Unit 3.6 - Human impact on the environment Flashcards
Why is biodiversity currently in a crisis?
Due to extinction happening at such a high rate
Why is extinction happening at such a high rate?
Humans effect the species richness of an area
Give 5 reasons why species are threatened by human activity
Land-use changes (urbanisation, farming)
Introducing exotic species
Pollution
Resource exploitation
Overhunting
What’s the name for the limit of the size of the human population that the planet can sustain?
Carrying capacity
Carrying capacity of the global ecosystem
The limit of the size of the human population that the planet can sustain
Describe human population growth
Exponential
What is an indication that we’re reaching the carrying capacity of the human population?
Human population growth is exponential, however recent research shows that population or what is slowing, implying that we’re reaching the carrying capacity
How can we increase the carrying capacity of the planet?
Use technology
What’s the problem with using technology to increase the carrying capacity of the planet for humans?
If we exploit the environment in this way, it effects the populations of other species, leading to biodiversity loss
3 main human activities that lead to biodiversity loss
Agricultural exploitation
Deforestation
Overfishing
Why do we have increased yields with current farming practices?
Intensive farming
What has intensive farming seen an increase in?
The use of chemical fertilisers, pesticide and herbicides
Mechanisation
What does increasing mechanisation for intensive farming need?
Large fields to accommodate large machinery
What has the requirement for larger fields for increased mechanisation in farming led to?
A reduction in the number of hedgerows
Why are hedgerows so important?
Provide habitats for insects
Provide nesting sites for birds and reptiles
Provide food for many species (e.g - herbivores, and a reduction in their numbers leads to reductions at higher trophic levels)
Varying light intensity and water availability for diverse plants
What does the loss of hedgerows lead to?
A reduction in biodiversity
What are many large fields in farmland used to grow?
Monocultures
Monoculture
The growth of large numbers of genetically identical crop plants (one species) in a defined area
The growth of large numbers of genetically identical crop plants (one species) in a defined area
Monoculture
What happens in a monoculture?
Larger fields are used to grow monocultures, in which a single crop (e.g: wheat, corn or barley) is grown on a massive scale
Why do monocultures reduce biodiversity?
Provide only one type of habitat
Nothing natural can grow in these areas, so other species are excluded from their habitat
What does less plant diversity lead to and why?
Less animal diversity
Less habitats for them
What is true due to all of the plants of a monoculture being genetically identical?
All of their roots grow down to the same level in the soil
Describe roots of plants with a higher biodiversity
Different lengths of roots in soil
What happens as a result of all of the plants of a monoculture having the same root length?
Plants extract minerals (e.g - nitrates) from the same depth of soil
This leads to low mineral levels here
What does monocultures roots all being the same length lead to the need for?
Chemical fertilisers
Why are chemical fertilisers used on monocultures?
All genetically identical = roots grow to the same level = Extract minerals from the same depth of soil = low mineral levels here = nutrients are depleted in this soil depth and soil becomes nutrient poor
Chemical fertilisers replace the natural minerals in the soil and keep the land fertile
Problem with using lots of chemical fertilisers
Eutrophication
Another issue relating the monocultures apart from the use of chemical fertilisers
Plants of the same species are grown so close together are susceptible to the same pests and diseases which are able to pass from plant to plant rapidly
Why are pests and diseases able to pass from plant to plant rapidly in monocultures?
Same species = susceptible to the same pests and diseases
Grown so close together
What are used to reduce damage to monocultures from pests and diseases?
Pesticides
Issue with using pesticides on monocultures
Many of the pests are insects and pesticides might kill all the other species of insect in that area
This may include the natural predator of the pest that’s naturally keeping the population down
When does overgrazing occur?
When cattle and sheep farming is done on a very large scale
What are cattle on overgrazed land fed and why?
Artificial feed
When land has been overgrazed, there’s no natural grazing for the animals (nothing natural growing)
What can overgrazing cause? How?
Soil compaction from the land being trampled
Issues with soil compaction (occurs during overgrazing)
Reduced air spaces = nitrogen fixing and nitrifying bacteria is inhibited = loss of soil fertility
Water is unable to penetrate compacted soil = stops the drainage of water to plants = grass and plant growth is inhibited
Why is compact soil not very fertile?
