Succession: How does biodiversity occur? Exam #4 W 4/23 in class (bring cheat sheet) Review T 4/22 at 5pm in WEL 1.316

CB 55.2 Genetic Diversity Biodiversity- number of species within an area Ecosystem Diversity

CB Ecosystems on Earth

Primary Succession- the first organisms to colonize bare rock Secondary Succession- recovery from a disturbance

Primary Succession- from non-living to living

CB Primary succession as this glacier retreats

Primary Succession after glacier retreat, years

CB Primary Succession: each stage helps enable the next

Primary succession after a volcanic eruption

CB 53.2 Competition limits where species can live

CB 53.2 niche- the specific environment where a species lives

CB 53.3 Tree species existing in different niches

CB Secondary Succession: after a fire

CB Grassland biodiversity and biomass are increased by regular burns

Secondary Succession of a field (20 yrs)

CB Human vs Natural Disturbances

Chernobyl fire April 26, 1986

The Chernobyl accident was by far the largest unintentional release of radioactive material into the environment and caused widespread contamination in Europe.

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.

The most heavily exposed emergency workers received doses that were sufficiently high to kill them in the weeks and months after the accident.

Chernobyl April 26, 1986 Cancer consequences of the Chernobyl accident: 20 years on J. Radiological Protection 26 (2006) 127–140 Elisabeth Cardis et al.

Mitosis

Cancer: Cell Division Gone Wrong

The rapidity of increased childhood thyroid cancer in the heavily contaminated areas of Belarus, Ukraine and Russia was surprising. 4 years

The issue of the effects on health of the Chernobyl accident has become part of the political debate over the future role of nuclear energy, which has inevitably led to dispute over the level of effects either observed or anticipated.

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:

What about non-human inhabitants? turtle in exclusion zone

The 30-km radius exclusion zone

Initially many animals 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 /21/ Many human tragedies have been a boon for native animal species:

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

A herd of Przewalski's horses roams Ukraine's Chernobyl exclusion zone.

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 /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.

Mutation isn't the only adverse effect of the radiation. Working in the Red Forest area, James Morris, a USC biologist, has observed some trees with very strange twisted shapes. The radiation, he says, is confusing the hormone signal that the trees use to determine which direction to grow. "These trees are having a terrible time knowing which way is up," Morris said.

Unusual growth in “Red Forest” pine trees

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 4/23 in class (bring cheat sheet) Review T 4/22 at 5pm in WEL 1.316