Eduqas Biology A Level C1 - Human Impact on the environment

What effect has human activity had on extinction rates?

Increased rates from about 1 species a year to 1000-10000 times that rate

How is the vulnerability of a species assessed?

Using numbers, rate of decline and distribution

List the ratings of vulnerability to extinction in order of increasing concern:

Least concern (LC)

Near Threatened (NT)

Vulnerable (VU)

Endangered (EN)

Critically Endangered (CR)

Extinct in the Wild (EW)

Extinct (EX)

7 reasons for vulnerability:

- Natural selection causes species with disadvantages to decline in numbers

- Environmental change occurs too fast for species to adapt

- Non-contiguous populations (numbers are important to ensure the continuation of a species, and separated groups cannot interbreed)

- Loss of habitat (for many reasons)

- Overhunting by humans

- Competition for introduced species

- Pollution

List some examples of loss of habitat

- Deforestation

- Drainage of wetlands

- Hedgerow loss

- Loss of coral reef for aquatic species

List some examples of Overhunting:

- Trophy Hunting

- Hunting for medicinal usage

- Bush meat industry (food)

- Overfishing

- Agricultural exploitation (producing animals and their products for human consumption)

Conservation definition

The conservation, preservation, management and restoration of natural habitats and their ecological communities to enhance biodiversity while allowing for suitable human activity

Methods of conservation:

- Protected areas like National Parks

- International co-operation restricting trade

- Gene banks

- Education

- Legislation

- Ecotourism

Give some examples of Gene banks

- Breeding programmes for threatened species

- Sperm banks

- Seed banks

- Rare breed societies

- Species reintroduction to habitats they were previously lost from

Examples of Gene banks:

- Breeding programmes preserve species

- Sperm banks

- Seed banks

- Rare breed societies

- Species reintroduction

Ecotourism definition

Responsible travel to natural areas that conserves the environment and improves the well-being of local people

How does Ecotourism help conserve a habitat?

- Tourists can contribute to conservation efforts

- Employs local people and gives money back to local communities

- Educates visitors about local environment and culture

- Encourages local people to manage natural areas

What are some reasons to conserve species?

- Ethical reasons (uniqueness of each species is considered very valuable)

- Agriculture and horticulture (some vital alleles in wild plants may be lost, impacting crops)

- Potential medical uses

2 examples of pollution

- Oil leakage causes death of many species

- Polychlorinated bipheyls (PCBs) are neurotoxins and were once used but are now banned. Waste was dumped and now enters the oceon

Agricultural Exploitation

The exploitation of natural resources for economic growth etc

Monoculture

The cultivation of a single crop in a given area.

Effects of agricultural exploitation:

- Many hedgerows are removed to make larger fields (decreases biodiversity)

- Large fields are used for monoculture which reduces species diversity

- Yeild decreases if the same crop is grown each year

- Overgrazing by cattle makes the soil compact and unsustainable grassland

Why are hedgerows important?

- They are a habitat for many species

- They provide food for many species

- They have varying light intensity and water availability for more diverse plants

- They act as wildlife corridors to allow organisms to travel from one area to another (maintains biodiversity)

How does growing the same crop in a field each year decrease yield?

- Roots are the same length so nutrients at that level are depleted

- The same species is susceptible to the same pests, so numbers increase

Reasons for deforestation

- Timber for building/burning

- Land for agriculture

- Grow crops for ethanol-based biofuels

- Grow rice

- Keep cattle for food

- Roads built to transport goods from deforested sites

Consequences of deforestation

- Soil erosion (as tree roots bind soil together and also shield the soil from rainfall)

- Lowland flooding

- Diminished quality of soil

- Less rainfall

- Habitat loss

- Effects on atmosphere composition

Soil erosion definition

The removal of topsoil, which contains valuable nutrients

How does deforestation lead to low quality soil?

Water is removed from the soil much faster by transpiration than by evaporation. When plants are removed, the only method of water removal left is evaporation. The soil becomes wetter and therefore colder, making it unsuitable for many plants. The soil is less fertile.

How does deforestation lead to less rainfall?

Without transpiration, water is returned to the atmosphere by evaporation only. Evaporation is much slower than transpiration and so less water returns to the atmosphere

How does deforestation affect the composition of the atmosphere?

Less carbon dioxide is removed from the atmosphere

Methods of forest management:

- Small scale cut and burning

- Coppicing

- Selective cutting

- Planting new trees a good distance apart

- Control pests and diseases

- Cutting a similar number of trees each year

Small scale cut and burning of trees

Trees are cut and the burnt, and then left to regrow. This is not suitable for large areas

Coppicing

Cutting down of trees close to the ground and leaving them for several years to re-grow

Selective cutting

Cutting down only some trees in a forest and leaving many trees behind, which reduces soil erasion

What is the benefit to planting trees a good distance apart?

It reduces competition between individuals

Why control pests and diseases when growing trees?

To ensure the trees grow well and the yield is maximum

How do you preserve nature woodlands?

Have organisations such as The National Trust and nature reserves that work to preserve habitats and maintain biodiversity

When does overfishing occur?

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

What are the two main types of net fishing?

Trawling and drift netting

What are the problems with drift netting?

Non-target species become trapped

What are the problems that come with Trawling?

The nets often catch other fish or marine life, apart from those desired. That decreases numbers of a species. This method also destroys the sea bed.

