human impact on the environment Flashcards
species extinction
the death of the last individual
of a species capable of
reproduction.
endangered species
one that is at risk of becoming extinct throughout all or a significant portion of its range.
what human activities result in biodiversity crisis and why
Human activities such as deforestation, agriculture, over shing, pollution,
forestry, mining and urban expansion have all resulted in widespread habitat
destruction, resulting in a biodiversity crisis as species compete for resources.
why have many species become endangered and extinct
Many species are becoming endangered and some have become extinct because of habitat destruction or through hunting and collecting, e.g. ivory.
what is species extinction caused by
- Changes in climate which reduce vegetation and decreases atmospheric
oxygen levels. - Human activity, e.g. the dodo bird was indigenous to Madagascar and
Mauritius, but habitat destruction and hunting by sailors resulted in the
bird’s extinction by 1662.
how are endangered species classified
Species are classi ed according
to their vulnerability to extinction: critically endangered, endangered, and
vulnerable.
name three threatened species
- mountain gorillas
- giant pandas
- polar bears
describe why species are at risk due to natural selection
- Requires mutations in the gene pool to confer a selectiveadvantage.
- Where species cannot adapt to changes in their habitats fast enough due to insufi cient mutations they can become threatened or extinct.
describe why species are at risk due to habitat destruction
- E.g. deforestation and hedgerow removal. Hedgerows contain many different plant species supporting a wide variety of animal life,
- but their removal to allow for larger elds to accommodate agricultural
machinery and the subsequent loss of wildlife corridors has reduced species
numbers and affected food chains.
describe why species are at risk due to pollution
- E.g. PCBs (polychlorinated biphenyls) were manufactured ascoolants and have since been banned due to their toxicity and carcinogenic nature.
- They are still found in the environment close to manufacturing sites.
why are species at risk due to oil
- Oil is shipped worldwide to meet our energy needs, but accidents at sea
have led to the discharge of millions of gallons of crude oil, - e.g. Exxon Valdez ran aground off Alaska in March 1989 discharging oil into the
estuary. - In February 1996 the Sea Empress ran aground off the coast of Milford Haven in Pembrokeshire, spilling oil into the Cleddau Estuary endangering sea birds and marine life.
why are species at risk due to overfishing and collecting
e.g. for food (bush meat), as exotic pets,
fashion, traditional medicine (tiger bone and rhino horn), and for souvenirs
and ornaments (turtle shell, ivory).
why are species at risk
- natural selection
- habitat destruction
- pollution
- oil
- overhunting and collecting
- overfishing and agricultural exploitation
- competition from introduced species
why does competition from introduced species cause species to be at risk
e.g. north American signal cray sh
was farmed in the UK but some escaped and now outcompete the
native cray fish.
conservation
the protection, preservation management and restoration of natural habitats and their ecological communities to enhance biodiversity.
what does conservation involve
Conservation involves the management of habitats to enhance biodiversity, and is important for a number of reasons:
why is conservation important
- Ethical reasons: we have a responsibility to preserve the environment, not
damage it. - Possible medical uses: many drugs have been extracted from plants, e.g.
quinine from Cinchona bark used to treat malaria, some chemotherapy
drugs have a plant origin, and presumably many are yet to be discovered. - Maintaining a healthy gene pool helps future-proof populations against
environmental changes. - Agriculture has selectively bred crops from wild varieties. In future, we
may need to look at wild varieties to select suitable alleles to grow crops in
harsher environments.
seed and sperm banks
gene banks, protecting the genes from economically important or threatened
plants and animals.
what are the four main conservation methods
- legislation
- captive breeding programmes
- education
- ecotourism
what are the three types of legislation
- Annually, international wildlife trade is estimated to be worth billions of
dollars. CITES (the Convention on International Trade in Endangered Species) agreement is enforced by strict customs controls, backed up by fines and
even jail sentences, but it is difficult to enforce because not all countries have
signed up, and it is very difficult to police or catch the smugglers involved.
■ The EU Habitats Directive prevents collection of some birds’ eggs, and
reduces the picking of wild owers and over shing.
