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Predation in ecology
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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 Park.
The authors begin by defining several terms in depth. First, the term trophic cascade is defined in the context of the study. In this study, the authors focus on top-down processes and the ways in which related trophic interactions could have effects on ecosystems. They also discuss ways in which predators can influence the size of prey species populations in large and small scales. Additionally, the nonlethal effect of changes in prey behavior are discussed; this can include changes in herbivores’ use of spaces such as foraging patters within a habitat or even habitat preference. These changes are caused by fear of predation. Next, prey and plant refugia are discussed. Prey refugia are areas occupied by prey where they are less likely to encounter a predator. In the status quo, predation risks may occur due to human hunting. A previous study found that in St. John, Montana, elk adjusted their eating behaviors by browsing far from roads in order to avoid human contact. The authors ...
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...k can in fact structure ecosystems. Based on their theories regarding trophic cascades and predation risks as well as other research conducted on similar issues, the authors determined that predation risk affects ecosystems in both subtle and dramatic ways through many interactions, some of which remain unknown.
Ultimately, the authors believe that based on their findings, the future of management of the northern range ungulate herds must focus on the recovery of natural processes. They also believe that in addition to restoring large carnivores such as wolves, it is also important to recover historic hoofed migrations. The authors finally concede to the fact that because their research focused solely on the northern range of Yellowstone National Park, it would be difficult to make conclusions about other areas in North America where wolves have been extirpated.
The history behind the extirpation of the grey wolf in the United States dates back to the very first European settlers that colonized eastern North America in the late 16th century. The killing of gray wolves was done primarily out of fear in an attempt to protect livestock, and, in some cases, to protect human life within the colonies. As more settlers expanded West, the practice of killing wolves was considerably increased to protect livestock that included cows, pigs, and chickens. As waves of European settlers expanded westward, they began to deplete the deer, moose, and elk populations. The gray wolves food source continual depletion gave rise to wolf populations actively targeting the settler’s livestock, causing great financial loss. The fiscal loss of livestock became such an issue to wealthy ranchers and settlers that they began to offer cash rewards for wolf pelts. This practice gave birth to a lucrative cottage industry of professional hunters and trappers. As the wolves began to move further West, and into Wyoming, they began to diminish the elk and moose population. To respond to this threat, Congress approved funding in 1914, to eliminate the native gray wolves from
Owen-Wilson suggests that wile megaherbivores are not particularly prone to disturbance by predators or the weather, their populations tend to grow up until the point of nutritional deficiency which curiously leads to other vegetation components being trampled or broken by the trampling of megaherbivores (Owen-Smith 355). Sometimes, such damage can actually lead to the creation of different landscapes that provide a "higher biomass of accessible forage" (Owen-Smith 355). However, not all land lends to this kind of lucky damage and megaherbivores can also severely decrease the biomass of accessible forage. In fact, whether or not the megaherbivore will help or hinder is largely dependent on the water resources in the trampled areas (Owen-Smith 356).
Timmons, J. B., Alldredge, B., Rogers, W. E., & Cathey, J. C. (2012). Feral hogs negatively affect native plant communities. Informally published manuscript, Texas AgriLife Extension Service, Texas A&M , College Station, TX, Retrieved from http://feralhogs.tamu.edu/files/2010/04/feral-hogs-native-plants.pdf
Wolves have always been a symbol of the wild, free in spirit and roamers of the land. These animals are considered majestic and protectors of the wilderness. They have always roamed the western United States, although their population has fluctuated over time. Over the past 10 years wolf reintroduction into Yellowstone National Park has been a controversial topic to those of the United States. As of 1995, wolves have been reintroduced into the park. This has come with some strong opposition and yet has prevailed. The future of the wolf in Yellowstone park is now looking bright, although not certain since there still are those who want them banished again.
Introduction Sea otters (Enhydra lutris) are marine mammals capable of spending their entire lives in water. Being carnivorous in nature, they feed on sea urchins, crabs, fishes, mussels and clams. They are referred to as keystone species due to their profound impact on marine ecology. The interaction between sea otters, sea urchins and kelp forests has been studied as a model for the impact of predator-prey interactions on community ecology. Sea otters are keystone predators, whose presence has a far-reaching influence on the marine food web by affecting the populations of sea urchins, which indirectly affects the populations of kelp forests & other marine organisms.
Hypotheses of the Effects of Wolf Predation Abstract: This paper discusses four hypotheses to explain the effects of wolf predation on prey populations of large ungulates. The four proposed hypotheses examined are the predation limiting hypothesis, the predation regulating hypothesis, the predator pit hypothesis, and the stable limit cycle hypothesis. There is much research literature that discusses how these hypotheses can be used to interpret various data sets obtained from field studies. It was concluded that the predation limiting hypothesis fit most study cases, but that more research is necessary to account for multiple predator - multiple prey relationships. The effects of predation can have an enormous impact on the ecological organization and structure of communities.
