Yes, when conducting tracheids and/or vessels are cut, as with a pruning wound, and with the water column(s) under tension, as they usually are, emboli form in the conducting elements. The cut surface is suddenly at atmospheric pressure, which is way higher than the negative pressure (tension) proximal to the cut surface. So... water is hammered away from the cut surface. The plugging events to reduce that water movement begin more-or-less instantaneously with tylosis formation, in those species that do it. The pits in "safer" conifer tracheids are small enough so that bubbles have a hard time passing through. the pits in much wider vessels, say oak earlywood do have end plates that may have small enough perforations to limit the movement of bubbles. *But* a single vessel assembly might be 1 meter long, resulting in the movement of the bubble in for 1 meter, conceviably.
Now, this speaks to differences between branch pruning and topping or the cutting through a codominant stem. The pre-formed and induced plugging at the base of branches is pretty effective at limiting the propagation and passage of bubbles. Sure, branches are naturally shed as part of normal forest stand development. There are no such pre-formed or "ready to go" boundaries along a stem. So a cut stem will support a much greater passage of bubbles and formation of emboli.
Sorry, probably no one is reading any more!
