human influences on ecosystems Flashcards
from what is the world’s food supply produced by
growing crops or by keeping animals
agricultural machinery
tractors combined by harvests have made a very big difference
farmers can now cultivate a much greater area of land in a much shorter time than using manual labor and animals to pull machinery
agricultural chemicals
to help improve the growth of their crops so they can get more yield.
they are expensive the costs outweigh by the increased quantity and quality of the yield
chemical fertilisers
-chemical fertilisers add more ions (nitrate) to soil that dont contain enough
insecticides
sprayed onto crops to kill insect pests that might harm and reduce yield or make crops look less appealing to buyers
herbicides
sprayed to kill weeds, which would compete with crop plants and reduce their growth
monoculture
area of ground covered by a single crop, with almost no other species present
more efficient for the farmer
why is monoculture more efficient for the farmer
using machinery to cultivate a large, uninterrupted land can be done more quickly than tending to small separate fields.
uniformed crop can all be harvested at the same time
a large area can all be treated with the same herbicides or pesticides
produce large quantities in the same quality and size, more profitable and easier to sell
disadvantages of monoculture
reduction in biodiversity-
increase in pests- if there is only one type of crop the pests will have a lot of food to grow from.
reduction in soil fertility- over time the minerals that the same plants need will be removed from the soil, they need to add fertilisers. growing different crops help maintain soil fertility
how can farmers reduce the quantity of pests as a result from monoculture
by spraying insecticides
this does kill harmless insects as well
expensive
become resistant
mixed cropping- makes it more difficult for insects to spread.
mixed cropping
only a small area of land are covered with the same crop at the same time of the year
extensive livestock production
Extensive livestock production is a farming system where animals are raised in large areas with low input of labor, capital, and resources.
intensive farming production
Intensive livestock production is a farming system where animals are raised in confined spaces with high inputs of labor, capital, and resources to maximize production.
intensive farming production advantages
can provide more food for people, and more cheap
takes up less land than extensive farming, so more land can be left in its natural state, providing habitats.
intensive farming disadvantges
welfare issues for the livestock, bc of crowded conditions.
diseases can easily spread among them, some countries give antibiotics.
waste can pollute land and waterways nearby
the food the animals eat, we could also eat, this means that if we ate them directly we could have more energy
alot of energy is needed: transporting, keeping the living conditions good (temp.)
large amounts of water is needed, if large amount of animals are kept in one place.
how do humans destroy the habitat by using the land for themselves
cutting down native vegetation for corps and farming livestock, buildings and factories
when we mine for natural resources (removes vegetation, toxic run-off can enter river and soil)
add pollutants to water which kill organisms that live there.
other than destroying the land, how else do we damage habitats
by removing key species from them, which endangers the remaining species, damaging the food webs in a habitat.
why do humans do deforestation
wood is an excellent fuel and building material
land on which trees grow can be used for growing crops for food or selling.
what are the main concern of deforestation (rainforests)
> rainforests area decreasing- rainforests have perfect conditions for the growth of plants -> high biodiversity. when its gone the soil is exposed and is washed away (roots bind it together) this soil erosion makes it difficult for the forest to grow back again, the water can overflow and causes flooding. loss of habitat
extinction
the complete loss of a species from earth
how human activities can increase soil erosion
trees cut down > land is overgrazed > the removal of grass cover allows soil to be blown or washed away > soil structure is blown of washed away > rivers travel the the topsoil away
how can the loss of tree affect the water cycle
when rains falls some lands on the leaves of the trees, it then evaporates and goes back into the atmosphere.
if no trees then water goes to the soil of rivers where less goes back into the atmosphere.
the air then becomes drier and less rain falls.
this makes it more difficult for crops to grow.
why is it hard to stop deforestation in poor countries and how can they help this issue
because people need to cut down these areas to grow their own food as they cant afford to buy and there is also no alternative given to them.
by giving money to the countries to provide other sources of income.
pollution meaning
addition to the environment of smth that harms it.
greenhouse gases
gases such as carbon dioxide and methane that trap heat within the atmosphere.
greenhouse effect
the heating effect on the earth of the trapping of heat by greenhouse gases; note that this is a natural and useful effect, as without it the earth would be too cold to support life.
how does the greenhouse effect works
short wavelength radiation from the sun passes through the earth’s atmosphere
ground absorbs short wavelength radiation, and re-emits it as long wavelength radiation
reflected radiation heats the earth some more
most long wavelength radiation is reflected back by greenhouse gases
only some long wavelength radiation escapes from earth
why do we need the greenhouse effect
if we didnt then the earth would be frozen and lifeless.
enhanced greenhouse effect
the increased heating effect caused by an increase of greenhouse effect caused by an increase of greenhouse gases in the atmosphere
sources of greenhouse gases
industrial revolution- the quantity of fossil fuels which have been burnt by industry. this releases co2
deforestation- increased amount of co2, fewer trees = less photosynthesis = less co2 absorbed, when trees are cut down and burnt = combustion = more co2
other gases also contribute
methane is produced by farming activities, it is released by bacteria which break down organic matter in the mud then to the animals. methane is also produced by decomposers acting on decaying rubbish in landfill sites.
as the earth’s temperature rises…
rising sea levels- ice caps melting = more water, low lying countries will be flooded.
higher temp. = more energy in the atmosphere which can lead to diff. wind pattern
hurricanes and tropical cyclones and droughts (more forest fires) happen stronger and more.
rainfalls may also happen at unexpected times of the year, flooding.
thermal expansion
the sea level rises because the vol. of a liquid increases as its temp. increases
