6.6 - Populations and Sustainability Flashcards
What is population size?
The total number of organisms of one species in habitat.
Explain and label the growth curve.
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.
What is the carrying capacity?
The maximum stable population size of a species that an ecosystem can support.
What is a population limiting factor?
The factor whose magnitude slows down the rate of a natural process.
What abiotic (non-living) factors affect population size and why?
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.
What biotic (living) factors affect population size?
Interspecific competition – competition between different species.
Intraspecific competition – competition within a species.
Predation – predator and prey populations are controlled by negative feedback.
What factors determine the carrying capacity of an ecosystem?
Limiting factors – both biotic & abiotic.
What is negative feedback?
A mechanism that restores the level to normal.
What is the difference between conservation and preservation?
Conservation - active management of ecosystems involving human intervention.
Preservation - protection of ecosystems keeping them exactly as they are.
How do we conserve ecosystems?
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.
How do we preserve ecosystems?
Banning or restricting humans from an ecosystem.
Limited tourism & scientific research.
No mining or other industrial activities allowed.
What are the economic, social & ethical reasons to conservation?
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.
Explain and justify sustainable management.
Allows biodiversity to be maintained whilst allowing economic benefits to be derived.
Ensures natural resources will still be available for future generations.
Describe sustainable methods used in woodland ecosystems.
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.
Suggest measures that an international treaty might impose, to prevent fishing from causing permanent damage to the Southern Ocean.
Fishing quotas, mesh size, species restriction, trawler size/days at sea, penalties, monitoring/surveillance, public education.
Identify the practical difficulties that might prevent measures from being effective. (Protecting the Southern Ocean).
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).
Describe the Terai Arc region.
Area of forest & grassland on the border between Nepal & India.
~ 7 million people live there.
What are the human needs in the Terai Arc?
Clear forest for housing, fuel, growing crops & grazing of livestock.
What animals are present in the Terai Arc forest?
Bengal tiger, Asian elephant + Indian rhino.
What are the issues in the Terai Arc?
Forest destruction brings animals into close contact with humans. Elephants eat & trample crop fields. Tigers kill livestock. Humans likely to then shoot & kill.
What are the solutions to the issues in the Terai Arc?
WWF has provided solar cookers & biogas generators so no need for wood as fuel.
Farmers plant mint hedges around crops to keep animals away.
Describe the Maasai Mara region.
It is a national reserve in Kenya, consisting mostly of grassland.
What are the human needs in the Maasai Mara?
Maasai people earn a living rearing livestock e.g. cattle.
What animals are present on the Maasai Mara grasslands?
Wildebeest, zebra, lions & cheetahs.
