DG, sounds like a start. How close is the antenna to the tree trunk? What direction inynchberg in relation to the tree/ antenna? What kind of antenna do you have?
VHF is a strange animal. It don't like hills other than the top, trees with leaves, etc. Also you can have high losses in effective power due to poor quality coax, really long runs of coax, poor antennas, poor or multiple connectors. There are so many things that can have an effect to some degree. Using a high quality coax is an excellent step. Keep your runs as short as possible with VHF. I've never used more than 100', so I don't know how much 250' will affect you. I do know for every 3db loss from your antenna system you loss 50% effective power. 250' is 150% longer than my expereince. You also should keep the number of connections as low as possible. I also use only gold plated connectors. I have saw a lot of difference in them and any other. Also depending on antenna, which can be anywhere from 0db or even a loss, up to maybe 9db for an omni non directional. 9db is a huge improvement over zero. If you have to reach a given location you may have to resort to some type of directional antenna. That way all energy is focused in one direction. Down side to that, you can't do much any other direction.
Thanks for the update. Keep at it. Good job.