3.6 Human Impact On The Environment Flashcards
What is extinction
It results in a loss of a species and decrease in biodiversity
What is an endangered species
A species that is seriously at risk of extinction
What is a natural reason for extinction to occur
Natural selection during evolution
What human impacts can cause species endangerment?
• habitat destruction
• pollution of the environment (PCBs oil and pesticides)
• over hunting/collecting by humans
• competition from domestic animals- introduction of alien species to an ecosystem may out-compete the native species
• monoculture
• building roads, houses and factories
What is conservation?
The sensible management of the biosphere and enhancement of biodiversity lovally
Why is conservation vital for maintaining biodiversity for the future?
It conserves existing gene pools in the wild and in captivity
How can conservation be achieved?
• habitat protection (nature reserves and SSSI)
• international cooperation restricting trade
• breeding programmes by zoo’s and botanic gardens
• sperm and seed banks
• reintroduction programmes eg red kits mid wales
• legislation to prevent overfishing, poaching, collecting birds eggs, picking wild flowers
What does it mean for the gene pool of that species is the species is conserved?
The gene pool is also conserved
What is a gene pool?
The total of all alleles for all of the genes in a population
Why are gene pools so important in the wild?
It maintains the genetic diversity of the species which is critical if the species is to survive changing environments as natural selection is dependent on variation in the species
Why are gene pools important in conservation and how is this done?
• captive breeding programmes - to maintain the genetic diversity of the stock to ensure the diversity of the species
• some organisms gave alleles that are useful to humans
- domestic animals and plants have wild relatives that may have useful alleles that could be bred back into domestic varieties (the point of sperm and seed banks - to be able to do this)
- many plants have medicinal properties and if they become extinct before investigation resource would be lost
• ethical reasons - uniqueness of each species is valuble
What is the tension between in agricultural exploitation?
The tension between an ever-increasing population to feed and so the need to produce more food and the need to conserve the environment and biodiversity
What is agriculture?
The means of producing food for human consumption in order to meet demands
What are 3 things agriculturalists have done to meet growing demand?
• created larger fields by removing hedges
• cultivated monocultures
• increased their use of fertilisers and pesticides
Why is removing hedgerows a problem?
They provide valuable habitats for wildlife and so their loss reduces biodiversity
Why is cultivating monocultures a problem
• only 1 type of habitat which reduces biodiversity
• reduces soil fertility- increases need for fertilisers
• plants grow very closely together and so are susceptible to the same pests and diseases which can pass around rapidly
What is a monoculture and why are they useful for agriculturalists?
It is the growing in large numbers of the same, genetically identical individuals in a given area
It allows farmers to grow crop that are easy to harvest mechanically
Why are fertilisers problematic?
Cause eutrophication of nearby water bodies as the excess leaches into rivers
Why are pesticides problematic?
They harm beneficial species as well as pests which causes them to decline in numbers
What is deforestation?
The complete loss of trees (due to human activity) in a defined area
What are the main concerns to do with deforestation?
The rate it is occuring
Trees are being cut down faster than forests can regenerate
What are the consequences of deforestation?
• habitat loss - reduced biodiversity
• desertification - soil becomes infertile and unable to sustain plant life
• lowland flooding
• increase in soil erosion which leads to nutrient loss
• climate change - less trees to absorb CO2
Why is forest management important?
It preserves natural woodland which enhances biodiversity
What does forest management involve?
Sustainable replanting and regeneration, protected areas to preserve species
What are three ways trees can be harvested through forest management
Coppicing
Selective cutting
Long rotation time
What is coppicing?
Tree trunks are cut at the base so new shoots grow from the stool which can be harvested at different diameters for different purposes
What is environmental monitoring?
Physical and biological measurements that are made over a period of time
Why is environmental monitoring required?
