Chapter 20 Terrestrial Biomes Geosystems 5e An Introduction to Physical Geography Robert W. Christopherson Charlie Thomsen
Final Exam On April 11 at the Alumni Hall (AH) STAGE. Will cover chapters 7,15,16,17,18,19,20, and 21. Will cover all information on the PowerPoint slides. It will contain 100 multiple choice and T/F questions. MUST BRING #2 Pencils !!! Exam will start at 2pm until ~ 4pm. Once you are finished please leave class quietly. Know the boldface terms at each chapter. Review summary questions at the end of each chapter – most of them I specifically answered in the PowerPoint presentations.
Key Learning Concepts: Define the concept of biogeographical realms of plants and animals and define ecotone, terrestrial ecosystem, and biome. Define six formation classes and the life-form designations and explain their relationship to plant communities. Describe ten major terrestrial biomes and locate them on a world map. Relate human impacts, real and potential, to several of the biomes.
2. What is a biogeographical realm 2. What is a biogeographical realm? How is the world subdivided according to plant and animal types? Biogeographical realms of plants and animals are geographic regions where groups of species evolved. From these centers, species migrate worldwide according to their niche requirements, reproductive success, competition, and climatic and topographic barriers. Recognition that such distinct regions of flora and fauna exist was an early beginning of biogeography as a discipline. The next two slides (maps) illustrate the botanical (plant) and zoological (animal) regions forming these biogeographical realms. Each realm contains many distinct ecosystems that distinguish it from other realms.
2. Describe a transition zone between two ecosystems 2. Describe a transition zone between two ecosystems. How wide is an ecotone? The transition zone between two ecosystems is called an ecotone. Boundaries between natural systems are “zones of shared traits,” therefore they are zones of mixed identity and composition, rather than rigidly defined boundaries. A tropical savanna is a good example of an ecotone. Situated between tropical forests and tropical steppes or deserts, tropical savanna is a mixture of trees and grasses. The savanna biome includes treeless tracts of grasslands, and in very dry savannas, grasses grow discontinuously in clumps, with bare ground between them.
3. Define biome. What is the basis of the designation? A large, stable terrestrial ecosystem is known as a biome. Specific plant and animal communities and their interrelationship with the physical environment characterize a biome. Each biome is usually named for its dominant vegetation. We further define these general biomes into more specific vegetation units called formation classes. These units refer to the structure and appearance of dominant plants in a terrestrial ecosystem, for example, equatorial rain forest, northern needleleaf forest, Mediterranean shrubland, arctic tundra.
4. Distinguish between formation classes and life-form designations as a basis for spatial classification. Interacting populations of plants and animals in an area form a community, or association of related species. Large vegetation units, the floristic component of a terrestrial ecosystem characterized by a dominant plant community, are called plant formation classes. Each formation includes numerous plant communities, and each community includes innumerable plant habitats. Within those habitats, Earth's diversity is expressed in approximately 250,000 plant species. More specific systems are used for the structural classification of plants. Such life-form designations are based on the outward physical properties of individual plants or the general form and structure of a vegetation cover. These physical life-forms, (see next slide), include trees (larger woody main trunk, perennial, usually exceeding 3 m); lianas (woody climbers and vines); shrubs (smaller woody plants; branching stems at ground); herbs (small plants without woody stems above ground); bryophytes (mosses, liverworts); epiphytes (plants growing above the ground on other plants, using them for support); and thallophytes, which lack true leaves, stems, or roots (bacteria, fungi, algae, lichens).
5. Describe the equatorial and tropical rain forests 5. Describe the equatorial and tropical rain forests. Why is the rain forest floor somewhat clear of plant growth? Why are logging activities for specific species so difficult there? Biomass in a rain forest is concentrated high up in the canopy, that dense mass of overhead leaves with a vertical distribution of life that is dependent on a competitive struggle for sunlight. The canopy is composed of a rich variety of plants and animals. Lianas (vines) branch from tree to tree, binding them together with cords that can reach 20 cm in diameter. Epiphytes (a plant that derives its moisture and nutrients from the air and rain and grows usually on another plant) flourish there as well. The floor of the rain forest and the floor of the ocean are roughly parallel in that both are dark or dimly lit, relatively barren, and a place of fewer life-forms–although the rainforest floor is much livelier than the sea floor. Logging is difficult because individual species are widely scattered; a species may occur only once or twice per square kilometer.
