Wait this is legal in Nigeria??

Technically, yes. Since there is no law/policy prohibiting such and if there are (I really dont know of any), I've never seen anyone being punished for such action.

Can you explain this part a little better, I think I've never heard about it.

When fuel loads is allowed to accumulate in forests, it increases the likelihood of damaging wildfires occurring. However, fuel loads are burned in a kind of 'controlled burn' either within the forest itself or in a chosen location, it greatly reduces the chances of damaging wildfire occurring within such forest. Hence, fire is a major forest management tool