Natural disturbances (grazing, fire, and weather [i.e., wind, ice, heat/cold, and drought or flood]) have occurred in the Wichita Mountains since prehistory. These disturbances have created the biodiversity we see today. Management practices of the Refuge cannot change weather but can, when possible (e.g., grazing and fire), strive to mimic historic disturbances and disturbance patterns to maintain biological integrity.
Early community ecologists could be grouped in two cohorts. The historic model, which remained in favor through the 1960s, asserted that plant assemblages reached climax as a community (Cowles 1910, Cowles 1911, Clements 1916; A. Tansley 1920, 1935, E. Warming 1909). The second model believed that biotic communities consist of species behaving individually or—phrased differently—that a fixed environment is not necessary to the life of any individual plant (Gleason 1917, Gleason 1926, Gleason 1939, G. Negri 1914, L. Ramensky 1924, 1925, 1952, 1970). These two trends are compared in detail by Ponyatovskaya (1961).
Whittaker (1953) considered previous “climax” theories and developed a concept of ecological continuum. He observed that the mono-climax models (proposed by Clements [1916] and cohorts) did not adequately describe communities. Whittaker’s evidence of problems in community climax theory was summarized using 1) succession, 2) convergence, 3) patterning, 4) continuity, 5) irregularity, and 6) instability. Considerable references were provided for each. He observed that the work of Gleason (1917, 1926, 1939) and L. Ramensky addressed some of these problems. Whittaker addressed scale as an ecological issue when he agrees with Cain (1939) that the difference between mono-climax and poly-climax is semantic. Whitta...
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... system disturbed beyond its limits of resilience will maintain a new sphere of activity (Denslow 1980, Denslow 1985, Pickett 1980, Hanski 1983, Collins and Barber 1985, Loucks et.al. 1985, Sousa 1985; Collins 1992, Collins 2000, Heino and Hanski 2001, D’Odorico et al. 2006, Beckage et. al. 2009). Perhaps the worst outcome of decreased biological diversity is a decrease in resilience and resistance to environmental change (Tartowski et. al. 1997). Departure from historic disturbance regimes affects competitive success of a species (Hanski 1983). Studying past patterns will help us understand patterns of the future (Christensen 1997). Practitioners must mimic historic disturbances to maintain existing ecosystems. Changes are persistent, and the ability to adapt, particularly at the Wichita Mountains Wildlife Refuge, is central to sustainability of ecosystem function.
Burton, Robert, ed. Nature's Last Strongholds. New York: Oxford UP, 1991. Print.
The next topic for discussion in this paper is ecology. This will include, preferred habitats and interactions with abiotic and biotic elements of the environment.
Other factors that influence the distribution of species and interspecific competition are weather, predation, intraspecific competition, disturbances and the characteristics of the competing species themselves (Connell 1983). The aim of this study was to see how the characteristics of competing species affect the outcomes of competitive interaction. What happens when values for initial abundance and alpha values are increased?
I recently watched a video called: “How wolves changed Yellowstone Park”. The video was about how the reintroduction of wolves into the park caused substantial changes in the entire ecosystem. The park’s plant life immediately began to regrow at a rapid pace, animals that were previously scarce began rising in population, the physical land began to change as rivers filled and started meandering less. All of this, caused by one small act.
A keystone species is a species that’s whose impact on its community or ecosystem is larger and greater than would be expected from its relative abundance or total biomass in the environment. The presence of keystone species maintains higher species diversity in ecosystems than if keystone species were absent. The role that a keystone species plays in its ecosystem is analogous to the role of a keystone inane arch. While the keystone is under 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 became a popular concept in conservation biology. Although the concept is valued as a descriptor for particularly strong inter-species interactions, and it has allowed easier communication between ecologists and conservation policy-makers, it has been criticized for oversimplifying complex ecological systems.
The understanding of the niche concept is an important component in any ecological studies, ranging from the study of individual species behavior, morphology and physiology to community level species participation in ecosystem structuring and functioning. The history of the use of initial niche concept can be traced down from Darwin’s (1859) and Wallace’s (1876) pioneer writings on natural selection and evolution where they implicitly refer to species roles in the environment as sited by Chase and Leibold (2003). Furthermore, it is possible to identify several naturalists who discussed concepts related to a species niche, but C...
