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Unit 16 – Human Impact on the Biosphere

Biology

Renewable Resources

•  Renewable resources replenish themselves or they are continuously available from natural sources.

•  These resources are essentially infinite – they will not be exhausted during the span of human existence.

•  Air, water, soil, trees, animals are examples of renewable resources

Renewable vs. Recyclable

Be careful NOT to confuse these terms: •  Renewable = “regrown” or replace

naturally, quickly (trees, water, air, soil) •  Recyclable = “reusable” via human

processes (glass, paper, aluminum, plastics)

“Renewable” depends on context

Ex: An individual tree can be re-grown, but a Population of trees in an ecosystem may NOT be replaceable if you remove them all!

RENEWABLE RESOURCES

“Renewable” depends on context

Many forests in USA have been logged at least once and have grown back naturally. Old Growth forests have never been cut. It takes centuries to replace these and species may be lost.

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•  Renewable does NOT mean unlimited

– Ex: freshwater is a renewable resource but can become limited by drought or overuse

“Renewable” depends on context Nonrenewable Resources •  Nonrenewable resources are

being used faster than then can be replaced by natural processes.

•  These resources have a finite amount and will eventually be exhausted by human activities. – Ex: Fossil Fuels – Coal, Oil and

Natural Gas – Ex: Metals mined from the earth.

•  Human activities can affect the quality and supply of renewable resources such as:

How can we provide for our needs

while maintaining ecosystem goods and services that are renewable?

1. Land/Soil 2. Forests 3. Fisheries

THE BIG QUESTION ?

4. Air 5. Fresh water

-It is a way of using natural resources without depleting them and providing for human needs without causing long term

environmental harm

SUSTAINABLE DEVELOPMENT The ANSWER:

A resource is anything an organism needs for survival

NATURAL RESOURCES =

LAND AIR FORESTS WATER

Provide space for human communities Provide raw materials for industry

LAND RESOURCES

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LAND RESOURCES Land resources include soil which is a renewable resource

if managed properly. Topsoil is made of sand, clay, and humus

(decayed organisms) and is produced and maintained by interactions

between soil and plants growing in it.

Soil Formation – Primary Succession

Step 1 - Weathering of Parent Material (ancient rock or cooled lava) Step 2 - Pioneer species (Lichens) begin to grow on the surface of exposed rocks – acid released during decomposition aids weathering

Soil Formation (cont’d)

Step 3 – small plants (grasses, ferns) begin to grow and further aid the weather process (mechanical and chemical) Step 4 – Organic matter (humus) begins to build up and the soil can hold more nutrients, this allows more complex plants and animals to survive

Primary Succession Diagram Secondary Succession •  Occurs after the plant life in an areas has

been damaged, disturbed, or destroyed – Ex- abandoned farmland, forest fires, areas

overharvested of their trees, hurricanes

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Secondary Succession LAND RESOURCES

Wearing away of topsoil = soil erosion Is caused by plowing land and removing plant roots

LAND RESOURCES Desertification = changing of fertile land in

dry climates into desert areas caused by farming, overgrazing, and drought 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

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.

Crop Rotation Different crops use and replenish different nutrients. By rotating crops, the loss of important plant nutrients is decreased.

A B C

Yr. 1

Yr. 2

Yr. 3

Section 6-4

corn

corn

corn

alfalfa

alfalfa

alfalfa

oats

oats

alfalfa (plowed in)

Sustainable Agriculture

Provide wood for products ranging from homes to paper Wood provides fuel in many

countries

FOREST RESOURCES

Forests have been called the “lungs of the Earth” because they remove Carbon dioxide and produce oxygen

FOREST RESOURCES

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Forests also: 1.  Store nutrients 2.  Provide habitats 3.  Moderate climate 4.  Prevent soil erosion 5.  Protect fresh water

FOREST RESOURCES FOREST RESOURCES Loss of forests: deforestation -can result in erosion and loss of nutrients

preventing regrowth

Sustainable Development: •  Selective harvest of mature trees •  Replanting of logged areas •  Tree farms •  Breeding new, faster growing species

Pollutant: harmful material that can enter the biosphere through land, air, or water Smog=

Mixture of chemicals that appear as gray-brown haze in the atmosphere

AIR RESOURCES

Burning fossil fuels releases nitrates, sulfates and particulate matter that cause smog and other problems in the atmosphere.

AIR RESOURCES

Toxic chemicals like nitrates, sulfates, and particulates can cause breathing problems like asthma

•  Smokestack “Scrubbers” can control emissions

•  Auto emission standards •  Clean air regulations •  Reduce use of fossil fuels

SUSTAINABLE DEVELOPMENT

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Americans use BILLIONS of gallons of freshwater daily for drinking, washing and watering crops

FRESH WATER RESOURCES Although water is a renewable resource,

the total supply of fresh water is limited.

FRESH WATER RESOURCES

Wetlands remove pollutants and Purify water passing through.

