Main and interactive effects of ozone and other climate factors on plant gas exchange, biomass production and allocation: A global meta-analysis

Abstract Elevated ground-level ozone (O3) is known to inhibit plant growth and development, but its interactive effects with other climate factors, such as elevated carbon dioxide, warming, drought, and nitrogen deposition, remain poorly understood. Here, a comprehensive meta-analysis was conducted to investigate the main and interactive effects of O3 and multiple climate factors on plant photosynthetic rate, stomatal conductance, biomass production, and allocation. Our findings revealed a consistent pattern of O3-induced overall reduction in plant photosynthesis, stomatal conductance, and biomass production across different CO2, temperature, drought, and nitrogen deposition conditions. Elevated O3 exposure caused significant declines in biomass production, with crops experiencing the largest reduction, followed by trees and grasses. The greater biomass loss in crops and trees may be due to their physiological traits, longer exposure durations, or agronomic management practices. Elevated CO2 alleviated the negative effects of O3 on plants, but it is reflected in the photosynthetic rate. Although the O3-induced decrease in stomatal conductance and root biomass was reduced by increasing temperatures, warming had a limited effect on improving plant resistance to O3. Interestingly, O3 damage was reduced by drought through decreased stomatal conductance, whereas nitrogen addition did not affect the harm caused by O3. Our findings provide insights into plant gas exchange, biomass, and allocation responses to the interaction of O3 and climate factors, improving the understanding of plant adaptative mechanisms in the context of global change.