Populations in Ecosystems Flashcards
community
all the populations of different species living and interacting in one area at the same time.
habitat
place where an organism lives within the ecosystem.
ecosystem
all the living organisms found in one area, combined with non-living aspects of their environment. Can very from very large to very small.
biotic and abiotic factors +examples
biotic: living features of an ecosystem e.g. predators, disease
abiotic: non-living features of an ecosystem e.g. light, temperature
microhabitat
smaller units within each habitat each with their own microclimate.
e.g. under a log-woodlice
niche
the role of a species within its habitat, consisting of both its biotic interactions e.g. what it eats, and abiotic interactions e.g. what time of day its active
population
group of individuals of one species that occupy the same habitat at the same time and are potentially able to interbreed.
carrying capacity
the maximum size of population and ecosystem can support.
4 abiotic factors that affect population gowth
temperature
light intensity
pH
water/humidity
interspecific and intraspecific competition
intraspecific = competition between organisms of the same species
interspecific = competition between organisms of different species.
resources that organisms may compete for
food
water
shelter
light
minerals
mates (intraspecific only)
effect of predator-prey relationship on population size
-prey is eaten by predator, resulting in predator population increasing and prey population decreasing.
-fewer prey means increased competition for food, so predator population decreases.
-fewer predators means more prey survives, prey population therefore increases and cycle starts again
how are quadrats used for estimating population size
can be placed on grid coordinates, or at intervals along a belt transect. Results reported as either percentage cover or frequency. For slow-moving or non-motile organisms.
how is mark-release-recapture used for estimating population size
a sample of a species is captured, marked, then released back into the same area they were caught.
after a certain period of time another sample of the organism is captured, and the number of marked organisms are counted.
for motile organisms
equation for mark-release-recapture
estimated population size= (total no. of individuals in the first sample X total no. of individuals in the second sample)/no. of marked individuals recaptured
assumptions for mark-release-recapture method
-marked individuals distributed evenly
-no migration in or out of the population
-few births or deaths
-method of marking does not affect survival
-mark does not come off
why are ecosystems dynamic
-populations constantly rise and fall
-any small change can have a large effect
-biotic and abiotic factors may alter the conditions of the ecosystem
primary succession
where an area previously devoid of life is colonised by a community of organisms
process of primary succession
-pioneer species can survive harsh conditions & colonise the area.
-they change abiotic factors of their
environment e.g. decomposition adds nutrients to ground
-overtime, this allows more complex organisms to survive.
climax community
the final stage of succession, where the ecosystem is balanced and stable. It is reached when the soil is rich enough to support large trees or shrubs, and the environments is no longer changing.
how might a species alter the environment that develops during succession
a species may improve the environment to make it more suitable for other species.
alternatively, a species may worsen the environment by making it less suitable for other species.
conservation
the protection and management of species and habitats, in order to maintain biodiversity.
methods need to be adapted to the ecosystem in question.
how might succession be managed in order to aid conservation
sometimes succession needs to be prevented in order to preserve an ecosystem at a certain point, e.g. stopping moorland from progressing into spruce forest.
-this is called plagioclimax
reasons for conservation
-personal: maintain planet therefore our life-support system
-ethical: respect for living things
-economic
-cultural and aesthetic
