ESS Glossary Flashcards
(86 cards)
Zonation
The arrangement or patterning of plant communities or ecosystems into parallel or sub - parallel bands in response to change, over a distance, in some environmental factor. The main biomes display zonation in relation to latitude and climate. Plant communities may also display zonation with altitude on a mountain, or around the edge of a pond in relation to soil moisture
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.
System, open
A system in which both matter and energy are exchanged with its surroundings (for example, natural ecosystems).
System
An assemblage of parts and the relationships between them, which together constitute an entity or whole.
System, isolated
A system that exchanges neither matter nor energy with its surroundings.
System, closed
A system in which energy, but not matter, is exchanged with its surroundings.
Sustainability
Use of global resources at a rate that allows natural regeneration and minimizes damage to the environment. For example, a system of harvesting renewable resources at a rate that will be replaced by natural growth might be considered to demonstrate sustainability.
Succession
The orderly process of change over time in a community. Changes in the community of organisms frequently cause changes in the physical environment that allow another community to become established and replace the former through competition. Often, but not inevitably, the later communities in such a sequence or sere are more complex than those that appear earlier.
Steady - state equilibrium
The condition of an open system in which there are no changes over the longer term, but in which there may be oscillations in the very short term. There are continuing inputs and outputs of matter and energy, but the system as a whole remains in a more or less constant state (for example, a climax ecosystem).
Abiotic factor
A non-living, physical factor that may influence an organism or ecosystem; for example, temperature, sunlight, pH, salinity, precipitation.
Biochemical oxygen demand (BOD)
A measure of the amount of dissolved oxygen required to break down the organic material in a given volume of water through aerobic biological activity.
Biodegradable
Capable of being broken down by natural biological processes; for example, the activities of decomposer organisms.
Biodiversity
The amount of biological or living diversity per unit area. It includes the concepts of species diversity, habitat diversity and genetic diversity.
Biomass
The mass of organic material in organisms or ecosystems, usually per unit area. Sometimes the term “dry weight biomass” is used where mass is measured after the removal of water. Water is not organic material and inorganic material is usually relatively insignificant in terms of mass.
Biome
A collection of ecosystems sharing similar climatic conditions; for example, tundra, tropical rainforest, desert.
Biosphere
That part of the Earth inhabited by organisms, that is, the narrow zone (a few kilometres in thickness) in which plants and animals exist. It extends from the upper part of the atmosphere (where birds, insects and windblown pollen may be found) down to the deepest part of the Earth’s crust to which living organisms venture.
Biotic factor
A living, biological factor that may influence an organism or ecosystem; for example, predation, parasitism, disease, competition.
Carrying capacity
The maximum number of a species or “load” that can be sustainably supported by a given environment.
Climax community
A community of organisms that is more or less stable, and that is in equilibrium with natural environmental conditions such as climate; the end point of ecological succession.
Community
A group of populations living and interacting with each other in a common habitat.
Competition
A common demand by two or more organisms upon a limited supply of a resource; for example, food, water, light, space, mates, nesting sites. It may be intraspecific or interspecific.
Correlation
A measure of the association between two variables. If two variables tend to move up or down together, they are said to be positively correlated. If they tend to move in opposite directions, they are said to be negatively correlated.
Crude birth rate
The number of births per thousand individuals in a population per year.
Crude death rate
The number of deaths per thousand individuals in a population per year.