lecture on biosphere

7/31/2019 Lecture on Biosphere

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ECOLOGY II: HUMAN EFFECTS ON THE BIOSPHERE


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Population age structure in industrialized countries

vs. developing countries

The average fertility rate required to achieve long term zero

population growth ( replacement fertility rate) is 2.1


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The expansion of human population and affluence,

especially in the developing world harms naturalecosystems


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What is the biosphere?

The biosphere includes all regions of Earth where organisms live

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What factors are studied when considering the biosphere?

Climate refers to the average weather conditions such as cloud cover,temperature, humidity and wind speed over time


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Biomes are areas of land characterized by their

climate and type of vegetation

Factors that cause differences in regional climates include wind and

ocean currents, intensity of sunlight, distribution of land masses

and seas, and elevation


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Global climate change, a topic that includes global

warming, refers to the relatively abrupt shift in

weather patterns during the last hundred years


8/19

Carbon dioxide and other global warming pollutants are

collecting in the atmosphere like a thickening blanket,

trapping the sun's heat and causing the planet to warm up


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Human activities are responsible for rising

concentration of greenhouse gas


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The rise in average temperature effects on the earth's

climate patterns and on all living things.

1) Weather patterns change as consequence of global warming

higher temperatures could lead to increased droughts and

wildfires, heavier rainfall and a greater number of category 4 and 5

hurricanes.%

2) Health problems associated with global warming include allergy

and asthma causes by smog pollution7%

3) Increasing global temperatures are expected to disrupt

ecosystems, pushing to extinction those species that cannot adapt.

Approximately 20 to 30 percent of plant and animal species

assessed so far are likely to be at increased risk of extinction if

global average temperature increases by more than 2.7 to 4.5

degrees Fahrenheit7%%


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The International Union of Conservation of Nature

reported that of 47,677 species analyzed, 36% were

threatened or endangered

Extirpation refers to the loss of a single population while extinction

means that all populations of a species have disappeared irreversibly


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Population growth of humans has also cause the unintended

decline of biodiversity, the HIPPO acronym

H Habitat loss, including that caused by human-induced

climate change.

I Invasive species (harmful aliens, including predators,

diseases, and competitors that displace native species

P Pollution

P Population, Human overpopulation to be exact, a root

cause of the other four factors

O Overharvesting, Overuse (hunting,

fishing, gathering)


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Habitat loss is the single greatest threat to biodiversity

throughout the biosphere

Desertification occurs when plowing or grazing removes plants and

exposes topsoil to wind erosion


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Invasive species ranks second behind habitat loss as a

threat to biodiversity

Brown tree snakes came on cargo planes to Guam and fed on

exotic birds, three bird species are now extinct in the island


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Overexploitation of wildlife by harvesting is another

major threat to biodiversity

Scientists estimate that we have removed as much as 90 percent of the

large predatory fish such as shark, swordfish and cod from the world's

oceans.


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Pollution (Oil spills, human agricultural waste, fertilization,

pesticides, acid deposition, greenhouse gases etc.) caused

by human activities has a negative effect on biodiversity


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When pollutants enter the food chain, top predators

most severely damaged

Biological magnification- the concentration of a chemical

increases as the the pollutant moves up the food chain


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Conservation biology is a goal oriented science that seems

to understand and counter the loss of biodiversity

Biodiversity hotspots refers to relatively small areas that have a large

number of endangered and threatened species and endemic species,

those found nowhere else


19/19

Science In the NewsScience NOW Magazine

Sea Turtles Suffer Collateral Damage From Fishing

More than 8 million sea turtles have died in the past 2 decades after

being accidentally caught by fishing vessels, a global analysis suggests.The researchers identify the Mediterranean Sea and the eastern Pacific

Ocean as particularly dangerous for sea turtles. Turtle deaths probably

are widely underreported, along coastlines with small-scale fishing.

lecture on biosphere

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