51 terms

IB Environmental Systems & Societies Glossary

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Abiotic factor
physical, or nonliving, factor that may influence an ecosystem or organism such as temperature, sunlight, pH, salinity, precipitation.
Biodiversity
The variety of organisms in a given area, the genetic variation within a population, the variety of species in a community, or the variety of communities in an ecosystem
Biomass
The mass of organic material in organisms or ecosystems, usually per unit area.
Biome
A collection of ecosystems sharing similar climatic conditions for example tundra, tropical rainforest,desert.
Biosphere
The part of the Earth that is inhabited by organisms, being the narrow zone in which plants and animals exist. It extends from the upper part of the atmosphere down to the deepest part of the Earth's crust to which living organisms venture.
Biotic factor
A living,biological factor 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.
Habitat Diversity
The range of different habitats or number of ecological niches per unit area in an ecosystem,community or biome. Conservation of habitat diversity usually leads to the conservation of species and genetic diversity.
Genetic Diversity
The range of genetic material present in a gene pool or population of a species.
Species Diversity
The variety of species per unit area. This includes both the number of species present and their relative abundance.
Ecosystem
A community of interdependent organisms and the physical environment they inhabit.
Entropy
A measure of the amount of disorder or chaos in a system: the greater the disorder, the higher the level of entropy.
Equilibrium
a state of balance among the components of a system.
Eutrophication
The natural or artificial enhancement of a body of water, particularly with respect to nitrates and phosphates, that results in depletion of the oxygen content of the water. Eutrophication is accelerated by human activities that add detergents, sewage or agricultural fertilizers to bodies of water.
Evolution
The cumulative, gradual change in the genetic characteristics of successive generations of a species or race of an organism, ultimately giving rise to species or races different from the common ancestor. Evolution reflects changes in the genetic composition of a population over time.
Feedback
The return of part of the output from a system as an input, so as to affect the succeeding outputs.
Negative feedback
Feedback that tends to neutralize or counteract any deviation from equilibrium, and promote stability of a system.
Positive feedback
Feedback that amplifies or increases change which leads to exponential deviation from an equilibrium.
Gaia Hypothesis
The Gaia hypothesis compares the Earth to a living organism in which feedback mechanisms maintain equilibrium.
Habitat
The environment in which a species normally lives.
Isolation
The process by which two populations become separated by geographical, behavioural,genetic or reproductive factors. If gene flow between the two subpopulations is prevented, new species may evolve.
K-strategist
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.
Model
A simplified description to show the structure or workings of an object, system, or concept.
Mutualism
A relationship between individuals of two or more species in which all benefit and none suffer.
Niche
A specie's share of a habitat and the resources in it. An organism's ecological niche depends not only on where it lives but also on what it does.
Parasitism
A relationship between two species in which one species (the parasite) lives in or on another (the host) gaining all or much (in the case of a partial parasite) of its food from it.
Plate tectonics
The movement of the eight major and several minor internally rigid plates of the Earth's lithosphere in relation to each other and to the partially mobile asthenosphere below.
Population
A group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding.
Gross Primary Productivity (GNP)
The total gain in energy or biomass per unit area per unit time fixed by photosynthesis in green plants.
Gross Secondary Productivity (GSP)
The total gain by consumers in energy or biomass per unit time per unit area through absorption.
Net Primary Productivity (NPP)
The gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses. This is potentially available to consumers in an ecosystem.
Net Secondary Productivity (NSP)
The gain by consumers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses.
Primary Productivity
The gain by producers in energy or biomass per unit area per unit time.
Secondary Productivity
The biomass gained y heterotrophic organisms, through feeding and absorption, measured in units of mass or energy per unit area per unit time.
r-strategist
Species that tend to spread their reproductive investment among a large number of offspring so that they are well adapted to colonize new habitats rapidly and make opportunistic use of short-lived resources.
Soil
A mixture of mineral particles and organic material that covers the land, and in which terrestrial plants grow.
Soil profile
A vertical section through a soil, from the surface down to the parents material, revealing the soil layers (horizons).
Speciation
The process through which new species form.
Species
A group of organisms that interbreed and produce fertile offspring.
Stable equilibrium
The condition of a system in which there is a tendency for it to return to a previous equilibrium state following disturbance.
Steady-state equilibrium
The condition of an open system in which there are no changes over the long term but in which there may be oscillations int eh 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).
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.
System
An assemblage of parts and the relationships between them,which together constitute an entity or whole.
Closed system
A system in which energy, but not matter, is exchanged with its surroundings.
Isolated system
A system that exchanges neither matter nor energy with its surroundings.
Open System
A system in which both matter and energy are exchanged with its surroundings (for example, natural ecosystems).
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 a food chain.
Zonation
The arrangement or patterning of plant communities or ecosystems into parallel bands in response to change in environmental factors. 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 edges of a pond in relation to soil moisture.
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