1. Human Impact

2. Do Now 1. List three ways humans have impacted the environment.
Section 6-3
1. List three ways humans have impacted the environment.
2. Do you think humans have had a positive impact or negative impact? Explain your answer.
3. Do you think it is important to preserve our environment? What can we do to preserve our environment?
Go to Section:

3. Changing landscape
Past and present humans have had a powerful influence on the physical and living world by modifying their environment.
Our practices have changed the environment!
From deforesting to fishing
We used the environment for food, medicine, wood, and fiber
We introduced new species, predators, agriculture, industry, and disease
The world is very different from what it was long ago.
Think of Earth as an island – all of the organisms that live on Earth share limited resources and increasing population sizes place greater demands on the biosphere

4. Human Activities
Humans have advantages in competing with other species for limited resources (food, energy, and space)
Humans are the most important source of environmental change on the planet, because we can change the flow of energy in an ecosystem and reduce the ability of ecosystems to recycle nutrients
Human activities that have transformed the biosphere include:
Hunting and gathering
Agriculture
Industry and urban development
Technology

5. Human Impact
Hunting and Gathering – the primary means of survival for most of human history, changed environment by diverting water, burning grasslands to grow certain plants, and causing major mass extinctions

6. Human Impact
Agriculture – farming began about 11,000 years ago supplying a dependable food source and beginning civilization development
Domestication of animals  provides humans’ energy to do work  overgrazing (changing ecosystem)
Human population growth  strain on world’s food supply  Green Revolution (new farming practices with increased yields and new hardier strains of plants)

7. Human Impact
Industrial growth and Urban development – added machines and factories to civilization during 1800s creating cities
Industrial Revolution (increased productivity and scientific knowledge)  increased energy use (coal, oil, gas)  increased waste/pollution (air, water, soil) and stress on natural habitats

8. Quick Activity
Classify the following resources as renewable or nonrenewable with your seat partner:
Solar energy
Wind/air
Water
Fossil fuels
Metals
Soil
Plants
Animals
} Biodiversity

9. Resources Environmental resources can be classified as:
Renewable = regenerate and replaceable (trees, water), but not necessarily unlimited
The classification “renewable” depends upon the context in which you use it. (For example, a forest is not renewable, because the climate would change if all trees were cut down, but individual trees are renewable)
Nonrenewable = cannot be replenished by natural processes (fossil fuels, coal, oil, natural gas)

10. Renewable resources
Human activities affect the supply and the quality of renewable resources including:
Land resources
Forest resources
Ocean resources
Air resources
Water resources

11. Land Resources
Provide space for cities and suburbs, raw materials for industry, and fertile soil with nutrients and moisture to grow plants with roots to hold soil against rain and wind
Negative activities:
Soil erosion = wearing away of surface soil by water and wind (usually results from removing roots that hold soil)
Desertification = turning once productive areas into deserts (usually results from farming, overgrazing, and drought)
Positive activities:
Sustainable agriculture = reduces soil erosion by conserving soil’s properties

12. Sustainable Agriculture
Section 6-4
Cover Crops
Legumes, grasses, and other
cover crops recycle soil nutrients,
reduce fertilizer need, and
prevent weed growth.
Controlled Grazing
By managing graze periods and herd
densities, farmers can improve nutrient
cycling, increase the effectiveness of
precipitation, and increase the carrying
capacity of pastures.
Biological Pest Control
The use of predators and parasites
to control destructive insects
minimizes pesticide use as well as
crop damage A B C
Contour Plowing
Contour plowing reduces
soil erosion from land runoff.
On hilly areas, plowing is done
across the hill rather than
straight up and down.
Yr. 1
Crop Rotation
Different crops use and
replenish different nutrients.
By rotating crops, the loss
of important plant nutrients
is decreased.
corn
oats
alfalfa
Yr. 2
alfalfa (plowed in)
corn
alfalfa
Yr. 3
oats
alfalfa
corn
Go to Section:

13. Forest resources
Provide wood for homes, paper, fuel and “lungs of the Earth” because they remove carbon dioxide and produce oxygen, store nutrients, provide habitats and food, moderate climates, limit soil erosion, and protect fresh water supplies
Negative activities:
Deforestation = loss of forests leading to soil erosion
Positive activities:
Tree farms = plant, promote growth, manage, harvest and replant trees to preserve the ecosystem

14. Ocean resources Provides protein-rich food (cod and shrimp)
Negative activities:
Overfishing = fish are being harvested faster than they can reproduce
Positive activities:
Limit the catch of fish
populations
Aquaculture = farming
of aquatic organisms

15. Amount of Fish per Person
Growth of Fish Catch
Larger fishing boats with better technology for locating and catching fish
Section 6-2
World Fish Catch
World Fish Catch per Person
Total Catch
(million tons)
Amount of Fish per Person
(kilograms)
Year
Year
Go to Section:

16. Air resources Used to breathe Negative activities:
Pollutant = harmful material that can enter the biosphere through the land/air/water
Smog = mixture of chemicals that results in a gray-brown haze in the atmosphere mostly due to car exhausts and industrial emissions causing respiratory conditions
Acid rain = mixture of acidic gases (nitrates and sulfates) from combustion with water vapor damaging plants, soil and water
Positive activities:
Clean-air regulations and controlling emissions has improved air quality

17. Chemical Transformation Emissions to Atmosphere
The Formation of Acid Rain
Section 6-2
Chemical Transformation
Nitric acid
Sulfuric acid
Condensation
Emissions to Atmosphere
Nitrogen oxides
Sulfur dioxide
Dry Fallout
Precipitation
Acid rain, fog,
snow, and mist
particulates, gases
Industry
Transportation
Ore smelting
Power generation
Go to Section:

