Biology Unit 3.6 - Human Impact on the Environment Flashcards
What is extinction?
Complete loss of a species, caused by climatic, geological or biotic changes
Normal background rate is 10^-6 y^-1
Why do species become endangered of extinct?
- Natural selection due to changing selection pressures
- Non-contiguous populations - populations too small to ensure continuation
- Loss of habitat e.g., deforestation, drainage of wetlands, etc
- Overhunting by humans
- Competition from alien species
- Pollution e.g., oil and PCBs
What is conservation?
Protection, preservation, management and restoration of natural habitats and their ecological communities, to enhance biodiversity while allowing for suitable human activity
Describe protecting habitats…
Protecting a habitat also protects the species living there and their genetic diversity
Describe international cooperation restricting trade…
Restricting trade of endangered species parts
Describe gene banks…
Endangered species are protected in zoos and entered into breeding programmes
Describe sperm banks…
Gametes are small and easy to freeze without damaging the cell of DNA, so banks are used to sore genes of economically important animals and threatened species
Describe Seed banks…
Maintain seed stocks of traditional crop varieties and vulnerable species
Describe rare breed societies…
Maintain older less commercial varieties for special characteristics
Describe species reintroduction…
Following captive breeding programmes these species are reintroduced into their former habitats
Describe education and increasing public awareness…
Organisation mount public awareness campaigns to educate and raise funds
Describe legislation…
Imposed a range of measures to protect habitats and increase biodiversity
What are the ethical reasons for conservation?
Species represent combinations of genes and alleles adapted to a particular environment which is intrinsically valuable
Simply the right thing to do, to preserve species for the future
What are the agricultural/horticultural reasons for conservation?
Genetic diversity could be lost
What are the genetic reasons for conservation?
Changes in the environment will lead to some alleles providing advantages to individuals, allowing them to survive
What are the medical reasons for conservation?
Antibiotics are derived from fungi, etc. Therefore, there must be potential medicinal dug sources yet to be discovered and therefore need to be preserved
Why is organic farming beneficial?
Fewer chemical and antibiotics are used, increasing biodiversity
Why are set-aside schemes beneficial?
Allow farmers to manage their farm’s biodiversity, where some land is given over to conservation
Why is Environment Act 1995 beneficial?
Loss of hedgerows has been reversed, providing habitats for insects and birds that live and feed on them, while providing nesting sites and protection from forest fires
What is deforestation?
Complete removal of trees in order to use the land for another purpose
What is the effect of deforestation on soil erosion?
- Removal of trees destabilises the soil as roots decompose and no longer bind it together
- Canpoy is no longer present, so soil is no longer shielded and topsoil is washed away
- Fertility is reduced, making the land less suitable for agriculture and inhibits reforestation
What is the effect of deforestation on lowland flooding?
Topsoil from uplands is washed into streams and rivers, clogging waterways, leading to flood
What is the effect of deforestation on desertification?
If trees are removed water evaporates directly from the soil surface lading to water logging, which inhibits germination, reducing soil fertility as denitrifying bacteria are encouraged, making conditions unsuitable for plants
What is the effect of deforestation on habitat loss?
Reduces biodiversity
What is the effect of deforestation on the atmosphere?
Less carbon dioxide is fixed by photosynthesis during the light-dependent stage, and cut trees may be left on the ground leading to increased decay, releasing more carbon dioxide into the atmosphere
What is forest management?
Sustainable replanting and regenration of vegetation
What is coppicing?
When trees are cut a stool is left behind allowing shoots to emerge from buds in the stool, which grow into poles that are then collected at different stages of growth to provide different width timbres
What is selective cutting?
Not all trees are harvested at once, protecting slopes from soil erosion and maintaining soil fertility
What is long rotation time?
Many years are left between harvesting adjacent areas of forest, allowing a variety of habitats to develop
What is the benefit of planting trees at an optimum distance apart?
Reduces competition for resources
What is the benefit of controlling pests and disease?
Allows the trees to grow well
What is the benefits of controlling timber cutting?
Allows ecosystems to be maintained as habitats are left intact and species thrive in the forest even though timber is extracted
No sharp shock to the ecosystem
What is the benefit of preserving native woodlands?
Maintains native and ancient species which increases biodiversity, which also forms gene banks for the future to help tackle climate change and disease
What is the effect of overfishing?
Depletion of fish stocks, which reults in a loss of biodiversity and extinction
What methods are used during commercial fishing?
- Drift netting - fish swim into a net, suspended from floats, stretched between two boats, where non-traget species can be trapped
- Trawling
How does regulating mesh size regulate fishing?
Should be large enough to allow young fish to swim through and survive so they can reproduce in the future
How do quotas regulate fishing?
Only allow a certain mass of fish to be brought to land
How do exclusion zones regulate fishing?
Allows fish to reproduce and replenish stocks
How do marine stewardship certification regulate fishing?
Limit the size of fishing fleats and the number of days that can be spent at sea
What are the disadvnatages of fish farming?
- Large amounts of antibiotics are needed
- Water can be polluted
- Pesticides may reduce fertility in organisms
- Fish waste can cause eutrophication
- If they escape they can out-compete wild fish
What methods are used to moniter environment quality?
- Air quality monitoring
- Soil monitoring
- Water quality monitoring
What are the chemical aspect of water quality?
- Increased acid rain and greenhouse hases lead to acidification of the waterways
- Oral contraceptives increse the concentration of environmental oestrogens, feminising aquatic organisms affecting embryo development
What are the biological aspects of water quality?
- Many animals act as indicator species
- Steep decline in salmon is an early indication of acid rain
- Mosses indicate heavy metal concentrations
- Eels are used to study halogenated organic chemicals
What are the microbiological aspects of water quality?
- Bacteria and viruses are monitored
- Many sewage treatment plants do not sterilise the water they release, meaning a viable count is carried out using a serial dilution technique
- Most bacteria are harmless, but if coliform bacteria counts are high water wil be tested and treated
What are planetary boundaries?
Definition of the safe operating space for humanity, where ecxeeding the operating space leads to a sudden and catastrophic change to environmental conditions
What are the nine planetary systems?
- Climate change boundary
- Biosphere inegrity boundary
- Land-system change boundary
- Biogeochemical flows boundary
- Stratospheric oxone boundary
- Ocean acidification boundary
- Fresh water use boundary
- Atmospheric aerosol boundary
- Introduction of novel entities boundary
