Human Impact

Biodiversity

Refers to 2 aspects of organisms in a given environment - the number of species and the number of organisms within each species

Reasons for species becoming endangered or extinct

Natural selection

Deforestation

Habitat destruction

Loss of hedgerows

Pollution

Hunting and collecting

Competition from domestic animals

Reason for natural selection being a reason for species endangered or extinct

Existing species do not have the ability to survive in a changing environment e.g. sabretooth cat, woolly mammoth

Reason for deforestation being a reason for species endangered or extinct

Loss of habitat e.g. birds and insects

Reason for habitat destruction being a reason for species endangered or extinct

Such as deforestation, drainage of wetlands and loss of hedgerows e.g. birds such as skylark, insects and reptiles

Reason for loss of hedgerows being a reason for species endangered or extinct

Loss of habitat for insects, nesting birds and reptiles

Loss of food for many species

Loss of varying light intensity and water availability for diverse plants

Reason for pollution being a reason for species endangered or extinct

Such as PCBs (which are toxins that can be ingested) and oil spills.

Oil floats prevent oxygenation of surface water - animals that break through surface are covered by a film of oil. e.g. shore-dwelling animals, birds and plants.

Reason for hunting and collecting being a reason for species endangered or extinct

Overhunting by humans include trophy hunting some traditional medical practices e.g. the use of rhino horns, the bush meat industry in which primates among others are killed for food, overfishing and agricultural exploitation.

Reason for competition from domestic animals being a reason for species endangered or extinct

The dodo was driven to extinction by rats brought on European ships ate the dodo eggs.

The north American signal crayfish has invaded UK streams and rivers and the native crayfish, which is smaller, has been out-competed.

Red squirrels out-competed by grey squirrels

Conservation

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

Conservation methods

SSSIs (sites of special scientific interest)

Restrictions on trade

Zoo breeding programmes

Sperm banks/seed banks

Reintroductions

How do SSSIs enhance biodiversity?

Protecting habitats protects the species that live there and communities act as living gene banks. These sites have varying levels of legal protection.

How do restrictions on trade enhance biodiversity?

International cooperation can restrict trade in products from endangered animals. For example, CITES has been in effect from 1975 and its aim is to ensure that trade in specimens of animals and plants doesn’t threaten survival of species in the wild.

How does zoo breeding programmes enhance biodiversity?

They have programmes established to help maintain genetic diversity by deliberate choice of parents.

Pandas are a famous example

How do sperm banks help enhance biodiversity?

Sperm banks can be used to store genes and sperm samples can be sent around the world as part of breeding programmes

How do seed banks help enhance biodiversity?

Seed banks store genes from plants. Seeds degrade over time so periodically samples are thawed and germinated and another generation of seeds is collected from them.

How do reintroductions help enhance biodiversity?

Following successful breeding programmes, species can be introduced to areas where they have previously gone extinct.

Been successful in the UK with the red kite

Why is conservation of species so important?

Potential medical uses - antibiotics are derived largely from fungi but many others of our medical drugs are synthesised by plants.

Some species act as keystone species - without them ecosystems can fail

Ethical reasons - each species represents a particular combination of genes and alleles adapted to a certain environment and its considered that the uniqueness of each is intrinsically valuable.

Agriculture and horticulture - plants and animals that have been developed from those in the wild need to be bred back into cultivated varieties using the wild plants and animals as a gene bank.

Humans depend on other species for food - wild species act as a gene pool. We could introduce these genes through cross-breeding or genetic engineering to improve the productivity of domestic species.

Agricultural exploitation

Agriculture is essential to produce the quantity and quality of food required to feed the increasing human population. The way agricultural land is used, however, often conflicts with maintaining habitats and biodiversity.

Strategies to increase agricultural production

Pesticides

Artificial fertilisers

Removal of hedgerows to increase field size

Drainage of water meadows

Monoculture

How do pesticides increase agricultural production?

Protecting crops from losses caused by pests, diseases and weeds, leading to higher yields and more efficient land use.

