I do not practice law in Alaska.
In Colorado, the owner of the cotton wood tree would indeed be responsible. Talk to your homeowner's insurance carrier to get the answer you need.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.
Call your homeowner's insurance carrier and find out. That is probably the quickest way to get an answer specific to your jurisdiction. You also may be able to read your policy and find out whether your insurance will cover it should your neighbor fail to carry the appropriate coverage on his property.
This answer is intended to be used for general purposes only; it does not create an attorney-client relationship.
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