I've gone and made my own mod to make ZH trees flammable. I also made them able to be destroyed by toxins (try an anthrax bomb on a forest and see the trees wither), explosions, and other damage. The burning ember objects are also improved, so keep your units away from burning trees.
The mod also makes all the invisible ZH shrubbery types visible (some look quite nice, like tumbleweed and desert shrubs), and it also makes rocks able to be cleared by building on them.
Beng's ZH Shrubbery Fix Mod - CnCMaps Map Editing Forums