6. What issues surround deforestation of the rain forest 6. What issues surround deforestation of the rain forest? What is the impact of these losses on the rest of the biosphere? Burning is more common than logging in deforestation because of the scattered distribution of specific types of trees mentioned earlier. Fires are used to clear land for agriculture, which is intended to feed the domestic population as well as to produce cash exports of beef, rubber, coffee, and other commodities. Every year, approximately 15.25 million acres are thus destroyed, and more than 10 million acres are selectively logged. The United Nations Food and Agricultural Organization (FAO) estimates that if this destruction to rain forests continues unabated, these forests will be completely removed by the year 2050! Another threat to the rain forest biome emerged in the 1990s: exploration for and development of oil reserves.
7. What do caatinga, chaco, brigalow, and dornveld refer to? Explain. Local names are applied to the tropical seasonal forest and scrub on the margins of the rain forest: the caatinga of northeast Brazil, chaco area of Paraguay and northern Argentina, the brigalow scrub of Australia, and the dornveld of southern Africa.
8. Why does the northern needleleaf forest biome not exist in the Southern Hemisphere? What is its relationship to climate type? Stretching from the East coast of Canada and the Maritimes westward to Alaska and continuing from Siberia across the entire extent of the Russia to the European Plain is the northern needleleaf forest, also called the taiga (a Russian word) or boreal forest. The Southern Hemisphere, lacking D climates except in mountainous locales, has no biome designated as such. However, forests of needleleaf trees exist worldwide at high elevation.
9. In which biome do we find Earth's tallest trees 9. In which biome do we find Earth's tallest trees? Which biome is dominated by small, stunted plants, lichens, and mosses? The temperate rain forest biome is recognized by its lush forests at middle and high latitudes, occurring only along narrow margins of the Pacific Northwest in North America, with some similar types in southern China, small portions of southern Japan, New Zealand, and a few areas of Chile. The tallest trees in the world, the coastal redwoods (Sequoia), are found in this biome (their distribution is shown on the map in the next slide). These trees can exceed 1,500 years of age and typically range in height from 60 to 90 m ,with some exceeding 100 m. Other representative trees—Douglas fir, spruce, cedar, and hemlock—have been reduced to a few remaining valleys in Oregon and Washington. Tundra vegetation is characterized by low, ground-level plants and some woody plants. Representative plant species are sedges, mosses, arctic meadow grass, snow lichen, and dwarf willow. They are found in the arctic tundra -the extreme northern area of North America and Russia, bordering on the Arctic Ocean.
10. What type of vegetation predominates in the Mediterranean dry summer climates? The dominant shrub formations that occupy these regions are short, stunted, and tough in their ability to withstand hot-summer drought. The vegetation is called sclerophyllous (from sclero for “hard” and phyllos for “leaf”); it averages a meter or two in height and has deep, well-developed roots, leathery leaves, and uneven low branches. Plant ecologists think that this biome is well adapted to frequent fires, for many of its characteristically deep-rooted plants have the ability to resprout from their roots after a fire.
11. Describe some of the unique adaptations found in a desert biome. Much as a group of humans in the desert might behave with short supplies, plant communities also compete for water and site advantage. Some desert plants, called ephemerals, wait years for a rainfall event, at which time their seeds germinate quickly, develop, flower, and produce new seeds, which then rest again until the next rainfall event. The seeds of some xerophytic species open only when fractured by the tumbling, churning action of flash floods cascading down a desert arroyo, and of course such an event produces the moisture that a germinating seed needs. Desert plants employ other strategies such as long, deep tap roots; succulence (that is, thick, fleshy, water-holding tissue such as that of cacti); spreading root systems to maximize water availability, waxy coatings and fine hairs on leaves to retard water loss; leafless conditions during dry periods; reflective surfaces to reduce leaf temperatures; and, tissue that tastes bad to discourage herbivores.
12. What is the relationship between island biogeography and biosphere reserves? Describe a biosphere reserve. Setting up formal natural reserves called biosphere reserves at continental sites involves principles of island biogeography. Island communities are special places for study because of their spatial isolation and the relatively small number of species present. They resemble natural experiments because the impact of individual factors, such as civilization, can be more easily assessed on islands than they can over larger continental areas. It is now known that the number of species should increase with the size of the island, decrease with increasing distance from the nearest continent, and remain about the same over time, even though composition may vary. These considerations are important to establishing the optimum dimensions for biosphere reserves. The race is on between setting aside tracts of land in reserves and the permanent loss of remaining natural biomes. The goal of biosphere reserves is to preserve species diversity.
