19. Populations in ecosystems Flashcards
define biodiversity
the range and variety of living organisms within a particular area
define biomass
the total mass of living material, normally measured in a specific area over a given period of time
define climax community
the organisms that make up the stable, final, community that exists in a balanced equilibrium
define community
the organisms of all species that live in the same area
define conservation
method of maintaining ecosystems and the living organisms that occupy them.
it requires planning and organisation to make best use of resources while preserving the natural landscape and wildlife
define habitat
the place where an organisms usually lives
define hostile/harsh
when abiotic conditions in an environment are at the extremes
define niche
all the conditions and resources required for an organism to survive and reproduce (AKA its ‘role’ in the ecosystem)
define pioneer species
a species that can colonise bare rock or ground
define primary succession
the progressive colonisation of bare rock or other barren terrain by living organisms
define secondary succession
the recolonisation of an area after an early community has been removed or destroyed.
define succession
the changes in an ecosystem, over time, in the species that occupy it
define population
the number of organisms of the same species that live in the same place at the same time
define carrying capacity
defined as the maximum size of the population
what eventually determines population size
limiting factors
abiotic stands for?
non-living
biotic stands for?
living
list some examples of abiotic factors?
temperature
light
PH
water
why is temperature considered an abiotic factor?
links to denaturing of enzymes
why is light considered an abiotic factor?
source of energy for most ecosystems
why is PH considered an abiotic factor?
affects enzyme action
why is water and humidity considered an abiotic factor?
links to transpiration rate
list some examples of biotic factors
competition
predators
parasites and disease
what is the competitive exclusion principle?
where populations of two species initially occupy the same niche, one will normally have the competitive advantage
what are some features of a pioneer species?
colonises an inhospitable environment
include features that suit them to colonisation
list some features of a pioneer species that allow them to colonise an environment
asexual reproduction production of seed/spores rapid germination photosynthesise nitrogen-fix tolerance to extremes
what are some features of a climax community?
a stable community over a long period of time
high biodiversity
consists of animals and plants
what happens during primary succession?
abiotic environment becomes less hostile greater number and variety of habitats and niches increased biodiversity more complex food webs increased biomass
what happens during secondary succession?
land altered in some way
recolonisation leads to climax community being different
In what ways can land become altered during secondary succession?
fire
disease
grazing
agriculture
