The eco-physiology of eucalyptus in a CO2-enriched environment depends on atmospheric demand? 

Seeking to understand the interaction between elevated CO2 concentration and atmospheric demand, characterized by air temperature (Temp) and vapor pressure deficit (VPD), master's student José Hamilton de Oliveira Braga studied the eco-physiology of eucalyptus clone seedlings grown inside open-top chambers (OTCs). Growing under two atmospheric demand conditions, low demand (Temp = 22°C and VPD = 0.41 Kpa) and high demand (Temp = 27°C and VPD = 1.90 Kpa), the seedlings were subjected to two atmospheric CO2 concentrations (450 and 850 ppm). Additionally, two soil water levels were adopted, one near field capacity (100% FC) and the other at half the substrate retention capacity (50% FC).

The study revealed different responses when atmospheric carbon dioxide enrichment occurred. The increase in CO2, without soil water restriction, did not result in an increase in total dry mass in the low-demand environment, but in the hotter atmosphere with higher vapor pressure deficit (high demand), growth was significantly higher. The curves of photosynthesis increment as a function of radiation help explain the findings. However, it was observed that the patterns change under water restriction conditions.

Thus, the results of José Hamilton de Oliveira Braga's dissertation highlight that studies on plants and increased atmospheric CO2, conducted in controlled environments, should consider other environmental variables in an integrated manner so that the results can truly contribute to understanding the impact of climate change on the forestry sector.

More details can be found in the complete dissertation of the student on our website.