Unit 3.6- Human impact on the environment

Define extinction

The complete loss of a species from the planet

Define endangered species

A species at serious risk of extinction

Why are species threatened? (6 ways)

1. Natural selection

2. Non-contiguous populations

3. Habitat destruction

4. Hunting and collecting by humans

5. Competition from introduced species and domestic animals

6. Pollution

What happens as the environment changes in natural selection?

Selective pressure changes, causing some individuals to die and others to survive

What can impact the rate of environmental change and how?

Human impact; new mutations cannot keep up with the change, leads to extinction

How do fragmented populations contribute towards species extinction?

Fragmented populations are very small, so very little genetic diversity, causing risk of extinction

What does habitat destruction eg deforestation lead to?

A decrease in biodiversity

Give some examples of hunting and collecting by humans

Petting zoos for big animals

Collecting birds eggs

Trophy hunting

Over fishing

Bush meat

Asian medicines

Intensive farming

Talk about the competition from introduced and domestic animals

Organisms fight for resources in short supply.

What are the two types of competition?

intraspecific and interspecific

Intra?

Competition between members of the same species

Inter?

Competition between members of different species

Would a grey squirrel competing with a red squirrel be intra or interspecific competition?

Interspecific

Define conservation

The sensible management of the biosphere to maintain habitats and enhance biodiversity, while allowing human activity

Give 8 conservation techniques

Habitat protection

International co-operation restricting trade

Sperm banks and seed stores

Reintroduction programmes

Breeding programmes by zoos and botanic gardens

Education

Legislation

Ecotourism

What does habitat protection entail?

Protecting the species that live in a certain habitat and communities act as living gene banks

National parks, SSSIs

What does SSSIs mean?

Site of special scientific interest

What does international co-operation mean?

Search at borders

Prevent ivory trade

Restricts trade

What does CITES stand for?

Convention on International Trade in Endangered Species

What do sperm banks do?

Increase genetic diversity by deliberate choice of parents

What do seed banks do?

Store seeds of traditional varieties and of vulnerable species

What do reintroduction programmes involve?

Breeding animals in captivity

Maintain their habitats

Reintroduce to habitat

What does WWFN stand for?

World Wide Fund for Nature

What does legislation do?

Protects habitats and enhances biodiversity, preventing overfishing and the hunting of game

What does the EU Habitats Directive do?

Offers farmers more money if they maintain hedgerows or keep a pond

What is ecotourism, and why is it important?

Tourism that is ecologically and socially sustainable

Contributes towards conservation efforts

Gives money back to local communities

What does the conservation of species in the wild and captivity ensure?

The conservation of existing gene pools

Why conserve? (4 reasons)

Ethical reasons

Agriculture and horticulture

Environmental change

Potential medical uses

What ethical reasons?

-Each species represents a particular combination of genes and alleles adapted to a particular environment

-Uniqueness of each species is intrinsically valuable

Agriculture and horticulture?

Some rarer alleles may have been lost in selective breeding. These need to be brought back using wild plants and animals as a gene bank.

Environmental change?

Some alleles will provide an advantage if the environment changes to the individuals who carry them, and those will be prevented from going extinct

Some examples of medical use?

-Antibiotics derived largely from fungi

-Medicinal drugs synthesised by plants- need to protect habitats so we can identify other plants that have medicinal uses

What is there a conflict between to maintain habitats and biodiversity?

Agricultural production and conservation

What are continually increased to meet the demand for food production?

Efficiency and intensity of food production

What has this resulted in?

Hedgerows being removed

Monoculture

Overgrazing

Why are hedgerows removed?

To make fields larger to enable machinery to be used effectively

What is monoculture? (Need to know definition)

The growth of a large number of genetically identical plants in a defined area

What does this do and how?

Reduces species diversity, as the roots from the same plants will extract the same minerals from the same depth of soil every year, increasing the need for fertilisers. Pesticides will need to be used.

Why use pesticides?

Monoculture enables a particular pest species to become established, which means you have to use pesticides to control the pest population. Pesticides are non-specific so may also kill beneficial insects/ non-target species, reducing biodiversity

What else does monoculture do?

Reduces plant diversity as only growing one crop- reduces animal biodiversity as different animals will feed and live on different plant species

What does overgrazing do?

Causes grassland to become unsustainable, as soil becomes so compacted that roots cannot grow

What does this lead to?

