Trophic Cascades

This in turn would lead to more consumption at the top of the food chain, eliminating the predators to creatures at the lower end

“Restoring an ecologically complete ecosystem in Yellowstone requires the return of willows--and with them, beavers. There's a clear threshold for ecosystem recovery. Willow stands must be more than 6 feet tall, the scientists found. That height is important, says Marshall. Then willows are beyond the reach of browsing elk, and can serve as seed sources for new young willows. Once willows have returned, beavers will gnaw down a certain number of them to build dams. The dams will further slow stream flow, allowing yet more willows to grow. The results offer new insights on the role of wolf-driven trophic cascades in the Yellowstone ecosystem, says Hobbs. Trophic cascades like that in Yellowstone occur when predators--or the lack thereof--in an ecosystem change the abundance or alter traits of their prey, in turn affecting the next lower trophic level.” ("National Science Foundation", 2013)

Say a frog eats a caterpillar, then a snake eats the frog, then finally a owl eats the snake. This is just a simple food chain but something called biodiversity, which means that’s there is a variety of things a that one animal can eat. An owl cant only eat a snake it could eat the frog or something smaller like a worm. This keeps form one species dying out completely, which would cause multiple species to die out. When someone releases a pet into the wild they are causing a disturbance into the wild habitat. When a python is released into a place full of crocodiles these two will start competing for food which would cause all of the lower species to start lowing in numbers faster until they become extinct which would then make the snakes and the crocodile die off too. If this keeps on happening the eventually every animal would die off!

The position is called a trophic level. For example, fox eats birds, so if the food chain contained a fox and a bird then the fox would be at a higher trophic level then the bird.

-Reintroduction of a top predator lowered the number of over grazing herbivores, leaving a more stable amount of food for many species of herbivores.

Since organisms living in communities form interdependent relationships, a change in the abundance of one species will not only affect the physical and more direct interactions, but could indirectly affect the number of other species within the community as a consequence (Wootton 1993). These indirect affects rise because the interactions between pairs of species are not independent of other species, such as increasing the density of vegetation may increase the survival rate of the prey, reducing the intensity of the interaction between the predator and prey (Wootton 1993, 1994). An

If a predator organism was removed from an ecosystem, it would allow the prey population to increase which could lead to not having enough food for these organisms to eat. For example, if wolves were eliminated from the taiga biome than there would be a dramatic increase in the population of moose. This would result in the moose not having enough jack pine and could lead to starvation. The wolves would then have to eat more rabbits, elk, and voles which would decrease their population and starve the organisms that rely on these animals.

This investigative study included whether gray wolves, a natural top predator to white tailed deer, create a trophic effect by reducing the deer and how it may affect saplings and vegetation in the Great Lakes forest area. The study was not conducted for direct kills, instead it was done to see the effects of the deer population and the plant and vegetation systems surrounding them. The expected effects were that in areas where wolves are less dense in the region it causes an increase of deer having a negative impact on plants and vegetation in the surrounding area. The recolonization of wolves in the area is generating trait-meditated effects in the Great Lakes forest and are

In this article, authors William Ripple and Robert Beschta focus on the issue of predation and the way it affects biodiversity and otherwise alters ecosystems. While many other studies have stressed the lethal effects of predation by carnivores, the authors of this study have chosen to focus on how nonlethal outcomes of predation affect the structure and function of ecosystems. The authors give two main objectives to their study: first to provide a short synthesis of the potential ecosystem responses to predation risk in a three-level trophic cascade involving large carnivores, hoofed animals, and vegetation; and secondly to present research that centers on wolves, elk, and woody browse species in the northern area of Yellowstone National

A keystone species is an organism that helps define an entire ecosystem. Without a keystone species, the ecosystem will either cease to exist or dramatically change. If a keystone species were to disappear from the ecosystem, no other species would be able to fill its ecological niche. This means that keystone species have low functional redundancy. This forces an ecosystem to radically change. This may allow new invasive species to populate the habitat. Keystone species can range from plants to fungi. They are usually not the most abundant species in the ecosystem. The way these animals impact the food web varies from habitat to habitat. Keystone species are usually a predator. An example of a keystone species is the gray wolves in the Greater Yellowstone Ecosystem (GYE). Elk, bison, rabbit, and bird population at GYE are

from ecosystems, destroying the relationships of which the energy flows in a food web, and

A keystone species is a species that has a disproportionate effect on its environment relative to its abundance. Such an organism plays a role in its ecosystem that is analogous to the role of a keystone in an arch. While the keystone feels the least pressure of any of the stones in an arch, the arch still collapses without it. Similarly, an ecosystem may experience a dramatic shift if a keystone species is removed, even though that species was a small part of the ecosystem by measures of biomass or productivity. It has become a very popular concept in conservation biology.

Influence on ecosystems range from human causes like the bulldozing of a forest to natural causes like a fire or a flood.  In recent times, the introduction and spread of invasive species has transformed native communities rapidly and, in some cases, created irreversible damages.  In the Earth’s history, changes have often occurred in the ecosystems.  For example, glaciers and the retreat of glaciers cause wide-spread changes.  However, although change is a constant in ecosystems, animals and habitats often cannot adapt to the rapid alterations of non-natural stresses.  Harm to the environment from the introduction of invasive species occurs through changes in the habitat and declines in the native species.  Invasive species

The role of predation is critical in shaping ecosystem structure and function (Berger et al., 2001; Hawlena and Schmitz, 2010). Predator-prey interactions can alter community composition (Kneite and Chase, 2004), mediate trophic cascades (Mooney et al., 2010), increase biodiversity (Letnic and Ritchie, 2012), and affect species invasions (Snyder et al. 2004). Furthermore, predators can control the dynamics of prey populations by influencing such aspects as survival, growth, behavior, size structure, and distribution (Beauchamp et al., 2007) while prey can likewise regulate predator populations (Yoshida et al., 2003; Ishii and Shimada, 2010). One of the primary components of predator-prey interactions is the behavior and subsequent survival of prey in the presence of predators which we focus on in this study.

45). Many recent conservation efforts have aimed at protecting these keystone predators because the loss of these species has the potential to powerfully alter the ecosystems in which they reside (Textbook pg. 47). For example, the gray wolf, a keystone species, has been a focus of conservation in Yellowstone National Park since their extirpation caused population booms in ungulate species and resulted in overgrazing of the vegetation (Textbook pg.