I saw this movie in 2012 on The Hub (Discovery Channel's kid network).
It takes place after an undefined apocalypse, where the earth is now mostly desert and the moon is shattered into pieces, after being destroyed due to an extremist bombing of a laboratory located there. Now all that is shown remaining on the planet is a human town bordering a jungle-like forest filled with animal-like plant monsters largely hostile to humans. The entire forest is a super-organism led by twin dryad-like beings that the people in the town treat like gods. The water supply of the planet is ever dropping, and the forest is taking most of it leaving the town dry.
Elsewhere, humanity is composed of a military-state in a partially underground base that is hostile to the forest and is also in need of water. The protagonist is a boy from the village who agrees to be turned into superpowered human-plant hybrid by the forest to fight this army, and his hair turns white and his clothing changes to being red and sleeve-less.