Chapter ten


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Chapter ten

  1. 1. Title Page Photo “ You will die but the carbon will not; its career does not end with you. It will return to the soil, and there a plant may take it up again in time, sending it once more on a cycle of plant and animal life.” — Jacob Bronowski (
  2. 2. Vocabulary <ul><li>biogeography (p. 289) </li></ul><ul><li>biomass (p. 292) </li></ul><ul><li>biota (p. 291) </li></ul><ul><li>carbon cycle (p. 294) </li></ul><ul><li>decomposers (p. 298) </li></ul><ul><li>denitrification (p. 296) </li></ul><ul><li>edaphic factors (p. 305) </li></ul><ul><li>fauna (p. 291) </li></ul><ul><li>flora (p. 291) </li></ul><ul><li>food chain (p. 297) </li></ul><ul><li>food pyramid (p. 297) </li></ul><ul><li>limiting factor (p. 304) </li></ul><ul><li>net primary productivity (p. 292) </li></ul><ul><li>nitrogen cycle (p. 296) </li></ul><ul><li>nitrogen fixation (p. 296) </li></ul><ul><li>oxygen cycle (p. 295) </li></ul><ul><li>photoperiodism (p. 304) </li></ul><ul><li>photosynthesis (p. 292) </li></ul><ul><li>plant respiration (p. 292) </li></ul><ul><li>plant succession (p. 302) </li></ul><ul><li>primary consumers (p. 297) </li></ul><ul><li>producers (p. 297) </li></ul><ul><li>secondary consumers (p. 297) </li></ul>
  3. 3. <ul><li>The Impact of Plants and Animals on the Landscape </li></ul><ul><li>The Geographical Approach to the Study of Organisms </li></ul><ul><li>Biochemical Cycles </li></ul><ul><li>Food Chains </li></ul><ul><li>Natural Distributions </li></ul><ul><li>Environmental Relationships </li></ul>Cycles and Patterns in the Biosphere
  4. 4. <ul><li>The Impact of Plants and Animals on the Landscape </li></ul><ul><li>Biosphere </li></ul><ul><li>Human Impacts Can Overwhelm the Biosphere </li></ul><ul><ul><ul><ul><li>Fig. 10-1a and 10-b </li></ul></ul></ul></ul>
  5. 5. <ul><li>Biosphere is still an integral part of the landscape </li></ul>Atmosphere (climate’s domain) Lithosphere: Land surface Hydrosphere: Ocean, freshwater, & ice Biosphere: Plants & Animals
  6. 6. The Impact of Plants and Animals on the Landscape <ul><li>Biosphere boundaries tough to pin down because biosphere impinges spatially on other three. </li></ul><ul><li>Both plants and animals interact with other components of natural landscape and may be important influence on development and evolution of soil, landforms, water, and more. </li></ul><ul><ul><li>Consists of all organisms that live on Earth. </li></ul></ul><ul><ul><ul><li>Vegetation used to cover most of land surface, but no more because of humans. </li></ul></ul></ul><ul><ul><ul><li>Humans have altered and modified much of remaining vegetation in world. </li></ul></ul></ul>
  7. 7. The Geographic Approach to the Study of Organisms <ul><li>Because of complexity of organisms, geographer can only focus on certain aspects rather than the whole. </li></ul><ul><ul><li>Seek generalizations and patterns (in distributions and relationships) and assess their overall significance. </li></ul></ul><ul><ul><li>Biogeography is the study of the distribution patterns of plants and animals, and how these patterns change over time. </li></ul></ul>
  8. 8. The Search for a Meaningful Classification Scheme <ul><li>Systematic study of plants and animals is domain of biologists. </li></ul><ul><ul><li>Linnaean system—most significant and widely used biological classification. </li></ul></ul><ul><ul><ul><li>Focuses on the morphology of the organisms and groups them on the basis of structural similarity. </li></ul></ul></ul><ul><ul><ul><li>Principal disadvantage for geographic use is that it is based entirely on anatomic similarities. </li></ul></ul></ul><ul><li>Geographers are more interested in distribution patterns and habitat preferences. </li></ul><ul><ul><li>Can’t come up with anything better. </li></ul></ul><ul><ul><li>Widespread agreement on a scheme very unlikely </li></ul></ul>
  9. 9. Seeking Pertinent Patterns <ul><li>Perhaps 600,000 plant species and more than twice as many animal species. </li></ul><ul><ul><li>Biota —the total complex of plant and animal life. </li></ul></ul><ul><ul><li>Fauna —animals. </li></ul></ul><ul><ul><li>Flora —plants. </li></ul></ul><ul><ul><ul><li>Terrestrial biota is much more diverse than its oceanic counterpart. </li></ul></ul></ul>
