Human Interaction

1. Human Interaction • Chapter 12

2. W O R K T O G E T H E R • “Sustainability” is a popular idea these days. • What does “sustainability” in the ecosystem mean? • What does “sustainability” in human communities mean?

3. The term “ecological footprint” means: • The ecological services of a natural area. • The complete bio-capacity of Earth. • The land and water area needed to sustain humans. • The risk of a species to extinction.

4. Natural Communities • Natural, self-renewing communities share several features: • Stable populations at or below carrying capacity • Biological diversity • Recycling of all raw materials • Reliance on sustainable energy (solar)

5. Human Communities • How well does our community score on each of these four points? • Stable populations at or below carrying capacity • Biological diversity • Recycling of all raw materials • Reliance on sustainable energy

6. Human Population 2012* 2006 Date Billions Time to add each billion (years) 1999 1804 1 All of human history 1987 1927 2 123 1975 1960 3 33 1974 4 14 billions of people 1987 5 13 1960 bubonic plague 1999 6 12 2012 7* 13 1930 *projected 1830 Technical and cultural advances Agricultural advances Industrial and medical advances We know that human population is increasing exponentially. Our resources are not.

7. Poll: The human species: • Is approaching carrying capacity. • Has overshot carrying capacity. • Can never reach carrying capacity.

8. Consequences of exceeding K. Population overshoots carrying capacity; environment is damaged. K (original) Low damage; resources recover, population fluctuates. K (reduced) Extreme damage; population dies out. High damage; carrying capacity permanently lowered. 0 time The problem is, we don’t know for sure where we are on this graph.

9. Bear in mind that this is what “overshoots carrying capacity” looks like.

10. When resources are highly limited, most individuals have access to only a small share of those resources.

11. 2006: 6.5 billion population (billions) developing countries developed countries year Presently, populations in developing nations are increasing, while developed nations are stabilizing.

12. World average: 1.2% Developing countries average: 1.4% Africa: 2.2% Latin America/Caribbean: 1.6% World regions Asia (excluding China): 1.6% China: 0.6% Developed countries average: 0.3% N. America: 0.6% Europe: –0.1% natural increase per year (percent) Breakdown of population increases in different parts of the world.

13. Population pyramids for Mexico Population pyramids for Sweden Sweden 2007 Mexico 2007 male female male female percent percent High birth rates increase population, but also provide many young people to support their elderly relatives. Low birth rates reduce or level off the population, but leave less support for the aging segment of the population.

14. Even with a modest 0.6% increase in the population each year, the U.S. shows exponential growth. U.S. population (in millions) year

15. In which area of Earth is the human population growing the fastest? • North America • Europe • Africa • Asia

16. On which continent are natural resources being used the fastest? • North America • Europe • Asia • Africa

17. While populations in developed nations are increasing slowly, individuals in developed nations use many times the amount of resources as individuals in developing nations. What happens if developing nations adopt the U.S. lifestyle?

18. This group promotes zero population growth, birth control, and social justice as means to improve society. In some countries, such as the United States, population control is a highly controversial issue. This group rejects birth control, believes people should have as many children as possible, and supports the rights of the individual.

19. In some developing nations, women’s education programs have taught women to read, write, and run small businesses. Where women are educated and most people have meaningful work, birth rates slow down and the quality of life improves.

20. Growth curves for the human population show that our species is experiencing: • Logistic growth • S-shaped growth • Exponential growth • Declining growth

21. Age structure diagrams show that human population is declining in which part of the world? • China • Latin America • United States • Africa • Europe

22. Humans affect natural populations • We are living in the middle of a mass-extinction event, and we are the cause. • We humans change our environment to meet our needs for food, shelter, and other resources. In doing so, we impact other species dramatically. • The larger our population gets, the faster we use up limited resources.

23. Extinction Risks • Specialization and resource partitioning increase diversity. • However, the tradeoff is that organisms become more vulnerable to extinction if the environment drastically changes.

24. Localized Distribution • By living in a limited area, a population avoids competition with other populations. • The risk is that a natural disaster will destroy the limited habitat. The Devil’s Hole Pupfish lives in a single waterhole in Nevada.

25. Overspecialization • Organisms that have specialized feeding habits reduce competition with other species. • If the limited food source goes extinct, so does the species feeding on it. Fender’s Blue Butterfly feeds only on Kinkaid’s Lupine.

26. Interactions • Isolation reduces competition and predation. • If a new predator or competitor is introduced, a formerly isolated species may be hunted or out-competed to extinction. Many Hawai’ian birds were driven to extinction by introduced predators.

27. Habitat Loss • The greatest cause of extinction is habitat loss. • Organisms with highly specialized habitat needs may avoid competition, but risk extinction if their habitat is threatened. Tropical rain forests are being logged at an alarming rate, mostly for grazing cattle.

