Add the script sktrees1 to your requiredfiles, "requiredfiles" "scripts/skgrasses1.txt scripts/sktrees1.txt".
Add something that you can't run and shoot through the trees.
Oh, I'm not sure if I already mentioned that, but if your map only supports one gamemode (worldspawn), then you don't need to add the gamemode to specific entities (e.g. bases, flags, player spawns).
One more screenshot...
Red: Move this texture faces up a little bit.
Green: Move this texture face to the right a little bit.
Beta 7 is online @ [OTB] Beta!