Reduced air spaces = nitrogen fixing and nitrifying bacteria is inhibited
Why is grass and plant growth inhibited in compact soi?
Water is unable to penetrate compacted soil = stops the drainage of water to plants
What’s being done for the future to tackle agricultural exploitation?
Schemes and legislation aims to reverse the decline in biodiversity and soil fertility
List the schemes and legislation aims to reverse the decline in biodiversity and soil fertility
Organic farming
Set-aside schemes
Legislation
What is organic farming?
Reduces the need for chemical fertilisers and pesticides and allows for crop rotation on smaller fields
Why would we want to move cows onto different fields?
Less pressure on the land
Why would we want to grow different crops during organic farming?
Provides a variety of habitats and increase biodiversity
Why is organic farming advantageous to the grower?
The farmer can sell for a higher cost
What are set-aside schemes?
Farmers manage their farms for biodiversity; land is set aside for conservation and wildlife + encourages to grow more trees on their land
Government grants compensate the farmer for loss of income
Why are set-aside schemes controversial?
Farmers need to make a living from their land and don’t want to exclude areas that they have
What has legislation in agricultural exploitation led to? Give an example
The environment act 1995
Loss of hedgerows has been reversed
What can hedgerows act as?
Corridors allowing wildlife to move from area to area safely
Deforestation
The complete loss of trees (due to human activity) in a defined area
Why is deforestation done?
Land used for agriculture, building or infrastructure
What’s the issue with the current rate of deforestation?
Trees are being cut down faster than they can regenerate
What were the areas that undergo deforestation previously?
Large natural forests
Why is deforestation happening on such a large scale?
Due to the increasing pressure on governments to sustain the population
List the consequences of deforestation
Soil erosion
Lowland flooding
Desertification
Habitat loss
Decrease in biodiversity
Climate change
Why does lowland flooding occur after deforestation?
When trees are cut down on hillsides, water that’s usually held by tree roots runs back down alleys and causes flooding in lowlands
Why does desertification occur after deforestation?
Soil becomes so infertile due to the lack of minerals in it, plants can’t be grown from it
What does deforestation contribute to climate change?
Trees store carbon and use CO2 from the atmosphere to make carbohydrates
It’s the carbon trapped in wood that makes it solid, demonstrating how massive of a carbon store trees are
So when trees are cut down, carbon is returned into the atmosphere, leading to an increase in the greenhouse effect
How do we know that trees are a massive carbon store?
It’s the carbon that makes wood solid
Why are woodlands important?
Highly productive and an important resource for humans
What does manages forestry involve?
Sustainable replanting and regeneration
List the method of forest management
Coppicing
Selective cutting
Long rotation time
Coppicing
Tree trunks are cut at their base, leaving a stool (stump) a few centimetres above the soil
Why does Coppicing work?
New shoots grow from the stool (the tree isn’t dead) which can be harvested at different diameters for different purposes
Different purposes of harvested coppiced woof
Building, fencing or fire wood
What does coppiced woodland at different stages provide?
A valet of habitats and increases biodiversity
Why does coppiced woodland increase biodiversity?
Provides a variety of habitats
What’s useful for us as people with Coppicing?
The tree can be harvested when new shoots grow at different diameters for different purposes
Biodiversity of coppiced woods
Is actually higher than natural forests
Selective cutting
Cut certain areas of forest for a particular purpose and then move onto a new big, allowing the original area to grow back via secondary succession
Only cut the trees that meet a certain criteria
Long rotation time (forest management)
Giving trees longer in their life cycle before being cut down
What type of trees are normally used in deforestation?
Fast growing trees that are cut down early in their life cycle to be used
What’s the idea behind long rotation time (forest management)?
If the trees are given longer to grown it will increase the biodiversity of the area
What are the problems related to overfishing?
Overfishing depletes fish stocks
Fish populations may become too low to recover —> they are no longer viable
This also impacts food chains and entire ecosystems
Methods of commercial fishing
- Drift netting
- Trawling
Drift netting
A net, suspended from floats, is stretched between 2 boats
What’s the problem with drift netting as a fishing method?