  10. 10. Biogeochemical Cycles <ul><li>Believed that for last billion years or so, composition of Earth’s atmosphere and hydrosphere had been relatively unchanged. </li></ul><ul><ul><li>Implies grand cycles that kept everything in steady-state condition: </li></ul></ul><ul><ul><li>Flow of energy through photosynthesis </li></ul></ul><ul><ul><ul><li>Hydrologic cycle </li></ul></ul></ul><ul><ul><ul><li>Carbon cycle </li></ul></ul></ul><ul><ul><ul><li>Oxygen cycle </li></ul></ul></ul><ul><ul><ul><li>Nitrogen cycle </li></ul></ul></ul><ul><ul><ul><li>Other mineral cycles </li></ul></ul></ul><ul><ul><ul><ul><li>Human impact is having a deleterious effect on every one of these cycles. </li></ul></ul></ul></ul>
  11. 11. Global Net Primary Productivity
  12. 12. The Flow of Energy <ul><li>Solar energy is the basic source of energy and is fundamental for life on Earth. </li></ul><ul><ul><li>Photosynthesis —the basic process whereby plants produce stored chemical energy from water and carbon dioxide and which is activated by sunlight. </li></ul></ul><ul><ul><ul><li>How solar energy ignites life processes in biosphere: </li></ul></ul></ul><ul><ul><ul><li>Solar energy becomes fixed in biosphere via photosynthesis by green plants. </li></ul></ul></ul><ul><ul><li>In presence of sunlight, green plant takes carbon dioxide from air, combines with water, and creates carbohydrate compounds, a form of chemical energy. </li></ul></ul><ul><ul><ul><li>This chemical energy then flows through biosphere when animals eat the plants or eat other animals that had eaten plants. </li></ul></ul></ul><ul><ul><ul><ul><li>Two main components are Hydrogen Cycle and Carbon Cycle. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>CO2 + H20 (via sunlight) -> carbohydrates + O2 </li></ul></ul></ul></ul>
  13. 13. The Flow of Energy <ul><li>Plant respiration —the consumption of stored energy in the form of carbohydrates by plants. </li></ul><ul><ul><li>The stored energy is oxidized by the plant, releasing water, carbon, dioxide, and heat energy. </li></ul></ul><ul><ul><li>Carbohydrates + O2 -> CO2 +H20 + energy (heat) </li></ul></ul>
  14. 14. The Flow of Energy <ul><li>Net Primary Productivity </li></ul><ul><ul><li>Net photosynthesis is the difference between the amount of carbohydrates produced in plant photosynthesis and lost via plant respiration. </li></ul></ul><ul><ul><li>Net primary productivity is the amount of net photosynthesis of a plant community over a period of a year or a measure of the biomass of that community. </li></ul></ul><ul><ul><ul><li>Net primary productivity varies geographically with the greatest productivity in the tropics and decreasing amounts toward the poles. </li></ul></ul></ul>
  15. 15. The Hydrologic Cycle <ul><li>Also called water cycle; imperative to life. </li></ul><ul><li>Water is found either in residence or in transit . </li></ul>Water Nutrients Energy
  16. 16. The Carbon Cycle <ul><li>Carbon cycle —the change from carbon dioxide to living matter and back to carbon dioxide. </li></ul><ul><ul><li>Atmospheric carbon dioxide is photosynthesized into carbohydrate compounds. </li></ul></ul><ul><ul><li>Some of the carbon dioxide is consumed directly by plant respiration. </li></ul></ul><ul><ul><li>Plant growth is dependent on a surplus of carbohydrate production. </li></ul></ul><ul><li>Humans have interfered with delicate balance in carbon cycle that had been fixed by photosynthesis. </li></ul><ul><li>Through burning of fossil fuels, humans rapidly accelerating the rate at which carbon is freed from reservoirs and converted into carbon dioxide. </li></ul>
  17. 17. Carbon moves constantly from the living system to organic reservoirs and back
  18. 18. The Oxygen Cycle <ul><li>Oxygen cycle —the movement of oxygen by various processes through the environment. </li></ul><ul><ul><li>An extremely complicated process because oxygen occurs in many chemical forms and is released into the atmosphere in a variety of ways. </li></ul></ul><ul><ul><li>Oxygen now in atmosphere is largely a byproduct of vegetable life </li></ul></ul>
  19. 19. The Nitrogen Cycle <ul><li>Nitrogen cycle —an endless series of processes in which nitrogen moves through the environment. </li></ul><ul><ul><li>Nitrogen comprises 78% of atmosphere, but only certain species of soil bacteria and blue-green algae can use it in this gaseous form; need nitrogen cycle so other life forms can assimilate it. </li></ul></ul><ul><ul><li>Nitrogen fixation —conversion of gaseous nitrogen into forms that can be used by plant life. </li></ul></ul><ul><ul><li>Denitrification —conversion of nitrates into free nitrogen in the air. </li></ul></ul><ul><li>Humans significantly altering balance of natural nitrogen cycle through agriculture processes and crop choices. </li></ul><ul><li>Affecting lakes and streams by depleting their oxygen supply. </li></ul>
