Tree knocking is believed to be a form of communication between Sasquatch. It is, perhaps, a way to warn others of the presence of humans. I think it may also be territorial in nature. When you hear it in the middle of the night it is very scary.
Dr. Meldrum and I spoke at the Orlando Skunk Ape Convention
Real Bigfoot Evidence from Florida
We have found evidence in the swamps and pine forest. Click image below to see the evidence