C. Ziegler et al., “Large hydraulic safety margins protect Neotropical canopy rainforest tree species against hydraulic failure during drought”
Tropical rainforests are under the thread of more frequent drought episodes, that may in places induce tree dieback. It is therefore of importance to better understand the physiological basis of the response of tropical trees to soil water deficits to check how they may cope with such stress situation. Camille Ziegler and co workers addressed this question by quantifying the vulnerability of xylem tissues to dehydration. They checked whether losses of hydraulic conductivity due to cavitation occur at similar dehydration levels than those inducing stomatal closure, or whether the two events are occurring at different levels of dehydration. Indeed, they found that there was a “safety margin” between the two events. This means that trees are to some extent protected by stomatal closure and reduced transpiration, against drought-induced cavitation during moderate water deficits. Such results are important to assess the severity of water shortages that ultimately may lead to tree death.
Such results are important as they contribute to a more accurate assessment of the responses of trees to water deficits, and help us understand how increasing frequency of drought episodes might impact tropical forests that were thought to be immune to drought.
The paper by Ziegler et al. has been published under an Open Access scheme and is accessible at: https://doi.org/10.1007/s13595-019-0905-0. You may also find a description on this blog at: https://ist.blogs.inrae.fr/afs/2020/02/13/large-hydraulic-safety-margins-protect-neotropical-canopy-rainforest-tree-species-against-hydraulic-failure-during-drought/.