Variations in C and N Storage and Use Strategies Between White Poplar Ploidy Levels After O₃ Exposure Cessations

Area of Science:

• Plant Physiology
• Ecology
• Forest Science

Background:

• Carbon (C) and nitrogen (N) strategies vary among species and are influenced by environmental stress.
• Limited data exists on resource storage and remobilization within species post-stress.

Purpose of the Study:

• To investigate the growth and C/N reserve dynamics of diploid and triploid Populus tomentosa under ambient and elevated ozone (O3) conditions, and after stress cessation.
• To quantify resource remobilization and usage in the year following O3 exposure.

Main Methods:

• Growth assessment of diploid and triploid Populus tomentosa over two years.
• Labeling of C and N reserves at the end of the first year.
• Tracking of labeled reserves in the second year to quantify remobilization and usage under non-stress conditions.

Main Results:

• Ozone exposure reduced shoot growth and C reserves in both ploidy levels; triploid plants also showed reduced root growth and N reserves.
• In the second year, growth compensated, but triploid plants depleted reserves for growth and metabolism, while diploid plants used reserves to sustain metabolism, not growth.
• Diploid plants demonstrated a conservative strategy with greater plasticity in C and N reserve use.

Conclusions:

• Diploid Populus tomentosa, employing a conservative strategy, showed higher plasticity in C and N reserve utilization.
• This plasticity suggests diploid plants may perform better under future climate change scenarios.
• Understanding species-specific resource allocation is crucial for predicting forest responses to environmental change.