28. “HIPPO” and Extinctions • Humans activity can contribute greatly to species extinction. • The acronym “HIPPO” can help us remember the major contributors to human-caused extinctions.

29. H Habitat destruction Humans plow up land for farms and housing developments, strip soil from mountains to mine minerals, damage ocean bottoms with deep-water nets, and cut down forests for wood products. All of these are habitats for wildlife.

30. I Invasive Species Humans have introduced species into areas where they have no natural predators. Without natural controls, the invasive species overpopulate rapidly, crowing out native species. Kudzu – there’s a house under there. Ivy Purple Loosestrife Starling

31. P Pollution Debris, oil spills, and toxic chemicals pollute waterways, air, and soil. Pesticides and herbicides used on farms, lawns gardens, and golf courses contribute to local pollution.

32. P Population Human population has increased exponentially and is still climbing. Large populations need large amounts of resources, but at the same time occupy land that might otherwise have supplied resources.

33. O Overharvest Ancient bison in North American may have been hunted to extinction. The dodo, the passenger pigeon, and the Great Auk have all gone extinct due to overhunting.

34. Of the five HIPPO factors, which causes extinctions the fastest? • Habitat destruction • Invasive species • Population (human) • Pollution • Overharvest

35. So why don’t people… • …simply stop polluting, reproducing excessively, and start using resources wisely? • The “Tragedy of the Commons” scenario helps explain the human mindset that interferes with this “simple” solution.

36. Common Pool Resources These are resource that: 1) are available in limited supply (either they do not renew, or renew more slowly than they are being used) 2) are openly available for use, and 3) it is costly to prevent people from using the resources.

37. When it comes to Common Pool Resources: It is in the community’s best interest to control how the resource is used so that the resource will not be depleted and will be available for all. It is in the individual’s best interest to get as much of the resource as possible.

38. Part of the problem is that nations all over the world have economies that rely on a linear system of resource extraction and disposal. Our linear system relies on over-exploitation of common pool resources. Linear systems are not sustainable. Material extraction MUST be tied to material recovery and re-use, just like a natural ecosystem, to be sustainable.

39. It has been estimated that if everyone in the world lived as people do in Western nations, we would need about 4 Earths to sustain us. In 2013, Earth Overshoot Day fell on August 20 – the day when the world has used as much of Earth’s resources as Earth can replace in one year. We only have this. We don’t have these. This is the definition of “overshooting carrying capacity.” The current situation was no accident. In the 1950s, the U.S. made a deliberate move from being a nation of producers to being a nation of consumers in order to grow the economy. Victor Lebow, U.S. economist under Eisenhower.

40. Is it hopeless? • Never in the history of the Earth has one species had such an enormous effect. • However, unlike other organisms, humans have choices about how they live and how they use resources. • Our past decisions have gotten us into this mess. Our future decisions can solve the problem.

41. Lessons from Nature • Remember the features of a renewable, self-sustaining natural community: • Stable populations at or below carrying capacity • Biological diversity • Recycling of all raw materials • Reliance on sustainable energy (solar)

42. Stable populations at or below carrying capacity Humans, unlike other organisms, have the ability to choose whether to reproduce or not. Some societies have created laws to regulate populations. Others have relied on incentives, or have left the issue to individual choice. The issue becomes complex if a society depends on a large number of young people to support the aged. Okay, not like this. What are some unexpected effects of small families?

43. Biological diversity Preserving biological diversity in nature, in agriculture, and even in our human communities is becoming increasingly important.

44. Ecosystem services Directly used substances • food plants and animals • building materials • fiber and fabric materials • fuel • medicinal plants • oxygen replenishment Indirect, beneficial services • maintaining soil fertility • pollination • seed dispersal • waste decomposition • regulation of local climate • flood control • erosion control • pollution control • pest control • wildlife habitat • repository of genes “Ecosystem services” are direct and indirect benefits humans receive from the environment.

45. Humans have directly benefitted from biodiversity. Drugs derived from plants and animals.

46. Forest mushrooms Tropical fruits Andean Potatoes A diverse ecosystem yields a diversity of foods.

47. Humans also benefit indirectly from intact, diverse ecosystems. Natural rivers meander, creating a richly diverse wetland ecosystem.

48. Channelizing rivers, reducing wetlands, and cutting down trees along rivers changes the ecosystem. Loss of wetland diversity means loss of species. Sediments that would be deposited along the river system and in islands around the mouth of the river flows straight out to sea.

49. New Orleans was once protected by the many islands in the Mississippi Delta. Much of the sediment that built those islands now runs out to the sea. The islands have eroded, leaving less protection against hurricanes.

50. The term “ecosystem services” refers to: • Direct and indirect benefits humans receive from the ecosystem. • How the ecosystem supplies our needs even when we extract resources at a high rate. • When humans do service projects to help restore ecosystems.