Abstract: As compared with others, keystone species have more farreaching influence to their ecosystems. In accordance with field survey and study of the author, keystone species perhaps can be divided into two types: the first one has an important active role for their ecosystems, it is nor-mally called keystone species, while they are threatened or disappeared, diversial species their sur-vival depended upon them will be threatened or disappeared from the ecosystems as well; the sec-ond one is in contrast with vast potential functional negative influence to the ecosystems, it may be called as "potential keystone species^, while they are developed, diversial species will lose their habits and disappear from the original ecosystems. It is obviously that the two kinds of keystone species need different strategy to manage for biodiversity conservation: protecting for the former and controlling for the later.

Key words: Ecosystem