Thousands of miles of nets worldwide are set and non-target species are often caught (e.g - dolphins and turtles)
Trawling
Weighted nets are dragged across the ocean floor
Problem with trawling
This method catches everything and damages the ocean floor, decimating habitats for many miles
Why is the fishing industry regulated?
To preserve fish stocks
List the ways in which the fishing industry is regulated
Regulating mesh size
Quotas and landing size regulations
Exclusion zones
Marine stewardship council certification
Legislation limiting the size of fishing fleets or controlling the number of days spent at sea
Fishing alternative, non-traditional, species
Using lines, not nets
What’s the idea behind regulating mesh size for commercial fishing?
Larger holes in the net = immature fish can escape
Only catches mature and larger fish that have had the chance to breed
Quotas (fishing industry)
Limits the amount of fish a particular boat/canopy can land in a season
Landing size regulations
Can’t sell dish that are too small (need to give them a chance to breed)
Exclusion zones (fishing industry)
Ban fishing in certain areas to give it a chance to recover
Explain the marine stewardship council certification
Boats and companies follow certain rules to get certified that they’re not environmentally damaging, making their catches easier to sell
Why are using lines better than nets for fishing?
Lines are less damaging
Are lines better than nets?
Yes, although they can still catch non-targeted species
How many planetary boundaries are there?
9
What do the planetary boundaries regulate?
The stability of the land, atmosphere and sea
What have scientists decided on in order to create the planetary boundaries?
On measurements for how human activity has impacted the different factors of the global ecosystem
What do planetary boundaries define?
The safe operating space for humanity
What would happen if we exceed all 9 planetary boundaries?
Planet earth may no longer be able to support a human population
What may be reached in any planetary boundary and what would occur in this circumstance?
A tipping point
At this point, a change in a process wouldn’t give a linear response. A small change may have a large and unpredictable effect on the environment
Estimates for what have been made with regards to the planetary boundaries?
Estimates for upper and lower values
Response to change between the upper and lower boundaries of planetary boundaries?
Gradual
Effect of exceeding the upper limit of a planetary boundary
Likely to produce sudden, catastrophic changes to the environment
What are the 9 planetary boundaries?
Climate change
Biosphere integrity
Land system change
Biogeochemical flows
Stratospheric ozone
Ocean acidification
Fresh water use
Aerosols
Introduction of novel entities
What do we call the area within the green circle with the planetary boundaries?
The safe operation zone
What do we call the area between the green and red circle with the planetary boundaries?
Zone of uncertainty (increasing risk)
What do we call the area beyond the red circle with the planetary boundaries?
Beyond zone of uncertainty
Describe the area beyond the zone of uncertainty with planetary boundaries
High risk - events are unpredictable
Global planetary boundaries
Climate change
Stratospheric ozone
Ocean acidification
Planetary boundaries that relate to the biosphere
Biosphere integrity
Land system change
Biogeochemical flows
Fresh water use
Planetary boundaries that are non-natural phenomena
Aerosols
Introduction of novel entities
Planetary boundaries that have been crossed
Climate change
Biosphere integrity
Land system change
Biogeochemical flows
Avoidable planetary boundaries
Ocean acidification
Fresh water use
avoided planetary boundary
Stratospheric ozone
Planetary boundaries that haven’t been quantified
Aerosols
Introduction of novel entities
Why are some of the planetary boundaries not quantified?
Haven’t agreed on an effective way to measure them
What type of boundary is the climate change boundary?
Core boundary
2 core boundaries
Climate change boundary
Biosphere integrity boundary
Core boundary
Crossing it would drive the earth into a new and unpredictable state with severe consequences for the biosphere
What would happen in terms of global warming if emissions stopped immediately and why?
The average global temperature would still continue to rise for decades
The planetary boundary is a core boundary that has been crossed
Biosphere integrity boundary
Speed of biodiversity loss and speed of species extinction
What has human activity caused the extinction of?
100s of species
Why do species become extinct?
Environmental changes are happening faster than natural selection can keep up with
Sometimes, species fail to reproduce enough to maintain the species, therefore they become extinct
Why are species becoming extinct in oceans?
Oceans polluted with acid, oil, plastic and pesticides, which have a global reach
What does coral reef leaching cause?
Species loss
How does coral bleaching occur?