  20. 20. Other Mineral Cycles <ul><li>Specific trace minerals, notably phosphorus, sulfur, and calcium, play important roles as nutrients for life. </li></ul><ul><ul><li>Like carbon, oxygen, and nitrogen, they move over and over through cycles. </li></ul></ul><ul><ul><li>Cycles are variable from place to place. </li></ul></ul><ul><ul><li>The amounts of biotic nutrients are finite. </li></ul></ul><ul><li>Human interference is either damaging or modifying some of these cycles. </li></ul>
  21. 21. Principal Chemical Components of Biosphere <ul><li>Principal chemical components of biosphere: </li></ul><ul><ul><li>Carbon </li></ul></ul><ul><ul><li>Oxygen </li></ul></ul><ul><ul><li>Nitrogen </li></ul></ul>
  22. 22. Food Chains <ul><li>Food chain —sequential predation in which organisms feed upon one another, with organisms at one level providing food for organisms at the next level, etc. Energy is thus transferred through the ecosystem. </li></ul><ul><ul><li>Chain is misleading because there is not an orderly linkage of equivalent units, as a chain implies. </li></ul></ul>
  23. 23. Food Chains <ul><li>Fundamental unit in any food chain are the producers (autotrophs), or plants. </li></ul><ul><ul><li>They trap solar energy through photosynthesis. </li></ul></ul><ul><ul><li>Followed by primary consumers and secondary consumers. </li></ul></ul><ul><ul><li>Decomposers serve as a critical player in returning nutrients back to the soil. </li></ul></ul><ul><ul><ul><li>Several levels of secondary consumers </li></ul></ul></ul>Fundamental Units of a Food Chain Plants are Autotrophs (Self-feeders that fix carbon – storing solar energy) Primary Consumers Herbivores (plant-eaters) Secondary Consumers Carnivores (meat-eaters) Animals are Heterotrophs (Consumers)
  24. 24. Food Chains <ul><li>Food pyramid —another conceptualization of energy transfer through the ecosystem from large numbers of “lower” forms of life through succeedingly smaller numbers of “higher” forms, as the organisms at one level are eaten by the organisms at the next higher level. </li></ul>— Decrease in number of consumers — Few Secondary Consumers Many primary consumers
  25. 25. <ul><ul><li>Large predators are at top of the pyramid </li></ul></ul><ul><ul><ul><ul><li>Fig. 10-11. A lynx pouncing on a snowshoe hare. </li></ul></ul></ul></ul>
  26. 26. Food Chains <ul><li>Pollutants in the Food Chain </li></ul><ul><ul><li>Increasing concern that some chemical pollutants can become concentrated in food chains. </li></ul></ul><ul><ul><li>Some stable substances (those resistant to degradation) such as DDT and heavy metals such as mercury and lead become concentrated at higher levels of a food chain. </li></ul></ul><ul><ul><li>These can result in harmful effects and even death of consumers at the top of the food chain. </li></ul></ul>
  27. 27. Natural Distributions <ul><li>Questions regarding distribution of organisms: </li></ul><ul><ul><li>What is the range of a certain species or group of plants/animals? </li></ul></ul><ul><ul><li>What are the reasons behind this distribution pattern? </li></ul></ul><ul><ul><li>What is the significance of the distribution? </li></ul></ul>
  28. 28. Natural Distributions <ul><li>Evolutionary Development </li></ul><ul><ul><li>Darwinian theory of natural selection explains the origin of species via descent with modification from parent forms. </li></ul></ul><ul><ul><ul><li>Progeny best adapted for a particular environment will survive. </li></ul></ul></ul><ul><ul><li>To understand the distribution of any species, we must first consider where it evolved. </li></ul></ul><ul><ul><ul><li>Acacia species – widespread distribution before the Pangaea break-up </li></ul></ul></ul>
  29. 29. Natural Distributions <ul><li>Migration/Dispersal </li></ul><ul><ul><li>Most plants and animals possess active mechanisms to disperse themselves or their progeny. </li></ul></ul><ul><ul><li>The contemporary distribution pattern of many organisms is often a result of dispersal from an original center. </li></ul></ul><ul><ul><ul><li>Coconut palms and cattle egrets serve as an example. </li></ul></ul></ul><ul><ul><li>Plants disperse seeds via wind, water, and animals. </li></ul></ul>