18. Water resources
Billions of gallons of water are used daily by Americans for drinking, washing, watering crops and making steel (“everyday use”)
Negative activities:
Our renewable water supply can be limited by drought, overuse, oil spills, improperly discarded chemicals and waste (sewage)
Positive activities:
Protect natural cycles because plants naturally filter and purify water = Fresh Water Wetlands Act
Water conservation
Clean Water Act

19. Which would you rather swim in? Why?

20. Which would you rather live in? Why?

21. Do Now
Section 6-3
1. List three ways in which other organisms have proved to be a benefit to humans.
2. Compare biodiversity with other natural resources, such as wood and fossil fuels. Do you think biodiversity is a renewable or a nonrenewable resource? Explain your answer.
3. What can be done to preserve the biodiversity of organisms?
Go to Section:

22. Biodiversity
Biological diversity or “Biodiversity” = the sum total of the genetically based variety of all organisms in the biosphere
Our existence relies on a great variety of other organisms.
Some branches within biodiversity:
Ecosystem diversity = variety of habitats, communities, and ecological processes in the living world
Species diversity = number of different species in the biosphere (about 1.5 million discovered)
Genetic diversity = sum total of all the different forms of genetic information carried by all organisms living on Earth today

23. Species Diversity Insects Protists Other Animals Plants Bacteria Fungi
Section 6-3
Insects
54.4%
Protists
Other Animals
4.2%
19.7%
Plants
18%
Bacteria
Fungi
0.3%
3.4%
Go to Section:

24. Value of Biodiversity
Biodiversity is one of Earth’s greatest natural resources providing us with food, industrial products, and medicines (painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs)
When biodiversity is lost, potential sources of material with significant value to the biosphere and to humankind may be lost.

25. Threats to Biodiversity
Human activities can reduce biodiversity by:
Habitat alteration
Hunting species to extinction
Extinction = occurs when a species disappears from all or part of its range
Endangered species = species in danger of extinction with declining population sizes
As the population declines, the species loses genetic diversity, making it more vulnerable to extinction
Introducing toxic compounds (pollutants) into food webs
Introducing foreign species to new environments

26. Habitat Alteration
When land is developed, natural habitats may be destroyed and the species that live in those habitats may vanish
Habitat fragmentation = development of land that splits ecosystems into pieces resulting in biological “islands” with fewer species and smaller populations more vulnerable to further disturbances or climate changes

27. Hunting
In the past, hunting for meat, fur, hides or other body parts caused the extinction of some species
Today, endangered species are protected from hunting by laws in most of the world

28. Pollution
Pollution can threaten biodiversity, because toxic compounds accumulate in tissue of organisms
Biological magnification = increasing concentrations of harmful substances at higher trophic levels in a food chain/web
Entire food web is affected, but top-level carnivores are at highest risk

29. Biological Magnification of DDT
Section 6-3
Magnification of
DDT Concentration
Fish-Eating Birds
10,000,000
Large
Fish
1,000,000
100,000
Small Fish
10,000
Zooplankton
1000
Producers
Water 1
Go to Section:

30. Introducing Foreign Species
Biodiversity is also threatened by apparently harmless plants and animals that humans transport around the world either accidentally or intentionally
Invasive species = organisms introduced into new habitats and reproduce rapidly lacking the parasites and predators that control population size in their native country
They can displace native species driving them close to extinction
Ex. Zebra Mussels

31. Conserving Biodiversity
Conservation = wise management of natural resources
Preservation of habitats and wildlife to protect Earth’s biodiversity for future generations, however protected areas may not be enough
Current conservation efforts focus on protecting individual species as well as entire ecosystems (to ensure natural habitats and interactions among
different species are preserved).
“Hot spots” = places around the world where everything possible is being done to conserve the ecosystem and species

32. Our Future
Since the human population is rapidly increasing, we are creating greater environmental changes.
Two major concerns are:
Ozone depletion
Global warming

33. Ozone Depletion
Ozone layer = a layer of concentrated ozone gas made up of three oxygen molecules (O3) between 20 and 50 kilometers above Earth’s surface absorbing harmful UV radiation
Ozone holes caused by CFCs (chlorofluorocarbons) breaking down ozone molecules
Increased UV radiation can cause cancer, eye damage, decreased resistance to disease, and tissue damage to plants and animals

34. Global Warming
A 0.5°C increase in the average temperature of the biosphere in the past 120 years (abiotic factor)
Some scientists believe the rising temperature may be due to natural variations in climate
Others believe it is caused by human activities adding carbon dioxide and other greenhouse gases into the atmosphere, making the atmosphere retain more heat
More carbon dioxide from burning fossil fuels, cutting down trees and burning forests
It may result in rising sea level causing more frequent and more severe weather disturbances
Environmental changes benefit some species, but greatly disturb others that may not survive

35. The Value of a Healthy Biosphere
A healthy biosphere provides us with many valuable goods and services (food, medicine, temperature control, water purification, soil formation, etc)
Make wise choices about resources used, disposal, recycling, and energy conservation

36. Ecosystem services are provided, but it’s your responsibility to help save the Earth!
Section 6-4
Solar energy
Production of oxygen
Storage and recycling of
nutrients
Regulation of climate
Purification of water and air
Storage and distribution of
fresh water
Food production
Nursery habits for wildlife
Detoxification of human and
industrial waste
Natural pest and disease
control
Management of soil erosion
and runoff
Go to Section: