human influences on ecosystems (topic 20) Flashcards
what are some methods that humans use to increase food production
agricultural machinery, chemical fertilisers, insecticides, herbicides, selective breeding
why is agricultural machinery used
reduces labor cost, time needed to farm, reduces food price, farmers can use more land to produce a greater quantity of food more efficiently,
why is chemical fertilisers used
fertiliser is a substance that contains important nutrient for plant growth eg. magnesium and nitrates
they increase yield of crops
natural fertilisers improve soil structure, artificial does not
why are insecticides used
Substances used to kill or control the number of unwanted insects. improved quality and yield
why are herbicides used
Substances intended to kill weeds and other plant pests. reduce competition with weeds
why is selective breeding used
improve production by
crop plants and livestock
what are examples of intensive farming methods
monoculture, intensive livestock production
monoculture
Growing a single crop across a large area.
advantages of intensive farming are
more simple- only one crop considered when preparing soil choosing fertiliser specific herbicides and insecticides can be used
improves efficiency and improves yield- crop or animal grows potimally produced in efficient way, large areas can be used
reduces production cost- farmer works in focused and efficient method costs lower, increases profit for farmer
disadvantages of intensive farming
land clearance- deforistation to crop plant, leads to lack of biodiversity
reduced biodiversity- pathogens and insect pasts grow more rapidly more insecticides used which may kill insects which arent pests, reducing food available for other animals
soil damage- heavy machinery used, compacts soil, reducing the amount of water and air it can hold, more difficult for plants to grow, can cause erosion, soil wahsed away by rain, wind or flooding, farmer only plants same plant nutrients used up, more fertilisers used, which can cause erosion
water pollution- water runoff from fields can carry fertilisers and herbicides, isnecticides, harm organisms in water, can cause eutrophication in rivers and lakes
air pollution- animal waste, methane, greenhouse gases,
biodiversity
the number of different
species that live in an area
what are the reasons for habitat destrcution
increased area for housing, crop plant
production and livestock production
extraction of natural resources (pollution is created by fuels when they are burned
the search for oil or gas damages natural habitats,drilling and mining operations need wells, roads, pipelines and other facilities.)
freshwater and marine pollution
how can humans have a negative impact on
habitats
altering food webs and chains
what can deforistation lead to
reduced biodiversity
flooding
loss of soil
extinction of species
an increase in carbon dioxide in the atmosphere.
how does deforestation lead to reduced biodiversity
As trees in a forest are the primary producers, they are the producers of many food webs. Trees also provide valuable habitats and food for many organisms in the forest. Certain creeping plants depend on the trees for access to sunlight (Figure 1). Without the trees, many food webs would collapse.
how does deforistation lead to flooding
trees removed water cycle affected, trees and other vegetation hold soil together, hold water in the ground, no vegetation rain flows directly into rivers and lakes wahses away more of the soil causing floodngs
how does deforistation lead to loss of soil
trees and vegetation help keep soil in place, reduce erosion, land cleared protective layer of vegetation lost, soil may then be blown away or washed away
how does deforistation lead to increased co2
during photosynthesis co2 is used as reactant, when trees or plants are cut down, this doesnt happen increasing presence of co2 in the atmosphere, also if vegetation cut down is burned this process releases co2
pollution
Release of any substance that has an undesired, unexpected, harmful or toxic effect on the environment.
what are some sources of water pollutants and their effects
untreated sewage- may carry harmful pathogens that cause disease; uses up oxygen when it rots; hormones affect reproduction of some organisms
fertiliser runoffs- causes algal blooms and eutrophication