Distribution of Organism
This is affected by:
- changes in competitor and predator
- outbreak of disease
- change in habitat
Trees take in carbon dioxide and give out oxygen. This keeps the right level in the atmosphere. Forests also store water because the leaves slow down evaporation. Deforestation, for timber, paper, farming and building land, disrupts the level of gas and water.
Earth radiates energy towards space but it is absorbed by greenhouse gases instead.The atmosphere absorbs too much heat, so it is warmer. This increases the greenhouse effect, sea levels rise, and there are changes in wind patterns and rainfall.
Chemicals causing Eutrophication
Fertiliser is used to grow crops and is leached (drained) out of the soil and into rivers after heavy rain. This causes algae and weeds to die and rot, so that bacterial decomposers thrive in the river bed. The bacteria use oxygen so that other water animals die of oxygen starvation.
Chemicals e.g. DTT are used to kill insects and stop a decrease in crops. These are dangerous and don't break down in animals so they pass along the food chain. Therefore they stay in the atmosphere.
Humans taking over land
Housing - Habitats are destroyed to make housing space
Quarrying - Stones are extracted from land to build roads and houses
Energy - Dams are build which flood land for hydroelectricity