Warm temperatures cause zooxanthellae that give corals colour to leave
Why is bleached coral bad?
The zooxanthellae that gave the corals colour’s photosynthesis was what fed the corals
How are biodiverse coastal communities being effected?
Submerged as sea levels rise, and are flooded with salt water
Why is an area being flooded with salt water bad?
Water loss by osmosis kills plants, which consequently kills the animals of communities
Example of land-system change
Deforestation
When has deforestation occurred largely?
Through the expansion of farming and raising livestock
In terms of the land-system change boundary, what have large forest areas been cleared for?
Plants such as oil palms and soya beans to make biofuels
What are oil palms and soya beans used to make?
Biofuels
What is using land for biofuel crops in direct conflict with?
The people’s need to grow food, and vice versa
What does the land-system change boundary represent?
The misuse of land that results in too little food being produced
What is land often used for in communities which is problematic?
To grow food for export instead of providing communities
Ways we can reverse the land-system change boundary and produce enough food
Concentrate farming into the most productive areas
Reduce global meat consumption
Use genetically modified plants
What does the Biogeochemical flows planetary boundary refer to?
The cycling of minerals through the biotic and abiotic components of an ecosystem
Why have the boundaries for both the nitrogen and phosphorus cycles been crossed?
Agricultural fertilisers used so intensively
Which minerals specifically have crossed their boundaries within the Biogeochemical flows planetary boundarry?
Both the nitrogen and phosphorus cycles
Problem with the boundaries for the nitrogen and phosphorus cycles being crossed
No longer self-sustaining
Eutrophication
How are we aiming to reduce fertiliser use?
Aims to transfer nitrogen fixing (nif) genes to crop plants, which hasn’t been possible yet
Ozone
O3
What is the ozone layer?
An O3 layer in the upper atmosphere
How are ozone and oxygen normally?
In equilibrium
What do CFC’s do to the ozone layer and why?
Break it down
They alter the position of equilibrium between ozone and oxygen and favour the breakdown of ozone
What do CFC’s do under the influence of UV light?
Release chlorine as free radicals and each one can break down 100,000 ozone molecules
Under which conditions do CFC’s release chlorine as free radicals?
Under the influence of UV light
What can chlorine free radicals do when CFC’s release them?
Break down ozone molecules
Why is the ozone layer useful?
Stops high energy radiation from the sun
Filters out most UV radiation onto earth
Where are CFC’s found?
Fringes
Propellant in aerosol spray cans
What did CFC’s and other polluting chemicals do at one point and how?
Formed a hole in the ozone later
These chemicals break the ozone layer down
Why was having a hole in the ozone layer an issue?
Intensity of UV radiation increases
Why was having increased UV radiation due to the hole in the ozone layer an issue?
Range of wavelength absorbed by ozone is strongly absorbed by DNA, so cataracts and skin cancers increased in number
What was done about CFC’s and what happened as a result?
Banned globally
Since then, the hole closed back up
Only planetary boundary crossing that’s been avoided
Ozone depletion boundary
What does the avoiding of crossing the ozone boundary give evidence of?
That when humans act globally these processes can be inversed
Are the planetary boundaries within our control? What does this mean for us?
Lots of them are
Could come back into the safe operating space if there’s a will globally
Equations for the reaction of CO2 in the atmosphere with water (ocean acidification boundary)
H2O + CO2 —> H2CO3 —> H+ + HCO3-
HCO3- —> H+ + CO3^2-
Carbonic acid
H2CO3
H2CO3
Carbonic acid
How does the ocean get more acidic?
Reaction of CO2 in the atmosphere with water
Increases the concentration of H+ ions
Decreases the pH = more acidic water
Give some examples of the effects of the ocean having a low pH (ocean acidification boundary)
- leaches calcium carbonate from mollusc and coral shells and arthropod exoskeletons, softening them so organisms are vulnerable to physical and chemical attack
- fish gill structure and functioning is damages
- bad for marine plankton (sensitive to pH changes)
Fresh water use boundary
The amount of water available for humans and plants
What must be done to avoid crossing the fresh water use boundary?
Fresh water use must be reduced
Where does fresh water occur naturally on earth’s surface? Give some examples
Rivers
Lakes
Ponds
Icebergs
Ice sheets
Ice caps
Glaciers
Where does fresh water come largely from?
