What is ecology

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What is ecology

  1. 1. ECOSYSTEMS<br />
  2. 2. What is ecology?<br />What is an Ecosystem?<br />All of Earth’s inhabitants are woven together into a complex web of relationships. Removing one species from an environment can have affects on the whole system.<br />Ecology is the study of the interactions of living organisms with one another and with their physical environment (soil, water, climate, etc.)<br />
  3. 3. Habitat and community<br />The place where a particular population of a species lives is it’s habitat.<br />A habitat could be a saltwater marsh, an undersea reef, or a grassland, desert, forest or swamp area. Wherever a particular species finds it’s home is it’s habitat.<br />The many different species that live together in a habitat are called a community.<br />Many different species may live together in a desert habitat.<br />
  4. 4. What is an ecosystem?<br />An ecosystem, or ecological system, consists of a community and all the physical aspects of it’s habitat; the living and nonliving parts (such as soil, water, and weather).<br />
  5. 5. Biotic and abiotic factors<br />The physical nonliving aspects of a habitat (weather, soil, etc) are called abiotic factors.<br />The living organisms that make up the community of the habitat are called biotic factors.<br />Together, the biotic and abiotic factors create the ecosystem.<br />
  6. 6. biodiversity<br />The variety of organisms, their genetic differences, and the communities and ecosystems in which they occur is termed biodiversity.<br />Imagine taking a square mile of a local forest, and cataloging every type of living organism from trees to plants to insects to animals. The total collection of all the living organisms in a habitat is it’s biodiversity.<br />The biodiversity of Australia’s Great Barrier Reef is enormous, numbering tens of thousands of species.<br />
  7. 7. Macrocosm to microcosm: range of biotic life forms<br />Many types of organisms inhabit an ecosystem together and support each other in a web of complex relationships.<br />Life forms, biotic forms, in a woodland environment may include large animals such as deer and coyote and extend to smaller animals such as squirrels, chipmunks, birds, snakes and lizards.<br />
  8. 8. Interactions of Organisms and their Environments<br />The living organisms extend down to the trees, grasses, and ferns on the forest floor. <br />Within the forest soil; insects, worms and even bacteria and microscopic eukaryotes are part of the biotic factors that make up the life of the ecosystem.<br /> Large to microscopic, all living organisms are included.<br />
  9. 9. Lichens and fungi<br />Many kinds of fungi and lichens grow on trees and rocks within a forest. <br />These fungi are important living members of the forest ecosystem as well playing an important role in helping break down living organisms after the organisms die.<br />
  10. 10. Abiotic factors<br />If you were to remove all these living parts; the animals, fungi, insects, birds, reptiles, and forest plants; the nonliving items remaining; the rocks, soil, climate minerals, organic compounds, rain, sunlight, etc, would make up the abiotic factors of the ecosystem<br />
  11. 11. Boundaries of an ecosystem<br />The physical boundaries of an ecosystem are not always obvious, and they depend on how an ecosystem is being studied.<br />For example, a scientist may consider a single rotting log on a forest floor if he or she is studying only the fungi and insects of the forest that live in logs.<br />
  12. 12. Interactions of Organisms and their Environments<br />Often individual fields, forests, lakes or wetlands are studied as an isolated ecosystem.<br />Of course, no location is entirely separated or isolated. Even oceanic islands get occasional migrant visitors such as birds blown off course.<br />
  13. 13. Succession, primary succession, and secondary succession<br />A regular procession of species replacement is called a succession.<br />Pioneer species are the first wave of life in a new habitat and are called the primary succession.<br />Succession that occurs where their have been areas of previous growth, such as abandon fields or forest clearings, are called secondary succession.<br />
  14. 14. Process of succession<br />It was once thought that stages of succession were predictable and that succession always led to the same final community of organisms within any particular ecosystem.<br />Ecologists now realize that initial conditions and random chance play a role in the process of succession.<br />For example, if two species are in competition for food, a sudden change in climate may favor the success of one species over the other. For this reason, no two successions are alike.<br />
  15. 15. Process of Succession<br />Glacier Bay:<br />A good example of a primary succession is a receding glacier because land is continually being exposed as the face of the glacier moves back.<br />The glacier that composes much of the head of Glacier Bay in Alaska has receded some 100 kilometers over the last 200 years. <br />The most recently exposed areas are piles of rocks and gravel that lack any usable nitrogen that is needed by plants to establish themselves.<br />
  16. 16. Process of Succession<br />Glacier Bay: example of succession<br />The seeds and spores of the first pioneer species are carried in by the wind.<br />These include lichens, mosses, fireweed, willows, cottonwoods, and dryas ( a plant about a foot across). <br />At first, all these plants grow low to the ground, severely stunted in their growth by a lack of mineral nutrients. <br />Eventually the dryas crowd out the other plants.<br />
  17. 17. Process of Succession<br />Glacier Bay: example of succession<br />After about 10 years, alder seeds blown in from distant sites take root. <br />Alder roots have nitrogen-fixing nodules so they are able to out-grow the dryas.<br />Dead leaves and branches from the alders gradually add more usable nitrogen to the soil. The added nitrogen allows cottonwoods and willows to invade and grow with increased numbers.<br />
  18. 18. Process of Succession<br />Glacier Bay: example of succession<br />After about 30 years, dense thickets of alder, willow, and cottonwood shade and eventually kill off the dryas.<br />The pioneer species make life possible for the later species which push them out once conditions exist to let them flourish.<br />
  19. 19. Process of Succession<br />Glacier Bay: example of succession<br />After 80 years after the glacier first exposes the land, Sitka spruce invades the thickets. <br />Spruce use the nitrogen released by the alders and eventually form a dense forest.<br />
  20. 20. Process of Succession<br />Glacier Bay: example of succession<br />The spruce blocks the sunlight from the alders and eventually the alders die off. <br />After the spruce becomes established, hemlock trees began to grow. Hemlocks are very shade tolerant and have a root system that works well with spruce, sharing the nitrogen in the soil so both species grow well in tandem.<br />
  21. 21. Process of Succession<br />Glacier Bay: example of Succession<br />This community of spruce and hemlock proves to be a very stable ecosystem from the perspective of human time scales.<br />This system is not permanent however. As the local climate changes, the forest ecosystem must change and adapt as well.<br />

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