Unit 2-Ecology

Chapter 6

Humans in the Biosphere

Humans influence on the Biosphere

Human activities that affect the biosphere

• Hunting& Gathering• Agriculture• Industry• Urban development• Austin Smart Growth Initiative

Types of resources

Nonrenewable resources: • unable to be replenished

through natural means– Ex: fossil fuels, natural

gas

Renewable resources: • able to be replenished but

is not unlimited– Ex: freshwater

Sustainable development

• A way to use natural resources without causing long term environmental problems

• This plan takes into consideration environmental, economic, and community demands

Problems land resources faceDesertification• the process of overusing land

and drought leading to the formation of arid, desert lands that cannot sustain agriculture

Soil erosion • loss of topsoil layer from over farming

(plowing) lands

Deforestation• The process of cutting down (logging) forests for lumber and land.• Leads to severe erosion during heavy rains.• Which can lead to permanent changes to local soils and

microclimates.

Overfishing• Harvesting fish faster than they can be

replaced by reproduction.

• What happens to aquatic food webs if overfishing continues to occur?

Aquaculture• raising water animals

for human use

• Pictured to the right are tilapia fish farms in Australia that then export the fish to markets.

Air pollution• Combustion of carbon

fuels released nitrogen and sulfur that combine with water to form acid rain.

• Pollutant: • any harmful substance

that enters the biosphere from land, air, or water

Acid rain

Why should we preserve biodiversity?

Biodiversity: • sum total of

genetically based variety of all organisms in the biosphere–Ecosystem diversity–Species

diversity

Why should we preserve biodiversity?

• Biodiversity is one of Earth’s greatest natural resources.

• Species of many kinds have provided us with foods, industrial products, and medicines – including painkillers, antibiotics, heart drugs, antidepressants and anticancer drugs.

Threats to species biodiversity

• Human activity can reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species to new environments.

Threats to species biodiversity

• Endangered: species that is declining in population size

• Extinction: species that disappears from all or part of its range

Endangered status:

Ailuropoda melanoleuca 

Habitat fragmentation• When land is developed through or around

ecosystems, the species residing within are impacted in what way?

Central Park in New York City is a perfect example of habitat fragmentation.

Biomagnification:• Increasing the concentration of harmful

materials up the food chain

Introduced species• Humans transport animal and plant species from

one part of the world to another.• Many of these species can become invasive.

They reproduce rapidly and lack parasites and predators that helped control their populations “back home.”

Nutrias are native to South America but have become pests in coastal US cities.

Conserving Biodiversity

• To conserve biodiversity and multi faceted approach is best:

• Protection of species

• Protection of habitat

• Protection of biodiversity

Conserving Biodiversity Challenges

• Balancing :

• Public need and economics

• Public policy

• Conservation

Charting a Course for the Future• Researchers are gathering data to monitor and

evaluate the effects of human activities on important systems in the biosphere.

• Issues:• Ozone depletion• CO2 emissions• Global warming• Alternative fuels• Alternative food sources

Ozone depletion

• Ozone: layer of concentrated gas that protects the Earth from harmful UV rays

• 1970s, scientists found a gap in the ozone layer near Antarctica.

NASA image

Global warming

• Compounding the ozone depletion was the buildup of CFCs (chlorofluorocarbons) from aerosols and AC units with Freon.

• CFCs trap heat, leading to a rise in the global temperature.

Ozone

Click on image to play video.

Value of a Healthy Biosphere

• More complex and diverse ecosystems are the more stable they are.

• Complexity + Diversity = Stability

• All ecosystems play a role in the health of the biosphere.