Chapter 19:Human influences on ecosystem Flashcards
how have humans increase food production
1-agricultural machinery to use larger areas of land and improve efficiency
2-chemical fertilisers to improve yields
3-insecticides to improve quality and yield
4-herbicides to reduce competition with weeds
5-selective breeding to improve production by crop plants and livestock
how do agricultural machinery increase food production
Agricultural machinery such as tractors allows a farmer to do much more work on the land in a day than using hand tools or machinery pulled by animals
how do chemical fertilisers help increase food production
chemical fertilisers containing mineral ions such as nitrate provide extra nutrients to grow crop plants.they grow faster and larger and produce greater yields
how do insecticides help increase food production
Chemicals that kill insects can be sprayed onto growing crops to kill pests than feed on the plants.this increases the yield from the crop
how do herbicides help increase food production
Chemicals that kill plants can be sprayed onto the crop to kill weeds .this reduces competition between the weeds and the crop plant for resources such as light and water,so the crop plants can grow faster and larger,increasing yield
how does selective breeding help increase food production
new varieties of animals and crop plants that grow faster are able to survive better in difficult conditions such as in time of drought
Define monocultures
an area of ground covered by a single crop,with almost no other species present
advantages of monocultures
1- using Machinery to cultivate a large, uninterrupted area of land can be done more quickly and efficiently than tending several small separate fields
2-a uniform crop, is likely to grow the same height and ripen at the same time, so it can all be harvested at once
3-A large area of the same crop can all be treated with the same herbicides and pesticides
4-A monoculture will probably produce large quantities of seed, fruits, or other harvestable parts that are all uniform in size and quality, make it easier for the farmer to market
disadvantages of monocultures
1- the biodiversity is low as only few species can live where the crop is growing
2-increase of pests and transfer viruses
3-reduction in soil fertility
Advantages of intensive farming
1-help provide more food for people
2-takes up less land than extensive farming
Disadvantages of intensive farming
1-there can be welfare issues for the livestock,which may suffer in the crowded conditions in which they are kept
2- diseases can spread easily among them
3-the waste from intensive farming unit can pollute land and waterways nearby
4-foods for the animal is often produced from food that we could eat ourselves
5-energy is used to transport feed to the livestock often over very long distances
6-large quantities of water may need to be provided if large number of animals are kept in one place
Why are habitats destroyed
-to provide more land for farming and housing
-to extract natural resources,such as mineral or fossil fuels
-by adding pollutants to the environment
Define biodiversity
The number of different species that live in an area
What are the effects of deforestation
- loss of habitat
-loss of soil
-increase flooding
-increase carbon dioxide in the atmosphere
how does deforestation cause loss of habitat
Plants and animals that live in forests have adaptions that allow them to live there. They may not survive when the forest is cut down and this could result in extension of species
how does deforestation cause loss of soil
Plant roots help to hold soil in place, especially on slopes.when trees are lost soil is easily eroded by wind or water
how does deforestation cause increased flooding
With no trees,rain water hits the ground directly,and is likely to run off rather than soak gently into the soil. Also there is no tree rooted to take up water from the ground
how does deforestation cause an increase carbon dioxide in the atmosphere
no tree means no photosynthesis to remove carbon dioxide from the air.if the trees are brunt,this produces more carbon dioxide
What are the two most important greenhouse gases
-carbon dioxide
-methane
What is the green house effect
The heating effect on the earth of the trapping of heat by greenhouse gases
explain eutrophication process
1- the extra nutrients such as nitrates increase and completely cover the water surface
2-the producers on the water surface prevent light reaching plants growing below them,so they cannot photosynthesis and die
3-the dead plants provide food for decomposers and the number of decomposers increase
4-many decomposers respire aerobically and use up most of the oxygen dissolved in the water
5-animals in the water now do not have enough oxygen so they move away and die
What’s the effect of untreated sewage and excess fertilisers on aquatic ecosystem
-untreated sewage may contain pathogens from humans and so can spread diseases such as cholera or polio
-both untreated sewage and fertilisers contain nutrients that increase plant growth if they enter rivers,lakes or the sea.this can cause algal blooms.the algae may produce toxins that can kill animals that drink the water
Describe the effects of non-biodegradable plastics in both aquatic and terrestrial ecosystems
-Non-biodegradable plastics plastics that cannot be broken down by decomposes.when they have been thrown away they remaining environment for a long time.
-Land animals, such as mice, may enter plastic bottles, and get trapped
-Sea turtles mistake them for jellyfish and eat them. This can block the alimentary canals of the turtles so that they cannot absorb nutrients and eventually die.
what is conservation
Looking after the natural environment and tries to maintain or increase the biodiversity
