Section 7 - 19 Populations in ecosystems Flashcards
What is ecology?
The study of the inter-relationships between organisms and their environment.
The environment included both non-living and living factors.
What is an ecosystem?
Dynamic systems made up of a community and all the non-living factors of its environment.
What are the two major processes that occur in ecosystems?
- the flow of energy through the system
- the cycling of elements within the system
What is a population?
A group of individuals of one species that occupy the same habitat at the same time and are potentially able to interbreed.
What is the carrying capacity?
An ecosystem supports a certain size of population of a species.
What factors affect the size of a population?
- the effect of abiotic factors
- interactions between organisms. - intraspecific and interspecific competition and predation.
What is a community?
All the populations of different species living and interacting in a particular place at the same time.
What is a habitat?
The place where an organism normally lives and is characterised by physical conditions and the other types of organisms present.
What is a microhabitat?
Smaller units inside a habitat that each have their own habitat.
What is a niche?
Descirbes how an organism fits into the environment.
Where an organism lives and what it does there.
Includes biotic and abiotic factors.
What is the competitive exclusion principle?
No two species occupy exactly the same niche.
What is a population?
A group of individuals of the same species that occupy a habitat at the same time.
what is the population size?
The number of individuals in a population.
When might it not be possible to plot a growth curve?
Where the population grow rapidly over a short period of time.
List abiotic factors that influence the size of a population
- temperature
- light
- pH
- water and humidity
What makes up an ecosystem?
The interacting biotic and abiotic factors in a particular area within which there are a number of communities of organisms.
In what two ways do species alter the environment during succession?
- Make it less suitable for the existing species - New species may out-compete the existing one and so take over a given area.
- Make more suitable for other species with different adaptions - this species may be out-competed by the better adapted new species.
What is the first stage of succession?
Colonisation of an inhospitable environment.
By organisms called pioneer species.
What is a pioneer species?
Organisms that can colonise an inhospitable environment.
In first stage of succession.
They make up a pioneer community and often have features that suit them to colonisation.
What features suits pioneer species to colonise?
- Asexual reproduction
- Production of vast quantities of wind-dispersed seeds or spores.
- rapid germination of seeds
- ability to photosynthesis.
- Ability to fix nitrogen from the atmosphere
- Tolerance to extreme conditions
Give an example of a pioneer species
Lichens
In the UK what is the most ultimate community?
Deciduous oak woodland.
What is a climax community?
State where many species flourish and there is much biodiversity.
Stable equilibrium with the prevailing climate. Abiotic factors such as climate that determine the dominant species of the community.
What are the common features that emerge during succession?
Each one leads to the next:
- non-living abiotic environment becomes less hostile
- greater number and variety of habitats and niches produce
- increased biodiversity.
- more complex food webs
- increased biomass.
What is secondary succession?
The process by which ecosystems return after the clearance of land for agriculture or a forest fire.
The climax community occurs more rapidly as soil already exists.
Describe the process of succession
What is conservation?
The management of the Earths natural resources by humans in such a way that maximum use of them can be made in the future.
Involves active intervention by humans to maintain ecosystems and biodiversity. - dynamic process
What are the main reasons for conservation?
Personal - maintain plant and our life support machine.
ethical - other species occupied Earth before humans
Economic - gigantic pool of genes with capacity of making millions of substances
cultural and aesthetic - habitats and organisms enrich our lives.
Why don’t original species still exist in the climax community?
Their habitats have diappeared as a result of succession or species have been out-cpmpeted by other species or been taken over for human activities.
How is a natural climatic climax achieved?
If the factor that is preventing further succession is removed then the ecosystem can develop naturally into its climatic climax.
secondary succession
