Children's book/story about ghosts allergic to wood

Question

I have vague memories of reading a story/book as a child, ~15 years ago.

Story points:

• The vast majority of the world's inhabitants are ghosts

• These ghosts turn normal humans into other ghosts by simply touching them

• I think maybe they only come out at night?

• Ghosts are allergic to wood. Simply being touched is enough to 'pop' them (permanent disappearance)
• There's a super-hero type dude that has a 'wand' (stick) and protects everyone from the ghosts
• I think the population hide in old wooded warehouses at night
• There's a big mansion made entirely of glass
• There is only one tree left in the world, the rest having been cut and burned to make the big glass mansion. It is guarded 24/7 by the ghosts
• I think they eventually get a bird to nick some seeds, grow more trees and kill all the ghosts

Answer 1

Rebecca's World by Terry Nation.

Here is a review that outlines the plot.

It turns out that a very nasty man, Mister Glister, is the richest man in this world, and as he explains to our heroine most seriously, 'I've made it my life's work to make everyone poor', and he has done it by burning all the trees down in the world to feed his industry and make himself rich. Some of the shelters from the said GHOSTS are made of the wood from these trees, but given Mister Glister's over the top approach to construction, there stands only one tree in this world, and it is guarded by the GHOSTS.

Captain 'K', however, owns a GHOST stick...a weedy twig, really, but one zap / kerpow / thunk in the direction of a GHOST, they 'pop' and disappear. hence why Mister Glister would like to have it for himself.

Rebecca and her new friends hatch a plan to get the map to this last tree (in Mister Glister's possession) to save the people of the world, and Rebecca hopes by then that she would find a way back home.

This is where the book really kicks off and we meet all manner of nasties, the Silkies, the Bad Habits, the Tongue Twister Monster.