ecosystems Flashcards
define ecosystem
all living organisms and non-living components in a specific habitat, and the interrelationships between them.
define habitat
the place where an organism lives.
Population
the number of individuals of the same species living in the same place and time
define community
all the organisms of all the different species living in a habitat
define niche
the role of an organism in the ecosystem
biotic factors
the effects of living organisms, e.g. food supply, predation, disease, competition.
abiotic factors
the effects of non-living components, e.g. temperature, pH of soil, soil type, light intensity, oxygen concentrations, carbon dioxide concentrations.
Autotroph
an organism that uses light energy to synthesise its own complex organic molecules.
Heterotroph
an organism that consumes complex organic molecules to gain nutrients, obtaining energy.
how is energy lost between trophic levels
- plant can’t use all light for photosynthesis as some sun light is wrong wavelength, some is reflected and some passes straight thru the leaves
- some sunlight can’t be used as it hits part of the plant that can’t photosynthesise like the bark
- some food is indigestible so act as waste (faeces)
- respiratory loss- some energy is lost to environment as organically use energy from respiration for movement or body heat which gets lost to the surroundings
- some energy becomes biomass of that trophic level as energy gets stored for growth
human activities which increase transfer of energy
herbicides kill weed that compete with agricultural crops
fungicides kill fungal infections which damage agricultural crops
insecticides kill insect pests that eat and damage crops
natural predators introduced to eat pest species
fertilisers provide crops with minerals to help them grow
define decomposers
an organism that break down dead or undigested organic material
what is energy stored as
biomass
what is net productivity
the amount of energy that is available for the next trophic level
how is carbon dioxide removed from the air
plants use carbon dioxide for photosynthesis
carbon dioxide is dissolved in oceans
how is carbon dioxide released back into the air
when organisms respire
when fossil fuels are burnt
by volcanoes
what happens when consumers die
the carbon compounds in the dead organism is digested by decomposers
how is carbon passed on to primary consumer
when they eat the plants
what is nitrogen fixation
when nitrogen gas in the atmosphere is turned into ammonia by bacteria such as Rhizobium and Azotobacter
what is ammonification
when nitrogen compounds from dead organism are turned into ammonia by decomposers which goes on to form ammonium
what is nitrificarion
when ammonia ions in soil are changed into nitrogen compounds that are then used by plants
first nitrifying bacteria called Nitrosomonas change ammonium ions to nitrites
then other nitrifying bacteria called nitro bacteria convert nitrites into nitrates
what is denitrification
when nitrates in the soul is converted into nitrogen gas by denitrifying bacteria under anaerobic conditions
what are the other ways nitrogen’s gets into the ecosystem
by lightning or artificial fertilisers
what is succession
the process by which an ecosystem changes over time
what are 2 types of succession
primary and secondary
what is primary succession
happens on land that’s been newly formed or exposed
so there is no soil or organic mater to begin with
what is secondary succession
this happens on land that has been cleared of plants but the soil remains
first stage of primary succession
a new species colonises a new land surface.
the first species to colonise is known as the pioneer species
when they die they decompose and change the abiotic conditions
decomposers break down the humus- dead organic matter
this forms basic soil making conditions less hostile
second stage of primary succession
more and more plants build up and die over time and decompose making the soil deeper and richer in materials meaning larger plants can live there
each stage different plants are better adapted than others so they can outcompete the other plants- dominant species
what happens to species diversity during succession
as succession goes on the ecosystem becomes more complex and new species move in alongside existing one
therefore species diversity increases
final stage of succession
climax community
the ecosystem is supporting the largest and most complex community of plants and animals and it won’t change much more
what can prevent succession
human activities
what is plagioclimax
The community that becomes established when deflected succession occurs. Chalk grassland is an example of a plagioclimax.
what is deflected succession
A succession that does not progress to the natural climax community; factors that cause this are grazing, mowing and fires.
what is abundance
the number of individuals of one species in a part area
what are 3 types of transects
line
belt
interrupted
what is a line transect
a tape measure placed along the transfer and the species that touch the tape measure are recorded
what is belt transect
data is collected along the transect using the frame quadrants placed next to each other
what is interrupted transect
taking measurements at intervals along its length
