3.6 human impact on the environment Flashcards
what is extinction
the total loss of a species
what are endangered species
are at risk of becoming extinct because there are few breading pairs left
what are some reasons for extinction
natural selection
habitat destruction (deforestration)
pollution
overhunting by humans
competition (interspecific)
what is conservation
the protection, preservation, management and restoration of natural habitats and their ecological communities. the aim is to maintain the species and genetic biodiversity while allowing human activity to continue
conservation methods
-nature reserves and SSSIs (sites of special scientific interest) are protected by law
-international restrictions in trade (agreed internationally
-captive breeding programmes in zoos and botanic gardens enhance species numbers
-sperm and seed banks preserve gene pools
-reintroduction of species
-ecotourism
what does ecotourism aim to do
aims to educate, conserve and contribute to local economies
what does biological monitoring contain
may involve field techniques such as random sampling and transects
what does monitoring enable (conservation)
enables prediction of possible effects of human activities to inform planning of conservation methods
what are governments trying to do to offset issues with agriculture exploitation
offering subsidies to improve biodiversity on their farms. this is to compensate for the loss in income from focusing on increasing biodiversity (which may cause a reduction in crop production)
what is there conflict between
the need for conservation of species and the demand for increased food production
what is agricultural exploitation
describes the need to increase efficient and intensity of food production to meet increasing demands by a rapidly increasing human population
what can agricultural exploitation involve
-removal of hedgerows-destroying habitats
-monocultures-reducing available niches
-the use of insecticide, fertilisers and herbicides-causing eutrophication and the death of beneficial insects, niches and habitats
-ecosystem destruction to provide additional agricultural land
what do monocultures provide
only one type of habitat, reduces biodiversity. reduce soil fertility (increases the need for chemical fertilisers)
why is conserving gene pools by conserving species important
plants may provide new machines for the future
many crop plants have wild relatives that may have useful genes that could be bred back into crops to increase productivity
what is deforestation
the removal of trees to use as timber or fuel or to repurpose the land use for agriculture or building
consequences of deforestation
soil erosion
flooding
habitat loss
global warming and climate change
disruption of the water cycle
land slides
decrease in biodiversity
what is soil erosion
soil is no longer protected from rain by the canopy as roots decompose, no longer hold the soil together so it is eroded by wind and rain
flooding
consequence of deforestation
evaporation from soil removes less water than transpiration, waterlogging encourages denitrification and soil loses nitrates
what does habitat lead to
consequence of deforestation
reduced biodiversity
explain how global warming and climate change occurs
consequence of deforestation
less photosynthesis meand that less CO2 is removed from the atmosphere. CO2 is a ‘greenhouse gas’ increased CO2 leads to global warming and climate change
solutions: deforestation
-coppicing
-selective cutting/felling
-replanting the correct mix of species, the correct distance apart, and allowing them to regenerate
-sustainable management
-protecting areas (legislations)
what is coppicing
solution of deforestation
tree trunks are cut at their base leaving a stump a few cm above the soil. new shoots grow from the stool which can be harvested at different diameters for different purposes e.g building or fire wood.
provide a variety of habitats and increases biodiversity
what does sustainable management do (deforestation)
ensures biodiversity of the area is not lost
what can overgrazing land cause
soil compaction, reducing air spaces and inhibiting nitrogen fixing and nitrifying bacteria- leading to a loss of soil fertility
schemes and legislations in place to reverse the decline in biodiversity and soil fertility
-organic farming
-set-aside schemes
-legislations
what do fishing policies attempt to do
set a harvesting level
what is overfishing
where fish are caught at a higher rate than they reproduce and grow. this occurs to the point where increased fishing efforts lead to declining catches
methods of fishing
-drift netting
-trawling (bigger fish can get caught)
consequences of overfishing
fish populations may be reduced in size to the extent that they lose genetic diversity
size of the fish caught is reduced as they don’t have time to grow
fish population has fewer individuals and cannot replace harvested fish
solution to overfishing and to preserve fish stocks
-regulating mesh sizes (bigger net so young fish are not caught)
-quotas and landing size regulations (relying on honest fisherman)
- exclusion zones (not at breeding times)
-legislations limiting the size of fishing fleets or controlling the number of days spent at sea
-use lines not nets
- restricting fishing seasons (particularly to allow fish to reproduce)
what is fish farming
where fish are intensively reared in ponds/tanks or nets; sea-fish are usually reared in large netted areas of the sea (a solution to overfishing)
what is controlled in fish farming
food, predation, disease and parasites
warm water is used to accelerate growth
positives of fish farming
less fish need to be harvested from the wild, allowing fish stocks to replenish,
fish have been selected for high growth rares and therefore large size and increased yield
consequences of fish farming
-excess fish food and excreta fall out of the nets and can cause eutrophication in the marine habitats.
