Human Impact Flashcards
What is biodiversity?
A variety of species present in an ecosystem, this can be calculated as the number of species in a specific area.
What is extinction?
It is a natural process which leads to the disappearance of a species or a population.
What has extinction been caused by?
It’s caused by changes in climate, geology, and biotic factors, as well as human activity.
What are the reasons for species to be threatened?
Natural selection Deforestation Habitat destruction Loss of hedgerows Hunting and collecting Competition from domestic animals Pollution (PCBs and oil)
Why has natural selection caused species to be threatened?
Existing species don’t have the ability to survive in a changing environment. Human activities are causing habitats to change faster than new mutations allow species to adapt e.g sabre tooth cat, woolly mammoth, cave bear.
Why has deforestation caused species to be threatened?
Removal of large areas of forests e.g oil plantations in borneo e.g orang-utan
Why has habitat destruction caused species to be threatened?
Wetland drainage for agricultural land or land for building e.g. pink headed duck, gangetic plains of India.
Why has a loss of hedgerows caused species to be threatened?
They provide a habitat for insects, nesting sites for birds and reptiles, food for many species and varying light intensity and water availability for diverse plants. Hedgerows act as wildlife corridors enabling reptiles, birds and mammals to move from one area to another helping maintain biodiversity. Removal occurs to increase field size for the use of machinery e.g dormouse, brown hair streak butterfly.
Why has collecting and hunting caused species to be threatened?
As species are collected for food or profit e.g ivory, dodo- food, tigers - rugs, rhino- horn.
Why has competition from domestic animals caused species to be threatened?
Introduced domesticated animals for food competition with native species e.g red squirrel, goats on Galapagos competition for grazing sites with tortoises.
Why has pollution caused species to be threatened?
Oil floats and prevents oxygenation of surface water. Animals which break through are covered in a film of oil. Bird feathers get clumped together so can’t provide insulation. Oil which is washed up onto beaches are ingested and poisons the species. PCBs are ingested with food and are neurotoxins, carcinogens and hormone disruptors. Unregulated industry are polluting rivers e.g Bajillions river dolphins
What is conservation?
The sensible management of the biosphere to maintain habitats and enhance biodiversity, whilst allowing human activity. It maintains genetic diversity both in the wild and in captivity.
What conservation methods are there?
- Protecting habitats using natural reserves and SSSI
- Restrictions on trade
- Zoo breeding programmes
- Sperm banks/ seed banks
- Reintroductions
- Education
- Ecotourism
- Legalisation
What does SSSI stand for?
Sites of Special Scientific Interest
How does the conservation method: Protecting habitats using natural reserves and SSSI’s work?
Natural reserves protect areas rich in biodiversity from being destroyed or damaged. They can be managed to maintain habitat quality and surveyed so that action plans for species are having intended results.
How does the conservation method: Restrictions on trade work?
Prevents trades on organisms whether dead, alive or part of an organism. It reduces the number killed, less harvesting increases biodiversity. e.g elephants ivory
How does the conservation method: Zoo breeding programmes work?
Animals on the edge on extinction can be taken to zoos before being returned to the habitat. It allows several subspecies to breed. Captive breeding means that animals can outbreed with animals from different zoos.
How does the conservation method: Sperm/ seed banks work?
They store material in a safe environment and ensure against damage or loss of a habitat. Animals which have small populations due to damaged ecosystems can be boosted by using sperm from a wide range of individuals increasing the potential gene pool and avoiding bottleneck problems.
How does the conservation method: Reintroductions work?
Species which have been lost can be reintroduced if the conditions are favourable for success.
How does the conservation method: Education work?
Proposes ecosystem management schemes and establishes nature reserves.
How does the conservation method: legalisation work?
A range of measures to protect habitats and enhance biodiversity, preventing over grazing, overfishing, hunting and collection of bird’s eggs
How does the conservation method: Ecotourism work?
It aims to: Contribute to conservation efforts, employ locals, give money to local communities, educate visitors. Cooperate with the locals in managing natural areas.
Why should we conserve?
It ensures the conservation of gene pools
What are the reasons for conservation?
Ethical reasons
Agriculture and horticulture
Environmental changes
Potential medical uses
The ethical reasons for conservation?
The uniqueness of each species is intrinsically valuable
The agriculture and horticulture reasons for conservation?