Reduced air spaces, which inhibits nitrogen fixing and nitrifying bacteria, leading to a loss of soil fertility

How are governments trying to reduce the decline in biodiversity?

-Organic faming, to reduce the need for chemical fertilisers and pesticides. Diff crops provide a variety of habitats and increase biodiversity

-Set-aside schemes- land set aside for conservation and wildlife

-Legislation- loss of hedgerows reversed

What do hedgerows and field margins provide?

Habitats and food sources for insects, birds and small mammals.

Nesting sites and act as wildlife corridors allowing life to move from one area to another under cover.

Define deforestation

The large-scale removal of trees from an area due to human activity

What are the 3 reasons for deforestation?

Timber- wood for building, burning etc

Farming- grazing cattle, clearing to grow biofuels

Infrastructure

Why can deforestation lead to an increase global warming?

Reduces Co2 uptake

Burning of felled trees puts Co2 in atmos

Decay of waste tree material

What are the consequences of deforestation?

1. Soil erosion

2. Lowland flooding

3. Reduced soil quality

4. Desertification

5. Habitat loss and reduced biodiversity

6. Climate change

How does deforestation lead to soil erosion?

The roots of trees bind soil together and if removed the topsoil is no longer bound and is vulnerable to erosion

Lowland flooding?

On hillsides, trees intercept water by water landing on canopy, so water takes longer to reach the soil so less chance of flooding. if trees cut down, runoff is much faster, causing flooding

Reduced soil quality?

Evaporation of water from soil instead of off leaves by transpiration. Leads to waterlogged soil which leads to low O2 levels and to it being cold, so temp too low for enzymes.

Poor growth of soil as low NO3-

Desertification?

Accelerates due to less rainfall as slow return of water to atmosphere so less precipitation

Climate change?

No photosynthetic biomass so no absorption of Co2 so global warming

Timber felled is combusted

Decay of waste matter

What are some forest management techniques?

Slash and burn- releases nutrients in soil

Coppicing

Selective cutting- only cut particular trees

How can land be used effectively with good forestry practice?

Make sure there's no disease

Preserve the trees

Define overfishing

When the rate at which fish are harvested exceeds the rate at which fish reproduce

What are the effects of overfishing?

Population size decreases, lose genetic diversity, overfished to extinction

How can overfishing be prevented?

Restrict mesh sizes- allow young fish to swim through and reproduce to replenish fish stocks

Fixed quotas to restrict no of fish brought ashore

Exclusion zones to prohibit fishing in certain areas at certain times of year e.g. breeding season

Consumer choice

Legislation controlling size of fishing fleets and no of days at sea

Using lines not nets

What are the advantages of fish farming?

-Farmed fish convert their food to protein more efficiently than other farmed animals

-Greater proportion of the fishes' bodies are edible

-Lower carbon footprint

-Wild fish stocks have a chance to replenish

Disadvantages?

-Rapid spread of disease and parasites. Stocks are dense so disease spreads.

-Nitrogenous waste pollution- results in dissolved oxygen depletion

-Escaped fish- outcompete wild fish for food, habitat and mates. Transmit parasites. Dilute gene pool when interbreed with wild fish

-Resource use- eat three times their body weight in fish feed

-Environmental toxins

-Environmental degradation- salinisation of soil and groundwater

Define sustainable development

Development that meets the needs of the present, without compromising the ability of future generations to meet their own needs

Environmental impact assessments

Define planetary boundary

Safe operating level for humanity, below this value the global processes will be stable

Define biodiversity

The number of species and the number of individuals of each species in a given environment

Define population

A group of organisms of a certain species that interbreed to produce fertile offspring and live in the same place at the same time

What happens when we cross a planetary boundary (the tipping point)

Risks triggering abrupt and irreversible environmental changes, pushing Earth out of its safe operating space

What are the nine planetary boundaries?

1. Climate Change (level of CO2 in the atmosphere) - crossed

2. The biodiversity boundary - crossed

3. Biogeochemical flows/ The nitrogen boundary - crossed

4. Land - system change boundary - crossed

5. The Freshwater boundary - avoidable

6. The Ocean Acidification boundary - avoidable

7. The Atmospheric Aerosol boundary - unquantified

8. The ozone boundary - avoided

9. The chemical pollution boundary - unquantified