Chapter 20 - Human influences on ecosystems Flashcards
Why has agricultural machinery replace humans?
Agricultural machinery has replaced humans and improved efficiency due to the ability to farm much larger areas of land.
Why are chemical fertilisers used in agriculture?
Chemical fertilisers to improve yields as fertilisers increase the amount of nutrients in the soil for plants, meaning that they can grow larger and produce more fruit.
Why are insecticides and herbicides used in agriculture?
Insecticides and herbicides as these chemical kill off unwanted insects and weed species meaning that there is less damage done to plants and fruits lost to insects as well as reducing competition from other species.
Why is selective breeding used in agriculture?
Selective breeding is when animals and crop plants which produce a large yield are selectively bred to produce breeds that reliably produce high yields.
Why are monocultures used in agriculture?
Monocultures are when only one type of crop is grown on a given area of land. This increases crop yield, can be managed more efficiently with agricultural machinery and it is more profitable, and crops has little competition. However, it lowers biodiversity, increases pest populations and the overuse of insecticides could lead to harmless insects being killed, pollution or resistance.
Why is intensive livestock farming used in agriculture?
Intensive livestock farming require less land to produce large amounts of food, food can be produced all year round in controlled environments, the cost of production is lower and there is a lower requirement for labour. However, the use of herbicides could result in eutrophication, pesticides could cause negative effects on the food chain, ethical issues arise due to the cruel treatment of animals, natural habitats may be destroyed, reduction in biodiversity, overgrazing can lead to soil erosion and large numbers of cattle produce large amounts of methane which is a greenhouse gas.
What is biodiversity?
Biodiversity is the number of different species that live in an area.
What are three causes of habitat destruction?
Increased area for housing, crop plant production and livestock production, extraction of natural resources and marine pollution?
How does increased area for housing, crop plant production and livestock production lead to habitat destruction?
Increased area for housing, crop plant production and livestock production as they all take up a large amount of space and as there is an increasing world population and the demand for food, the amount of land available for these things must be increased by clearing habitats such as forests.
How does extraction of natural resources lead to habitat destruction?
Extraction of natural resources as resources such as wood, stone and metals must be gathered to make different products. Therefore, many trees are cut down, destroying forest habitats. In addition, some resource extraction takes up a large amount of space.
How does marine pollution lead to habitat destruction?
Marine pollution as human activities lead to the pollution of marine habitats. In many places, oil spills and other waste pollutes the oceans, killing sea life. Also, eutrophication can occur when fertilisers from intensively farmed fields enters waterways. This causes a huge decrease in biodiversity in these areas as most aquatic species living in these waterways die from a lack of oxygen.
How can humans negatively impact habitats?
Through the altering food webs and food chains, human can have a negative impact on habitats.
What are four undesirable effects of deforestation?
Extinction/loss of biodiversity, soil erosion, flooding and increased carbon dioxide in atmosphere
What is the consequence of extinction/loss of biodiversity?
Forest habitats, especially tropical rainforests, have a huge rage of biodiversity and as habitats are destroyed it cause the loss of large numbers of plant and animal species. Many of these species are only found in these areas and therefore will become extinct.
What is the consequence of soil erosion?
Tree roots help to stabilise the soil, preventing it from being eroded by rain. Trees usually take up nutrients and minerals from the soil through their roots. Without trees, nutrients and minerals will remain unused in the soil so will be washed away into rivers and lakes by rain (leaching). The loss of soil nutrients is permanent and makes it very difficult for forest trees to regrow, even if the land is not cultivated with crop plants or grass for cattle.
What is the consequence of flooding?
Without trees the topsoil will be loose and unstable so will be easily washed away by rain, increasing the risk of flash flooding and landslides.
What is the consequence of increase carbon dioxide in the atmosphere?
Trees carry out photosynthesis during which they take in carbon dioxide and release oxygen. The removal of significant numbers of trees means less carbon dioxide is being removed from the atmosphere and less oxygen released. When areas of land in forests are cleared for land use, the trees are often burned as opposed to being cut down, this releases carbon dioxide (combustion) further increasing carbon dioxide levels in the atmosphere and contributing to global warming.
