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Ecology Defns L2 NZ

Selected biology definitions for NZ Level 2 ecology topic

COMMUNITY All the populations in a defined area.
ECOSYSTEM A community plus all the non-living matter in the area, e.g. a forest includes not only the inhabitants but also the non-living parts of the soil.
AUTOTROPH or PRODUCER Organism that makes its own organic compounds from CO2 and water, and is thus independent of other organisms for energy; includes green plants and some bacteria.
HETEROTROPH Organism that obtains its energy by feeding on other organisms.
CONSUMER Organism that feeds on other organisms or parts of other organisms, which it kills in the process.
HERBIVORE Animal that feeds on plants.
CARNIVORE Animal that feeds on other animals.
OMNIVORE Animal that feeds on both plants and animals.
PARASITE Organism that feeds on another organism (the host) without killing it.
DECOMPOSER Organism that feeds on dead organic matter.
ENERGY and NUTRIENT FLOW The energy that drives an ecosystem is ultimately converted to heat, which cannot be reused and is radiated out into space. Energy flow through an ecosystem is thus linear. Matter, on the other hand, is recycled.
FOOD CHAIN A series of organisms through which energy flows; first link is always a plant.
GRAZING FOOD CHAIN Food chain in which the first link is living plant matter and the second link is a herbivore.
DETRITUS FOOD CHAIN Food chain in which the first link is dead plant matter and the second link is a decomposer
FOOD WEB A system of interconnected food chains
TROPHIC LEVEL Position of an organism in a food chain; plants occupy the first trophic level, herbivores the second, etc.
SUCCESSION Progressive change in the composition of a community over time, leading eventually to a stable, climax community.
STRATIFICATION Vertical layering of the vegetation in a forest into emergents, canopy, sub-canopy, shrub layer, ground layer.
ZONATION Change in the composition of a community along a physical environmental gradient, e.g. up a rocky shore or up a mountain.
HABITAT The place where an organism lives.
ENVIRONMENT The sum total of all the factors in the surroundings that influence an organism.
NICHE The way an organism makes its living, its role in the community.
PRIMARY SUCCESSION Primary succession begins with initially hostile conditions often rock, that are gradually made more fertile as a result of colonisation by pioneer plants replaced by other plants to reach a stable community.
SECONDARY SUCCESSION Secondary succession begins after sudden removal of existing plants/vegetation, and thus with fertile soil to reach a new climax community.
ADAPTATION Any inherited feature that increases the chances that an organism will survive and reproduce.
PHYSICAL ENVIRONMENT Includes such factors such as temperature, light intensity, humidity, salinity, pH, wind, water flow.
BIOTIC ENVIRONMENT Includes factors such as food, organisms, competition, predation, parasitism.
COMPETITION a state of affairs in which demand for a resource exceeds its supply
INTRASPECIFIC COMPETITION competition between members of the same species, e.g. competition for territory (an area occupied by an animal and which it defends against others).
INTERSPECIFIC COMPETITION competition between members of different species.
GAUZES PRINCIPLE (Competitive Exclusion Principle) No two species can occupy the same niche in the same habitat indefinitely.
PREDATION A predator is an organism that feeds on other organisms and kills them.
PARASITISM A parasite is an organism that obtains food from another organism (the host), which it does not usually kill.
MUTUALISM Relationship between two species in which both benefit.
COMMENSALISM Relationship between two species in which one benefits and the other is not affected.
ALLEOPATHY Inhibition by a plant of potential competitors by production of chemicals. Antibiosis is a similar phenomenon, but it applies to inhibition of bacteria by fungi.
POPULATION All the organisms of a given species occupying a defined area.
POPULATION GROWTH A population may grow as a result of reproduction and/or immigration, and it may decrease as a result of deaths and/or emigration. A population increases if reproduction + immigration exceeds death + emigration.
NATALITY Number of new individuals per thousand per year.
MORTALITY Number of deaths per thousand per year.
CARRYING CAPACITY The maximum numbers of individuals that can be supported by a given environment.
EXPONENTIAL GROWTH Growth by a constant proportion each unit of time e.g. doubling every week.
SIGMOID GROWTH S-shaped growth curve in which numbers increase exponentially at first, followed by levelling off of growth rate till numbers stabilise at the carrying capacity.
SURVIVORSHIP CURVE Graph of mortality against age.
POPULATION REGULATION Populations can be regulated by such biotic factors as predation, competition, parasitism, but only if they act in a density-dependent manner. A factor acts in a density-dependent manner if its intensity influences natality and/or mortality
Created by: simkar