1. Human Impact on Ecosytems
Chapter 16

2. Human Population Growth and Natural Resources
Human Population Growing
Thomas Malthus Essay
Human Population cannot grow forever
Claimed population was growing faster than resource production
1700’s – 1 billion
Now - ~6 billion
Carrying capacity?

3. Human Population Growth and Natural Resources
Technology and Population Growth
How has technology affected:
Agriculture
Medicine
Sanitation
Transportation
Is this all a good thing?
Carrying capacity changes as the environment changes
Gas powered farm equipment allows for the production of mass quantities of food
In infants per 1000 births died – in per 1000
This is due to better medicine and better sanitation
Food and products are moved more easily now with transportation

4. Human Population Growth and Natural Resources
Population Growth and Resources
Two major energy resources
Oil
Coal
Renewable energy resources
Wind
Solar
Drinking water
Oil and coal are non-renewable resources – used faster than they are formed
2006 – humans used about 77 million barrels per day
Keystone XL Transcanada oil project-pipileine that would run from Alberta, CA to Steele City, NE – Hundereds of thousands of barrels of oil per dayM
Renewable resources are not used as fast as they are produced

5. Human Population Growth and Natural Resources
Management of Resources
Easter island
Inhabited around A.D.
Population grew over next 1000 years
Harvested trees faster than they could regrow
Animal populations destroyed, soil washed away
Human population crash

6. Human Population Growth and Natural Resources
Ecological Footprint
Amount of land needed to maintain enough food, water, and shelter
Dependent upon efficient use of resources
Developing countries
Footprint getting bigger in developing countries, but so is population
U.S. has big footprint, but other countries have more “feet”

7. Air Quality Pollutants
Human activity directly and indirectly effect Earth
Smog and Ozone
Acid Rain
Creates pollution
Any undesireable factor added to the atmosphere

8. Air Quality Smog and Ozone
Most common air pollution comes from human activities
Burning fossil fuels causes chemicals to recombine forming pollutants
Smog – sunlight interacting with pollutants
Particulates can be inhaled causing health problems
Ozone – Nitrous oxide interacts with ground level oxygen giving ozone
Most common is burning fossil fuels
Ozone can be harmful to asthmatics and people with breathing problems, but is a big part atmosphere

9. Air Quality
Acid rain
Chemicals from fossil fuels can also interact with rain
Cause the pH to drop
Normal rain is slightly acidic – 5.6
With emissions can drop below that
Can cause declines in growth rates and also break down of bark

10. Air Quality Greenhouse Effect Sunlight Greenhouse gases
Some is absorbed by atmosphere
Some gets to Earth’s surface
This is radiated as infrared heat
Greenhouse gases
Create a blanket and insulate the Earth
Gases – Water vapor, methane gas, carbon dioxide

11. Air Quality Global Warming
Temperature rising – 0.6 degrees C over last 100 years
Due to increased concentrations of greenhouse gases
Disagreement on the impact of humans
Creating increased flooding, stronger storms, melting ice caps

12. Water Quality Water Pollution Chemicals can contaminate water supplies
Raw sewage
Farm runoff
Algae build up
Scientists study indicator species
Provides a sign as to the quality of an ecosystem’s conditions
Algae can reduce dissolved oxygen levels-this can lead to a reduction in breakdown by detrivores
This leads to a buildup in ponds and lakes called eutrophication
Gender bending fish-traces of female hormones have been found in lakes from human medications-fish starting to change from male to female

13. Water Quality Biomagnification Movement of toxins up the food chain
Causes an accumulation of the toxin in predators
Organisms at higher trophic levels eat more organisms which causes increases in toxicity
Has greatest effect on species at top of food chaing
Many chemicals are fat soluble meaning they stay in the body of an organism
When that organism is eaten the predator gets everything that is trapped in the organism
This could start as low as phytoplankton and move up through the chain

14. Threats to Biodiversity
Loss of Biodiversity
Loss of habitat and pollution
Effects plant and animal species
Losing species directly affects humans
Almost half the prescribed medicines come from plants
Technological advances often start in nature
Loss of a single species can have a rippling effect
Some scientists use what they see in nature for creating new technology – mussels and adhesives
Sri Lanka – 95% of their rainforests are gone-this has caused 19 species of frogs to go extinct

15. Threats to Biodiversity
Habitat Loss
Humans are moving into wilderness areas
Causing a loss of animal habitat
Between % of wetlands lost
Many migrating bird species lost
Habitat Fragmentation
Barrier forms preventing a species from access to entire home range
Fragmentation is caused by building roads or harvesting forests which prevents the species from accessing the entire ecosystem
Create wildlife overpasses

16. Threats to Biodiversity
Introduced (Invasive) Species
Species introduced to an ecosystem by human activity
Can threaten native species
Can lead to economic damage
Often times exploit a new niche
Is a better competitor than native species

17. Threats to Biodiversity
10 worst invasive species
Kudzu
Rabbits
Starlings
Burmese pythons
Cane toads
Snakehead fish
Gray squirrels
Killer bees
Asian carp
Rats

18. Threats to Biodiversity
Native Species effects
Invasive species can cause threaten species to become extinct
Burmese python

19. Threats to Biodiversity
Economic Impact
House mice
Exponentially increase every 4-5 years
Rainy seasons increase crop production
This in turn increases mice populations
Creates crop damage

20. Conservation Sustainable Development
Resources are used in a responsible manner
Ensures future generations have resources
Methods of harvesting and foresting
Sustainable fisheries
Rotation
Fishing gear
Harvest reduction
Fishing bans
Rotation – rotate catches between different species giving off species time to recover
Fishing gear – using gear that minimizes unintentional catches; reduces damage to sea floor and reefs
Harvest reduction – slow the harvest of deep water species that grow much slower allowing time for recovery
Fishing bans – banning fishing areas and species to allow for recovery of certain species

21. Conservation Species Protection Endangered Species Act
Protects species near extinction and its habitat
Often benefits other species – Umbrella Species
Protection of one species provides benefits to other species
Ex. Manatees
Northern spotted owls and old growth forest : ex. Molluscs and salamanders are within the protective boundaries of the northern spotted owl.
Bay checkerspot butterfly and grasslands
Tigers in India and elsewhere. Project Tiger was launched to save the tiger and thereby its habitat and other species within it.
Manatee protection includes a large area from Florida to Texas-protection of sea grass-only 3000 manatees exist

22. Conservation Importance of Resources
Protection has both practical and economic benefits
Medications come from ecosystems
Nutrients cycle through
Value of resources is approximately $30 trillion
Threatened by global warming, pollution, and loss of biodiversity

23. Conservation Protecting Resources Environmental Protection Act (EPA)
Established in 1970
Develop polices and laws to protect the environment
Created such laws as:
Clean Water Act
Clean Air Act
Endangered Species Act
Grants for National Parks

24. Conservation Sustainable Earth
Humans have the greatest impact on resources
Control the use
How fast populations grow
Develop technologies to produce more food
Ability to change practices regarding forestry, fishing, harvesting
No where on Earth is exempt from human interaction