Human Impact On The Environment Flashcards
How are human activities altering ecosystems ?
Massive destruction of habits throughout the world has been brought about by:
- agriculture
- urban development
- forest
- mining
- environmental pollution
What are the main reasons for extinction?
Climatic, geological and biotic changes as well as human activity
The IUCN, the international union for the conservation of nature, makes assessment, of plants and animals and grades them according to their vulnerability to extinction. Species ar e rated depending on their numbers, rate of decline and distribution:
(EX) Extinct
(EW) Extinct in the wild
Threatened:
(CR) Critically endangered
(EN) Endangered
(VU) Vulnerable
(NT) Near threatened
(LC) Least concern
Species become endangered or extinct for many reasons: Natural selection
- natural selection occurs when individuals less suited to prevailing conditions reproduce less successfully.
- Their numbers decrease, which may lead to their extinction.
- Human activities are causing habitats to change faster than new mutations allow species to adapt and so they are driven to extinction at a faster rate than before humans had such influence over their environment
Species become endangered or extinct for many reasons: Non-contagious populations
- The total number of individuals in a species may suggest that numbers are sufficient to ensure that the continuation of the species
- But if groups are isolated from each other, they cannot interbreed and each group functions as a separate population
- There may be too little genetic diversity in each to ensure a healthy population, leading to their extinction
Species become endangered or extinct for many reasons: loss of habitat
- deforestation
- drainage of wetlands
Species become endangered or extinct for many reasons: hedgerow loss
- hedgerows separate fields
- 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
- they enable wildlife to move from one area to another
- their removal to accommodate large agricultural machinery used in modern farming has destroyed large areas of specialised habitat
Species become endangered or extinct for many reasons: time of year that farmers sow crops
-farmers often sow crops in the autumn rather than spring, which means that plans are an unsuitable height for the birds nests
Species become endangered or extinct for many reasons: overhanging by humans
- trophy hunting by humans
- traditional medical practices
- the bush meat industry
- overfishing
Agricultural exploitation
Species become endangered or extinct for many reasons: completion from introduced species
- outcompeting native species
Species become endangered or extinct for many reasons: pollution (oil)
- oil spills
- oil floats and prevents oxygenation of surface water. animals that break through the surface are covered by s film of oil. Birds are chilled to death because their feathers clump together and cannot provide insulation
- oil washes up on beaches is ingested by shore-dwelling animals, which are poisoned by it
Species become endangered or extinct for many reasons: (PCBs)
Polychlorinated biphenyls
- They are ingested with food
- They are neurotoxins, carcinogens and hormone disruptors
What is conservation ?
-the sensible management of the biosphere to maintain and enhance biodiversity, while allowing human activity
Conservation is addressed in various ways, at local, national and international levels: SSIs and SACs
- Protecting habitats protects the species that live there and communities act as living gene banks
- Official designation recognises local nature reserves sometimes as small as a few hectares
- sites have varying levels of legal protection and may be managed and monitored by wardens
- Conservation is addressed in various ways, at local, national and international levels: Intentional co-operation restricting trade
- e.g. ivory and whaling
- international law allows some countries to practice ‘scientific whaling’
- Conservation is addressed in various ways, at local, national and international levels: Gene banks
- endangered species are protected and entered into breeding programmes in specialised zoos and botanic gardens
- Conservation is addressed in various ways, at local, national and international levels: sperm banks
- stores genes of economically important animals and of threatened species
- rather than moving animals, sperm samples can be sent around the world to be used in breeding programmes in other zoos
- Conservation is addressed in various ways, at local, national and international levels seed banks
- maintain stocks of seeds of traditional varieties and of vulnerable species, in highly controlled conditions, often liquid nitrogen
- seeds degrade over time so periodically samples are thawed and germinated
- plants grown from them reproduce and another generation of seeds is collected
- some seed banks are viewed as a potential source of food in case of catastrophic environmental degradation
- Conservation is addressed in various ways, at local, national and international levels: rare breed societies
- Rare breed societies maintain older, less commercial varieties for special characteristics e.g. hardiness, owl production
- Conservation is addressed in various ways, at local, national and international levels: species reintroduction
- following successful breeding programmes, they have been reintroduced to their former habits
- Conservation is addressed in various ways, at local, national and international levels: education
- global organisations, such as the world wide fund for nature, mount public awareness campaigns
- in the UK, the countryside commission, a government body promoting nature conservation, advises government groups whose activities affect wildlife and their habitats
- It produces publications, proposes ecosystem management schemes and establishes nature reserves
- Conservation is addressed in various ways, at local, national and international levels: Legislation
- The EU habitats directive has imposed a range of measures to protect habitats and enhance biodiversity throughout Europe, preventing overgrazing, overfishing, hunting of game, collection of birds eggs, picking wild flowers and plant collecting
- Conservation is addressed in various ways, at local, national and international levels: Ecotourism
- Recognises that mass travel is harmful globally and specific to habitats. It aims to:
~ Contribute to conservation efforts
~ Employ local people and give money back to local communities
~ Educate visitors about local environment and culture
~ Co-operate with local people and manage natural areas
What are the ethical reasons for conservation?
- Each species represents a particular combination of genes and alleles adapted to a particular environment and it is considered that the uniqueness of each is intrinsically valuable
What are the agricultural/ horticultural reasons for conservation?
- Selective breeding increase genetic uniformity, with loss of rarer alleles
- In the past breeders may have neglected some important qualities, such as resistance to cold or disease
- These need to be bred back into cultivated varieties, using the wild plants and animals as a gene bank.
- If habitats that live in them are threatened, it may not be possible
How can conservation prevent extinction?
- If the environment changes, some alleles will provide an advantage to the individuals that carry them, and those individuals will be selected for, preventing the extinction of the species
Why are potential medical uses a reason for conservation?
Give an example
- The antibiotics we use are derived largely from fungi but many other of our medicinal drugs are synthesised by plants
- There are potential drugs, not yet discovered, that could be of immense value
- The extinction of any plant species before its chemical properties have been investigated could be an incalculable loss
~Quinine is extracted from the bark of Cinchona, an Amazon rain forest tree, to treat malaria
