Human influences on ecosystems Flashcards
Ways humans increased food production
- Agricultural machinery to use larger areas of land and increase efficency (by saving manual labour)
- Chemical fertilisers to increase yield
- Insecticides to improve quality and yield
- Herbicides to reduce competition with weeds
- Selective breeding to improve production by crop plants and livestock
What is monoculture farming?
Monoculture farming means that on a given area of agricultural landonly one species of crop is grown
Advantages of monoculture
- More efficient (only need to buy equipment for one crop type, can harvest at same time)
- Crops can be optimised for highest quality and yield (promotes agricultural technology)
- Higher profits
Disadvantages of monoculture
- Pathogens/disease affect the entire crop
- Destroys soil nutrients (different plants use different nutrients)
- Has large impacts on local ecosystem and reduces biodiversity
- Can lead to soil erosion due to lack of established roots in the soil
- Increased pest issues, issues with insecticides (harming the environment)
What is intensive livestock production?
In developed countries,large numbers of livestockare often kept in an area that wouldnot normally be able to support more than a very small number. They are often fedhigh energy foods, regularly given medication such asantibioticsas a preventative measure against disease and kept inartificially warm temperaturesand small spaces thatdo not allow for much movement
Advantages of intensive livestock production
- Less land is required to produce large amounts of food
- Food can be produced all year round in controlled environments
- Cost of production is lower (therefore food can be sold for cheap prices)
- Lower requirement for labour to produce the food
Disadvantages of intensive livestock production
- Higher risk of disease outbreaks
- Herbicides and pesticides tend to be used potentially causing eutrophication and negative effects to food chains
- Reduction in biodiversity
- Large amounts of cattle produce a large amount of methane + overgrazing can lead to soil erosion
- Ethical issues with the cruel treatment of animals
Biodiversity definition
the number of different species that live in an area
How can humans have a negative impact on habitats?
Humans can have a negative impact on habitats through altering food webs and food chains
Reasons for habitat destruction
Increased area for housing, crop plant production and livestock production
- Crops, livestock and homes all take up a large amount of space. Since there is an increasing population for food, the amount of land available for this must be increased by clearing habitats (like forests in deforestation)
Extraction of natural resources
- Natural resources such as wood and stone must be gathered to make different products. Therefore, many trees are cut down, destroying forest habitats and resource extraction takes a lot of space (ex mining) so the land must be cleared first
Freshwater and marine pollution
- Human activities lead to pollution of marine habitats. In many places, oil spills pollute the oceans killing marine life. In addition, eutrophication can occur when fertilisers from intensively farmed fields enter waterways causing a decrease in biodiversity as most aquatic species will die from lack of oxygen in that area
What is deforestation?
Deforestation involves cutting down large amounts of trees to gather as resources for manufacturing or to clear space for other economic activities. It is normally an unsustainable practice
Undesirable effects of deforestation
Reducing biodiversity
- When forests are cleared, the habitats of many species are destroyed. These species may not be able to survive elsewhere. This is especially apparent in tropical rainforests which have a huge range of biodiversity and as the habitat is destroyed it causes the loss of a large number of animal and plant species disrupting food chains and food webs
Extinction
- Forest habitats contain many endemic species and when habitats are lost due to deforestation, these species have nowhere to go and aren’t adapted to other environments, leading to population declines and, ultimately, extinction
Loss of soil
- Tree roots help to stabilise the soil preventing it from being eroded by the rain. Trees normally take up nutrients and minerals from the soil through their roots and without trees the nutrients and minerals remain unused in the soil and are washed away into the rivers and lakes by rain (process called leaching). This makes it very difficult for forest trees to regrow and essentially turns the land into a desert
Flooding
- Without trees the topsoil is loose and unstable so it will be easily washed away by the rain which increases the risk of flashflooding and landslides. The loss of flora also means that there are no plant roots to take up rainwater, which means more rainwater washes into nearby streams and rivers. This makes flooding easier.
Increase of carbon dioxide in the atmosphere
- Forests have high rates of photosynthesis, which means a great deal of carbon dioxide is removed from the atmosphere by the flora in forests. Therefore, deforestation means that a lot less carbon dioxide will be removed from the atmosphere, causing an increase in the CO2levels in the atmosphere. Additionally, when forests are cleared for land the trees are often burnt which releases carbon dioxide through combustion further increasing the CO2 levels.
How can water be polluted by untreated sewage?
Untreated sewage contains organic matter, harmful pathogens, and chemicals that can severely impact aquatic ecosystems. Firstly it provides a good food source for bacteria. Bacteria decompose the organic matter in sewage through aerobic respiration, which consumes oxygen in the process. This causes the death of aquatic organisms such as fish. Untreated sewage also often contains harmful bacteria, viruses, and parasites that can contaminate water, posing health risks to both aquatic life and humans.
How can water be polluted by excess fertiliser?
Excess nutrients from fertilizers lead to eutrophication, which is an over-enrichment of water with nutrients. This stimulates the rapid growth of algae and other aquatic plants. Algae blooms often form which can block sunlight, preventing aquatic plants from photosynthesizing and producing oxygen. When these algae die and decompose, bacteria consume large amounts of oxygen during decomposition, further depleting oxygen levels in the water. The sudden increase in algae and plant growth disrupts the natural food chains, reducing the diversity of species and altering the balance of the ecosystem.
How can water be polluted by non-biodegradable plastics?
Non-biodegradable plastics remain in the environment for hundreds of years causing them to accumulate in the environment. Marine life can become entangled in plastic waste and also ingest the plastic when it’s in smaller pieces (this could block the digestive system, cause internal injuries, and lead to starvation, as the animal feels full without gaining any nutrients). Microplastics (tiny plastic particles) are particularly dangerous as they are consumed by a wide range of organisms, from plankton to fish, and can accumulate up the food chain, ultimately affecting predators
