CHAPTER 20 Human Impacts on the Environment Outline: I. Introduced species II. Human impacts III....
-
Upload
theresa-boyd -
Category
Documents
-
view
216 -
download
0
Transcript of 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