■ Establish protected areas, e.g. Sites of Special Scienti c Interest (SSSIs), and
nature reserves, e.g. Gower coast.
what are the four types of captive breeding programmea in zoos and botanic gardens
- Seed banks hold seeds from rare and traditional varieties in controlled
environments, to protect against extinction of species.
■ Sperm banks store sperm from threatened species and are used in captive breeding to ensure genetic variety within populations.
■ Rare breed societies maintain older less commercial varieties.
■ Species reintroduction has been used successfully following captive
breeding programmes to reintroduce species back into the wild, e.g. the red
kite has been reintroduced back into mid-Wales.
describe how education is a form of conservation
- Education through WWF (World-Wide Fund for Nature) and the Countryside Commission, which are responsible for raising awareness.
- The Countryside Commission is also responsible for establishing nature reserves.
how is ecotourism a form of conservation
- Ecotourism, e.g. safaris, provides education and raises money to fund
local conservation efforts by employing local people. - This way, species have
more value alive so there are clear incentives to conserve.
ecotourism
responsible travel to natural areas that
conserves the environment and improves the well-being of local people.
monoculture
the cultivation of a single species of crop
what is agricultural exploitation and what are it’s problems
- This refers to the way in which food production has had to increase in
efficiency and intensity to maximise crop yields in order to feed a growing
population. - Agricultural exploitation causes conflict between conservation and the need to mass produce food.
- Following World War II, larger elds
were created by removing hedgerows to allow for larger machinery, which
led to the loss of habitat for many organisms and reduced biodiversity. - Farmers also employed monoculture by growing a single species of crop, e.g.
wheat, to further increase yields, as all plants required the same nutrients,
and harvesting was easier.
what are the disadvantages of monoculture
■ It reduces biodiversity as there is only one habitat.
■ It provides an ideal environment for pests, so pesticides and herbicides have
to be used.
■ Farming reduces the ow of recycling of nutrients as when plants die and
decompose their constituent elements are returned to the soil, but farmers
often remove crop residue and therefore minerals from the soil.
* Farmers have to add inorganic fertilisers to their elds to increase nutrient content.
* This can cause eutrophication of waterways.
what are farmers doing to prevent agricultural exploitation
Farmers are encouraged through the use of subsidies, where they are paid to manage their farms to increase biodiversity.
what are the causes of deforestation
■ Use of land for agriculture for both subsistence farming and cash crops, e.g.
■ Palm oil
■ Soya bean
■ Biofuels
■ Cattle ranching
■ Timber extraction.
what are the consequences of deforestation
- Habitat loss increases causing a reduction in biodiversity.
- Soil erosion increases as tree roots no longer bind soil, so rainfall on
exposed slopes can remove top soil. - Increase in sedimentation, as top soil is removed from upper slopes
and deposited downstream by rivers, increasing the risk of ooding.
Soil quality and structure deteriorates as there is no humus added to it
from trees. - Climate change due to reduced carbon dioxide uptake during
photosynthesis. - Less transpiration by trees reduces the amount of water vapour returning
to the atmosphere, which reduces the amount of rainfall. - Loss of plant species and potentially valuable plant chemicals that could be
used to treat disease. - Desertification.
soil erosion
the removal of topsoil, which contains valuable nutrients.
how can woodlands be managed more sustainably
- by employing:
- ■ Selective cutting, where individual trees are removed, leaving space for
remaining tress to grow. The habitat is largely left in place.
■ Coppicing, which is the process of cutting trees down, allowing the stumps
to regenerate for a number of years (usually 7–25) and then harvesting
the resulting stems. This encourages great biodiversity in the coppiced
woodlands, e.g. wild owers, grasses and brambles would progressively
colonise each new glade as the tree canopy was opened up. The animal
species associated with these plants would also then follow.
coppicing
cutting down trees close to the ground
and leaving them for several
years to re-grow.
what do native woodlands include and how are they native
- Native woodland consists mainly of native trees, that is those that have grown
there naturally since the last Ice Age and have not been introduced by humans. - Native woodland supports a very rich biodiversity, but only 1% of UK woodland
is native. - The majority of managed woodland in the UK is managed by the forestry Commission, and is still largely non-native species such as pine.
overfishing
occurs when
the rate at which fi sh are
harvested exceeds the rate
at which they reproduce.
