Trees respond to what we animals would call pain
Citation, please?
Cause and effect from how the tree reacts after the fact. Remove too much bark, and it's akin to skinning something alive. The tree will often die from the removal, just as a human would die from the shock.
Even if such a tree exhibits such cause and effect, that does not mean it feels pain. Those are more likely chemical or physical reactions to external stimuli, which can very well occur without the tree feeling pain. Pain is a stimulus that motivates an animal to move for sake of its own survival. Trees can not move. So why they would evolve such an elaborate system makes little to no sense. It offers nothing of value while taking up precious resources. Further, trees lack a central nervous system required to feel pain.
Next, removing bark is a very poor metaphor. The tree will die from neither shock nor pain, but because you removed a large chunk of it from the larger body. If I go out to my car and remove random parts from my engine, the car won't start, but it never felt pain. The same can be said for many appliances from computers to refrigerators, but that doesn't amount to pain.
That. The reason I said "what we animals would call pain" was to indicate that I'm not necessarily saying the tree itself FEELS pain, but responds to things that would cause it in us animals.
Zach, words have meanings. If you say "plants experience/respond what we animals call pain" it's goalpost shifting for you to take a more abstract response to focusing on the "respond" part of your point. Pain is the sensation of feeling hurt. So if you say they respond to pain, then for that statement to stand, trees have to feel hurt and respond for that reason. That is what you said, trees can get hurt and respond. Further, not
all animals experience pain, many insects do not have a central nervous system developed enough to feel pain. Reaction in general can and does exist independent of reaction to pain.
Also, some plants release a gas into the air when damaged in some way.
Again, reaction to stimuli does not cause pain. Reaction to stimuli you think would hurt does not constitute pain. Maybe you should have worded your statement ("Trees respond to what we animals would call pain") a little better.