Glossary

• Assimilation

  The conversion of nutrients obtained from outside the body into a useful form that is incorporated into the tissues and organs.
• Autotroph

  An organism that can produce its own food, usually a green plant that produces its own food via photosynthesis, through the conversion of light energy into chemical energy. Also known as a producer.
• Biomass

  The mass of organisms in a given area or volume.
• Carnivore

  An animal that obtains its energy by consuming other animals.
• Carrying Capacity

  The maximum population size of a species that the environment can sustain indefinitely.
• Climax Community

  The final stage of succession in which a community of plants and animals remains stable and exists in balance with each other and their environment.
• Community

  All the organisms that live together in an ecosystem.
• Competition

  An interaction that occurs between organisms whenever there is shared demand for a limited resource.
• Consumer

  Any organism that gains its energy from other organisms. Also known as a hetertroph.
• Decomposer

  An organism that obtains its energy by breaking down dead organic matter.
• Density-Dependent

  Interactions between organisms which reduce the population when numbers are high and allow the population to increase when numbers are low.
• Density-Independent

  Factors, usually natural disasters, which reduce the reproduction rate or increase the death rate of organisms independently of population density.
• Detritivore

  An animal that obtains its energy by consuming dead organic matter.
• Ecological Efficiency

  The percentage of biomass produced by one trophic level that is transferred and incorporated into biomass at the next trophic level.
• Ectotherm

  An animal that relies on external environments for temperature control instead of generating their own body heat.
• Edaphic

  Relating to the physical, chemical and biological characteristics of soil that affect living organisms.
• Endotherm

  An animal that uses internally generated heat to maintain body temperature independent of external temperature change.
• Exponential Population Growth Model

  A model which illustrates how a population may grow over time if there are no limits to resources. If plotted, the line forms a J shape and is sometimes called a J curve.
• Grazing

  A method of feeding in which herbivores feed on grasses and herbage.
• Gross Primary Productivity

  The rate at which autotrophs produce biomass in a given area and time period.
• Herbivore

  An animal that feeds on plant material.
• Heterotroph

  An animal that must meet its energy requirements by ingesting other organisms or organic matter derived originally from plants.
• Interdependence

  A relationship between species that helps to prevent overpopulation of a particular species to ensure the survival of the species as a whole.
• Inter-specific competition

  Competition between individuals belonging to two or more different species who have very similar resource requirements which are in short supply.
• Intra-specific competition

  Competition between individuals of the same species for the same limited resource.
• Logistic Population Growth Model

  A model which illustrates how a population may grow exponentially until it reaches the carrying capacity of its environment, then will slow until resources become available again. If plotted, the line forms an S shape and is often called an s curve.
• Net Primary Productivity

  The rate at which an ecosystem accumulates energy or biomass, excluding the energy used for the process of respiration.
• Niche

  The role played by a species within a community: where it lives, what it eats, and what eats it.
• Omnivore

  An animal that obtains its energy by consuming both plant and animal material.
• Parasitism

  A symbiotic relationship between organisms of different species in which the host is a source of food and a habitat for the parasite. The parasite is dependent on the host but the host can live without the parasite.
• Population

  A group of individuals of the same species living in the same area at the same time.
• Population Crash

  A sudden decline in the numbers of individual members in a population, species or group of organisms, usually in response to scarcity of resources, intra-specific competition and/or other biotic factors.
• Population Dynamics

  The study of the factors and their interactions that influence the number and density of populations in time and space.
• Population Growth

  An increase in the size of a population over a given time period.
• Population Oscillation

  A pattern characterised by a population explosion, resulting in overshoot of the carrying capacity, followed by population crash, then recovery of the environment and resources, which allows the population to recover and then exceed the carrying capacity again.
• Population Overshoot

  A temporary situation that occurs when a population exceeds its carrying capacity, before lack of resources causes a population crash.
• Predator

  An animal that lives by killing and consuming other animals.
• Predator-Prey Cycle

  As a population of one species increases, its predator populations will increase in response. As the prey numbers fall due to predation, the predator numbers will also fall due to reducing resource availability.
• Prey

  An animal that is hunted and killed by another for food.
• Primary Consumer

  A herbivore that eats the autotroph/producer in a food chain.