<P> The jaguar is an umbrella species, flagship species, and wilderness quality indicator . It promotes the goals of carnivore recovery, protecting and restoring connectivity through Madrean woodland and riparian areas, and protecting and restoring riparian areas...A reserve system that protects jaguars is an umbrella for many other species...the jaguar (is) a keystone in subtropical and tropical America...</P> <P> Sea otters protect kelp forests from damage by sea urchins . When the sea otters of the North American west coast were hunted commercially for their fur, their numbers fell to such low levels--fewer than 1000 in the north Pacific ocean--that they were unable to control the sea urchin population . The urchins in turn grazed the holdfasts of kelp so heavily that the kelp forests largely disappeared, along with all the species that depended on them . Reintroducing the sea otters has enabled the kelp ecosystem to be restored . For example, in Southeast Alaska some 400 sea otters were released, and they have bred to form a population approaching 25,000 . </P> <P> Keystone predators may increase the biodiversity of communities by preventing a single species from becoming dominant . They can have a profound influence on the balance of organisms in a particular ecosystem . Introduction or removal of this predator, or changes in its population density, can have drastic cascading effects on the equilibrium of many other populations in the ecosystem . For example, grazers of a grassland may prevent a single dominant species from taking over . </P> <P> The elimination of the gray wolf from Yellowstone National Park had profound impacts on the trophic pyramid . Without predation, herbivores began to over-graze many woody browse species, affecting the area's plant populations . In addition, wolves often kept animals from grazing in riparian areas, which protected beavers from having their food sources encroached upon . The removal of wolves had a direct effect on beaver populations, as their habitat became territory for grazing . Increased browsing on willows and conifers along Blacktail Creek due to a lack of predation caused channel incision because the beavers helped slow the water down, allowing soil to stay in place . Furthermore, predation keeps hydrological features such as creeks and streams in normal working order . When wolves were reintroduced, the beaver population and the whole riparian ecosystem recovered dramatically within a few years . </P>

What happens when a keystone species is removed from an ecosystem apex
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