This forest is made of gigantic toxics mushrooms and has regrown since the catastrophe (there is an incredibly low gravity here, that’s why the mushrooms are gigantic). Remember we’re in a desert, the drawing must have this yellow-orange light typical of a desert (cf right column of the samples in the next page) and it must not seem welcoming or enchanting.
The Rift, the post-apocalyptic area of Cross The Ages®, is known to be unstable: physical laws here are constantly challenged, which causes anomalies. The Rift is mostly a desert with ruins, which can take weird colors sometime (chromatic anomalies) but two forests exist there… and they are not pleasant ones. The catastrophe was caused by a blast of the vibration (the source of magical and technological power of CTA®) so we call these areas “vibradiated nature”.