FAQ: Ecosystem Dynamics

Transcription

1 Question 1: Why is environmental science called an applied science? Answer 1: Basic scientific research seeks to expand our knowledge about the way the world operates while applied science seeks to find practical solutions to problems (Basic vs. Applied Research, n.d.). Environmental science is an applied science because it results from experiments. Ecosystem models (computer simulations) are used to determine how to manage, preserve, or restore ecosystems and to inform the public of environmental policies and regulations. Question 2: What is the difference between an environmental scientist and an environmentalist? Answer 2: An environmental scientist uses the scientific method to study ecosystems and their components. An environmentalist is a person who seeks to protect the environment from destruction or pollution (Environmentalist, n.d.). The scientific method is an objective procedure that tests a hypothesis or an educated guess about what has been observed. Results are quantitative and can be analyzed with statistics to state a conclusion. Environmentalists may use scientific data to support a position about the environment. In addition, environmentalists might use philosophical arguments about the role of humans in nature or the inherent value of other species. Question 3: What are the major components of ecosystems? Answer 3: Ecosystems are ecological systems that are formed by the interaction of abiotic factors and biotic components, as follows: Abiotic factors: These include light, climate, and soil type. Biotic components: These form the biological community that is composed of all of the species in the ecosystem. Each species has a range of abiotic conditions under which it can grow and reproduce. This is called the species range of tolerance (Pidwirny, 2006). For example, a tropical plant would not likely flourish in colder climates. Different species of fish are found in salt or fresh water. This sets the stage for the types of organisms that will be found in the biological community. The number of species in the biological community can be counted as a measure of the biodiversity of the ecosystem. Ecosystems found in harsh environments will have lower biodiversity than ecosystems found in 1

2 conditions that are more moderate. Examples of ecosystems with high biodiversity are tropical rainforests and coral reefs (The Problem of Biodeiversity, 2001). Question 4: What is an ecological niche? Answer 4: Each species in an ecosystem fulfills a particular function or role. This function is called the ecological niche. One way of describing a species role in the ecosystem is to determine its trophic or feeding level as a producer or consumer. Plants are photosynthetic and therefore are producers. Consumers include herbivores that eat plants, carnivores that eat animals, and omnivores that eat both plants and animals. Humans are omnivores. Some consumer organisms in the ecosystem eat dead organic matter, and they are called detritus feeders, such as earthworms. The decomposers, bacteria, and fungi break down dead organic matter and return elements such as carbon, nitrogen, and phosphorus to the ecosystem. When organic matter rots, it is the work of a decomposer. We can also investigate how species interact with other species. These interactions can be labeled as competition, predator-prey, parasite-host, or mutualism in which both species benefit from the interaction. Question 5: What is the role of a decomposer in an ecosystem? Answer 5: Decomposers break down organic matter into smaller molecules and help to cycle elements in ecosystems. As a result of decomposition (rotting), elements such as carbon, nitrogen, or phosphorus are released from dead organic matter back to the ecosystem where they can be used again by the living organisms. While nutrients cycle through an ecosystem, energy flows through an ecosystem and must be continuously replenished from an energy source, such as sunlight. Question 6: Can we put clearly defined boundaries around an ecosystem? Why or why not? Answer 6: It can be difficult to put clear boundaries around an ecosystem. Usually, one ecosystem blends into another ecosystem. You might see this where grassland borders a forest. The transition from one ecosystem to another can be gradual; the transitional zone between two ecosystems is 2

3 called an ecotone. Ecotones have abiotic characteristics that change gradually from one ecosystem to the next. For example, a marsh may represent the ecotone between a pond and a higher and drier land ecosystem. Species from the neighboring ecosystems may move through the ecotone or spend some time there, or the ecotone may have a different biological community adapted to conditions in the ecotone (Ecotone, 2008). Question 7: What is a climax ecosystem? Answer 7: Theoretically, in a given area, a stable ecosystem will develop over time. This is called the climax ecosystem, or climax community. The species composition in the climax community is theorized to represent the end of the ecological succession process. This ecosystem is characterized by a biological community that is in equilibrium with the prevailing abiotic and climatic conditions. Large-scale climax communities can also be referred to as biomes (Ecology, 2007). For example, these include the tundra, different types of grasslands, or forests (Woodward, 2003). More recently, ecologists have modified this idea to include the fact that natural areas are subject to disturbance and that a climax community may include patches that have been disturbed at different times and are in varying stages of recovery (Ecology, 2007). When managing an ecosystem, it is important to understand the disturbance patterns and the patchiness that might naturally be found in a climax ecosystem. Question 8: What is ecological succession? Answer 8: Ecological succession is a process by which the climax community is established in a particular area. Succession proceeds as a bare or disturbed area becomes filled in with vegetation and animals. The types of vegetation and animals found in the area undergoing succession will change with changing abiotic conditions from one stage to the next until the climax community is reached. For example, a plowed field will have high light and low moisture, and weeds (pioneer species) may be the first plants on the site. As the site becomes vegetated, it becomes shadier and different plants will replace the weeds and so on until the climax ecosystem is established. Question 9: What types of natural and human caused disturbances might 3

4 impact an ecosystem? Answer 9: A disturbance is any factor or event that changes ecosystem structure or processes (Averill, Larson, Saveland, Wargo, & Williams, 2005). Vegetation may be removed, or abiotic conditions can be altered. There are many kinds of disturbances that might impact an ecosystem, either natural or human caused (e.g., anthropogenic). Examples of natural disturbances include fires caused by lightning, floods, windstorms, or droughts. Examples of human-caused disturbances include fires caused by humans, altering the natural flow of a river, clearing or draining land for development or agriculture, and pollution. Sometimes human alteration of an area might interact with a natural disturbance. For example, if wetlands or coastline vegetation is removed, the impacts of a hurricane could be more severe. Question 10: What factors might affect ecosystem resilience? Answer 10: Resilience is the ability of an ecosystem to recover from a disturbance. Many factors need to be considered when assessing an ecosystem s resilience. Some ecosystems exist in harsh environmental conditions that do not promote the regrowth of vegetation, such as in a desert or the tundra. These sensitive systems may take a long time to recover or may not recover at all. Recovery also depends upon the characteristics of the disturbance. Disturbances that are more severe, more extensive, or that happen repeatedly will slow down recovery or might prevent the ecosystem from recovering at all. The impact of a Category 5 hurricane will be more severe than a Category 1 storm. Overgrazing an arid (dry) rangeland repeatedly may eventually lead to a permanent change in the species composition or to desertification resulting in the replacement of grassland with a less productive ecosystem (Desertification, 2007). References Averill, R. D., Larson, L., Saveland, J., Wargo, P., & Williams, J. (2005). Disturbance processes and ecosystem management. Retrieved from the U.S. Forest Service Web site: 4

5 Basic vs. applied research. (n.d.). Retrieved from the Lawrence Berkeley National Laboratory's ELSI Project Web site: Desertification. (2007). Retrieved from the USGS Web site: Ecology. (2007). Retrieved from the Bartleby Web site: Ecotone. (2008). Retrieved from Encyclopædia Britannica Online Web site: Environmentalist. (n.d.). Retrieved from The Free Dictionary by Farlex Web site: Pidwirny, M. (2006). The fundamentals of physical geography. Retrieved from the Kelowna: University of British Columbia Okanagan Web site: The problem of biodiversity. (2001). Retrieved from the U.S. Department of State's Bureau of International Information Programs Web site: Woodward, S. L. (2003). Biomes of earth, terrestrial, aquatic, and humandominated. Retrieved from the Radford University Web site: 5