6 - Human Impact on the Environment (C1) Flashcards
What is the problem of land use change caused by?
Natural ecosystems, such as rain forests, have been used for urban development, raising livestock and farming, including growing biofuel crops
What are 3 examples of endangered species?
- Black rhino - Orangutan - Bengal tiger
What is biodiversity?
The variety of life on the plant (species number and evenness)
How does pollution of inorganic chemicals cause extinction?
- Industrial chemicals such as PCBs and pesticides are not biodegradable so accumulate through the food chain - Most of these pollutants are fat soluble and accumulate in body tissues
Why is manure and compost often added to soils?
To add nitrate to the soil
What is coppicing?
A technique whereby trees are cut down close to the ground and then left for several years to re-grow shoots
What is monoculture?
The simultaneous growth of a large number of crop plants of similar age and type within a defined area
What are some reasons for deforestation?
- Land needed for agriculture - Land needed for road and housing development - For resources e.g. timber
What is selective cutting?
Cutting only some trees, leaving the others in place
What steps can be taken to improve the efficiency of forestry?
- Planting trees optimum distance apart - Controlling pests and diseases
- Cutting a similar number of trees each year for long periods of time, allowing the forest ecosystem to be maintained
What are advantages and disadvantages of coppicing?
+ Promotes regrowth and a sustainable supply of timber for future generations - Time consuming and labour intensive
What are advantages and disadvantages of selective cutting?
+ Helps maintain nutrients in forest soil + Minimises amount of soil washed into nearby waterways - Expensive - Time consuming - Some species won’t regrow as fast
What is long rotation time?
When many years are left between harvesting adjacent areas of forest
What are advantages and disadvantages of long rotation time?
+ Increases sustainability + Allows a variety of habitats to develop - Time consuming
What is replanting trees?
When all trees in the area are cut down at the same time
What are advantages and disadvantages of replanting trees?
+ Supplies resources for future generation - Care must be taken to ensure trees are being planted specific distances from other trees
What is regeneration?
The process by which new tree seedlings become established after forest trees have been harvested or died
What are advantages and disadvantages of regenerating trees?
+ Cheap, native plants that grow this way are likely to be well adapted to the area - Little control over spacing - May require some preharvesting operations to ensure regeneration
What do fishing exclusion zones do?
Prohibit fishing in certain areas and certain times of the year, allowing fish to reproduce
What do fishing quotas do?
Ensure only a certain mass of fish can be brought to land
What does increasing the fishing mesh size do?
Ensures young fish that are not yet sexually active are not caught
What are some methods of combatting over fishing?
- Exclusion zones - Removing subsidies - Quotas - Reducing vessels and fishing time - Controlling mesh size - Eating non-traditional fish
Why are diseases common on fish farms and why do treatments lead to environmental problems?
- Fish are crowded together so diseases spread easily - Many treatments are toxic to other organisms - Antibiotics used may lead to antibiotic resistant bacteria developing
What are benefits of fish farming?
- Food security for expanding population - Employment - Makes fish more affordable
Why does fish farming cause eutrophication?
High levels of protein in food of predatory fish, therefore large amounts of nitrogenous waste
What are the 9 planetary boundary global processes?
- Climate change
- Biodiversity
- Land use change
- Nitrate and phosphate
- Ozone
- Acidification
- Freshwater
- Aerosol
- Inorganic pollution
What is meant by the term planetary boundary?
A threshold value for a global process that is affected by human activity. Crossing these boundaries could lead to abrupt or irreversible environmental changes
What is the ozone problem?
- Conc of ozone in the stratosphere has decreased, creating a hole in the ozone layer
- Due to use of CFCs as aerosols
What are consequences of the hole in the ozone layer?
- More UV light penetrates atmosphere
- UV light generates mutations in DNA and causes damage to living organisms
What is an endangered species?
A species of plant or animal that is low in number and at serious risk of extinction
Why is secondary succession often quicker than primary succession?
- There is already an existing seed bank of suitable plants in the soil
- Root systems undisturbed in the soil, stumps and other plant parts from previously existing plants can rapidly regenerate
- The fertility and structure of the soil has already been substantially modified by previous organisms to make it more suitable for growth and colonisation
How does non-contiguous populations cause animals to become endangered or extinct?
- If groups of members of species are isolated, they can’t interbreed and each group functions as a separate population
- There may be too little genetic diversity to ensure a healthy population, leading to extinction
Why can a loss of hedgerows cause animals to become endangered or extinct?
