Define ecosystem
The interactions between all the living organisms found in one area, combined with non-living aspects of their environment. Can vary from very large to very small.
Define community.
All the different species that live in one area and interact with each other.
Define population.
All the individuals of a species that live in the same habitat at a given time.
Define abundance
All the individuals of a species that live in the same habitat at a given time.
Define habitat.
The place where an organism lives within an ecosystem.
Define biotic factors and give an example.
Living features of an ecosystem e.g. predators, disease.
Define abiotic factors and give an example.
Non-living features of an ecosystem e.g. light, temperature, pH of water/soil.
Define a niche and give an example
The role of a species within its habitat, consisting of both its biotic interactions e.g. what it eats, and abiotic interactions e.g. time of day it is active.
Define distribution
Where an organism is within a particular area
Define interspecific competition
Competition for resources that occurs between different species
Define intraspepcific competition
Competition for resources that occurs within the same species
Give an example of how distribution is affected by abiotic factors
Plants that need a lot of light only grow on south facing slopes
Give an example of how distribution is affected by biotic factors
Interspecific competition between two species may cause one species to become extinct in that particular area
Give an example of how abundance is affected by biotic factors
Interspecific and intraspecific competition can cause the number of species in an area to decrease
Give an example of how abundance is affected by abiotic factors
If the temperature of a mammals surroundings is significantly lower than optimum, the mammal will expend a lot of energy keeping warm meaning less energy is available for growth and reproduction thus reducing the number of species of that mammal
How can a quadrat be used to randomly sample an area?
Randomly placed 10 times using random coordinate generator. Percentage cover/number of organisms counted.
How can a qudrat be used to systematically sample an area?
Place a transect. Place the quadrat at regular intervals along transect. Record percentage cover/number of species plus other abiotic factors. Repeat.
When is random sampling used?
When comparing two or more distinct areas
When is systematic sampling used?
When seeing how a factor that changes over one area affects abundance or distribution
List some abiotic factors that should also be recorded when sampling an area
Light levels, tempreature, topography, soil and water pH, humidity, oxygen concentration (water)
What is meant by primary succession?
Where an area previously devoid of life is colonised by a community of organisms.
Summarise the process of primary succession.
● Pioneer species can survive harsh conditions & colonise the area.
● They change abiotic factors of their environment e.g. decomposition adds organic matter forming soil.
● Overtime, more complex organisms survive and outcompete the initial species. A climax community is reached.
What is a climax community?
Final stage of succession. Ecosystem is stable in dynamic equilibrium over a long period of time. Usually dominated by large species in rich soil.
How is the soil improved for other species during succesion?
Organisms die and are decomposed adding organic matter to the soil. This means the soil holds more water and minerals for other species.