  30. 30. Natural Distributions <ul><li>Reproductive Success </li></ul><ul><ul><li>Reproductive success is critical for the survival of a species. </li></ul></ul><ul><ul><li>Poor reproductive success can be a result of several factors: </li></ul></ul><ul><ul><ul><li>Heavy predation </li></ul></ul></ul><ul><ul><ul><li>Climatic change </li></ul></ul></ul><ul><ul><ul><li>Failure of food supply </li></ul></ul></ul><ul><ul><ul><li>Changing environmental conditions can also favor one group over another. </li></ul></ul></ul><ul><ul><li>Reproductive success allows one competing population to flourish while another languishes. </li></ul></ul><ul><ul><ul><li>Example: American bison </li></ul></ul></ul>
  31. 31. Natural Distributions <ul><li>Extinction </li></ul><ul><ul><li>Species range can be diminished by the dying out f some or all of it. </li></ul></ul><ul><ul><li>Plant Succession —when one type of vegetation is replaced naturally by another. </li></ul></ul><ul><ul><ul><li>Usually a sequence of a lake to a field to grasses and shrubs to forest vegetation. </li></ul></ul></ul><ul><ul><ul><ul><li>Extinction is permanent, but species succession is not. </li></ul></ul></ul></ul>
  32. 32. Environmental Relationships <ul><li>A generalization that is true on one scale may be invalid at another. </li></ul><ul><ul><li>Whatever the scale, there are nearly always exceptions to the generalizations. </li></ul></ul><ul><ul><li>The smaller the scale, the more numerous the exceptions. </li></ul></ul><ul><ul><ul><li>Small-scale shows a relatively large portion of Earth’s surface. </li></ul></ul></ul><ul><ul><li>In environmental relationships, two types of competition at work: </li></ul></ul><ul><ul><ul><li>Intraspecific competition—among members of the same species. </li></ul></ul></ul><ul><ul><ul><li>Interspecific competition—among members of different species. </li></ul></ul></ul><ul><ul><li>Limiting is the most important variable determining the survival of an organism </li></ul></ul>
  33. 33. The Influence of Climate <ul><li>Various climatic factors exert the most prominent environmental constraints: </li></ul><ul><ul><li>Light </li></ul></ul><ul><ul><li>Moisture </li></ul></ul><ul><ul><li>Temperature </li></ul></ul><ul><ul><li>Wind </li></ul></ul>
  34. 34. The Influence of Climate <ul><li>Photoperiodism —the response of an organism to the length of exposure to light in a 24-hour period. </li></ul><ul><ul><li>Availability of moisture governs broad distribution patterns of the biota more significantly than any other climatic feature. </li></ul></ul><ul><ul><li>Wind is not as influential as other climatic factors, except where winds are persistent. </li></ul></ul><ul><ul><li>Influences temperature and moisture. </li></ul></ul>
  35. 35. Edaphic Influences <ul><li>Edaphic factor —soil characteristics. </li></ul><ul><ul><li>Influence biotic distributions: </li></ul></ul><ul><ul><li>Directly affecting flora; </li></ul></ul><ul><ul><li>Usually indirectly affecting fauna. </li></ul></ul>
  36. 36. Environmental Relationships <ul><li>Topographic Influences </li></ul><ul><ul><li>On global scale, topographic influences are the most important factor affecting distribution. </li></ul></ul><ul><li>Wildfire </li></ul><ul><ul><li>Wildfire is the most important of the abrupt and catastrophic events that affect the distribution of plants and animals. </li></ul></ul><ul><ul><li>Has a widespread influence, affecting all portions of the continents except for always-wet regions and always-dry regions where there is not enough combustible vegetation. </li></ul></ul>
  37. 37. Environmental Correlations: Example of Selva <ul><li>Climate influences vegetation distributions more than any other environmental factor. </li></ul><ul><li>Also influences faunal distribution, not as much as vegetation patterns do. </li></ul><ul><li>Selva, or tropical rainforest, serves as an example. </li></ul><ul><li>Climate </li></ul><ul><ul><li>Abundant precipitation and uniformly warm temperatures has a large influence on tropical vegetation. </li></ul></ul>
  38. 38. Environmental Correlations: Example of Selva <ul><li>Flora </li></ul><ul><ul><li>Abundant broadleaf evergreen vegetation thrive in the continually warm and moist climatic conditions. </li></ul></ul><ul><ul><ul><li>Layered canopy because of the limited penetration of light to the forest floor. </li></ul></ul></ul><ul><li>Soil </li></ul><ul><ul><li>Continuous percolation of moisture from the constant rainfall leads to deep, but ironically well-leached and infertile soils. </li></ul></ul><ul><ul><li>Laterization is the principal soil-forming process with rapid weathering of mineral matter and rapid decomposition of organic matter. </li></ul></ul>
