Is there anything i could do to stop my neighbors from cutting down the historic tree?
Has your municipality designated the tree as “historic”? If not, you have no power to stop the landowner from cutting it down. How do you know that the willow is 200 years old? I suspect that you didn’t plant it. You can tell the age of a tree by taking a boring and counting the growth rings. Just being large means nothing. Willows can grow really quickly under the right conditions, especially when they are near water. That tree might be less than half as old as you think.