-parasites and diseases spread quickly through the overcrowded fish (may carry to wild fish as well)
-pesticide bioaccumulation
-nitrogenous waste pollution
-farmed fish are larger and outcompete wild fish for resources if they escape
- the feed is often made from harvested wild fish (ethical?
sustainability and decision-making
what is important?
monitoring allows us to determine the quality of the environment and also assess any decline in quality over time
-air, soil and water quality is monitored
what is an EIA
-environmental impact assessment is a document which uses data to predict the environmental effects of a proposed project
what should an EIA include
-description of the site and proposed projecy
-description of abiotic and biotic factors
-mitigation-ways of limiting environmental damage and maintaining biodiversity
what does the term ‘planetary boundary’ mean
a safe operating space for humanity. above this value the global process will not be stable
what are the 9 planetary boundaries
climate change
biosphere integrity
land system change
biogeochemical flows
ozone depletion in the stratosphere
ocean acidification
fresh water use
atmospheric aerosols
introduction of novel entities
what 4 planetary boundaries have been crossed
climate change
biosphere integrity
land system change
biogeochemical flows
what planetary boundary has avoided being crossed
ozone depletion in the stratosphere
what planetary boundary is avoidable
ocean acidification
fresh water use
what boundaries and not quantified
atmospheric aerosols
introduction of novel entities
problem with the climate change boundary
- disruption of carbon cycle due to bruning fossil fuels, deforestation, increased decomposition.
- higher CO2, hihgher global temperature (affects weather, e.g. warmer seas melt polar ice)
solutions of the climate change boundary
- international agreements, set targets for reducing the greenhouse gases in the atmosphere
where is the climate change boundary at
crossed
-CO2 levels are at 400ppm and climbing
position of the biosphere integrity boundary
crossed
problems with the biosphere integrity boundary
- habitat destruction has occurred in many ecosystems e.g. coral reefs, tropical rain forests
-population of living organisms are reduced
-increased risk of extinction
solutions of biosphere integrity boundary
-monitor biodiversity
-species conservation (speed/sperm banks)
-prohibit international trade in endangered species and products (ivory)
-limit fishing
-limit the use of pesticides/ fertilisers
position of the biogeochemical flows boundary
crossed
problems with the biogeochemical flows boundary
- disruption of the nitrogen cycle due to inhibition of nitrogen fixing and nitrifying bacteria and denitrification in waterlogged or compacted soil
- combustion of fossil fuels
-eutrophication due to nitrogen pollution in water ways
solutions of the biogeochemical flows boundary
-transfer nitrogen fixing genes to crop plants (yet to be successful)
position of the ozone depletion in the stratosphere boundary
avoided
problem with the ozone depletion in the stratosphere boundary
- by 1970, the concentration of ozone in the stratosphere had decreased so much that a hole in the ozone layer could be detected
-much more UV was penetrating the atmosphere
-UV generates mutations in DNA and causes damages to living organisms
solutions of the ozone depletion in the stratosphere boundary
the use of chlorinated and brominated hydrocarbones (ozone-destroying) were phased out
-use of CFCs in aerosols and fridges reduced
position of the ocean acidification boundary
avoidable
problem with the ocean acidification boundary
-atmospheres CO2 dissolves in bodies of water i.e. ocean (decreases pH)
-fish gills are damaged by low pH (gas exchange less efficient)
-photosynthesis is compromised
solutions of the ozone depletion in the stratosphere boundary
-current levels are very close to the proposed boundary. preventing a large increase in CO2 levels (atmosphere) would likely prevent the boundary being crossed
position of the fresh water use boundary
avoidable
problem with the fresh water use boundary
all organisms need regular access to fresh water. climate change and chemical pollution may limit freshwater sources
solutions of the fresh water use boundary
-limit the volume of water we take from rivers
-reduce,re use, recycle
-use desalinated water
position of the atmospheric aerosols boundary
not quantified
problem with the atmospheric aerosols boundary
-aerosols released into the atmosphere by combustion of fuels and by dust from digging and mining
solutions of the atmospheric aerosols boundary
not possible to determine safe layers as the effects of atmosphere particles are so variable
position of the introduction of novel entities boundary
not quantified
problems with the introduction of novel entities boundary
- new technologies and materials release more novel types of pollution i.e. radioactive materials/plastic
-some chemicals are so toxic they’ve already been banned (DDT/DCBs)
solutions of the introduction of novel entities boundary
Not yet possible to establish one
