Moving beyond the cambium necrosis hypothesis of post‐fire tree mortality: cavitation and deformation of xylem in forest fires

• DOI: 10.1111/j.1469-8137.2011.04021.x
• Publication Date: 2012-01-25T23:51:10Z
• Authors: S. T. Michaletz; E. A. Johnson; M. T. Tyree
• Keywords: Parenchyma

• It is widely assumed that post-fire tree mortality results from necrosis of phloem and vascular cambium in stems, despite strong evidence reduced xylem conductivity also plays an important role. In this study, experiments with Populus balsamifera were used to demonstrate two mechanisms by which heat reduces the hydraulic xylem: air seed cavitation conduit wall deformation. Heat effects on quantified using injection isolate potential temperature-dependent changes sap surface tension pit membrane pore diameters. structure demonstrated measurements light microscopy. Heating increased vulnerability because varies inversely temperature. did not affect via diameters, but cause significant reductions associated deformation walls (probably resulting thermal softening viscoelastic cell polymers). Additional work required understand relative roles reduction conductivity, how roots, branches correlates interacts foliage root necroses mortality. Future research should examine ray parenchyma cells affects refilling embolisms occur during after fire event.