Ozone effects on plants in natural ecosystems

Area of Science:

• Ecology
• Environmental Science
• Plant Physiology

Background:

• Tropospheric ozone (O3) is a significant environmental stressor impacting natural ecosystems.
• Ozone's effects on individual plants scale up to influence ecosystem-level carbon, nutrient, and hydrologic dynamics.
• Foliar injury from ozone is observed globally, but impacts on plant physiology can occur without visible symptoms.

Purpose of the Study:

• To assess the impacts of tropospheric ozone on ecosystem processes and plant health.
• To investigate how ozone sensitivity varies across different plant physiognomic classes.
• To evaluate the role of stomatal ozone uptake in determining species sensitivity.

Main Methods:

• Systematic foliar injury surveys across various plant species and global locations.
• Controlled studies on seedlings and investigations of mature tree radial growth.
• Modeling of tree physiology and forest stand dynamics to predict long-term ozone impacts.

Main Results:

• Ozone exposure causes foliar injury in sensitive species and affects plant carbon, water, and nutrient balance, even without visible damage.
• Ambient ozone has been shown to reduce the growth of mature trees in certain areas.
• Ozone's effects can be exacerbated by other stressors like drought and nitrogen deposition, potentially altering species interactions and forest composition over time.

Conclusions:

• Tropospheric ozone poses a significant threat to ecosystem health and function.
• Ozone's cumulative effects and interactions with other environmental factors can lead to shifts in forest species composition.
• Continued increases in ozone due to fossil fuel combustion will likely exacerbate these impacts in the future.