This protection helps ensure greater food security and can improve farm economics.

How do artificial fertilisers increase agricultural production?

They directly provide the plant with essential nutrients like nitrogen, phosphorus and potassium, which are depleted from the soil through crop harvesting. The nutrients can be absorbed quickly, leading to rapid plant growth and higher yields.

How does removal of hedgerows increase agricultural production?

Can boost agricultural production primarily by facilitating the use of larger, more efficient machinery and increasing the total area for cultivation.

Allows for faster and more efficient farming operations, leading to higher crop yields and increased profits for farmers.

How does drainage of water meadows increase agricultural production?

By promoting earlier and more vigorous grass growth, providing an ‘early bite’ for livestock and increasing the quantity of hay and grazing available throughout the year. This is achieved through a system that warms the soil, delivers nutrients and prevents waterlogging while allowing for aeration.

How does monoculture increase agricultural production?

Can increase agricultural production primarily through enhanced efficiency in machinery use, planting and harvesting, which optimises yields and lowers costs compared to diverse farming systems.

How do pesticides affect the environment?

Causes chemical pollution in water and soil, driving biodiversity loss, and harming non-target organisms including beneficial insects, birds and aquatic life.

Water contamination

Pest resistance

How do artificial fertilisers affect the environment?

Water pollution through leaching and runoff

Air pollution from ammonia emissions

Climate change due to nitrous oxide emissions

Production of artificial fertilisers relies heavily on non-renewable sources like fossil fuels.

How does removal of hedges affect the environment?

Reduces biodiversity

Increases soil erosion and water runoff

Diminishes the landscape’s aesthetic and ecological value

Loss of habitat, food and corridors for wildlife

How does drainage of water meadows affect the environment?

Alters hydrology

Reduces biodiversity

Causes soil degradation, especially in pent soils which release CO2 upon drying and oxidation.

Impact on water quality

How does monoculture affect the environment?

Reduces biodiversity

Depletes soil nutrients

Increases vulnerability to pests and diseases

Contributing to climate change and pollution

Habitat loss and deforestation

Reasons for deforestation

Timber extraction - for building materials, paper or fuel

Clear land for farming

Consequences of deforestation

Reduces biodiversity

Causes soil erosion

Habitat loss

Can cause droughts, accelerating desertification or lowland flooding

Contributes to global warming

Soil erosion

Tree roots bind soil together. Topsoil is the most fertile soil, so what remains is often not suitable for crop growth.

How does deforestation cause droughts, accelerating desertification or lowland flooding?

Trees create a microclimate. Leaf litter soaks up heavy rainfall and releases water to the atmosphere.

Accelerating desertification

Process by which fertile land becomes desert

How does deforestation contribute to global warming?

Less photosynthesis

Cut down trees are either burned or left to decay

Both of which release CO2 into the atmosphere

Different methods for managing forests

Coppicing

Selective cutting

Long rotation time

Coppicing

A tree trunk is cut, leaving a ‘stool’ a few cms high. Shoots can still emerge from the buds in the stool and can be cut on rotation to provide timber of different widths.

Advantages of coppicing

Coppiced plants can regenerate over long periods of time

Disadvantages of coppicing

Labour intensive

Disruptive to forest ecosystems

Low regrowth initially

Stress on trees

Habitat reduction

Selective cutting

Removing some of the trees rather than all the trees at one time, meaning the soil is less vulnerable to erosion.

Advantages of selective cutting

Valuable on steep slopes where the total removal of trees would leave the soil very vulnerable to erosion.

Helps to maintain nutrients in the forest soil and minimises the amount of soil that is washed into nearby waterways.

Disadvantages of selective cutting

Reduced carbon storage

Habitat loss

Damage to remaining trees

Long rotation time

Increases sustainability as many years are left between harvesting and more diverse wildlife can develop

Disadvantages of long rotation time

Reduced harvest volume in long term

Increased disturbances and damage

What steps can be taken to improve the efficiency of forestry?

