Structural and functional responses of coffee trees to elevated [CO2]

Air [CO2] tends to increase due to climate changes, affecting plant growth. Field-grown Coffea arabica trees were grown under actual and elevated [CO2] for four years. Rakocevic et al. find that elevated [CO2] stimulated stomatal conductance and whole-plant photosynthesis, increasing water-use efficiency during the fourth dry period.

Reconstructions of Arabica coffee plants cultivated under elevated (e[CO2], in A) and actual (a[CO2], in B)
Reconstructions of Arabica coffee plants cultivated under elevated (e[CO2], in A) and actual (a[CO2], in B) air [CO2] environments and mean (n = 8, ± s.e.) leaf area (cm2), reconstructed for the fourth cold-dry season (July 2015) per layer of the vertical profile of plants. ANOVA P-values are indicated. The colours separate three plant layers L1 (0–50 cm), L2 (50–100 cm) and L3 (>100 cm).

Elevated [CO2] reduced leaf area and carbon investment in 2nd order branches, but also changed plant carbon partitioning by elevated [CO2], with plants showing structure rejuvenation. Data also suggest carbon allocation to root system under elevated [CO2]. After long-term exposure to elevated [CO2], structural and functional responses balanced each other and must be considered when studying impacts of elevated [CO2] in perennial species.