試試看如果只砍一棵樹他們是否接受 (Even you can offer you will pay for this about $400)!
(2) You should also check with your home owner association to see if your home owner association can do anything for you ! (Since the tree is located on your property)
(3)Let your neighnor understand if they use any camcials to kill your tree, you will contact your county office to file a complain base on environment issuse. (Soil polution, ground water polution etc) Also you will file a complain to EPS to make as a federal case. This will at least let your neighbor back to table to make a deal with you.
(4) The worst case, hire a lawer to settle down this issue.
Good Luck !