Planting trees the optimum distance apart - if too close, intra-specific competition occurs and trees grow tall and thin, producing poor quality timber.

Controlling pests and diseases so that trees grow well, producing high quality timber. Fewer trees need to be felled and best use of land, reducing the total area required.

Cutting a similar number of trees each year for long periods of time allows the forest ecosystem to be maintained. Habitats are kept intact and species are able to live in forest even though timber is being extracted.

Why is the preservation of native woodlands so important?

It is essential that native woodlands are preserved to maintain and enhance biodiversity.

Overfishing

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

How has overfishing led to a loss of biodiversity?

When trawlers spread their nets, they catch a fish called capelin. These are not eaten by humans but by an important prey species for cod, so removing them from the sea has contributed to the decline in cod stocks.

Strategies to combat overfishing

Exclusion zones

Removing subsidies

Quotas

Reducing vessels

Reducing fishing

Controlling mesh size

Eating MSC fish

Eating non-traditional fish

Advantages of exclusion zones

Prohibit fishing in certain areas at certain times (breeding seasons) allowing fish to reproduce.

Ensure fish maintain healthy populations

Disadvantages of exclusion zones

Loss of biodiversity in other areas that aren’t protected

Advantages of removing subsidies

Free up funds that could be better spent to protect our ocean and support fishing communities.

Decreases size of fleet

Disadvantages of removing subsidies

Threatens the commercial existence of many fisheries

Advantages of quotas

Quotas can be set so that only a certain mass of fish can be brought to land.

Limit how many members of any one species can be caught

Heavy fines are imposed for exceeding quotas

Disadvantages of quotas

It appears more fish are taken than allowed by quotas and they are thrown back dead into the sea. EU legislation is progressively making them illegal.

Advantages of reducing vessels

Less fish can be caught

Reduces fishing effort and range of boats

Disadvantages of reducing vessels

Threatens the commercial existence of many fisheries

Advantages of reducing fishing time

Less fish can be caught

Disadvantages of reducing fishing time

Threatens the commercial existence of many fisheries

Advantages of controlling mesh size

Smaller mesh sizes can catch more fish so by having a minimum mesh size, larger fish will be caught but smaller fish will be able to escape from the nets and go on to breed.

Disadvantages of controlling mesh size

Potential for increased discarding of undersized fish.

Difficulties in demonstrating effectiveness due to natural fluctuations in fish stocks and potential negative impacts on marine mammal populations if not carefully considered.

Advantages of eating MSC fish

Ensure fish are taken from sustainable sources

Disadvantages of eating MSC fish

More expensive

Advantages of eating non-traditional fish

Maintain healthy populations in most species as eating more variety of species.

Reduces discarding of fish

Disadvantages of eating non-traditional fish

Don’t know whether it’s safe to eat

Why are diseases common on fish farms and why do treatments lead to environmental problems?

Farmed salmon are often very densely stocked and so they can easily transmit disease. Huge doses of antibiotics are required to keep them moderately healthy. The pesticides used to control fish parasites, such as sea lice, are known to harm marine invertebrates, especially molluscs.

Negative effectives of fish farming on the environment

Pollution

Escaped fish

Environmental toxins

Poor resource use

Environmental degradation

Diseased fish

How does pollution due to fish farming negatively impact the environment?

The ecological balance of the waterways may be upset. Eutrophication can result when fish excreta, waste food and fertiliser are carried into the water around the rearing pens.

How does escaped fish due to fish farming negatively impact the environment?

Farmed fish have been selected for very rapid growth. If they escape, they out-compete wild fish for food, habitat and males. They also transmit parasites and other infections. Escaped farmed fish interbreed with wild fish and set-up fast growing colonies which can push wild fish to extinction.

How does environmental toxins due to fish farming negatively impact the environment?

e.g. methhyl mercurry, PCBs, dioxins and pesticides

How does poor resource use due to fish farming negatively impact the environment?

Farmed salmon eat 3x their bodyweight in fish feed, which is made from other fish.

