Slash and burn (a specific practice that may be part of shifting cultivation or swidden-fallow agriculture) is an agricultural procedure widely used in forested areas. Although it was practised historically in temperate regions, where it was termed assarting, it is most widely associated with tropical agriculture today. Slash and burn is a specific functional element of certain farming practices, often shifting cultivation systems. In some cases such as parts of Madagascar, slash and burn may have no cyclical aspects (e.g some slash and burn activities can render soils incapable of further yields for generations), or may be practiced on its own as a single cycle farming activity with no follow on cropping cycle. Shifting cultivation normally implies the existence of a cropping cycle component, whereas slash-and-burn actions may or may not be followed by cropping. Slash-and-burn agriculture is usually labeled as ecologically destructive, but it may be workable when practiced by small populations in large forests, where fields have sufficient time to recover before again being slashed, burned, and cultivated. Tropical forests are habitats for extremely biologically diverse ecosystems, typically containing large numbers of endemic and endangered species which can be threatened by slash-and-burn actions.