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Chapter 12

Chapter 12. Human Impacts upon Earth Historical Basis of Pollution Pollution: Human released products in the amounts and durations that cause adverse effects. Two primary factors that affect damage done technological “inventions” population size  Biodegradable

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Chapter 12

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  1. Chapter 12 Human Impacts upon Earth • Historical Basis of Pollution • Pollution: Human released products in the amounts and durations that cause adverse effects. • Two primary factors that affect damage done • technological “inventions” • population size  • Biodegradable • Easily broken down into simpler compounds • Non-biodegradable • Won’t break down or break down very slowly

  2. Chapter 12 • Population size: wastes produced faster than ecosystem could dispose. • Sewage • Urban centers enhanced this problem.  • Eliminate “misery and disease”: often causes other problems. • Pesticides. • Often, pollution is in the eye of the beholder. • Uranium ore • arsenic in water

  3. Chapter 12 Renewable and Nonrenewable Resources • Natural Resources: things usable by humans, but which cannot be “created” by humans. • limited and unlimited • intensive exploitation moves unlimited to limited resources. • renewable • vs. “natural • nonrenewable processes”

  4. Chapter 12 Mineral Resources—non-renewable • Locations of mineral resources is not based on political boundaries • international trade required to bring in all types needed • (U.S. & Canada has about 5.2% of world’s population, and consumes about 30% of mineral resources.) • Costs • Economic Costs ($$ to exploit resource) • Energy Costs (to do the exploiting) • Environmental Costs (pollution, habitat loss etc)

  5. Chapter 12 Steps : each step has costs •  Exploration • time & technology • some energy • some environmental • becomes more intense as “easy” resources are consumed. • Mining • Labor • Equipment • Energy (large costs) • Environmental (significant) • mine tailings • water pollution & erosion • land disturbance

  6. Chapter 12 Refining (often part of mining) • labor • equipment • energy • environmental • air pollution • water pollution Transportation • energy • some environmental Manufacturing • labor • equipment • energy • environmental

  7. Chapter 12 Recycling • Can save significant costs by using materials which do not require all of the above steps.  • As energy costs go up, recycling will become more common.  • Many pay the environmental costs, rather than the few who use a product. • H/W must be able to collect easily and must have high economic value

  8. Chapter 12 Pristine Areas • Remote areas with harsh conditions are typically pristine (e.g. arctic poles, mountain tops, open ocean) • Areas that won’t support agriculture. • Won’t support dense human population • Other areas which until recently have been unaffected are being impacted. • will support limited agriculture or other human uses. • As human population grows.....

  9. Chapter 12 • Many “parks” and protected areas have been designated as pristine areas become more rare. • “Wilderness” areas: where humans are visitors, and do not remain. (U.S. definition) • Parks becoming more noticeable in Africa, C/S/N America, Australia • Until recently had large amount of relatively untouched land, now trying to preserve it

  10. Chapter 12 Modifications by Humans About 40% of world’s land surface converted to cropland and permanent pasture. Forest • Originally, 1/2 of U.S., 3/4 of Canada, 9/10 of Europe, and much of rest of world. • Very large demand for wood. • Sustained yield: harvest rate equals rate of regrowth. • Tropical forests are currently treated as nonrenewable resource, with extremely fast rate of depletion

  11. Chapter 12 Forests reduce energy in rainfall, and practically stop erosion by slowing runoff. • Water is “evapo-transpirated” in large volumes. • Shade and humidity moderate temperature extremes. Tropical forests trap much CO2 but are in areas of highest population growth pressures.

  12. Chapter 12 Management of forests require a compromise between economic forces and environmental viewpoints. • Clear-cutting • Patchwork clear-cutting • Selective harvesting • Reforestation •  Different species need different things in a forest (e.g. Red-Cockaded Woodpecker)

  13. Chapter 12 • Deciding what to do with a forest requires a conscious decision: • known value of world’s forests • can assign value to wildlife and water within • Wilderness value is very difficult to determine .... and forest can not be both an economic resource and a wilderness area. • Have to choose in some cases or find way to satisfy both sides of issue

  14. Chapter 12 Rangelands  • Arid and semiarid lands that can’t support typical agriculture, but can support some grazing animals.  • Grazing animals selectively reduce some plant species (and inadvertently encourage others). Managers do the same.  • Most grazing animals which are herded are “exotic” species, and reduce native species. • Population pressures force people to graze too many animals (Tragedy of the Commons), remove trees for wood (nutrient removal) and push land towards “desertification”.

  15. Chapter 12 Aquatic Systems • Large areas of the ocean are still considered pristine. • Most productive areas in the oceans are close to shore: • nutrients/sunlight/ offshore currents bring nutrients up from bottom • Concentrates pressure • Fishing selectively removes some species. • Methods for catching bottom dwellers disturbs habitat and wastes 25% of fish caught

  16. Chapter 12 • Most freshwater systems have been altered by humans. • water quality changes • exotic species • thermal pollution • Many systems are manipulated to enhance some desirable species. • Recreational and commercial interests • Difficult to predict all the consequences of managing large natural systems. • Difficult to manage all inputs to lake that may affect ecosystem

  17. Chapter 12 Wildlife Management • Improving conditions for species desirable to humans. Manipulate one of the following:  • -food and water • -cover (shelter): • -escape from competitors • -protection from weather • -resting and sleeping • -mating and raising young • Quail

  18. Chapter 12 • Must understand niche very well before attempting “habitat management”. • Trying to improve the habitat for one species often harms the habitat of another. • Difficult role to try and take over mgmt of • Migrating species require special considerations.

  19. Chapter 12 Natural Selection and Extinction • Extinction: elimination of all individuals of a particular species (local and global). • Natural phenomenon .... estimated that only about 1 or 2% of all species which have existed are still alive today. • Speciation: appearance of a new species. • Since things change, a species must adapt or become extinct.

  20. Chapter 12 Extinction happens more often when:  • species has small population/low reproduction rate • dispersed individuals • species occurs in small, restricted areas • species is very specialized

  21. Chapter 12 Accelerated Extinction • Humans are among the most successful species currently on earth: • adaptable • Intelligent • high reproductive capability • few enemies As human population grows: • other species displaced (habitat alteration) • species utilized as food • used as ornaments • used for medicine • eliminated as pests =accelerated extinction

  22. Chapter 12 Why worry? • Many species may be useful to us. • food & medicine • Certain species play key roles in the ecosystems that we utilize. • Most people find nature beautiful, and “monocultures” are found disturbingly sterile. • Do all species have a fundamental right to exist?

  23. Chapter 12 Actions: • Protection of “threatened” and “endangered” species. • More action in developed nations than in less developed nations. • Bias in protecting certain types of species: • birds • mammals • butterflies • a few mollusks, fish and plants

  24. Chapter 12 World Conservation Union (former International Union for the Conservation of Nature) Work (without much power, but much prestige) around the world, especially in less developed nations. U.S. Endangered Species Act (1973)  • Attempts to protect threatened and endangered species from governmental actions. • Political amendments and effects • Endangered Species Review Committee • Can sanction extinction if economic benefits warrant • Weakened ability to add species to list

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