community
Consists of all populations living in the same area at the same time
population
Members of one species living in the same area at the same time
ecosystem
Consists of a living community, its physical surroundings and the interactions both within the community and between the community and its surroundings. organismsThe interaction between the living and non-living, biotic and abiotic, organisims and their s
competition
An interaction between individuals of the same or different species that use the same resources in the same area
predator-prey
An interaction within a community that involves the eating of one species, the prey, by another, the predator
parasitism
An interaction where one organisim that lives on or in another organisim and feeds from it (usually without killing it)
mutualism
An association between two species in which both species gain benefit
commensalism
An association between two species in which one species benefits and the other neither gains nor is harmed
source of energy for ecosystems
The main source of energy for ecosystems is the sun.
producers
Producers are called Autotrophs. They transform radiant energy (sun) to chemical energy.
consumers
Consumers are called Heterotrophs. They get their energy from eating producers or other consumers.
decomposers
Usually a decomposer is fungi. They can break down and absorb organic matter of dead organisms. They recycle organic matter.
trophic level 1
Producers. Make energy from sunlight.
trophic level 2
Primary consumer. (Herbivores). Eat the plants (producers).
trophic level 3
Secondary consumer. (Carnivores). Eat herbivores (plant eaters).
trophic level 4
Tertiary consumer. (Top Carnivores). Eat predators.
energy loss at transfer
Most energy is lost as heat during transfer between trophic levels. Only about 5-20% is available for the next level (usually approximated to 10%).
food chain
A representation which shows chemical energy flow within an ecosystem. Begins with producers.
food web
A representation of interrelated food chains showing energy flow in an ecosystem.
ecological pyramids
Show aspects of trophic levels in an ecosystem such as numbers, biomass and energy.
inverted ecological pyramids
Occurs when the number of producers is less than primary consumers (eg. trees - very big) or the biomass of producers is less (antarctic phytoplankton - very short lived). Never occurs in Pyramids of Energy.
carbon cycle
Cyclic processing of carbon between various parts of biosphere. Has gaseous phase.
nitrogen cycle
Cyclic processing of nitrogen between various parts of biosphere. Has gaseous phase. Relies on Denitrifying bacteria.
phosphorus cycle
Cyclic processing of phosphorus between various parts of biosphere. Does not have gaseous phase.
bioaccumulation
Increasing accumulation of non-biodegradable susbstance as progress through trophic levels. eg. mercury in Port Phillip Bay.
age structure of populations
Identifies the proportion of its members that are; pre-reproductive stage, at reproductive age, post-reproductive stage. Can be used to predict population growth rate.
sampling
Using a part of a population to estimate the size of the population.
quadrats
Use of a square to sample populations of sessile or slow moving organisms.
transects
Use of a line or strip to sample populations of larger/fast moving organisms.
mark-recapture
Technique involving capture and marking of organisms followed by recapture of organisms and counting marked ones. Used to estimate population size.
variables
Affect the population size/growth; includes: birth rate, death rate, migration rate
exponential growth
Unlimited growth of a population when abundant resources and little or no predation/disease; this can occur for several generations as long as conditions remain.
S-shape growth
When the population growth slows down and the population stabilises at carrying capacity of habitat after period of exponential growth.
r- selected
Giving birth to a lot of young in a short period of time without having to take care of them. Energy is put into producing offspring.
K- selected
Giving birth to less young and taking a lot of care of them. Energy is put into caring for (raising) offspring.
introduced (exotic) species
A species which does not occur naturally in a region but has been introduced by humans, either deliberately or accidentally.
overharvesting
A situation when too many breeding individuals have been removed from a population for the population to replace them naturally.
salinity
Refers to the salt concentration in soils. Land degradation (removing trees) caues water table to rise and increases salinity.
river flow
Damming of rivers affects their flow which can change the water temperature or prevent water from reaching areas. This can affect populations in these areas.
nutrient overload (eutrophication)
The accumulation of dissolved mineral nutrients in a body of water. Can cause toxic blooms of cyanobacteria and reduce light available for underwater plants.
waste disposal
Can result in the release of toxic/non-biodegradable chemicals which can undergo bioaccumulation.
natural change - fire
Various strategies have evolved in Australian flora to enable survival of the species in fire-affected ecosystems. The frequency of fires in these ecosystems can have a major effect.
succession
The natural process in which the community living in an area changes over time.