To monitor the effect, assess the effectiveness and measure the environment impact of conservation and re-introduction programmes
Some aspects that are routinely monitored
• chemicals - pH, CO2, nitrates, ammonium
• biotic - animals and plants - especially ones sensitive to change
• radiation
• microbes- especially areas which are used for recreation which could be unsafe if levels become dangerous
What is a plantery boundary
It defines a safe operating space for humanity
What does the scientific research involved with planetary boundaries indicate?
That since the Industrial Revolution human actions have gradually becomes the main driver of global environmental ghange
What could happen is 1 or more planetary boundary thresholds are exceeded
A possibility of abrupt and irreversible environmental change
Biodiversity planetary boundary
• Crossed
• Extinction- natural selection
• Change of habitats effect indigenous species eg marine, tundra, coral reefs and coastal plains
• Biodiversity monitoring - gene banks
• Public awareness
Climate change planetary boundary
• crossed
• greenhouse gases (CO2) and their sources
• effects the human population
• effects plant and animal populations
• rise in sea levels, rise in global temperature
• deforestation and weekend carbon sinks
Ozone depletion planetary boundary
• avoided
• depleted in recent decades due to chemical pollutions from CFCs
• Montreal protocol 1987 - banned manufacture of CFCs found in propellants and refrigerants
Aerosol planertary boundary
• unquantified
• aerosols are atmospheric polluants
• effect are complex
Ocean acidification planetary boundaries
• avoidable
• owing to increased CO2 dissolving into oceans and forming carbonic acid
• organisms with calcium carbonate shells eg corals and molluscs can’t make shells in acid water
• knock-on effect on food chains and webs and could drastically reduce fish stocks
Biochemical flows planetary boundary
• crossed
• concerns nitrogen and phosphorus cycles
• both fertilisers but up-take by plants leads to eutrophication
Freshwater planetary boundary
• avoidable
• globally fresh water is becoming scarce because of modification of water bodies and land use change
• desalination of sea water could be an answer
Land system change planetary boundary
• crossed
• describes land converted for human use eg for agriculture
• eg deforestation, livestock rearing and cultivation of biofuels crops
• represents the misuse of land resulting in too little food being produced
What is overfishing?
Level of fishing where increased effort results in a declining catch
Examples of overfishing
Drift netting
Trawling
What is drift netting?
Use of massive nets and non-target species
What is trawling
Weighted nets dragged along the floor of sea
Ways to reduce impact of overfishing
• fish quotas
• reduce size of fishing fleets
• restricting season for fishing
• restricting mesh sizes for nets
• exclusion zones
• fish farming
How does fish quotas reduce impact of overfishing
Limits how many of each species can be caught
Heavy fines are set
How does reducing size of fishing fleets reduce impact of overfishing
Less boats out
How does restricting season for fishing reduce impact of overfishing
Allows fish stocks have time to replenish
How does restricting mesh sizes for nets reduce impact of overfishing
Smaller fish can escape and go on to breed
How does exclusion zones reduce impact of overfishing
Fish populations will remain at sustainable levels
What is fish farming
Isolating area of sea for the purpose of breeding and growing fish in managed conditions
Fish are fed, treated with chemicals then harvested
The problems involved with fish farming
• addition of nutrients can lead to eutrophication
• overuse of antibiotics can cause resistance
• non-specific pesticides can leak out
• fish can be overcrowded which means diseases can spread rapidly
• fish in captivity may be GM for fast growth and larger sizes - will cause problems with wild stocks if they espace
How is the provision of additional nutrients a problem of fish farming
It can lead to excess nutrients in the area leaking out and causing eutrophication
This causes oxygen depletion which can cause the fish to suffocate
How is overuse of antibiotics a problem of fish farming
It can cause resistance in pathogenic bacteria
How are non-specific pesticides a problem of fish farming
If they leak out they can affect the marine food chain
How is fish being netted off and overcrowded a problem of fish farming
Diseases and pests can spread rapidly and easily
How are fish in captivity maybe being genetically modified a problem of fish farming
They’re genetically modified for fast growth and larger sizes
If they escape and breed with wild stocks or compete with them for food it could push wild fish to extinction
What is an SSSI
Site of special scientific intrest
