[hijack1968]

You can also name any texture that you wish with '...._Fields.tga' and no more trees will spawn on that texture (unless you create a ... .tree.tga file).

Thanks AG, yes this is what i had done up untill now not realising that objects would stop them spawning. So my maps were devoid of any random trees except along the river banks and object trees that i had placed elsewhere. now i'm reverting back to the originals to get some trees back...