How does overfishing effect organisms other than fish?

- Some are caught in the net along with the target fish

- Small fish caught in the net provide the food for many larger organisms and so removing them has an effect on the whole food chain

- Reduction of fish stock also damages the livelihood of fishers

Methods to reduce overfishing:

- Regulate the mesh size of nets, so the holes are big enough for young fish to slip through

- Quotas set so only a certain amount of fish are brought to land

- Exclusion zones

- Consumers choosing fish that are certified by the Marine Stewardship Council

- Legislation controlling the size of fishing fleets

- Legislation controlling the numbers of days spent at sea

- Fish farming may reduce overfishing

Eutrophication

The artificial enrichment of aquatic habitats by excess nutrients

How can setting quotas for the amount of fish brought to land be problematic?

If fishers catch more than is allowed they throw the dead fish back into the sea. This is a problem.

How do exclusion zones work to regulate fishing?

They prohibit fishing in defined areas at certain times of the year, which allows fish to reproduce

Why is eating only fish certified by the Marine Stewardship Council helping to regulate fishing?

The Marine Stewardship Council ensures fish are taken from sustainable sources

Why is raising fish more advantageous than pork/poultry/beef?

- Fish convert their food into protein more efficiently

- A greater proportion of fishes' bodies are edible

- Fish farming has a lower carbon footprint

Problems of fish farming:

- Diseased fish

- Pollution

- Escaped fish

- Resource use

- Environmental toxins

- Environmental degradation

Why are diseased fish a problem in fish farming?

- Fish are often raised very densely stocked and so diseases are transmitted very easily - so many antibiotics are needed to keep them healthy

- Pesticides used may harm other organisms in the habitat

Why are escaped fish a problem of fish farming?

They grow very rapidly, and will outcompete wild fish for food, space and mates

They also transmit parasites and other infections

Why is the resource use associated with fish farming a problem?

Some fish are carnivorous and many smaller fish are needed to feed them. This is a poor use of resources from an environmental point of view

How do environmental toxins come into the topic of fish farming?

Many toxins are in higher concentraions in farmed fish than in wild fish, though these are so small that the health benefits of eating fish are still valid

What are 3 methods of assessing the stability and health of the environment?

- Monitoring air quality for concentrations of pollutants

- Monitoring the soil structure and density

- Monitoring the water quality (chemical, biological and microbiological)

What is a planetary boundary?

A limit between which global systems must operate to prevent abrupt and irreversible environmental change

How many planetary boundaries are there?

9

What are the 9 planetary boundaries?

- Atmosphere aerosols

- Biogeochemical flows

- Biosphere integrity

- Climate change

- Fresh water use

- Land system change

- Novel entities

- Ocean acidification

- Ozone depletion

What 4 planetary boundaries have been crossed?

- Biogeochemical flows

- Biosphere integrity

- Climate change

- Land system change

What is a core planetary boundary?

A planetary boundary that, when crossed, would drive the earth into a new and unpredictable state with severe consequences for the biosphere

What are the two core boundaries?

Biosphere integrity and Climate change

What does the mnemonic BOB IS CALF stand for?

Each of the planetary boundaries:

Biosphere integrity

Ocean acidification

Biogeochemical flows

Introduction of novel entities

Stratospheric ozone

Climate change

Atmospheric aerosols

Land-system change

Fresh water use

What are the effects of climate change?

- Rising sea levels

- Increased desertification

- Increase in droughts

- More extreme weather events

How is the climate change boundary measured?

By monitoring the change in the average global temperature

What are some ways to reduce the impact of climate change?

- Switch to renewable energy sources

- Switch to nuclear power

- Reduce or stop the burning of fossil fuels

- Conserve rainforests and other forested areas

- Reduce meat consumption

- Use alternative fuels for cars

- Recycle and other methods for reducing your carbon footprint

What are some potential issues of nuclear power?

It increases the amount of novel entities and there are risks of dangerous meltdowns

What are some benefits of biofuels?

- They are a renewable energy source

- Growing biofuels removes carbon dioxide from the atmosphere

What are the disadvantages of biofuels?

- Forests have been cleared to make room to grow biofuels, destroying habitats

- Conflicts with using land for food or fuel

- Increased use of fertilisers (leads to eutrophication)

- Biofuel crops require a large amount of water

- Combustion of biodiesel produces more nitrous oxide gas than fossil fuels

What is meant by the biosphere integrity boundary?

The planetary boundary relating to the functions of ecosystems and biodiversity loss

How is the biosphere integrity boundary effected?

- Climate change

- Deforestation and other habitat loss

- Hunting

- Pollution

- Eutrophication

- Natural disasters

How are Tundra ecosystems changing?

Over the years, temperature is rising and more species are able to grow, increasing biodiversity

How are marine ecosystems changing?

Oceans are becoming polluted with oil, acid, plastic and pesticides. Biodiversity is rapidly falling. Much more data is needed to identify species at risk

What is meant by the land system change boundary?

Use of land and how it has changed (e.g. deforestation)

Why is the land system change boundary important?

For maintaining habitats, maintaining biodiversity and for farming

What can be done to reduce the impact of the land system boundary from being exceeded?

- Farming should be concentrated into the most productive areas

- Global reduction of meat comsumption

What is the biogeochemical flows boundary?

The boundary referring to cycling of minerals through an ecosystem