Chumbe hosts a highly specialised plant community that has developed to survive without any groundwater, instead depending on capturing the moisture from the humid air and storing the rainfall during the rainy seasons. The bedrock of the island is made up of an impressive substrate of fossilized coral. You can still see the skeletal structures of corals and giant clams - a gentle reminder of the passage of time. More staggering still is the coral-rag forest. The density of the forest is spectacular, as adventitious roots thrust out in all directions and epiphytic species cling to life by wrapping themselves around all available surfaces. Researchers have taken up to four hours to transverse the 1 km stretch through the central forest reserve and the crags and caves hidden underfoot as remnant of the reef structure of this fossilized coral habitat, makes studying this environment both challenging and consistently rewarding as new discoveries are constantly uncovered. For guests the nature trails provided allow for an insight into this otherwise virtually impenetrable habitat.

In the management of this habitat, materials imported onto the island are carefully screened to avoid any non-indigenous elements intruding into this spectacularly preserved environment. Such practice was unfortunately not in place in the early 1900's when rats were accidentally introduced onto the island (probably by the British ships bringing materials when the lighthouse was established). However, after the successful conclusion of the rat eradication campaign in May 1997, managed by CHICOP with support from specialists from Cork University in Ireland and the Zanzibari Plant Protection Division, the island was freed from this non-indigenous species and the island's flora (that had been under pressure from competition from the rats consuming the vital regenerating fruiting bodies) improved conditions further for the sanctuary.