Testing the plant pneumatic method to estimate xylem embolism resistance in stems of temperate trees
2018
Zhang, Ya | Lamarque, Laurent J | Torres-Ruiz, José M | Schuldt, Bernhard | Karimi, Zohreh | Li, Shan | Qin, De-Wen | Bittencourt, Paulo | Burlett, Régis | Cao, Kun-Fang | Delzon, Sylvain | Oliveira, Rafael | Pereira, Luciano | Jansen, Steven | Mencuccini, M., (Maurizio)
Methods to estimate xylem embolism resistance generally rely on hydraulic measurements, which can be far from straightforward. Recently, a pneumatic method based on air flow measurements of terminal branch ends was proposed to construct vulnerability curves by linking the amount of air extracted from a branch with the degree of embolism. We applied this novel technique for 10 temperate tree species, including six diffuse, two ring-porous and two gymnosperm species, and compared the pneumatic curves with hydraulic ones obtained from either the flow-centrifuge or the hydraulic-bench dehydration method. We found that the pneumatic method provides a good estimate of the degree of xylem embolism for all angiosperm species. The xylem pressure at 50% and 88% loss of hydraulic conductivity (i.e., Ψ₅₀ and Ψ₈₈) based on the methods applied showed a strongly significant correlation for all eight angiosperms. However, the pneumatic method showed significantly reduced Ψ₅₀ values for the two conifers. Our findings suggest that the pneumatic method could provide a fast and accurate approach for angiosperms due to its convenience and feasibility, at least within the range of embolism resistances covered by our samples.
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