Ecosystems - Key terms


A measure of the degree to which an ecosystem possesses large numbers of particular species. An abundant ecosystem may or may not have a wide array of different species. Compare with complexity.


A type of plant that produces flowers during sexual reproduction.


The changes that particular elements undergo as they pass back and forth through the various earth systems and particularly between living and nonliving matter. The elements involved in biogeochemical cycles are hydrogen, oxygen, carbon, nitrogen, phosphorus, and sulfur.


A combination of all flora and fauna (plant and animal life, respectively) in a region.


The upper portion of the trees in a forest. In a closed-canopy forest the canopy (which may be several hundredfeet, or well over 50 meters, high) protects the soil and lower areas from sun and torrential rainfall.


A meat-eating organism.


A measure of the degree to which an ecosystem possesses a wide array of species. These species may or may not appear in large numbers. Compare with abundance.


A substance made up of atoms of more than one element chemically bonded to one another.


Organisms that obtain their energy from the chemical breakdown of dead organisms as well as from animal and plant waste products. The principal forms of decomposer are bacteria and fungi.


A chemical reaction in which a compound is broken down into simpler compounds or into its constituent elements. On Earth, this often is achieved through the help of detritivores and decomposers.


Organisms that feed on waste matter, breaking down organic material into inorganic substances that then can become available to the biosphere in the form of nutrients for plants. Their function is similar to that of decomposers, but unlike decomposers—which tend to be bacteria or fungi—detritivores are relatively complex organisms, such as earthworms or maggots.


A community of interdependent organisms along with the inorganic components of their environment.


A substance made up of only one kind of atom. Unlike compounds, elements cannot be broken chemically into other substances.


The flow of energy between organisms in a food web.


A term describing the interaction of plants, herbivores, carnivores, omnivores, decomposers, and detritivores in an ecosystem. Each consumes nutrients and passes it along to other organisms. Earth scientists typically prefer this name to food chain, an everyday term for a similar phenomenon. A food chain is a series of singular organisms in which each plant or animal depends on the organism that precedes or follows it. Food chains rarely exist in nature.


The upper part of Earth's continental crust, or that portion of the solid earth on which human beings live and which provides them with most of their food and natural resources.


A type of plant that reproduces sexually through the use of seeds that are exposed, not hidden in an ovary, as with an angiosperm.


A plant-eating organism.


The entirety of Earth's water, excluding water vapor in the atmosphere but including all oceans, lakes, streams, groundwater, snow, and ice.


A term referring to the role that a particular organism plays within its biological community.


An organism that eats both plants and other animals.


At one time, chemists used the term organic only in reference to living things. Now the word is applied to most compounds containing carbon and hydrogen, thus excluding carbonates (which are minerals) and oxides, such as carbondioxide.


The biological conversion of light energy (that is, electromagnetic energy) from the Sun to chemical energy in plants.


Any set of interactions that can be set apart mentally from the rest of the universe for the purposes of study, observation, and measurement.

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