Humans in the Biosphere

Changing LandscapeResources

BiodiversityThe Future

Humans in the Biosphere

• All the organisms, including humans, live on Earth and share limited resources and depend on them for their survival.

• We all depend on natural ecological processes that sustain these resources (succession, nutrient recycling, decomposition)

Humans in the Biosphere

• Human activities can change local and global environments

• Examples of these activities include: – Hunting and gathering– Agriculture– Industry– Urban development

Humans in the Biosphere• Hunting and Gathering– First humans arrived in North America 12,000

years ago– Their arrival resulted in mass extinctions of

animals such as the wooly mammoth, giant sloth, and saber-toothed tiger

Humans in the Biosphere

• Agriculture– 11,000 years ago humans began farming and

raising livestock. – This allowed for a dependable food supply– Humans transitioned from nomads to settlements

(permanent homes)

Humans in the Biosphere

• Farming– Gradually increased due to the use of machinery

(plows, seed drills)– Improved economic situations for many…Crops

were a form of “money”; Crops could be exchanged for goods from other parts of the country and eventually the world

– Science and technology increased productivity

Humans in the Biosphere

• Green Revolution: A movement to increase food production in countries with food shortages; this movement has doubled the food production in the last 50 years

• Challenges: Monoculture (1 crop fields) lead to problems with pests and disease which increases the use of pesticides on crops. Irrigation of these fields has also become a problem.

Humans in the Biosphere

• Biological Magnification: when concentrations of harmful substances (pesticide) increase in the organisms at higher trophic levels in a food chain or web. Top level carnivores are at highest risk.

• Example: DDT use in the 1950’s and 1960’s almost pushed bald eagles to extinction in the US. DDT (pesticide) made the bird’s eggshells more fragile. Eggs didn’t survive which caused a decrease in the birth rate of eagles and nearly wiped our the eagle population in a decade.

Biological Magnification

Humans in the Biosphere

• Industrial Growth– Industrial Revolution during the 1800’s increased

the number of • HOMES• CLOTHES/TEXTILES• ELECTRONIC DEVICES (light bulb)• INVENTION OF FARM EQUIPMENT• ENERGY PRODUCTION

Humans in the Biosphere• Urban Development– Cities became too

crowded and people began to move to the suburbs

– This created more waste, decreased available farmland, and destroyed natural habitats

Resources• Renewable Resources: can regenerate if they are

alive or can be replenished by biochemical cycles if they are nonliving– Water, trees

• Nonrenewable resources: cannot be replenished by natural process– Fossil fuels (coal, oil, natural gas)

• Sustainable Development: a way of using natural resources without depleting them

Resources- Land

• Land Resources: provides space for humans and raw materials for industry.

• If managed properly SOIL is RENEWABLE• Soil Erosion: The wearing away of soil by water

and wind. Humans plow land and remove roots that hold the soil in place.

• Desertification: when productive areas turn to deserts due to soil erosion– HOW? Overgrazing, drought, farming

Resources- Land

• Over millions of years resources have been stored below the surface of the land.

• Fossil Fuel resources are the result of decomposing organic matter. There resources include coal, oil and natural gas.

• Fossil Fuels and other resources are retrieved by a process of mining which also destroys the layout of an ecosystem by erosion and habitat destruction

Resources- Forests• Forest Resources: important to sustaining the

ecosystem and providing raw materials for industrial products – Ecosystem uses: store nutrients, habitats and food,

moderate climate (water cycle), limit soil erosion, protect freshwater supplies

• Approximately ½ of the world’s forests have been cleared

• OLD GROWTH forests are a NONRENEWABLE resource due to the amount of time it takes for the trees to grow (Boreal Forest, NW Coniferous Forest)

Resources- Forests

• Deforestation: loss of forests– Effects include severe erosion

• Forest Management: – Harvested selectively to promote growth of

younger trees and preserve the ecosystem– Planting, managing, harvesting and REPLANTING

of trees creates a renewable resource

Resources- Fish

• Fisheries- valuable food source• Overfishing: In nature we have harvested fish

faster than they can reproduce and replenish• Sustainable Development: US National Marine

Fisheries Service have established guidelines of how many fish and what size can be caught

• Aquaculture: Fish farms raise aquatic animals for human consumption. This has helped to maintain natural fish resources, however improper management may result in water pollution.

Resources- Air• Air Resources: The condition of the air affects a

person’s health• Smog: mixture of chemical that occur in a gray

brown haze. Caused by car exhaust and industrial emissions. Smog is a pollutant– Preventative actions: catalytic converters, scrubbers on

smoke stacks• Acid Rain: Nitrogen and Sulfur from released by

industries mixes with water in the atmosphere and create Nitric Acid and Sulfuric Acid. When this acidic water falls to the ground it kills plants and aquatic organisms.

Resources- Freshwater• Water Resources: make up approximately 3% of

the surface water covering the world• Water is a RENEWABLE resource but must be

protected from pollution– Governments have regulated the chemicals dumped

into streams and rivers• Wasted discarded on land• Sewage• Fertilizer run-off (nitrogen and phosphorus cause algal

blooms)

• Wetlands are now protected because they are a natural water purifier for the water cycle

Resource-Organisms• Biodiversity- all the living organisms– Earth’s greatest natural resources: they provide

food, industrial products, and medicine• Threats: habitat destruction, overhunting,

introduced species, toxins• If biodiversity is not managed properly

organisms go extinct.• Organisms that are threatened are put on the

endangered species list and protected in hopes of preventing extinction.

Threat to Biodiversity

• Invasive Species- non-native species that have been introduced to an area and begin to reproduce very rapidly (exponential growth) because the new habitat doesn’t have any predators or parasites (diseases) to control their population numbers.

• They will out compete the native species and push the native species to extinction

• Examples: pythons, monitor lizards, snakehead fish, zebra mussels, silver carp

Hole in the Ozone Layer

• Ozone Layer: layer of ozone gas (O3) is part of earth’s atmosphere that absorbs UV radiation before it reaches earth’s surface. It’s like global sunscreen

• Threat: In the 1970’s a “hole” was discovered in the ozone layer. The hole is over Antarctica. It is the result of a chemical reaction between the Ozone and chemical called chlorofluorocarbons (CFC’s) . The CFC’s destroy the ozone. CFC’s have since been banned

Global Warming• Global Warming: increase in the average temperature of the

biosphere. • How do we know?– Geological record shows natural cycles of highs and lows but the

current changes are attributed to human activity. We seem to be speeding things up.

• How does it happen?– Greenhouse gases are added to the atmosphere by human activity

by the burning of fossil fuels, trapping more heat than normal• Effects of Global Warming?– Global increase in temperature– Sea level will rise b/c polar ice cap is melting– droughts