Mader,T.R. Wolf reintroduction in the Yellowstone National Park: a historical perspective. Common Man Institute. 1998. 26 pgs.
Coyotes and bears are a common sight in the woods. These animals, along with others, are predators that help to control deer population but also decrease the amount of land allowed to the deer. In Western NC, deer rates have fallen and bag limits have been reduced. In Pennsylvania, biologists have conducted a lengthy study to determine fawn mortality and predation. Predators killed 46% of fawns, (Hart). A study about coyotes in Ohio found that even though they kill numerous fawns, the population of deer continues to grow, (Hart). It would be critical to maintain...
It is early in the morning with the majestic Elk bugles in the distance. The sun kisses the tops of the peaks with the most beautiful gold, and paints the clouds rose red. Men and women who enjoy the outdoors, whether it is hunting or just hiking, help make these types of moments possible. Hunting and the ecosystem is tied closely to conservation of land and animals. The articles on “Hunting and the ecosystem” written by the South Dakota Game Fish and Parks Department (SDGFP), and “Facts and statistics on wildlife conservation” written by Roger Holmes, director of the Fish and Wildlife, touch on how hunting is important to the environment to keep a good balance in the ecosystem.
In the last decade, from the Rockies to New England and the Deep South, rural and suburban areas have been beset by white-tailed deer gnawing shrubbery and crops, spreading disease and causing hundreds of thousands of auto wrecks. But the deer problem has proved even more profound, biologists say. Fast-multiplying herds are altering the ecology of forests, stripping them of native vegetation and eliminating niches for other wildlife. ' 'I don 't want to paint deer as Eastern devils, ' ' said Dr. McShea, a wildlife biologist associated with the National Zoo in Washington, ' 'but this is indicative of what happens when an ecosystem is out of whack. ' ' The damage is worse than anyone expected, he and other scientists say. Higher deer densities have affected growth, survival, and reproduction of many plant species which have aesthetic, economic or ecological value. In some cases, many species of trees have also been shown to have reduced growth as a result of high deer density (Environmental Benefits of Hunting, 1). Deer prefer certain plant species over others and frequently feed on economically valuable tree species. For example, they prefer oak and sugar maple seedlings, as well as acorns, over less palatable species like American Beech and striped maple. Thus, less marketable species are more likely to survive to maturity,
The goal that the authors, Taal Levi and Christopher C. Wilmers, are trying to accomplish is to show their audience how the abundance of three species, wolves, coyotes, and foxes, can impact each other and the ecosystem in Minnesota, USA in three different habitats, forest, transition fields, and farmland. The question that I believe that this journal is asking whether or not predation or the lack of it can act as a domino effect if wolves suppress coyotes in an environment, then that could possibly save the fox population and maybe other species along the way.
When the reintroduction of wolves began in the state of Wisconsin, a goal of 350 wolves was set, and this number was reached successfully in a short amount of time. Once this was reached, however, the population continued to rise dramatically and exponentially, and is now in the upper 600s (Allen). The problems now come down to a few simple questions that have complex answers. Will a regulated hunt get out of control, and a repeat of the past begins? Are the wolves posing any sort of threat in the present? Who or what would a hunt benefit? First, the issue of the past must be addressed. Back in the earlier years of the United States, wolves roamed free, and when farmers moved their livestock into what was then the wolves' territo...
National Parks are the cornerstone of every country because it preserves the rich cultural and natural resources of a nation, such as Yellowstone in the United States of America. Yellowstone National Park is the World’s First National Park which brings millions of attraction each year, it is larger than Rhode Island and Delaware combine and have over a thousand species of plants and animal (Yellowstone Media). However, a very important type of species has been missing in Yellowstone National Park for a very long time. Wolves, which got reintroduce back into Yellowstone National Park, should stay there because without them the ecosystem would be out of balance.
Studies show that wolves play a significant role in maintaining healthy ecosystems, and could even help stave off some of the effects of climate change. They help keep large animal herd populations in check, which can benefit numerous other plan...
One of the big causes of extinction or the endangerment of species is foreign species entering a habitat. This species that are not native to the land can disrupt the food web in that community. These species take control of the food web and endanger some of the other species. The native species become endangered and over the course of many years they either adapt to their new way or life, the foreign predator leaves or is killed off due to the different environment, or the species is killed off and becomes extinct. Organizations like the “World Wild Li...