Human influences on ecosystems Flashcards
How humans have increased food production:
agricultural machinery to use larger areas of land and improve efficiency
chemical fertilisers to improve yields
insecticides to improve quality and yield
herbicides to reduce competition with weeds
selective breeding to improve production by crop plants and livestock
Disadvantages of monoculture:
loss of biodiversity
outbreaks
extinction of species
disruption of food chain
Advantages of monoculture:
higher revenue.
easier to manage.
yields maximization.
specialised production.
increased productivity and
efficiency.
Disadvantages of intensive livestock production:
loss of biodiversity ;
deforestation / habitat loss ;
effect of waste (faeces and urine) on, waterways/crops;
disease spreading to, wild populations / humans ;
use of antibiotics and (spread of) antibiotic resistance ;
Advantages of intensive livestock production:
help to provide more food for people
sometime provide food more cheaply than extensive systems
fewer people go hungry
take up less land
more land could be left in its natural state, providing habitats for other species
Biodiversity
number of different species that live in an area.
Reasons for habitat destruction:
increased area for housing, crop plant production and livestock production
extraction of natural resources
freshwater and marine pollution
Through altering food webs and food chains, humans can have a negative impact on
habitats.
Effects of deforestation:
habitat destruction
reducing biodiversity
extinction
loss of soil
flooding
increase of carbon dioxide in the atmosphere
Effect of pollution and excess fertilisers in aquatic ecosystems:
lake/ river pH decrease
aluminium ions become mobile
nutrients leached
shell damage
fish/ frog fail to reproduce
aquatic plants die
disruption of food chain
loss of biodiversity
Biology notes By Vasumitra Gajbhiye 51
low pH toxic to aquatic animals
fish produce mucus which blocks gills.
Effect of plastic on aquatic ecosystem:
plastic remains /persists / lasts a long time/ not decomposed ;
swallowed/ ingested/eaten/ cannot be digested/ blocks gut ;
caught, around/ strangle/trapped/ entangled/ smother/ suffocate / injure/ cut /
trap/ stuck in, organism AW ;
plastic blocks light for, photosynthesis ;
may, contain/release, (oil-soluble) toxins / poisons / harmful chemicals;
blocks the flow of water in streams or rivers ;
so less aeration of water/reduces concentration of (dissolved) oxygen ;
destruction of, habitat/ ecosystem/ food chain ;
idea of bioaccumulation/ biomagnification ;
trapped / stationary water acts as a breeding site for mosquitoes ;
AVP ; e.g. visual pollution /releases hormone-like chemicals / less oxygen from
photosynthesis
Effect of plastic on terrestrial ecosystem:
CHOKES/ strangles / traps / blocks digestive systems / AW (of animals)
ingested ;
reference to, chemical exposure / fumes / toxins ;
(plastic) accumulates in an organism / is passed down a food chain ;
(described) habitat destruction ;
e.g. plastic covers the habitats (plastic) blocks (light / water for) photosynthesis
(for land plants) ;
visual pollution ;
(plastic) block roots / prevents root growth ;
remain in the ecosystem (for a very long time) ;
green house gases
Methane and carbon dioxide
how do greenhouse gasses affect climate
They trap infrared radiation
emitted from the sun towards the earth. This keeps the planet warm enough to
support life. If level of these green house gases rise, more infrared radiation is
trapped, this increase the average temperature of earth. Resulting in enhanced
green house effect, leading to climate change.
Eutrophication of water:
increased availability of nitrate and other ions
increased growth of producers
increased decomposition after death of producers
increased aerobic respiration by decomposers
reduction in dissolved oxygen
death of organisms requiring dissolved oxygen in water
Sustainable resource
one which is produced as rapidly as it is removed from the
environment so that it does not run out