deacribe overfishing and how the net size affects it
When the harvesting rate is higher than the fish reproductive rate, the sh
population size falls. Fishing using nets with a small mesh results in the
depletion of younger sh so that the breeding
what are disadvantages of commerical fishing
- Commercial fishing using drift netting for pelagic sh, where nets are suspended
in the water from oats on the surface, traps non-target species like dolphin and
turtles. - Trawling for fish in deep water again catches non-target species but is
more damaging as it damages the ocean beds, destroying habitats.
what are examples of international aggreents to regualte fishing and make it sustainable allowing the population level to be maintianed
■ Imposing shing quotas based on scienti c estimates of size of sh stocks.
■ Enforcing exclusion zones preventing shing in over shed areas.
■ Restricting mesh size of nets so only the ‘correct’ age sh are caught. Larger
mesh sizes allow younger sh to escape, survive and reproduce.
■ Returning young sh that are caught to sea.
■ Forced reduction in eet size.
■ Enforcing shing seasons (so no shing in breeding season).
■ Allow some sh to return to sea for breeding.
■ Encourage shing of non-traditional varieties.
■ Encourage consumer/supermarket to stock ethically shed supplies.
what are the benefits of fish farming
- Fish farming has been seen as a good way to reduce overfishing, and is a
better way of producing meat as they convert their food into body protein
more efficiently than other animals. - Heating of the environment is not
required, which lowers the energy input. This has resulted in trout and
salmon being routinely farmed in the UK,
what are problems with fish farming
■ The farms are very densely stocked, meaning that disease spreads more
easily, and there is a risk that disease could also spread to wild sh in the
vicinity. Antibiotics and pesticides may be overused on the farms, which
could lead to antibiotic and pesticide resistance.
■ Pesticides used to control sh parasites also harm marine invertebrates.
■ The excretory products from the farmed sh are converted into nitrates
by bacteria, increasing nitrate concentration in the water, leading to
eutrophication.
■ Fish can escape and outcompete native species for food.
describe the tupe of environmental monitoring to determine wether a development is sustainable
■ Monitoring air quality to identify possible risks to human health.
■ Monitoring soil structure, drainage, pH, organic matter and the diversity of
living organisms.
■ Monitoring water quality in terms of chemical composition, species
composition (freshwater invertebrates are a good indicator of pollution,
e.g. may y nymphs are sensitive to low dissolved oxygen, and cannot
survive), and microbial counts.
what are enviornmental impact assesments and what do they do
- Environmental Impact Assessments (EIAs) must be performed before
new developments are given the go ahead. - These were introduced by the
EU in 1985 and must consider the environmental consequences of the
development. - Initially the environment is surveyed so impact upon existing
flora and fauna can be considered.
what are the 9 plantary boundaries
- atomespheric aerosols
- biodiversity integrity
- fresh water use
- climate change
- ozone depletion
- biochemical flows
- novel entities
- land system change
- ocean acidification
describe the categories in which the 9 planetary boundaries lay in
Some of these boundaries have been
crossed as a result of human activities: four have been crossed, meaning
further events are unpredictable, the crossing of a further two boundaries
may have been preventable, and the crossing of one has been avoided.
planetary boundary
the limits between which
global systems must operate
to prevent abrupt and
irreversible environmental
change.
what is the climate change boundary
This is one of two core boundaries, and its boundary has been crossed, due to the large volumes of greenhouse
gases emitted over the past century. Even drastic reductions in emissions will still only reduce global temperature
rise by 2°C, from the 5°C predicted by some scientists.
what are the three types of biofuel
- bioethanol
- biodiesel
- biogas
how do biofuels reduce emissions but give a counter argument
- The use of biofuels is seen as a way to achieve this, as by
growing them they remove carbon dioxide from the atmosphere during photosynthesis. - They are not completely
carbon-neutral as energy is used in their production, processing and distribution. Using land for the production
of biofuels has it problems: - in the UK if all arable land was used to produce biofuels, we wouldn’t be able to
produce enough to meet our needs and we would have no land to grow food!
how is bioethanol produced
Bioethanol is produced from
crops such as sugar cane and up
to 15% can be added to regular
petrol. It is made via simple
alcoholic fermentation.
