozone effects on plant physiology and ecosystem dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Net primary productivity (NPP): The net gain of carbon by plants after accounting for respiratory losses.

Gross primary productivity (GPP): The total carbon fixed by photosynthesis before plant respiration.

Stomatal conductance: The rate at which gases pass through stomatal pores, influencing CO₂ uptake and water loss.

Reactive oxygen species (ROS): Highly reactive molecules formed during ozone detoxification that can damage cellular components.

Free-air controlled exposure (FACE): A field system that exposes plants to elevated ozone under natural growing conditions.

Visible foliar symptoms (VFS): Discrete patterns of necrosis or chlorosis on leaves directly attributable to ozone injury.

References

1. Reduced productivity and carbon drawdown of tropical forests from ground-level ozone exposure. Nature Geoscience (2024).
2. Fire air pollution reduces global terrestrial productivity. Nature Communications (2018).
3. Ozone-induced stomatal sluggishness changes carbon and water balance of temperate deciduous forests. Scientific Reports (2015).
4. Comet assay as an early predictor tool to detect ozone enhanced sensitivity of vegetation in a free-air controlled long-term exposure. Plant Stress (2023).
5. The fingerprint of tropospheric ozone on broadleaved forest vegetation in Europe. Ecological Indicators (2024).
6. Ozone — the persistent menace: interactions with the N cycle and climate change. Current Opinion in Environmental Sustainability (2014).
7. Effects of ozone–vegetation coupling on surface ozone air quality via biogeochemical and meteorological feedbacks. Atmospheric Chemistry and Physics (2017).