Species used in agriculture have been developed from those in the wild. Selective breeding increases genetic uniformity with the loss of genetic diversity. If genetic differences are needed to be bred back into agricultural varieties they may be lost.
The environmental change reasons for conservation?
Alleles found in individuals will be selected preventing the extinction of the species.
The medical usage reasons for conservation?
Conservation of habitats helps identify plants which could be potentially useful drugs before extinction.
How does pesticides increase production?
Reduces competition from other plants.
Reduces damage and disease
Increases yield and quality
How does pesticides effect the environment?
Lower biodiversity as fewer weeds and animals which they support die.
May kill pollination and natural predators of pests.
How does artificial fertilisers increase production?
Higher yield. Nutrients aren’t limited, no need to rotate crops, constant growth of most valuable crop.
How does artificial fertilisers affect the environment?
It reduces biodiversity in pastures as grass grows rapidly in outcompete wild crops. Eutrophication
How does removal of hedges to increase the field size increase production?
Allows large machinery to work efficiently. Reduces labour/labour costs. Faster harvesting. More land.
How does the removal of hedges to increase field size affect the environment?
Loss of habitats/nesting size/food for wildlife. No wildlife corridors connecting isolated woods. Animal populations can inbreed.
How does drainage of watermeadows increase production?
More land can be found. More fertile soil as aerobic nitrifying bacteria do well.
How does drainage of watermeadows affect the environment?
It causes a loss of scarce wetland habitat.
How does large areas of monoculture (one crop type) increase production?
Increased efficiency, the best use of expensive specialised machinery. The crop with the best profit can be widely grown.
How does large areas of monoculture affect the environment?
Less biodiversity. Greater attention of a soil nutrient deficiency and if disease/pests occur they were spread widely.
What are the reasons for deforestation?
Road and housing development
Wood for timber, fuel and other products e.g. paper.
Clearing the land agriculture both subsistence and the ranches/palm oil plantations.
What are the consequences for deforestation?
Loss of habitats and therefore loss of biodiversity. Leading to a loss of future use of some organisms as medicine, foods or research.
Burning trees releases CO2 leading to increase levels in the atmosphere less can be absorbed in photosynthesis which leads to more greenhouse effect.
Forest trap water and protect soil from heavy rain so without them soil erosion leads to the loss of topsoil and nutrients due to heavy rainfall. Water flows quickly down valleys causing flooding and landslides.
Rainforests effect rainfall without transpiration from these less rainfall is increasing desertification.
Where is biodiversity highest in?
Tropical areas with much of the biodiversity not being fully investigated for future use. Poor countries can exploit these resources and use them as food or for export as medicines.
What are the ways that forests can be managed?
Coppicing - a trunk is cut leaving a stool
Selective Cutting
Long rotation time
What is the advantage of coppicing?
It allows light onto the forest floor, increasing growth and biodiversity. Produces new growth called poles which can be harvested and used to produce timber a specific widths
What are the disadvantages of coppicing?
It takes time to produce new poles.
What are the advantages of selective cutting?
It’s useful on slopes as removing all trees would lead to soil erosion. It helps maintain soil fertility.
What are the disadvantages of selective cutting?
Only a small amount of timber is removed each year.
What is the advantage of long rotation time?
Many years are left between harvesting so variety of habitats and diverse range of wildlife can develop.
What is the disadvantage of long rotation time?
A long time between harvesting wood.
What improvements can be made for the efficiency of forestry?
Cutting trees in a cycle where areas are left uncut so wildlife can persist and there is sustainability in production of selective felling which prevents soil being left bare.
Cutting a similar number of trees each year for long periods of time. Growing trees in sustainable conditions choosing fast-growing or economic valuable trees.
Spacing trees out so they aren’t overcrowded and intraspecific competition is minimised so will produce high-quality and expensive timber.
Prevention of pests and diseases e.g. sprays.
Why should native woodland be preserved?
So biodiversity can be maintained and hunts and provide habitats for native species.
How has overfishing lead to loss of biodiversity?
The introduction of large vessels and new technology has allowed more fish to be caught.
Fewer fish can breed (small mesh net catch fish before they can breed).
Reduces the amount of prey available to predators leading to a loss of predatory species.
What are the strategies to combat overfishing?
Exclusion zones removing subsidies quotas/landing reducing vessels reducing fishing time controlling mess mesh size (set to a minimum)/discarding young fish eating MSC fish eating non-traditional fish