how is biodiesle made
is widely used in
Europe. It is made from
vegetable oils, where the fatty
acids are reacted with alcohol to
produce methyl ester (biodiesel).
how is biogas made
- Biogas is methane from the
digestion of organic plant and
animal wastes. - Aerobic digestion
of proteins, fats and carbohydrates produces their respective monomers. Methanogenesis from carbohydrate molecules under anaerobic conditions produces methane and carbon dioxide. - Methane is naturally produced
by decaying organic material at land ll sites, so this can also be collected and used.
core boundary
crossing
this planetary boundary
would drive the Earth into a
new and unpredictable state
with severe consequences
for the biosphere.
biofuel
a fuel made by a
biological process such as
anaerobic digestion, rather
than by geological processes
that formed fossil fuels.
describe the biosphere integrity boundary
- Previously known as biodiversity loss and species extinction boundary, it represents the biodiversity of
ecosystems, and is the second core boundary to be crossed. - Habitat destruction, pollution and climate change
are all responsible for reducing biodiversity. - It has been estimated that without signi cant change, more than
half of the ocean’s species will be lost by the year 2100. The symbiotic relationship between coral and algae is a
fragile one: just a 2°C rise in sea temperatures would cause the coral to expel the algae and the coral would die –
this is known as coral bleaching.
describe the land system change boundary
An example of this is deforestation for agriculture, livestock rearing, and the
cultivation of biofuel crops. This boundary represents the the misuse of land
resulting in too little food being produced.
what is the biogeochemical flows boundary
This boundary refers to the cycling of minerals through cycles like the carbon,
phosphorus and nitrogen cycles. Overuse of nitrogen and phosphorus-based
fertilisers means that this boundary has already been crossed, and the cycles
are no longer self-sustaining.
fresh water
has a low
concentration of dissolved
minerals i.e. <0.05% (w/v).
desalination
the removal
of salt and other minerals
from saline water.
describe the stratospheric ozone boundary
This boundary represents the destruction of stratospheric ozone by CFCs found in propellants and refrigerants prior
to 1987 when the Montreal protocols banned their manufacture following the discovery of a ‘hole’ in the ozone
layer over Antarctica. This action has reversed the crossing of this boundary.
describe the ocean acidification boundary
The pH of the oceans has fallen from 8.16 to 8.03 in the past three centuries which represents a 30% decrease
(due to the scale being logarithmic). Fish and invertebrates are particularly sensitive to reductions in pH. Swift
action to reduce carbon emissions may prevent this boundary being crossed.
what are methods for increasing the availability of fresh water
- Using water-effient appliances.
- Reclaiming waste water for irrigation and industrial use.
- Stop irrigating non-food crops.
- Irrigate crops by using drip-irrigation systems.
- Capture storm water run-off for recharging reservoirs.
- Desalinate salt water.
why has fresh water availaibility decreases
Fresh water availability has decreased due to: irrigation for agriculture,
deforestation, water pollution, draining wetlands, increasing population size
and per capita (per person) use.
describe the fresh water use boundary
This represents the boundary at which organisms do not have enough regular
fresh water to survive. Crossing this boundary is avoidable if fresh water use
can be reduced. The majority of water on Earth (97%) is saline, and a large
proportion of the remaining fresh water is locked up in ice, or is undrinkable
due to pollution. Unfortunately, fresh water is not evenly distributed: India
has 10% of the world’s water but has over 17% of the world’s population.
what are the two main methods of desalination
Desalination works by two main methods: reverse osmosis which separates
fresh and seawater by use of a selectively permeable membrane and pressure
to force water against its water potential gradient, and the use of solar stills
that use the sun’s energy to distill water.
what is the atmospheric aeorol loading boundary
This boundary represents the atmospheric microscopic particles from fossil fuels and dust from quarries. These
particles worsen respiratory diseases like asthma, and settle on plant leaves blocking sunlight. This boundary has
not been quanti ed.
what is the introduction to novel entities boundary
Originally called the chemical pollution boundary, it represents pollution from new manufacturing, radioactive
materials and nanomaterials. Some chemicals have already been banned due to their toxicity, e.g. PCBs and
DDT. The interaction of these chemicals is still relatively unknown, hence it has not been possible to quantify
this boundary.
