Glossary: K


Philippine term for temporary agricultural plots cleared from the forest by native people. The soil of such plots is rapidly exhausted and new plots have to be cleared every few years.

keystone species

a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).


Small crustaceans which occur in huge numbers in polar seas, particularly off of Antarctica. They comprise the main prey of baleen whales. The term can be used generally to apply to all such food organisms, but it is frequently used to refer specifically to shrimp-like animals of the group Euphausiacae, especially the Antarctic krill, Euphausia superba. This species is the most important food source for southern whales and other animals. It is about 2.5 cm (1) long, and has been observed in swarms as large as an estimated 2.5 million metric tons (2.8 million tons) (Bonner 1989).