BIOL 4015 EXAM 2: Habitat Destruction

habitat loss

- number one reason of biodiversity loss

- caused by human expansion and activities

principal threats to habitat

1. agriculture

2. commercial developments

3. water projects

4. outdoor recreation

5. livestock grazing

6. pollution

7. infrastructure and roads

8. disruption of fire ecology

threatened habitats: tropical rain forest

- 40% of tropical forests in brazil

destruction of tropical rain forest caused by

- demand for rubber, palm oil, cocoa, soybean, orange juice, beef, and woof products

desertification

- dry land areas degraded and turn into deserts

- include grassland, scrub, deciduous forest, temperate shrub lands

- repeated cultivation during dry/ windy years often leads to soil erosion and loss of water-holding capacity

- overgrazing, fuelwood collection

wetlands and aquatic habitats destroyed by

- land conversion

- water withdrawal: domestic, industrial and ag used

inland aquatic habitat

1. land conversion (clearing and drainage) for agriculture

2. withdrawal of fresh water

- 70% water used for irrigation

2. excessive nutrient loading

- nitrogen and phosphorous in fertilizers

3. siltation

4. dredging and channelization

5. changes in water temperature

excessive nutrient loading

nitrogen and phosphorus in fertilizers

- plankton blooms

siltation

blockage by sand or soil deposited into water

dredging and channelization

dredging: removal of sediments at bottom of water; loss of wetland habitat

marine coastal areas

- land conversion

- diversion of freshwater flows

- nitrogen loading

- dredging and channelization

mangroves

important wetland in tropical areas: breeding and feeding ground for shrimp and fish

mangroves protect against ____________; cleared for ______________

storms and tsunamis, cleared for rice and hatcheries

coral reefs

- degraded by overfishing, pollution, invasive species