human influences on ecosystems Flashcards
why has food production increased
- improved machinery
- fertilizers
- insecticides
- herbicides
- artificial selection and genetic modification
reasons for food shortages
Fast increase in population
Increasing use of crops for fuel
Decrease of farming = Climate change/Urbanization
what is famine
Wide spread scarcity of food
main causes of famine
The rapid rate of population increase
Long term climatic change
Soil erosion and desertification
Economic pressure
Unequal distribution of food
Drought
Flood
what is monoculture
the continuous production of one type of crop that is often genetically uniform.
negative impacts of monoculture
If a natural disaster were to occur, the whole crop could be wiped out.
If pests & disease attacked crop, it could harm it easily
Using large fields and pesticides reduces the variety of species. This hinders biodiversity.
negative impacts of intensive livestock production
Welfare issues for the livestock
Diseases can spread easily among them
Waste can pollute land and waterways nearby
reasons for habitat destruction
Increased area for food crop growth, livestock production and housing
Extraction of natural resources
Marine pollution
Through altering food webs, and food chains, humans can have a negative impact on habitats
effects of deforestation
Reduced biodiversity/destroys habitats/extinction
Loss of CO2 fixation, thus increase in CO2, thus global warming
Soil erosion: tree roots cannot retain soil, goes into rivers making the water dirty & causes blockages, soil becomes less fertile
Flooding: usually 75% of water is absorbed by foliage, root systems or evaporates. After deforestation water, accumulates in valleys
examples of water and air pollution
Chemical waste and sewage in rivers results in water not being drinkable and eutrophication can occur
Sulphur dioxide dissolves in rain, causing acid rain which increases acidity of lakes and leaches aluminium out of the soil
effects of acid rain
The fishes’ gills are damaged, eventually killing them. This is fixed by adding calcium hydroxide (slaked lime)
Destroys top of trees and aluminium damages tree roots = dead tree, important nutrients leached away
SO2 poses health hazards for humans (asthma sufferers)
Damages limestone buildings and sculptures
Fewer crops can be grown on an acidic field (fixed by adding lime)
pollution due to pesticides
Insecticides (kill insects): meant to kill insects which eat crops, but can kill other, useful insects such as bees which are pollinators, or by bioaccumulation (the increase in dose of toxin from one level of the food chain to the next)
Herbicides (kill weeds): can be harmful to animals which eat the plants
effects of nuclear fall out
Radioactive particles are sprayed into the atmosphere in a nuclear accident or bombing;
These particle “rain” back to earth from clouds, sometimes far from the accident site;
The radioactivity damages DNA and causes cancer and radiation illness at every level of the food chain.
effects of non-biodegradable plastics
Choke birds, fish and other animals
Fill up the animals’ stomachs so that they can’t eat food
Collect in rivers, and get in the way of fish
acid rain causes and effects
Caused by sulphur dioxide (burning fossil fuels) and nitrogen oxides (nitrogen reacting hot engines), as they dissolve and cause acid rain
Damages trees and plants, and kills fish and other river life
prevention of acid rain measures
Prevention: catalytic converters, in factories slaked lime neutralizes these acidic oxides and use of flue-gas desulfurization
negative impact of female contraceptive hormones in water courses
Reduced sperm count in men and feminisation of aquatic organisms
what is eutrophication
when water plants receive too many nutrients.
process of eutrofication
Fertilisers put in soil by farmers
Fertilisers with nitrates / detergents with phosphates leach into rivers and lakes after rain
Water plants grow more than usual
They block sunlight and kill plants underneath
They die and sink to bottom
Bacteria/fungi decompose remains using the O2 and decreasing the O2 concentration
Fish and other creatures die from oxygen starvation
what is a sustainable resource
one which is produced as rapidly as it is removed from the environment so that it does not run out
what is sustainable development
development providing for the needs of an increasing human population without harming the environment
what does sustainable development require
Management of conflicting demands
Planning and co-operation at local, national and international levels
how can resources be maintained
Some resources can be maintained, limited to forests and fish stocks.
They can be sustained using:
Education
Legal quotas
Re-stocking
water as a natural resource
used to grow food, keep clean, provide power, control fires and to drink. We get water constantly through rainfall but we are using up planet’s fresh water faster than it can be replenished.
