Ecosystems Flashcards
Definition of Habitat Population Community Ecosystem
Habitat - The place where an organism lives
Population- All the organisms of one species in a habitat
Community - Populations of different species in a habitat
Ecosystem - A community and all the abiotic conditions in the area in which it lives
Definition of Abiotic conditions
The non-living features of the ecosystem
Temperature + availability of water
Definition of Biotic conditions
The living features of the ecosystem
Presence of predators + food
Definition of Niche
The role of a species in a habitat
Species and niches
Involves it biotic interactions - what it eats e.g.
It abiotic interactions - the oxygen it breathes in e.g.
Every species has a unique niche - can only be occupied by one species
If two species occupy the same niche one will outcompete the other
Definition of Carrying capacity
The maximum stable population size of a species that a an ecosystem can support - result of abiotic and biotic factors
Interspecific competition
Competition between different species
Results in less resources available to both populations
Results in smaller populations of both
The better adapted population will eventually outcompete the other
Grey Squirrel outcompeting native Red Squirrel
Intraspecific competition
Competition within a species
When resources are plentiful the population increases meaning its competition for food and space
Eventually the resources become limiting and so the population goes into decline
A smaller population means there is less competition for food and space
Better for growth and reproduction so the population grows again
CYCLE
Predator and Prey Cycles
Prey population increases so there is more food for predators
Predator population grows too
Predator population grows increasing predation on prey so the prey population falls
Means there is less food for predators so the population of predators decreases
The predation therefore decreases so the prey population begins to grow
Lag period between changes due to reproduction times
Complication of predator and prey cycles
Other factors involved
Like the availability of food for the prey
Predators may find a new prey
Quadrat random sampling
Non-motile organisms
Draw a grid of area
Find co-ordinates to sample using random generated numbers
Place quadrats at these random co-ordinates
Find species frequency or percentage cover (quick way for species which are hard to quantify - mainly plants)
Repeat in other co-ordinates
Calculate mean abundance in the area
Transect lines random sampling
Belt transect - quadrats placed along transect line, end to end
Work out species frequency or percentage cover
Interrupted belt transect - distance between quadrats along line
Mark-release-Recapture equation
Used for motile species
Capture, count, mark, release, recapture, re-count
Total population size = 1st capture number x 2nd capture number / Number marked in 2nd sample
Mark-release recapture assumptions?
Marked sample has had the opportunity to mix back into the population and is therefore representative
Marking hasn’t affected the individual’ chance of survival
No change in population size - births, deaths, migration
What is primary succession?
Happens on land that has been newly formed or exposed
No soil or organic material to start with
