Human Impact on the Environment

Transcription

1 Human Impact on the Environment

2 We share the Earth

3 with a whole lot of other creatures

4 We don t share very well.

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6 Human Activities Humans have always altered the Earth s ecosystems: Hunting, fishing, gathering of food Agriculture -- deliberate planting of crops and raising of livestock (made larger settlements possible) Farming technology:, irrigation, fertilizers pesticides and monoculture (one type of crop) which reduces! biodiversity

7 Ecological Succession Ecosystems may seem, stable but they are constantly changing in response to natural and human disturbances. Older inhabitants die and make room for newer inhabitants. After a, disturbance there are a predictable series of changes that occur over time.

8 Primary Succession Describes changes on surfaces with no. soil (Bare.) rock Pioneer species are the first to populate an area ( lichens and ). mosses When the pioneer species die, their remains are broken down to begin forming. soil

9 Over hundreds of years, more soil is added, making it possible for larger plants to grow. Eventually, the ecosystem will reach the climax community, which is a stable ecosystem.

10 Secondary Succession Secondary succession is to restore the ecosystem to its original conditions after natural events ( ) fire or human events ( ). farming **But some events can dramatically affect these communities and they may not be able to recover from long-term activities...

11 Industrial Growth The Industrial Revolution added pollution to the atmosphere and water supplies. Burning of fossil fuels increases the concentration of CO 2 in the atmosphere, adding to the greenhouse effect. This also adds soot to the atmosphere and causes. acid rain Cities produce large amounts of waste that contaminate soil and. water

12 Renewable/Nonrenewable Renewable resources can regenerate if. alive (Example: ) trees Replanting doesn t restore the whole! ecosystem Biodiversity is greatly reduced, and may not be able to... recover

13 Nonenewable resources cannot be replenished by natural processes. (Example: ) fossil fuels Sustainable development: a method of using natural resources without depleting them. This provides for human needs without causing long-term environmental. damage

14 Land Resources Soil CAN be renewable but can become permanently damaged if mismanaged. Good soil provides moisture and adequate drainage and. nutrients Removing plants causes erosion of topsoil and will prevent further. growth Soil also needs time for decomposers to return nutrients to the ecosystem!

15 Forest Resources Wood is used for homes and. paper Trees also provide habitats for animals and limit erosion of topsoil. Old-growth forests (have never been cut and are hundreds of years old!) are!!! nonrenewable Forest : Management selectively harvest older trees to give the younger trees a better chance for. survival

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17 Ocean Resources Fish are a source of food for most of the world s population! Overfishing takes the larger breeding stock, leaving the. juveniles This decreases growth rates for the species and some may disappear permanently! Sustainable fishing sets limits for the size of fish, size of catch and season -- to ensure that breeding continues.

18 Air Resources Pollution is any harmful material in the, biosphere spread through, land air or. water Burning of fossil fuels puts, nitrates sulfates and particulates into the air. These can cause, acid rain which can damage soil and water supplies and destroy. plants

19 Biodiversity Biodiversity is the total of all - genetically based variation of all organisms in an. ecosystem **Biodiversity is one of Earth s greatest!!! natural resources We have found, food industrial products and medicines like, antidepressants heart drugs and anticancer medications!

20 Many human activities are a threat to biodiversity. Habit Alteration: humans can alter or destroy habitats. This can fragment communities, causing islands with fewer, species smaller populations and less. variation This will make them more vulnerable and less able to recover from disturbance.

21 Wildlife products: used for, meat, fur medicine or decoration -- we have hunted some animals to. extinction Pollution: we use pesticides to control insect populations, without realizing the damage caused to the whole. ecosystem

22 Conserving Biodiversity We need to conserve biodiversity for. future generations Conservation is the wise management of natural resources to preserve habitats and. wildlife

23 Challenges to Conservation Captive breeding programs in zoos preserve only one species -- we should be just as concerned about the interactions between species in the! ecosystem Limiting the harvesting of resources changes and limits the way that people. earn a living ** Can cause severe financial, hardship but if steps aren t taken to protect resources, they may!!! disappear forever

24 DDT and Biomagnification DDT is a pesticide that seemed perfect it was, cheap worked against many different, pests and didn t break down in the environment. BUT it drained into streams and rivers in low enough concentrations that no one was concerned. In the water supply, DDT was taken up by plants and. bacteria

25 Herbivores eat plants. Because of the energy loss between trophic levels, they must eat LOTS of plants increasing the DDT level 10 X from plant level. Carnivores must eat many, herbivores which increases the DDT concentration in the bodies of the carnivores. Top carnivores have the highest risk, and suffer the greatest. effects **Responsible for decrease in eagle and osprey populations caused fragile! eggs

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27 Biological Controls If you can t use chemicals to control pests what s the solution? Find the pest s! natural enemy We can use predators ( ), ladybugs parasitoids (wasps that lay eggs on ), larvae pathogens ( ) bacteria or insects that target specific. weeds This method controls pest populations without harming the rest of the! ecosystem

28 Invasive Species Humans have introduced species to areas where they did not. evolve In many cases, these new species are better adapted to the new environment and able to out-compete the native species! They also have no natural, predators so there is no check on their population. growth

29 Invasive Species Examples: Snakehead fish Asian carp Gray squirrel Purple loosestrife Zebra mussel

30 Major Environmental Concerns There are 2 major concerns for the future of Earth s ecosystems: Depletion of the Ozone Layer Global Warming

31 Ozone Layer Ozone is a gas in the atmosphere that absorbs harmful UV rays from the sun like Earth s. sunscreen In the 1970 s, a hole was discovered over Antarctica -- and scientists found that CFC s (chlorofluorocarbons) found in aerosol cans were making it larger. CFC s are now banned in the US but effects can linger for 100 years, and other countries still use CFC s

32 Global Climate Change Life in the biosphere is adapted to live in a very narrow range of. temperatures Our global climate is getting, warmer which have serious side effects: Melting polar ice caps Rising water levels at coastlines Destruction of coral reefs

33 Geologic evidence shows that warming trends have happened in the past but Did we cause this one? Cutting forests and burning fossil fuels adds CO 2 to the atmosphere much faster than it can be. cycled Increased CO 2 levels contribute to the greenhouse effect and make the Earth. warmer

34 Long-Term Effects The average surface temperature on the Earth is expected to rise 1-2 ºC by the year This will cause: Flooding in coastal areas Drought during the summer months Change in species composition in ecosystems Will alter feeding relationships as some species become extinct

35 The Bottom Line? Why does any of this matter? EVERYTHING in the biosphere is, connected so if we don t make an effort to preserve our resources, the next food chain we destroy may be. OURS Once it s gone, it s gone folks. No going back. We must be good stewards of the Earth we don t own it we borrow it from our. children