© 1992 Heron Publishing—Victoria, Canada
Vulnerability of several conifers to air embolism
Hervé Cochard
Laboratoire d’Ecophysiologie Forestière, INRA, Centre de Nancy, F-54280 Champenoux, France / Received August 14, 1991
Summary
Hydraulic properties of xylem in seven species of conifer were studied during late winter and early spring 1991. Vulnerability
to cavitation and air embolism was investigated using hydraulic conductivity and acoustic techniques. Embolisms were induced
in branches excised from mature trees by air-drying them in the laboratory. Both techniques gave comparable results indicating
that they both assess the same phenomenon. Within a tree, vulnerability was related to the permeability of the xylem, the
largest stems tended to cavitate before the smallest ones when water deficits developed in a branch. Interspecific comparisons
showed large differences in the xylem water potential needed to induce significant embolism, values ranged from –2.5 MPa in
Pinus sylvestris to –4 MPa in Cedrus atlantica, but these differences did not correlate with differences in the xylem permeability of the species. The vulnerability of
a species to air embolism was found to be consistent with its ecophysiological behavior in the presence of water stress, drought-tolerant
species being less vulnerable than drought-avoiding species.
