Trophic cascades revealed in diverse ecosystems

New studies are documenting trophic cascades in theoretically unlikely syst ems such as tropical forests and the open ocean. Together with increasing e vidence of cascades, there is a deepening understanding of the conditions t hat promote and inhibit the transmission of predatory effects. These condit ions include the relative productivity of ecosystems, presence of refuges a nd the potential for compensation. However, trophic cascades are also alter ed by humans. Analyses of the extirpation of large animals reveal loss of c ascades, and the potential of conservation to restore not only predator pop ulations but also the ecosystem-level effects that ramify from their presen ce.