Inter-genotypic differences in drought tolerance of maritime pine are modified by elevated [CO2]

Area of Science:

• Plant physiology
• Ecology
• Climate change biology

Background:

• Tree growth and survival depend on carbon dioxide (CO2) and water availability.
• Intraspecific variation in functional traits is poorly understood under combined CO2 and water stress, especially in conifers.

Purpose of the Study:

• To investigate how elevated CO2 affects drought tolerance within a tree species.
• To determine if CO2 influences intraspecific functional trait variation under water stress.

Main Methods:

• A factorial experiment using maritime pine clones subjected to varying water availability and CO2 levels (ambient and elevated).
• Drought stress was simulated through soil water depletion and recovery cycles.
• Leaf gas exchange, growth, and leaf functional traits were measured across four genotypes.

Main Results:

• Elevated CO2 (eCO2) attenuated genotypic differences in drought tolerance, unlike ambient CO2 (aCO2).
• eCO2 aggravated drought impacts on drought-tolerant genotypes but had a neutral effect on sensitive ones.
• Genotypic variation was observed in specific leaf area and leaf nitrogen content under both CO2 levels.

Conclusions:

• Elevated CO2 can modify the range of drought tolerance within tree species.
• Understanding these interactions is vital for predicting forest responses to climate change.