B1NatalieG.3

Economic, ecological ethical and esthetic reasons.

new commodities - possibly new medicines or materials
new crop plants or farm animals-improve existing spieces or develope new species using genes from the wild
ecotourism - provide considerable income

native species are well adapted to local conditions - new species that may replace them, are less likely to be adapted

species in natural communites are interdependent- one goes, the rest is threatened

damage to ecosystems effects; soil erosion, silting up rivers, flooding and change in weather patterns

every species has a right to live - harmful to humans or not

the wildlife of an area is culturally important to humans in the area and wrong to destroy

wrong to deprive future generations of experiences of Earth's biodiversity

natural ecosystems and species are beautiful and give great enjoyment

painters, writers and composers have been inspired by the nature around them

conuropsis carolinenis - parrots that were once common in the forests east of the Mississippi, New York to Florida. clearance of forests reduced habitat and started to feed on crop. Farmers killed many. some killed for feathers - womens clothing. also pets. by 1900 no more.

Calochortus indecorus - grew on Sexton mountain in Oregon. building of interstate highway destroys the habitat and so did the plant species. almost certainly extinct, no other known habitat.

measures a species richnes. high D values is a stable and ancient site, low d suggests pollution, recent colonization or agricultural management. used normally for studies in vegetation.

1. use a random sampling technique to search for organisms in the ecosystem
2. identify each of the organisms found
3. count the total number of individuals of each species
4. calculated the index (D).

if the numbers of adult fish fall below a critical level, spawning fails. over fishing a major factor. if a certain fish, ex. the anchoveta is a key species in its ecosystem, predator populations also greatly reduce.

these species need a particular environment to live in and show what the conditions in an ecosystem are.

they are also often used to assess pollustion levels in aquatic ecosystems. Stonefly mayfly and caddis fly larvae require unpolluted well-oxygenated water. othre speices. ex. chironomid midge larvae, rat tailed maggot larvae and tubifex worms indicate low oxygen levels and excessive levels of suspended organic matter

lichens tolerance to sulphur dioxide varies considerably from the most tolerant to the least tolerant.

using a biotic index

it usually involves multiplying the number of individuals of each indicator species by its pollution tolerance rating. and abundance of tolerant species give a low score and if a lot of intolerance species is found, it gives it a high score.