How does environmental degradation due to fish farming negatively impact the environment?

The shrimp industry in particular have been blamed for the salination of soil and groundwater and the destruction of the mangroves that normally protect coastal communities from tropical storms.

How does diseased fish due to fish farming negatively impact the environment?

The pesticides used to control fish parasites are known to harm marine invertebrates.

Positive benefits of fish farming

Raising fish rather than pork, poultry and beef has advantages:

Fish convert their food into protein more efficiently

A greater proportion of fishes’ bodies are edible

Fish farming has a lower carbon footprint

Why is it important to monitor populations and biodiversity in areas where human development is planned?

Avoid losses in biodiversity

Retain species diverse areas free from development

To half any changes that may bring about species loss or to make mitigations

Why is it important for scientists to be involved in decision making?

They are able to analyse and evaluate data

They should be independent and not under financial pressure to implement changes

Examples of how we could improve biodiversity beyond current levels

Re-routing roads to avoid areas of high biodiversity

Avoiding wind turbines in areas of high bird and bat use

Sowing field margins with wild flower seeds for pollinating insects

Tunnels under roads for hedgehogs, badgers and otters

Putting bird nest boxes in the most appropriate places

Green bridges linking habitats reduce human as well as animal fatalities

Identify future needs

Why is there often conflict between conservationists, government and farmers?

They have different priorities and are under different pressures. In the past a strategy to deal with this has been by paying subsidies, e.g. to farmers to preserve some land for biodiversity.

This could be beneficial to governments financially. For example, paying farmers to preserve wetlands would reduce the risk of flooding. Dealing with the economic cost of the flooding of residential areas may be more expensive than paying subsidies.

Planetary boundaries

A threshold value for a global process that is affected by human activity.

Crossing these boundaries could cause irreversible environmental changes.

What are the 9 planetary boundaries?

Climate change

Biodiversity

Land use change

Nitrate and phosphate

Ozone

Ocean acidification

Freshwater use

Aerosol

Novel entities

Climate change boundary has been…

Crossed

Climate change boundary causes

Caused by greenhouse gas levels rising due to burning of fossil fuels and deforestation. This leads to global warming.

Climate change boundary consequences

Increased global temperatures

Impacts on wind patterns/ocean currents/rainfall

Thermal expansion and melting of polar ice caps leading to flooding of low lying land, habitat destruction and reduction in biodiversity.

Climate change boundary possible solutions

Reduce/stop burning fossil fuels

Reduce deforestation

Use alternative fuel sources including biofuels

Biodiversity boundary has been…

Crossed

Biodiversity boundary causes

Habitat destruction e.g. coral reef/TRF and hunting

Biodiversity boundary consequences

Human caused environmental changes occur too quickly and species cannot evolve quickly enough to adapt to the change, and so reduction in species number/extinction.

Biodiversity boundary possible solutions

Monitor biodiversity

Species conservation

International Trade Agreements

Education

Land use change boundary has been…

Crossed

Land use change boundary causes

Land use change for food and biofuel production, urbanisation and livestock farming

Land use change boundary consequences

Production of biofuel crops and those grown for export means insufficient food crops for local use.

Reduced biodiversity

Land use change boundary possible solutions

Concentrate farming in most productive areas

Reduce meat consumption

More efficient crops

Nitrate and phosphate boundary has been…

Crossed

Nitrate and phosphate boundary causes

Use of fertilisers containing nitrate or phosphate

Nitrate and phosphate boundary consequences

Eutrophication from nitrate and phosphate run off into bodies of water - water contamination

Nitrate and phosphate boundary possible solutions

Reduce use of fertilisers

Ozone boundary has been…

Avoided

Ozone boundary causes

Manufacture and use of of Chlorinated Fluorocarbons (CFC’s) in aerosols

Ozone boundary consequences

Ozone layer destruction leading to ‘hole’ in the ozone layer and harmful UV rays not absorbed increasing risk of DNA mutations, skin cancer and cataracts