- Hedgerows provide a habitat for insects, birds and reptiles, and provide food
- Vary light intensity and water availability for plants
- Act as wildlife corridors, enabling animals to move from one area to another, helping to maintain biodiversity
What are some examples of overhunting by humans?
- Trophy hunting
- Traditional medical practices
- For food
- Overfishing
Why can oil spilt into water kill animals?
- Oil floats and prevents oxygenation of surface water
- Animals that break through the surface are covered by a film of oil. Animals such as birds are chilled to death as their feathers clump and can’t provide insulation
What are some reasons why species are endangered or extinct?
- Human activities are causing habitats to change faster than natural selection allows species to adapt
- Non-contiguous populations
- Loss of habitat: deforestation, drainage of wetlands, hedgerow loss, also farmers often sow crops in autumn rather than spring so plants are an unsuitable height for birds to build nests
- Overhunting by humans
- Competition from introduced species
- Pollution
What is conservation?
The protection and management of natural habitats and their ecological communities, to enhance biodiversity while allowing for suitable human activity
How can species be conserved?
- Nature reserves
- Sperm banks
- Education
- Legislations
- Ecotourism
How do sperm banks work?
Store genes of economically important animals and of threatened species
What is ecotourism?
Responsible travel to natural areas that conserves the environment and improves the well-being of local people
What are reasons for species conservation?
- Ethical reasons
- Agriculture
- If the environment changes, some alleles will provide an advantage to individuals, preventing the extinction of the species
- Potential medical uses
What is soil erosion?
The removal of topsoil, which contains valuable nutrients
Other than CO2 production, what are consequences of deforestation?
- Soil erosion
- Deforestation of uplands causes lowland flooding
- Destruction of habitats, reducing biodiversity
- Less rainfall, as water only returns to the atmosphere by evaporation from the soil, not by transpiration, and evaporation is slow
Why is raising fish rather than pork, poultry and beef better?
- Fish convert their food into protein more efficiently
- A greater proportion of fishes’ bodies are edible
- Fish farming has a lower carbon footprint
What are problems that fish farming causes?
- Diseased fish: pesticides used to control fish parasites harm invertebrates
- Pollution and eutrophication
- Escaped fish outcompete wild fish for food, habitat and mates
- Resource use: farmed salmon eat 3 times their bodyweight of other fish
What are the 4 planetary boundaries that have been crossed?
- Climate change
- Biodiversity
- Land use change
- Nitrate and phosphate (biochemical flows)
What is a biofuel?
A fuel made by a biological process, such as anaerobic digestion
What are some concerns related to biofuel production?
- ‘Food vs fuel’: land used to grow food is now used for crop production for biofuels, so less food is produced
- Carbon emissions: European bioethanol production and use reduce greenhouse gas production
- Deforestation occurs to grow biofuel crops
- Reduction in water availability, as biofuel crops require a large volume of irrigation water
- Combustion of biodiesel produces more nitrous oxide, a greenhouse gas, than fossil fuel
What is the difference between the composition of biodiesel and petrodiesel?
- Biodiesel contains less carbon and more hydrogen and oxygen than petrodiesel
- Biodiesel releases less carbon particles and less carbon monoxide, but more nitrous oxide
What planetary boundary has been avoided, which are avoidable and which are unknown?
Avoided: Ozone boundary
Avoidable: Ocean acidification, fresh water
Unknown: Aerosol use, inorganic pollution
What are some reasons for the reduction in freshwater availability?
- Changing landscapes: deforestation, draining wetlands and soil erosion influence the flow of fresh water
- Agriculture consumes more fresh water than any other human activity
- Water pollution e.g. eutrophication
- Climate change: rising sea levels that contaminate freshwater
- Increase in population due to increasing life expectancy
What are some methods to increase freshwater availability?
- Water conservation
- Wastewater reclamation
- Desalination: where minerals are removed from salt water producing fresh water
What are some environmental problems caused by desalination? (removing minerals from salt water)
- Brine (concentrated sodium chloride solution) is discharged, but is diluted before returning to ocean
- Brine is denser than seawater so sinks and damages seabed ecosystem
- Burning of fossil fuels to generate heat to run the desalination system
What are atmospheric aerosols?
The microscopic particles put into the atmosphere by combustion of fuels, specifically diesel motor vehicles, and by creating dust from digging and quarrying
