exam #4 w 4/29 from 7:30-9pm in bur 106. how many animals do we want to save? the many ways of...
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Exam #4 W 4/29 from 7:30-9pm in BUR 106
How Many Animals Do We Want to Save? The Many Ways of Setting Population Target Levels for ConservationERIC W. SANDERSONNovember 2006 / Vol. 56 No. 11 BioScience 911
ExtinctionVortex
A population of a few individuals cannot survive
Similar toFig 55.12
Attwater Prairie Chicken
As population declined, genetic diversity declined
Attwater Prairie Chicken
Individuals brought from other populations increased reproduction and population
Similar toFig 55.12
Can a number of individuals be set?
•Scientists are reluctant to set a specific number
•Policymakers want information from scientists
What criteria do we use to set limits?•Money•Land•Development
Who benefits?•Animals- what is the minimum number for sustainable survival•Ecosystem- What is the minimum number to maintain a healthy ecosystem?•Humans- How many do we need to derive some beneifit?
Who benefits?•Ecosystem and Humans- How many do we need to derive some beneifit?
Ecosystem benefits- seed dispersal, pollinators, nutrient recycling
These functions cannot practically or economically be carried out by humans
How many animals do we want to save?
Complex interactions of science, economics, and ethics. (Cultural, Aesthetic, Spiritual)
How many animals do we want to save?
Most of human history includes critical and profound interactions with other organisms. That is now diminished or gone.
How many animals do we want to save?
Most of human history includes critical and profound interactions with other organisms. That is now diminished or gone.
How many animals do we want to save?
Complex interactions of science, economics, and ethics.
If a number is set, it may stay static as conditions change.
How many animals do we want to save?Sanderson’s proposed solution:
How many animals do we want to save?Sanderson’s proposed solution- multilayered
approach:1. Demographic sustainability
How many animals do we want to save?Sanderson’s proposed solution- multilayered
approach:
1. Demographic Sustainability
2. Ecological Functions (includes ability to
freely evolve)
How many animals do we want to save?Sanderson’s proposed solution- multilayered
approach:
1. Demographic Sustainability
2. Ecological Functions
3. Human Use and Interactions
How many animals do we want to save?Sanderson’s proposed solution- multilayered
approach:
1. Demographic Sustainability
2. Ecological Functions
3. Human Use and Interactions
4. Can we return animals to levels that existed
before humans had a negative impact?
Instead of a single number…A number for each level can be determined.
How many animals do we want to save?
1. Demographic Sustainability
2. Ecological Functions
3. Human Use and Interactions
4. Can we return animals to levels that existed
before humans had a negative impact?
Not all habitats are equal
How do stable ecosystems develop?
Primary Succession- the first organisms to colonize bare rock
Secondary Succession- recovery from a disturbance
Primary Succession- from non-living to living
Primary succession as this glacier retreats
Fig 53.22
Primary Successionafter glacier retreat,150-300 years
Fig 53.22
Primary Succession: each stage helps enable the next
Secondary Succession: after a fire
Grassland biodiversity and biomass are increased by regular burns
Secondary Succession of a field(20 yrs)
Fig 53.21
Human vs Natural Disturbances
Chernobyl fireApril 26, 1986
http://video.google.com/videoplay?docid=1108163171078608385
The Chernobyl accident was by far the largest unintentional release of radioactive material into the environment and caused widespread contamination in Europe.
The most heavily exposed emergency workers received doses that were sufficiently high to kill them in the weeks and months after the accident.
After the accident on April 26, 1986, ~116,000 people were evacuated, most from a zone of 30-km radius. That included about 45,000 people from the town of Pripyat.
For more pictures: http://www.nikongear.com/Chernobyl/Chernobyl_1.htm
Initially many organisms died from the huge doses of radiation they received.
The red color of withered pine needles earned one large area near the reactor the name Red Forest.
"Now it is not the Red Forest but a real green forest, due to [growing] birch trees," said Sergey Gaschak from the International Radioecology Laboratory in Kiev, Ukraine.
Science v. 269 pg. 304 7/21/1995
http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=15362
Many human tragedies have been a boon for native animal species:
http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=15362
Korean DMZ: Among the species making their homes in the DMZ are endangered Asian cranes, black-faced spoonbills, angora goats, Amur leopards, and even bears.
Savanah River nuclear site in Georgia:forest remnant
And in the towns where humans have moved out, plants and animals have moved in.
Background radiation levels near the Chernobyl reactor are 3000 times higher than near the Savannah River nuclear reactor
Science v. 269 pg. 304 7/21/1995
Late last year Moller and Mousseau published a paper in the Journal of Animal Ecology showing that reproductive rates and annual survival rates are much lower in the Chernobyl birds than in control populations.
"In Italy around 40 percent of the barn swallows return each year, whereas the annual survival rate is 15 percent or less for Chernobyl.
The most recent count by the authorities showed that the zone (including a larger contaminated area in neighbouring Belarus) is home to 66 different species of mammals, including 7,000 wild boar, 600 wolves, 3,000 deer, 1,500 beavers, 1,200 foxes, 15 lynx and several thousand elk.
The area is also estimated to be home to 280 species of birds, many of them rare and endangered. Breeding birds include the rare green crane, black stork, white-tailed sea eagle and fish hawk.
But Mousseau is less optimistic. "One of the great ironies of this particular tragedy is that many animals are doing considerably better than when the humans were there," he said.
"But it would be a mistake to conclude they are doing better than in a control area. We just don't know what is normal [for Chernobyl]. There just haven't been enough scientific studies done."
Exam #4 W 4/29 from 7:30-9pm in BUR 106