  39. 39. Environmental Correlations: Example of Selva <ul><li>Hydrographic </li></ul><ul><ul><li>Abundant runoff feeds well-established surface drainage systems. </li></ul></ul><ul><ul><li>Lakes are uncommon because there is enough erosion to drain them naturally. </li></ul></ul>
  40. 40. People and the Environment: Changing Climate Affects Bird Populations <ul><li>Birds can serve as indicators to climate change because many species have specific environmental requirements for feeding, nesting, and migration. </li></ul><ul><li>Data suggest that higher global temperatures are already having an effect on some bird populations. </li></ul><ul><li>Data revealed that in warmer years, most bird species do not fly as far south in the winter as compared to cooler years. </li></ul><ul><li>Birds may also spend summers farther north during warmer years. </li></ul>
  41. 41. People and the Environment: Changing Climate Affects Bird Populations <ul><li>Climate change may also have an effect on the timing of bird migrations. </li></ul><ul><li>Some species are arriving north to Michigan two to three weeks earlier than normal because of the earlier blooming of plants and subsequent proliferation of insects. </li></ul><ul><li>They then lay their eggs sooner than normal. </li></ul><ul><li>Some species may not be able to respond to such changes and not be able to so readily shift their habitats further north. </li></ul><ul><li>This could lead to dislocated and altered habitats for birds and other species. </li></ul>
  42. 42. People and the Environment: Wildfires in Yellowstone <ul><li>National Park Service policy to let natural fires burn unless they threatened human life, private property, or significant natural resources. </li></ul><ul><li>Followed theory that ecosystem in parks should be allowed to function naturally, so shouldn’t interfere with natural processes. </li></ul>
  43. 43. People and the Environment: Wildfires in Yellowstone <ul><li>Horrendous weather conditions made Yellowstone ripe for conflagration. </li></ul><ul><li>Suppression often caused more harm than benefit, with bulldozer scars lasting 10 times as long as any scars from fire. </li></ul><ul><li>Number of animals killed relatively close to average number killed by cars in an average summer. </li></ul>
  44. 44. People and the Environment: Wildfires in Yellowstone <ul><li>Positive results of fires far outweigh the negative ones. </li></ul><ul><ul><li>Created a healthier, more diverse ecosystem. </li></ul></ul><ul><ul><ul><li>Mosaic of vegetation rather than prevalence of lodgepole pine. </li></ul></ul></ul><ul><ul><li>Prompted seedlings of coniferous trees. </li></ul></ul><ul><ul><ul><li>Recycled bound-up nutrients. </li></ul></ul></ul><ul><ul><li>Allowed for vigorous growth of grasses, herbs, and shrubs. </li></ul></ul><ul><ul><li>New vegetative growth supports large populations of arthropods and rodents, which invigorate food web. </li></ul></ul>
  45. 45. <ul><li>The biosphere consists of all plant and animal life forms on Earth. It overlaps with the other three environmental spheres. </li></ul><ul><li>All life forms depend on three ingredients: solar energy, water, and nutrients. These ingredients are unevenly distributed on Earth’s surface. </li></ul><ul><li>The three ingredients continuously cycle through the biosphere, as organisms absorb and return them to the other three spheres. </li></ul><ul><li>Summary </li></ul>
  46. 46. <ul><li>The most prominent geochemical cycles involve water, carbon, oxygen, and nitrogen. </li></ul><ul><li>Floral-faunal relationships can be described as a food chain or food pyramid. </li></ul><ul><li>Plants are the “self-feeders”; they are the first link in the food chain and at the bottom of the food pyramid. </li></ul><ul><li>Animals are either primary or secondary consumers of energy stored by plants. </li></ul><ul><li>Summary </li></ul>
  47. 47. <ul><li>Factors in the environment that determine the survival of plants and animals are limiting factors. The main limiting factors are light, water, shelter, and nutrients. </li></ul><ul><li>Climate is the main influence on how the limiting factors vary from place to place on Earth, but soils, topography, and wildfires also influence local plant and animal distributions. </li></ul><ul><li>Summary </li></ul>