3.6 Human Impact on the Environment

State the reasons for extinction

-Natural selection

• Habitat destruction

• Pollution

• Hunting and collecting

• Competition from domestic animals

Define biodiversity

A measure of the number of different species and number of individuals in the species, living in a specified area

Define an Endangered species

A species at risk of becoming extinct because there are few breeding pairs left

Define extinction

The total loss of a species

What does IUCN stand for

International Union for Conservation of Nature

What does IUCN do

makes assessments of plants and animals, grading them to their vulnerability to extinction

State the gradings given by the IUCN

EX - extinct
EW - extinct in the wild
CR - critically endangered
EN - endangered
VU - vulnerable
NT - near threatened
LC - least concern

State the 3 aspects of biodiversity

Genetic diversity
Species diversity
Ecosystem diversity

Define conservation

The planned management of ecosystems to enhance biodiversity and protect gene pools

State the main reasons for conservation

Ethical
Economic
Cultural and aesthetic

State the ethical reason for conservation

It is unethical to drive species to extinction and reduce biodiversity

Other species have occupied earth far longer than we have and should be allowed to coexist with us

State the economic reason for conservation

Living organisms contain a gigantic pool of genes with the capacity to make millions of substances such as medicines

State the cultural and aesthetic reason for conservation

Habitats and organisms enrich our lives.

State ways in which conservation may be achieved

Habitat protection by nature reserves and SSSI

International cooperation between governments and organisations

Restricting activities that threaten an endangered species

Legislation to prevent overfishing and poaching

Breeding programmes

Sperm banks and seed stores

Reintroduction programmes

Pollution control

With good forestry practice. How can efficiency be increased

Planting trees the optimum distance apart - planting trees together will result in intraspecific competition

Controlling pests and disease

What is selective logging

Involves felling only some of the largest trees.

Pros of selective logging

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

maintains nutrients in the forest soil

Cons of selective cutting

Uses large machinery which causes disturbance to the area

How is deforestation causing soil erosion

Removal of vegetation leads to a reduction in rainfall accelerating desertification

Removal of vegetation on the higher slopes of valleys results in heavy rain sweeping exposed soil to the flood plains below

On the lower slope the absence of plants results in only evaporation occurring which is generally slower than transpiration in returning water vapour to the atmosphere so soil conditions become wetter

How is deforestation causing climate change

Cutting down forest reduces the rate of removal or carbon dioxide from the atmosphere by photosynthesis

How can the different stages of coppicing help increase biodiversity

-More varied habitats/creates more niches
-Secondary succession occurs
-More types of food

• Changing light level resulting in flowers thriving in open areas

What is coppicing

A system based on the fact that most deciduous trees grow from the base when their trunks are cut down. The trees are cut down close to the ground and then left for several years to regrow

Consequences of deforestation

Climate change

Destruction of natural habitats leading to loss of biodiversity

Soil erosion caused by loosening of topsoil through digging and ploughing

What is long rotation time

Involves leaving each part of the forest for many years before re-harvesting it

Reasons for deforestation

World demand for timber as a building material
Wood is used as a fuel

land is cleared for agriculture by subsistence farmers and cash crops

New roads are built to provide a transport infra structure

There is a demand for paper and packaging

What is the effect of monocultures

Decrease hybrid vigour
increase in homozygosity

What happens if the same crop is grown on the same plot year after year

Yield progressively decline because…

The roots are always the same length so they extract the same minerals from the same depth in the soil.

This has increased the use of fertilisers
Same crop is always susceptible to the same pests which increase in number

suggest how the conflicts of interest between food production and conservation can be resolved.

▪ Sustainable farming techniques / or description/ less (nitrate) fertiliser (close to water courses)/ owtte

▪ Regeneration of forests / planting endemic species.

▪ Change to lifestyle e.g. encourage eating less meat/ Alternatives to palm oil

▪ National parks / SSSIs / encourage ecotourism as alternative source of income/ seed banks

▪ Change in government policy / public awareness/ education

Schemes and legislation that aims to reverse the effect of agricultural exploitation

Organic farming
Set aside schemes
Legislation

Define monoculture

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

How are hedges valuable to wildlife

They provide wildlife corridors
Habitats

How are agriculturists meeting the growing demand

Creating larger fields by removing hedges

Cultivated monoculture

Increased their use of fertilisers and pesticides

What do ecotourism do

Minimise the negative impacts of tourism

Contributes to conservation efforts

Employ local people and give money back to the community

Educate visitors about the local environment and culture

Cooperate with local people to manage natural areas

Define overfishing

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

Describe drift netting

Involves suspending a net from floats stretched between two boats so that fish swim into it

Describe trawling

Involves dragging a large net through the water,

Issue of trawling

Damages the ocean bed, destroying the habitats

Issue of drift netting

Non target species become caught

State the ways to reduce the impact of overfishing

Fishing quotas
Reducing size of fishing fleets
Restricting seasons for fishing
Restricting mesh sizes for fishing nets
Banning fishing from some zones
Fish farming

Benefit of restricting mesh sizes

By having a minimum mesh size, larger fish will be caught but smaller fish who are often juvenile will be able to escape from the nets and go on to breed

State the problems around fish farming

Fish are very densely stocked so disease can be spread easily which can spread to wild fish

Huge amount of antibiotics are used to keep the fish healthy

Pesticides used to control fish parasites are known to harm marine invertebrates

When fish escape the farmed fish interbreed with wild fish and potentially weaken wild stocks as they have a selective advantage over wild fish

Eutrophication

Define planetary boundary

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

Describe a safe operating space for humanity

Where planetary systems are stable

Name the planetary boundaries

Biosphere integrity
Climate change
Chemical pollution and novel entities
Ozone depletion
Aerosol loading
Ocean acidification
Biochemical flows
Freshwater consumption and the water cycle
Land system change

Genetic diversity

Variety of alleles within a species

Species diversity

Variety of species within a habitat

Ecosystem diversity

Variety of habitats within a ecosystem