FRESH WATER RESOURCES Nutrient Limits •  Limiting nutrient -

lack of a nutrient or if a cycle slows down in an ecosystem. –  Less nutrient, limits

growth of producers.

•  An influx of excess nutrients causes rapid growth of producers in aquatic ecosystems

Algal Bloom •  Algal blooms occur after a limiting nutrient

is added to an aquatic ecosystem; Nutrient is either nitrogen or phosphorous (commonly found in fertilizers)

•  Causes a chain reaction of events – Too much growth of algae – Algae die and are decomposed – Decomposers grow rapidly using all available

oxygen – Fish and other organisms suffocate

Algal Blooms

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•  Water conservation •  Protect wetlands and forests

•  Water treatment plants •  Clean water regulations

SUSTAINABLE DEVELOPMENT DON’T FORGET THE WATER WE CAN’T SEE!

The PRODUCTION OF: •  1 kg wheat costs 1,300 L water •  kg rice costs 3,400 L water •  1 kg eggs costs 3,300 L water •  1 kg beef costs 15,000 L water •  1 cotton shirt costs 2,500 L water •  1000 g of blue jeans costs 10,850 liters water •  1 ton passenger car costs 400,000 liters of water •  Building a house uses about 6 million liters of water

WAYS TO CONSERVE WATER

http://www.watersavingtips.org/images/saving_1.jpg

Fisheries

•  Fisheries: area with an associated fish or aquatic population which is harvested for commercial value (i.e. selling them for food) – Ex: The Pacific's greatest asset is its fish. The

shoreline waters of the continents and the more temperate islands yield herring, salmon, sardines, snapper, swordfish, and tuna as well as shellfish.

Concerns

•  “The Tragedy of the Commons” •  Issues with wild fisheries:

– Overfishing – Pollution from human activities

•  Significant wild fisheries have collapsed or are in danger of collapsing

•  Overall, production from fisheries is leveling out or declining

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Sustainable Development

•  Fish need to be harvested at a sustainable rate, where the fish population does not decline over time because of fishing practices

•  Avoiding overfishing through techniques such as fishing quotas

The Importance of Diversity

Ecosystem Diversity •  Variety of

habitats and communities in the biosphere

Species Diversity

•  Number of different species in the biosphere

•  Characterized by Species Richness and Relative Abundance

Genetic Diversity

•  Sum total of all the different genetic information carried by living organisms

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Biodiversity

•  The sum total of genetically based variety of living things in the biosphere

•  “Variety of Living Things”

Biodiversity Benefits •  Biodiversity is needed to maintain the

overall “healthy” conditions of the biosphere

•  Source of Food for Humans •  Source of Industrial Products – Lumber •  Source of Medicine

Threats to Biodiversity •  Human Activities •  Habitat

Fragmentation •  Demands for Wildlife

Products •  Pollution (Biological

Magnification of Non-biodegradable toxins)

•  Introduced Species

Human Activities

•  Altering Habitats •  Overhunting •  Dumping Toxic

Compounds •  Introduced

Species The chemical BPA in waterways is causing male animals to be born with damaged reproductive organs – BPA makes them more female

Habit Fragmentation

•  Building Roads and developments breaks up natural habitats.

Demands for Wildlife Products

•  Overhunting, Overfishing for food or animal parts (ivory)

•  Overuse of farm or grazing land

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Biological Magnification •  Concentrations of

harmful substances increase at higher trophic levels on the food chain.

•  These are non-biodegradable substances (DDT, mercury, BPA)

Introduced Species

•  The movement of apparently harmless plants or animals into new ecosystems

•  Invasive species often reproduce rapidly and alter the natural food web because they do not have natural predators in this new ecosystem

Conservation Biology Goals: 1.  Identify “hot spots” of

biodiversity 2.  Protect ecosystems and

individual species 3.  Study habitats and species

interaction so that they can be protected

4.  Balancing the needs of society and the protection of habitats; very difficult

Hot Spots

Ozone Depletion and Global Warming

Global Issues

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Ozone •  Ozone = O3 •  Ozone Layer - Absorbs UV

radiation •  What disease can UV

radiation cause? •  Holes in layer found over

the poles •  Holes in Ozone Layer

caused by CFCs

CFCs •  CFCs =

Chlorofluorocarbons •  Were used in

refrigerators as a coolant and in aerosol cans as a propellant

•  CFCs banned in US today

•  Ozone Layer should recover within the next 50 years

Global Climate Change

•  Earth’s climate has changed periodically

•  Last ice age ended about 10,000 years ago

•  Currently we are experiencing a warming trend; may be related to human activity (increased CO2 emissions)

Global Warming •  Global Warming- increase in

average global temperatures

•  Very difficult to predict effects of global warming –  May result in melting of polar

ice caps and higher sea levels.

–  Increased ocean temps may cause hurricanes to become stronger