Hi Pam,
I have also had good experiences with using the mesh vinyl (as David Lewis suggested) for this kind of application.
We have also had success using roller blinds, We silk screened images of people on them. Printing trees across them would be fun. Silk screen ink is quite lightfast so it has greater longevity compared with inkjet printing.You can choose the translucency of the fabric and control the UV. Our supplier fitted the blind with a channel on either side to prevent light spill.
Alternatively, if it is just the UV you are concerned with and you have a wonderful forest view you could use a UV filter over the glass. We have used a company called
SUN-X who have recently expanded into the US - a bit expensive though as they have to fit it themselves.
Best Wishes
Alexander Hawkey
Exhibition Designer
Royal Pavilion, Art Galleries & Museums
Brighton & Hove UK