Can Eucalyptus drought vulnerability be explained by climate of origin, life history and functional traits?
Climate change is evident with the increasing frequency and intensity of drought events; forest all over the world are experiencing drought mortality events with enormous ecological consequences. Not all species are being impacted equally in documented mass dieback events; conservation prioritization urgently needs quantification of species vulnerability to drought to ensure the persistence of our unique native forests.
To inform conservation management it is essential to obtain a mechanistic understanding of the factors that make plants vulnerable to drought. Water is conducted in plants by xylem under tension from roots to leaves where water is lost through stomata. As water limitation increases, the tension increases as more water is lost. Under higher tension xylem vessels are prone to cavitation where an air bubble impedes the flow of water resulting in loss of hydraulic function. Lower tree mortality events have been related with a higher capacity of plants to avoid cavitation, that is, higher hydraulic resistance. In my PhD I am integrating climate-of-origin, morphological and history life traits, and hydraulic resistance to achieve three aims:
- predict vulnerability to drought,
- find the relation between climate of origin, regeneration strategy, a forgotten life history trait, and vulnerability to drought, and
- explore environmental plasticity in relation to species distributions.
To answer these aims I am focusing on Eucalyptus because it is a widely distributed genus with high morphological diversity and regeneration strategies which evolution occurred during transition to greater aridity.
Figure 1. This plant was killed in the name of science. We dehydrated it in the bench laboratory following its water potential and the percentage of cavitation across dehydration of the leaf and the stem with Raspberry Pi cameras inserted inside of the white clamps. To know more about this technique, you can read Brodribb et al. (2017). Plant Physiol. 174:2054-2061.
Figure 2. Measuring gas exchange and stomatal conductance in response to low water soil availability.
Dr Paul Rymer, Distinguished Professor David Tissue, A/Professor Brendan Choat, Distinguished Professor Belinda Medlyn