Precipitation as mist, rain and snow
What is most of earth’s water?
Saline
Potable
Drinkable
Why is fresh water not always potable?
It carries materials blown in the wind
Describe how freshwater can be in industrialised areas
Acidic
Describe how freshwater can be in coastal areas
May contain salts
Describe how freshwater can be in desert or dusty soils
May contain sand and dust
Give some reasons for the diminished supply of fresh water
Changing landscapes (deforestation, soil erosion)
Agriculture
Moving to places with warmer climates and low levels of fresh water
Water pollution (e.g - eutrophication)
Increase in use
Increase in population through increases in life expectancy
Climate change
Semi-arid and arid places relying on rain, which has its periods disrupted
Ways in which climate change is diminishing freshwater supplies?
Glaciers melting
Rising sea levels
How does melting glaciers diminish freshwater supplies?
Availability initially increases, but there may be flooding, then availability decreases, causing drought
How do rising sea levels diminish freshwater supplies?
Ground water becomes too salty for drinking and irrigation
Why are semi-arid and arid areas suffering from dimished water supplies?
Rely on rain as their water supply
Rain occurs in a short space of time and these periods are already disrupted
atmospheric aerosols
the microscopic particles put into the atmosphere by combustion of fuels and by creating dust from digging and quarrying
problems with atmospheric aerosols
respiratory problems
on leaves –> reduces sunlight for photosynthesis = reduced crop yield
sulphates –> reflect sunlight = cooling effect
soot –> absorbs sunlight and reradiates it = increases warming
= balance between these two isn’t clear
problems with atmospheric aerosols on leaves
reduces sunlight for photosynthesis = reduced crop yield
why haven’t we suggested planetary boundaries for aerosols
too viable
introduction of novel entities boundary
chemical pollution boundary
what types of pollution does the introduction of novel entities planetary boundary include?
organic pollutants
radioactive materials
nanomaterials
micro-plastics
what’s the problem with the introduction of novel entities?
there are 100,000 different manufactured chemicals in use in different products, which may interact with each other to cause harmful effects
why haven’t planetary boundaries been identified for the introduction of novel entities boundary?
not possible to quantify the effects of these pollutants
What is the problem with invasive species?
May not have a natural predator
Introduction of disease
Compete
Breed and reduce genetic diversity (=increased extinction risk of other species)
Describe and explain the advantages of selective cutting
-soil erosion less likely
-allows light to reach ground level to stimulate growth
-seeds from nearby trees reach the area
-secondary succession
-habitats maintained and more niches available
-dead leaves can add nutrients to the soil
-soil not as wet as in mass felling
= more oxygen available for root growth
=less denitrification
Describe the soil when comparing mass felling and selective cutting
Mass felling causes wetter soil
What does less wet soil lead to?
More oxygen available for root growth
Less denitrification
What can dead leaves do to soil?
Add nutrients
When is soil erosion more likely - with mass felling or selective cutting?
Mass felling
How come habitats are maintained with selective cutting?
Allows light to reach ground level to stimulate growth
Seeds form nearby trees reach the area
Secondary succession
Describe planetary systems within the safe operating space
Stable
Changes are reversible
Describe planetary systems beyond the safe operating zone
High risk
Unpredictable
Irreversible
How deforestation affects the planetary boundary for climate change?
Reduces CO2 uptake
Decay of waste tree material
Burning of felled trees puts CO2 into the atmosphere
Why are more species becoming extinct recently?
Changing environment = selected against
Increasing human population is causing environmental change
Cannot evolve in a relatively short period of time - slow mutation rates
Ways of delaying biodiversity loss with conservation methods
Sperm/seed banks for rare species
Natural parks and conservation areas and ecotourism
Breeding programmes
Fishing quota
Legislation
Management of wild populations
Restrict habitat restriction
Why is eliminating lice a problem for fish farms?
As they cannot easily be killed as they’re resistant to pesticides
Why is it important to prevent farmed fish from escaping their pens?
Invasive species —> reduce wild fish numbers and diversity of species
Compete for food and habitat = food chains effected
Spread disease to native fish
Breed with wild fish and reduce genetic diversity (dilute gene pool) = effects long term survival
