Page 674 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

638 part IV Soils, ecosystems, and Biomes
17. What is a limiting factor? How does it function to
control populations of plant and animal species?
■ Outline the stages of ecological succession in both terrestrial and aquatic ecosystems.
Natural and anthropogenic disturbance are common in most ecosystems. Wildfire can have far-ranging effects on communities; the science of fire ecology examines the role of fire in ecosystem maintenance. Ecological succession describes the process whereby communities of plants and animals change over time, often after an initial disturbance. An area of bare rock and soil with no trace of a former com- munity can be a site for primary succession. The species that first establish in a disturbed area make up the pioneer community that then alters the habitat such that different species arrive. Secondary succession begins in an area that has a vestige of a previously functioning community in place. Rather than progressing smoothly to a definable stable endpoint, ecosystems tend to operate in a dynamic condition, with intermittent disturbance that forms a mo- saic of habitats at different successional stages. Aquatic ecosystems also undergo succession; eutrophication is the gradual enrichment of water bodies that occurs with nutri- ent inputs, either natural or human-caused.
fire ecology (p. 623) ecological succession (p. 623) primary succession (p. 624) pioneer community (p. 624) secondary succession (p. 624) eutrophication (p. 626)
18. How does ecological succession proceed? Describe the character of a pioneer community. What is
the difference between primary and secondary succession?
19. How are wildfires important for ecological succes- sion? How have species and ecosystems adapted for frequent wildfire?
20. Assess the impact of climate change on natural communities and ecosystems. Examples are changes in species’ distributions or the changes and effects of wildfire.
21. Summarize the process of succession in a body of water. What is meant by eutrophication?
22. Is eutrophication occurring in the Great Lakes ecosystems? How does eutrophication relate to the formation of dead zones in freshwater ecosystems?
■ Explain how biological evolution led to the biodiversity of life on Earth.
Biodiversity (a combination of biological and diversity) includes the number and variety of different species, the genetic diversity within species, and ecosystem and habi- tat diversity. The greater the biodiversity is within an eco- system, the more stable and resilient the system is and the more productive it will be. Modern agriculture often creates a nondiverse monoculture that is particularly vul- nerable to failure.
Evolution states that single-cell organisms adapted, modified, and passed along inherited changes to multi- cellular organisms. The genetic makeup of successive generations was shaped by environmental factors, physi- ological functions, and behaviours that created a greater rate of survival and reproduction; these successful traits were passed along through natural selection.
biodiversity (p. 628) evolution (p. 628)
23. Give some of the reasons why biodiversity infers more stable, efficient, and sustainable ecosystems.
24. Referring to Chapter 1, define the scientific method and a theory, and describe the progressive stages that lead to the development of a theory.
25. What is meant by ecosystem stability?
26. What do prairie ecosystems teach us about commu-
nities and biodiversity?
looking for additional review and test prep materials? Visit the Study area in MasteringGeographyTM to enhance your geographic literacy, spatial reasoning skills, and understanding of this chapter’s content by accessing a variety of resources, including interactive maps, geoscience animations, satellite loops, author notebooks, videos, rSS feeds, web links, self-study quizzes, and an eText version of Geosystems.