2. Ecosystems and ecology Flashcards
Definitions
Species
a group of organisms that interbreed and can produce fertile offspring
Population
a group of organisms of the same species living in the same area at the same time and which can interbreed
Habitat
the environment in which a species normally lives
Niche
the particular set of abiotic and biotic conditions and resources that an organism responds to
Fundamental niche
the full range of conditions and resources where a species could survive and reproduce
Realised niche
the actual conditions and resources that a species exists in due to biotic interactions
Abiotic factor (and examples)
non living, physical factors that influence organisms/ecosystems like temperature, sunlight, pH, salinity, precipitation
Biotic factor
interactions between the organisms such as predation, herbivory, parasitism, mutualism, disease, competition
Competition
a common demand by 2 or more organisms for a limited supply of a resource like food, water, light, space
Carrying capacity
the maximum number of a species or load that can be sustainably supported by a given environment
Biosphere
The part of the earth inhabited by organisms
Ecosystem
A community and the physical environment with which it interacts
Community
A group of populations living and interacting with each other in a common habitat
Trophic level
The position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains
Bioaccumulation
The build-up of persistent or non-biodegradable pollutants within an organism or trophic level because they can’t be broken down
Biomagnification
The increase in concentration of persistent or non-biodegradable pollutants along a food chain.
Gross productivity (GP)
total gain in energy per unit area per unit time (e.g through photosynthesis in primary producers)
Net productivity (NP)
the gain in energy per unit area per unit time remaining after allowing for respiratory losses (R)
Primary productivity
Gain by producers in energy per unit area per unit time (can refer to GP or NP)
Secondary productivity
the biomass gained by consumers through feeding and absorption (measured in units of mass or energy per unit area per unit time)
Gross primary productivity (GPP)
total gain in energy per unit time fixed by photosynthesis in green plants
Net primary productivity (NPP)
subtracting respiratory losses (R) from GPP
Gross Secondary productivity (GSP)
The total gain by consumers in energy or biomass per unit area per unit time through absorption
Net secondary productivity (NSP)
The gain by consumers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses
Sustainable yield
when a natural resource can be harvested at a rate equal to or less than its natural productivity so that the natural capital is not diminished
Biome
A collection of ecosystems sharing similar climatic conditions- for example, tundra, tropical rainforest and desert.
Latitude
The angular distance from the equator (north or south of it) as measured from the centre of the earth (usually in degrees)
Succession
The orderly process of change over time in a community
K strategists
Species that usually concentrate their reproductive investment in a small number of offspring, thus increasing their survival rate and adapting them for living in long-term climax communities
R strategists
Species that tend to spread their reproductive investment among a large number of offspring so that they are well adapted to colonise new habitats rapidly and make opportunistic use of short-lived resources.
Zonation
The arrangement or patterning of plant communities or ecosystems into parallel bands in response to change, over a distance, in some environmental factor
Motile organism
organism that can actively move under its own power from place to place
Non-motile organism
one that cannot move or can only move very very slowly (limpets on rocky shore)
Biomass
The mass of organic material in organisms or ecosystems, usually stated per unit area.
Diversity
a generic term for variation. can refer to species, habitat or gene diversity.