Geosystems 5e An Introduction to Physical Geography End of Chapter 20 Geosystems 5e An Introduction to Physical Geography Robert W. Christopherson Charlie Thomsen
Chapter 21 Earth and the Human Denominator Geosystems 5e An Introduction to Physical Geography Robert W. Christopherson Charlie Thomsen
Key Learning Concepts: Determine an answer for Carl Sagan's question, “Who speaks for Earth?” Describe the growth in human population and speculate on possible future trends. List the subjects of recent environmental agreements, conventions, and protocols and relate them to physical geography and Earth systems science (geosystems). Appraise your place in the biosphere and realize your physical identity as an Earthling. Analyze the “An Oily Bird” and relate your analysis to energy consumption patterns in the United States and Canada.
1. Who speaks for Earth? Carl Sagan answered his question “who speaks for Earth” with this perspective: “We have begun to contemplate our origins: starstuff pondering the stars; organized assemblages of ten billion billion billion atoms considering the evolution of atoms; tracing the long journey by which, here at least, consciousness arose. Our loyalties are to the species and the planet. We speak for Earth. Our obligation to survive is owed not just to ourselves but also to that Cosmos, ancient and vast, from which we spring.” (Carl Sagan, Cosmos, New York: Random House, 1980, p. 345.)
2. What is meant by the Gaia hypothesis? Just as the abiotic spheres affect the biosphere, so do living processes affect abiotic functions. All of these interactive effects in concert influence Earth's overall ecosystem. In essence, the planetary ecosystem sets the physical limits for life, which in turn evolves and helps to shape the planet. Thus, Earth can be viewed as one vast, self-regulating organism. The hypothesis contends that life processes control and shape inorganic physical and chemical processes. The biosphere is so interactive that a very small mass can affect a very large mass. Thus, Lovelock and Margulis think that the material environment and the evolution of species are tightly joined; as the species evolve through natural selection, they in turn affect their environment.
3.What factors led to the Exxon Valdez accident? On 24 March 1989, in Prince William Sound off the southern coast of Alaska, in clear weather and calm seas, a single-hulled supertanker operated by Exxon Corporation, an international energy corporation, struck a reef that was outside the normal shipping lane. The tanker spilled 41.64 million liters of oil. It took only 12 hours for the Exxon Valdez to spill its contents, yet a reasonable cleanup will take years and billions of dollars. Because contingency emergency plans were not in place, and promised equipment was unavailable, response by the oil industry took 10 to 12 hours to activate, about the same time that it took the ship to empty. The immediate effect on wildlife was contamination and death, but the issues involved are bigger than these damaged ecosystems. Many factors influence our demand for oil. Well over half of our imported oil goes for transportation. The death toll for animals was massive: at least 3000 sea otters killed (or about 20% of the resident otters), 300,000 birds, and uncounted fish, shellfish, plants, and aquatic microorganisms. Sublethal effects, namely mutations, now are appearing in fish. This latter side effect of the spill is serious because salmon fishing is the main economy in Prince William Sound, not oil. Many factors influence our demand for oil. Improvement in automobile efficiency began in 1975 due to federal regulations. During the 1980's, there was a rollback of auto efficiency standards, a reduction in gasoline prices, large reductions in funding for rapid transit development, and the continuing slow demise of America's railroad network. The demand for fossil fuels was also affected by the slowing of domestic conservation programs, elimination of research for energy alternatives, such as solar and wind power, and even the political delay of a law requiring small appliances to be more energy-efficient. Conservation plans again were politically blocked in the Department of Energy in 1990 and early 1991.
3a.What factors led to the Exxon Valdez accident? In 2001, comparatively inefficient sports utility vehicles represented more than half of new car sales. These SUVs are classified as light trucks and are thus exempt from auto-efficiency and some pollution standards—they burn more gas to go fewer miles and pollute more per mile driven and they are involved in a disproportionate share of accidents. A combination of waste, low prices, and a lack of alternatives has spurred the demand for petroleum. In addition in 2002 the U.S. Administration formally abandoned funding for efforts to make vehicles more efficient and instead announced an effort to develop fuel cells for future times. Alternatives such as conservation, efficiency strategies, solar, wind, and photovoltaic cells also took budgetary hits.
Worldwide Oil Spills
Movie: “AMERICA'S BIGGEST OIL SPILL.” In 1989, the Exxon Valdez ran ashore on a well-known nautical hazard in Prince William Sound. Within 48 hours, over 48 million gallons of crude oil had spewed out into the environment. Can this happen again? Why did it happen this time? Are we ready? Actual footage.
Geosystems 5e An Introduction to Physical Geography End of Chapter 21 Geosystems 5e An Introduction to Physical Geography Robert W. Christopherson Charlie Thomsen