LF: Tree Losses

["Walter Blanchard" <blanch@pncl.co.uk>]

At  73/136 khz how far away from a wet tree do you have to be not to see 
any RF loss?  At one extreme if your ant runs through it you will lose a 
lot; at the other if it is several kms away you won't lose anything. Is 
there a critical distance? And the reverse -  if there's a wet tree close 
to you in the same direction as a transmitter, will you receive a much 
weaker signal than you ought? Does it act like a metal plate does at 
microwaves?
Walter G3JKV.