chapter 20 human impacts on the environment outline: i. introduced species ii. human impacts iii....

CHAPTER 20 Human Impacts on the

Environment

Outline:

I. Introduced species

II. Human impacts

III. The biodiversity crisis

IV. Conservation biology

V. The goal of sustainable development

About 12% of all known bird species

are endangered

One-third of all vertebrate species

live on just 15% of Earth’s land

Purposefully introduced invasive species have cost the US economy $130 billion

Human impact

I. Introduced Species

• Are species that humans intentionally or accidentally move from the species’ native (home) locations to new geographic regions.

• Examples:– The European starling– Argentine ants– The zebra mussel

Can you name some species native to the US?What is the number of introduced species in the US?

European starlings

Argentine ants ganging up on a NATIVE red ant

Zebra mussels

II. Human Impact on Ecosystems

– Human population has markedly changed natural habitat systems.

• A. Impacts on Chemical cycles

– Carbon- increased burning of fossil fuels – Nitrogen & Phosphorus - fertilizers & sewage

treatment facilities

– Water – irrigating crops & deforestation

Carbon dioxide producers

Eutrophication causing algal bloom

Deforestation

Human impacts of releasing toxins

– The release of new toxic materials cannot be degraded by microorganisms

– Toxins can accumulate in tissues of animals

– Biological magnification• A process in which toxins become more

concentrated in successive trophic levels of a food web

Human Impact on the Atmosphere and Climate

– Carbon Dioxide Emissions• Since industrial revolution CO2 has increased in

atmosphere

– The Greenhouse Effect• Retains solar heat in the atmosphere

– Increased global temperatures have potentially disastrous consequences

Remember the film?

Increase atmospheric CO2, temp variation

Factors influencing greenhouse effect

How do changes in number of producers and consumers influence production and uptake of global CO2?

How do different types of industry influence global CO2?

– Depletion of Atmospheric Ozone

• The ozone layer absorbs UV radiation

• Thinning since 1975 due to CFC’s

• Consequences-

– Increased skin cancer, cataracts

– Amphibian population declines

Thickness of ozone layer decreasing

1979

2000

III. The Biodiversity Crisis

– Human activity is causing a decline in the Earth’s great variety of life

– A. Biodiversity has three main components1. the diversity of ecosystems

2. the variety of species that makeup communities

3. the genetic variation within each species

Tropical rain forest

– B. The Loss of Species – The current mass extinction - worldwide

• Caused by human activity• Broader & faster than past extinctions• 12% of known bird species • 24% of known mammal species are threatened

with extinction• Biologist Edward O. Wilson has compiled the

Hundred Heartbeat Club– Species with fewer than 100 individuals

Chinese river dolphin

Javan rhinoceros

Philippine eagle

C. Three Main Causes of the Biodiversity Crisis

–1. Habitat Destruction

• Is the single greatest threat to biodiversity

–2. Introduced Species• Ranks second behind habitat loss. Can cause

rapid extinctions

– 3. Overexploitation of wildlife

Habitat destruction

Introduced species

Lake Victoria, East Africa

Overexploitation

Do you like bluefin tuna? Do you eat sushi?

D. Why Biodiversity Matters

– Humans rely on biodiversity for• Food, clothing, shelter, oxygen, soil fertility,

medicinal substances

– Endemic species• Are those found nowhere else

– The loss of diversity• Limits the potential for new discoveries of food

and medicine

IV. Conservation Biology

A science that seeks to counter the loss of biodiversity

– Biodiversity hot spots

• Small areas with an exceptional concentration of species, including endemics

Do you understand why its important to preserve biodiversity in CA?

Terrestrial biodiversity hot spots

Notice California

Conservation at the Population & Species Levels

– The U.S. Endangered Species Act (ESA)

• Definition: endangered species

– “…a species in danger of extinction throughout all or a significant portion of its range”

• Definition: threatened species

– “…a species likely to become endangered in the foreseeable future”

Habitat & Population Fragmentation

– Fragmentation can results in

• A decrease in the overall size of populations

• A reduction in gene flow among subpopulations

• Harmful side effect of human habitation

Mt. Hood National Forest

Northern spotted owl

?

What Makes a Good Habitat?

– Identifying the specific combination of habitat factors that is critical for a species is fundamental to conservation biology

• Example: Polar Bears

Conserving Species amid Conflicting Demands

– Competing demands for habitat

– Edges and corridors between ecosystems• Promote dispersal & help sustain populationsEspecially important to species that migrate

between different habitats seasonally

• The owl• Wolf• Grizzly bear• Bull trout

• Jobs in • Timber• Mining

• Loss of livestock• Camping safety

VS

Natural edges between ecosystems

Edges created by human activities

Heavily logged rain forest in Malaysia

An artificial corridor

V. The Goal of Sustainable Development

– Sustainable development• Balances human needs with the health of the

biosphere

– The goal of sustainable development• Is the long-term prosperity of human societies

and the ecosystems that support them

Some Ways You Can Promote Sustainability

Reduce consumption

• Buy less• Avoid excess packaging• Avoid products make from non-renewable resources• Fix things rather than discarding them

Be more energy efficient• Bike, walk, take public transportation, drive less• Share rides• Purchase efficient appliances and vehicles

Promote recycling

• Recycle at home and at work• Purchase products made from recycled materials

Promote research and education

• Talk about environmental issues with friends, family• Sponsor environmental initiatives on your campus • Serve as a role model through your actions

…more on Table 20.1

Biophilia and an Environmental Ethic

– Edward O. Wilson

• Biophilia

the human desire to affiliate with other life in its many forms, is innate

…Respect Earth’s biodiversity

Near Walden pond

…the look of ‘biophilia’ on his face

2. Carbon dioxide traps heat and warms the atmosphere, a process called the _________ effect.

3. It is hard to protect species such as the monarch butterfly, sea turtles, and many songbirds, because they _________.

1. Severe population _________ is one of the most severe consequences of habitat degradation.

5. Fertilizer runoff can result in the _________ of lakes.

6. The goal of _________ development is to ensure that each generation inherits adequate resources and a stable environment.

7. Most biodiversity hot spots are in the _________.

14. The Earth is facing a serious _________ crisis.

20. In the US, 25% of prescriptions contain substances derived from _________.

22. Burning of _________ fuels produces carbon dioxide that may contribute to global warming.

8. Biological _________ of pesticides harms animals at the top of the food chain.

18. The _________ is a law that protects endangered and threatened species.

10. Human alteration of _________ is the greatest threat to biodiversity.

Reading Assignment for:

Next week, 12/4/07 & 12/6/07

Chapter 17The Evolution of Animals