Examine critically the Equilibrium Theory of island biogeography. In your answer you are expected to critique its validity and practical usefulness
Realistic aquatic and terrestrial ecosystems are constantly adapting to various disturbances of anthropogenic and natural origin. According to the “Alternative stable state theory” ecosystem has various states and can switch from one state to another when ecosystem conditions are changing (Holling, 1973; Scheffer, 2001). When the magnitude of such disturbance is negligible, the shift in the ecosystem structure and functioning does not occur. In this case the ecosystem resilience allows it to return to its original state (REF). Population densities are changing rapidly in response to a small disturbance. Such quantitative change does not necessarily lead to ecosystem structural and functional shift. On the other way around, when perturbation is large enough, ecosystem may shift to a different state. When the critical point is reached the change is not reversible and return to the original state is not possible. The threshold at which the shift happens depends on the extent of disturbance and on the degree of ecosystem resilience (REF). This ability of ecosystem to resist changing cond...
The bottom line is that complex landscapes beget complex interactions and it will require some clever manipulative experiments to untangle the often confounding effects of boundary quantity, boundary quality, matrix habitat, patch area and patch isolation on different species. This separation is crucial for conservation purposes, seeing as fragmentation and habitat loss are among the most important causes of species decline worldwide (Haila et al., 1994; Murcia, 1995; Didham et al., 1996; Didham, 1997).
Smith, T. M., & Smith, R. L. (2009). Elements of ecology (7 ed.). San Francisco, Calif.
Prior to writing this semester paper, I have identified Bronfenbrenner’s ecological systems theory and provided a concise
There is a developing importance among the nature conservationists in connection with the hypothesis of rewilding, which is defined as an ambitious model of ecological restoration that aims to generate ecosystem services through a natural process, rather than the micro-management associated with traditional approaches to conserving endangered species (Rubenstein et al., 2003). al. 2005). The 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Second It is usually a hands-off method of reintroduce keystone species such as beaver and wolves which are capable of re-organising the whole ecosystems through the predictor behavioral effects (Donlan et al. 2005). The 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Secondary' of the 'Second
Rosen when he organised what is nowadays known as the National Forum on Biodiversity that occurred in 1986 in Washington D.C. In 1987, the US Office of Technological Assessment (OTA) issued a report named ‘Technologies to maintain Biological Diversity’ in which they start with the question “What is Biological Diversity?” “Biological Diversity refers to the variety and variability among living organisms and the ecological complexes in which they occur”. In fact, they also defined diversity as “the number of different items and their relative frequency”. They also wanted to emphasize on the fact that diversity vary within ecosystems, species and genetic levels. In fact, ecosystem diversity, species diversity, genetic diversity can vary in many different ways. In the OTA’s report, they give the example of ecosystem diversity by saying that a landscape that is interspersed with grasslands, croplands and woodlands for example has more diversity than a landscape with most of the woodlands converted to grasslands and croplands. We can see through this example that biodiversity is a complex concept and that is the reason why it is difficult to explain it. Being aware of this, we will conclude this section by giving a very broad definition of biodiversity as the “life on Earth, the variety of living organisms, their habitats and the interaction between them” (DAC, 2010) knowing that no definition can fully cover the complex concept that is
Smith, T. M., & Smith, R. L. (2012). Elements of ecology (8th ed.). San Francisco: Pearson Benjamin Cummings.
In changing the way environmental management was framed, conservation efforts now sought to shelter the natural world from interference by human activities (Wendell, 2002), and now understood nature had intrinsic value other than economic gain (Meffe et al., 2002). Hence, conservationists progressed toward a preservationist approach, which works “[…] to maintain or prevent the loss of biodiversity by preserving and restoring species and habitats threatened by the activity of people” (Wendell, 2002 p. X). This new point of view additionally changed the definition of ecosystems to account for its “responses to manipulation [that] are not linear, but involve thresholds; and there are many unforeseen consequences and externalities” (Meffe et al., 2002 p.X). The historical timeline of environmental management take on the same progression toward a more egalitarian approach to natural conservation in both authors’ theses (Wendell, 2002; Meffe et al., 2002), and Meffe et al. (2002) expands on the shift by exploring a new definition of ecosystems as a dynamic system with non-equilibrium and acknowledges that disturbances are needed in order to maintain the balance of the biodiversity. As the supply needs of