7.4 - Populations in Ecosystems Flashcards
What is a habitat?
The part of an ecosystem where a particular organism lives, e.g. a rocky shore or a field.
What is a population?
All the organisms of one species in a habitat.
What is a community?
Populations of different species in a habitat make up a community.
What is an ecosystem?
A community, plus all the non-living conditions in the area in which it lives.
What are abiotic factors?
The non-living features of an ecosystem.
What are biotic factors?
The living features of an ecosystem.
What is a niche?
The role of a species within its habitat.
What is adaptation?
A feature that members of a species have that increases their chance of survival and reproduction.
How can the size of a population be estimated?
- Randomly placing quadrats, or quadrats along a belt transect, for slow-moving or non-motile organisms.
- The mark-release-recapture method for motile organisms.
What is population size?
The total number of organisms of one species in a habitat.
What is the carrying capacity?
The maximum stable population size of a species that an ecosystem can support.
What is interspecific variation?
Interspecific competition is when organisms of different species compete with each other for the same resources.
What is intraspecific variation?
Intraspecific variation is when organisms of the same species compete with each other for the same resources.
What is predation?
Predation is where an organism kills and eats another organism. Predator-prey relationships are usually complicated because there are other factors involved, like availability or food for the prey.
What is succession?
Succession is the process by which an ecosystem changes over time. The biotic conditions change as the abiotic conditions change.
What are the two types of succession?
1) Primary succession
2) Secondary succession
What is primary succession?
This happens on land that’s been newly formed or exposed.
What is secondary succession?
This happens on land that’s been cleared of all the plants, but where the soil remains.
Describe the process of primary succession
- Primary succession starts when species colonise a new land surface. Seeds and spores are blown in the wind and begin to grow.
- The first species to colonise the area is called pioneer species, they only grow because they’re specially adapted to cope with the harsh conditions.
- The pioneer species change the abiotic conditions as they die and decompose, forming basic soil.
- This makes the conditions less hostile, which means that new organisms with different adaptations can move in and grow. These then die and decompose, adding more organic material, making the soil deeper and richer in minerals. This means that larger shrubs can start to grow in deeper soil, which retains more water.
- Some new species may change the environment so that it becomes less suitable for the previous species. This makes the conditions less suitable for pioneer species.
Describe the process of secondary succession
Secondary succession works in a similar way to primary succession but because there is already a soil layer succession starts at a later stage and the pioneer species are larger plants such as shrubs.
What is the final stage of succession?
Climax community
What is a climax community?
The ecosystem is supporting the largest and most complex community of plants and animals it can and it in a steady state.
What is a plagioclimax?
When succession is stopped artificially.
What different processes can prevent succession?
- Human activities (plagioclimax).
- Conservation - too preserve an ecosystem in its current stage of succession.
