Biology Paper 2 - 6.6 Populations and Sustainability

The total number of organisms of one species in habitat.

Slow growth as the initial small number of individuals build up their numbers.
Rapid growth as the number of individuals keep reproducing. Resources are plentiful.
Stable state as the number of resources becomes a limiting factor for population size. There are not enough resources for the whole population. The population then begins to decline. A smaller population means there is less competition for space and food, which is better for growth & reproduction. The population starts to grow again.

The maximum stable population size of a species that an ecosystem can support.

The factor whose magnitude slows down the rate of a natural process.

Abiotic factors, e.g. amount of light, water, space, temperature, chemical composition.
When abiotic factors are ideal a species can grow fast & reproduce successfully & vice versa.

Interspecific competition – competition between different species.
Intraspecific competition – competition within a species.
Predation – predator and prey populations are controlled by negative feedback.

Limiting factors – both biotic & abiotic.

A mechanism that restores the level to normal.

Conservation - active management of ecosystems involving human intervention.
Preservation - protection of ecosystems keeping them exactly as they are.

Protection – natural resources in them can be used by do not run out.
Management – how resources are used and replaced.
Reclamation – restoring ecosystems that have been damaged or destroyed.

Banning or restricting humans from an ecosystem.
Limited tourism & scientific research.
No mining or other industrial activities allowed.

Social – many ecosystems bring much joy to many people – birdwatching, walking.
Economical – resources drive trade in many countries – timber & tourism.
Ethical – humans should not destroy an ecosystem – conservation is the right thing to do.

Allows biodiversity to be maintained whilst allowing economic benefits to be derived.
Ensures natural resources will still be available for future generations.

For every tree cut down, a new one is planted in its place.
Trees are cleared in patches as woodland grows back more quickly in small areas between existing woodland.
Timber is often harvested by coppicing – tree trunk is cut close to the ground to encourage new growth.

Fishing quotas, mesh size, species restriction, trawler size/days at sea, penalties, monitoring/surveillance, public education.

Area too large, expense of monitoring, monitoring hampered by weather, false reporting of catches/trawler size/days at sea.
Death of fish caught but not kept (because of restrictions).

Area of forest & grassland on the border between Nepal & India.
~ 7 million people live there.

Clear forest for housing, fuel, growing crops & grazing of livestock.

Bengal tiger, Asian elephant + Indian rhino.

Forest destruction brings animals into close contact with humans. Elephants eat & trample crop fields. Tigers kill livestock. Humans likely to then shoot & kill.

WWF has provided solar cookers & biogas generators so no need for wood as fuel.
Farmers plant mint hedges around crops to keep animals away.

It is a national reserve in Kenya, consisting mostly of grassland.

Maasai people earn a living rearing livestock e.g. cattle.

Wildebeest, zebra, lions & cheetahs.

Overgrazing by livestock can destroy grassland for wildlife.

Support Maasai people to make money from their land through conservation & ecotourism + encourage sustainable farming methods.

Partially decomposed organic matter created in wetland environments that are acidic & anaerobic.
They are a major carbon sink.
They are an important water store – provides 3⁄4 of our drinking water.
They are home to lots of different plants & animals.

Grazing sheep & deer. Gardeners use peat based compost as rich in nutrients.

Overgrazing leads to loss of moss species & soil compaction – increasing water run-off & erosion.

Farmers given grants to use peat bogs in a sustainable way – lower number of livestock grazing on peat bogs & remove livestock over the winter.
Educating & encouraging gardeners to use peat free compost.

The economic needs of the farmer need to be met to allow the farmer to continue to make a living, whilst also conserving the areas in which they farm.

Small group of islands in the Pacific Ocean. Many rare species of plants & animals.
What problems have humans caused to the Galapagos Islands?
Non-native animals & plants introduced to the islands. Many native species have been eaten – both plant & animals.

Eradication programmes have removed wild goats & wild dogs from some islands.

The world’s southernmost continent. Plants & animals that have adapted to icy conditions.

Sewage pollution into the sea & leaving rubbish.

| Hunting, whaling & fishing all reduced populations.

All sewage treated before releasing it. All waste taken away by ship. Hunting & whaling have been banned.

Areas of hills & lakes in the UK – millions of visitors each year.

Erosion of footpaths & loss of soil from hillsides.
Soil ends up in waterways & can disturb the pH.
Walkers trample & destroy vegetation either side of the paths.

Regular repairs & maintenance work on the paths.
Encourage the regrowth of damaged vegetation.
Educate walkers about the importance of staying on the path – shortcuts increase erosion.