%0 Journal Article %1 Cochard_Tyree_90 %A Cochard, H. %A Tyree, M. T. %D 1990 %J Tree Physiology %K bibtex-import, citeulikeExport diameter, droughtbolism, freezebolism, papercopy, snowgumpapermaybe %P 393--407 %T Xylem dysfunction in Quercus: vessel sizes, tyloses, cavitation and seasonal changes in embolism %V 6 %X The seasonal progression of xylem dysfunction from tyloses and embolism induced both by cavitation and frost was studied in Quercus rubra L. and Quercus alba L. branches. Vessel lengths and diameters were measured in current-year rings of branches of various ages. Vessels in current-year shoots are about the same size as those in many diffuse porous trees, but vessels in older branches are two to six times larger in diameter and typically more than 10 times longer. Large Quercus vessels were more vulnerable to cavitation than small vessels. The small vessels in current-year shoots were more vulnerable to cavitation than vessels of comparable size in diffuse porous species. Earlywood vessels are completely blocked by tyloses within a year of their formation. Tylose growth starts in winter, but the vessels are not fully blocked until the next summer. Many latewood vessels, by contrast, remain free of complete blockage for several years. In Q. rubra, loss of hydraulic conductivity in current-year shoots due to cavitation reaches 20\% by August and > 90\% after the first hard frost. Both laboratory and field observations confirm that the role of frost in causing loss of hydraulic conduction by embolism is much more dramatic in Quercus than in conifers and diffuse porous hardwoods.

@article{Cochard_Tyree_90, abstract = {{The seasonal progression of xylem dysfunction from tyloses and embolism induced both by cavitation and frost was studied in Quercus rubra L. and Quercus alba L. branches. Vessel lengths and diameters were measured in current-year rings of branches of various ages. Vessels in current-year shoots are about the same size as those in many diffuse porous trees, but vessels in older branches are two to six times larger in diameter and typically more than 10 times longer. Large Quercus vessels were more vulnerable to cavitation than small vessels. The small vessels in current-year shoots were more vulnerable to cavitation than vessels of comparable size in diffuse porous species. Earlywood vessels are completely blocked by tyloses within a year of their formation. Tylose growth starts in winter, but the vessels are not fully blocked until the next summer. Many latewood vessels, by contrast, remain free of complete blockage for several years. In Q. rubra, loss of hydraulic conductivity in current-year shoots due to cavitation reaches 20\% by August and > 90\% after the first hard frost. Both laboratory and field observations confirm that the role of frost in causing loss of hydraulic conduction by embolism is much more dramatic in Quercus than in conifers and diffuse porous hardwoods.}}, added-at = {2019-03-31T01:14:40.000+0100}, author = {Cochard, H. and Tyree, M. T.}, biburl = {https://www.bibsonomy.org/bibtex/2e567aaaf6e765b2b01752924b0622463/dianella}, citeulike-article-id = {1523654}, comment = {(private-note)correlation between volume and vulnerability Big conduits (large diameter and long) are viewed as being efficient for conduction but highly vulnerable to cavitation compared to small conduits (e.g., Carlquist 1977, Baas 1982 and Zimmermann 1983). There is evidence that these concepts apply when comparing large to small conduits in a stem (Tyree and Sperry 1989). Unfortunately, these ideas have no support in fact when making interspecific comparisons. staining techniques "An alternative explanation is that the size of bubbles formed during a freeze depends on the diameter of the conduit and that large bubbles take a long tmie to dissolve and thus are more likely to be enlarged by tensions induced by transpiration after the thaw (Ewers 1985)."}, interhash = {f328c75a06685fc0424226de438beb47}, intrahash = {e567aaaf6e765b2b01752924b0622463}, journal = {Tree Physiology}, keywords = {bibtex-import, citeulikeExport diameter, droughtbolism, freezebolism, papercopy, snowgumpapermaybe}, pages = {393--407}, posted-at = {2007-07-31 06:12:43}, priority = {0}, timestamp = {2019-03-31T01:16:26.000+0100}, title = {{Xylem dysfunction in Quercus: vessel sizes, tyloses, cavitation and seasonal changes in embolism}}, volume = 6, year = 1990 }