I would expect absorption and scattering to be greater with the tree material parallel with the electric field. I no longer have access to the neat little kit that we used to teach this sort of thing.
As I recall the students all assumed that our parallel wire grid acted as a cage to keep the waves in rather than warming up as an absorber. Perhaps someone is still teaching this and can give a proper experimental answer.
PS lovely piece of work that wood based Yagi antenna Andrew illustrated; no idea which Andrew or where I found that, so commenting here,