Cohesion also explains why any wounding, cuts, compressions, spiking etc. demands that both ends of the carrying vessel get immediately plugged to keep chain intact (and prevent 'bleeding out' too). For if they don't, an air embolism will result, and break the cohesion chain. On that particular vessel travel then, the plant would have to pump the full weight and friction of the water-but transpiration only gives weak pull that just can move molecules at front of chain. So, the system would fail. But, if no embolism; we have a complete cohesion chain, whereby the transpiration moves molecules at the front of the chain, and the rest of the chain obliges to move forward to replace-without the weak draw having to bear the pull of the whole weight of the chain. Moving water 300' uphill is a large task, that needs all the help and strategy it can get; or trees would be 3' tall or so like me!
So, if we spike, both ends at wound must plug. If we wound parent on a branch removal, parent tissue must get plugged at that site; and sealing has to come not so much from collar, but farther out, so must travel farther, and from tissues not specialized to this sealing task as collar is.
The vessel walls are semi-permeable, so water will try to reroute to this new path of least resistance to another vessel, then back-but takes more work to get same or less nutrition. Maybe some leaves would get too little and die or wilt, maybe some roots would not get used and die-reducing anchoring etc.
Removed and ground 2 Ficus microcarpa var. hillii today. One was pushing against a fence and was sandwiched between moss rocks and had lifted the paving and invaded the sewer pipe. 
