IB Environmental Systems and Societies

Abiotic Factor

A non-living, physical factor that may influence an organism or ecosystem; i.e. 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; i.e. 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/ Standing Crop

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; i.e. tundra, tropical rainforest, desert.

Biosphere

That part of the Earth inhabited by organisms, that is, the narrow zone (a few km thick) in which plants and animals exist. It extends from the upper part of the atmosphere (where birds, insects and wind-blown 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; i.e. predation, parasitism, disease, competition.

Carrying Capacity

The maximum number of 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 2 or more organisms upon limited supply of a resource; i.e. food, water, light, space, mates, nesting sites. It may be intraspecific or interspecific.

Correlation

A measure of the association between 2 variables. If 2 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.

Demographic Translation

A general model describing the changing levels of fertility and mortality in a human population over time. It was developed with reference to the transition experienced as developed countries (i.e. those of North America, Europe, Australia) passed through the processes of industrialization and urbanization.

Diversity

A generic term for heterogeneity. The scientific meaning of the diversity becomes clease from the context in which it is used; it may refer to heterogeneity of species of habitat, or to genetic heterogeneity.

Genetic Diversity

The range of genetic material present in a gene pool or population of a species.

Habitat Diversity

The range of different habitats or numbers of ecological niches per unit area in an ecosystem, community or biome. Conseravtion of habitat diversity usually leads to the conservation of species and genetic diversity.

Diversity Index

A numerical measure of species diversity that is derived from both the number of species (variety) and their proportional abundance.

Species Diversity

The variety of species per unit area. This includes both the number of species present and their relative abundance.

Doubling Time

The number of years it would take a population to double its size at its current growth rate. A natural increase rate of 1% will enable a human population to double in 70 years. Other doubling times can then be calculated approximately, that it, the doubling time for any human population is equal to 70 divided by the natural increase rate.

Ecological Footprint

The area of land and water required to support a defined human population at a given standard of living. The measure takes account of the area required to provide all the resources needed be the population, an the assimilation of all wastes.

Ecosystem

A community of interdependent organisms and the physical environment they inhabit.

Entropy

A measure of the amount of disorder, chaos or randomness in a system; the greater the disorder, the higher the level of entropy.

Environmental Impact Assessment (EIA)

A method of detailed survey required, in many countries, before a major development. Ideally it should be independent of, but paid for by, the developer. Such a survey should include a baseline study to measure environmental conditions before development commences, and to identify areas and species of conservation importance.

Equilibrium

A state of balance among the components of a system.

Eutrophication

The natural or artificial enrichment of a body of water, particularly with respect to nitrates and phosphates, that result 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 input, so as to affect succeeding outputs.

Negative Feedback

Feedback that tends to damp down, neutralize or counteract any deviation from an equilibrium, and promotes stability.

Positive Feedback

Feedback that amplifies or increases change; it leads to exponential deviation away from an equilibrium.

Fertility

In the context of human populations, this refers to the potential for reproduction exhibited in a population. It may be measured as fertility rate, which is the number of births per thousand women of child- bearing age. Alternatively it may be measured as total fertility, which is simply the average number of children a women has in her lifetime.

Gaia

Hypothesis developed by James Lovelock and named after an ancient Greek Earth goddess. It compares the Earth to a living organism in which feedback mechanisms maintain equilibrium.

Global Warming

An increase in average temperature of the Earth's atmosphere.

Gross National Production (GNP)

The current value if all goods and services produced in a country per year.

Greenhouse Gases

Those atmospheric gases which absorb infrared radiation, causing world temperatures to be warmer than they would otherwise be.

Habitat

The environment in which a species normally lives.

Halogenated Organic Gases

Usually known as halocarbons and first indentified as depleting the ozone layer in the stratosphere. Now known to be potent greenhouse gases. The most well known are chlorofluorocarbons.

Isolation

The process by which 2 populations become separated by geographical, behavioral, genetic ore reproductive factors. If gene flow between the 2 subpopulations is prevented, new species may evolve.

K- Strategist

Species that usually concentrate their reproductive investment in a small number of offspring, thus increasing the survival rate and adapting them for living in long- term climax communities.

Latitude

The angular distance from the equator (that is, north or south of it) as measured from the centre of the Earth (in degrees).

Less Economically Developed Country(LEDC)

A country with low to moderate industrialization and low to moderate GNP per capita.

More Economically Developed Country(MEDC)

A highly industrialized country with high average GNP per capita.

Model

A simplified description designed to show the structure or workings of an object, system or concept.

Mutualism

A relationship between individuals of 2 or more species in which all benefit and none suffer. symbiosis relationship, e.g. lichen and river she-oak tree.

Natural Capital

A term sometimes used be economists for natural resources that, if appropriately managed, can produce a "natural income" of goods and services.

Non- Renewable Natural Capital

Natural resources that cannot be replenished within a timescale of that same order as that at which they are taken from the environment and used; i.e. fossil fuels.

Replenishable Natural Capital

Non-living natural resources that depend on the energy of the Sun for their replenishment; i.e. groundwater.

Rate of Natural Increase

The form in which human population growth rates are usually expressed:

crude birth rate- crude death rate/ 10

(inward and outward migration are ignored)

Niche

A species' share of a habitat and the resources in it. Depends on where the specie lives and what it does.

Parasitism

A relationship between 2 species in which one species lives in or on another, gaining all or much of its food from it. its a symbiotic relationship. e.g. a tick feeding on a dog

Plate Tectonics

The movement of the 8 major and several minor internally rigid plates of the Earth's lithosphere in relation to each other and to the partially mobile asthenosphere below.

Pollution

The addition to an environment of a substance or an agent (such as heat) by human activity, at a rate greater than that at which it can be rendered harmless by the environment, and which has an appreciable effect on the organism within it.

Non- Point Source Pollution

The release of pollutants from numerous, widely dispersed origins; i.e. gases from exhaust systems in vehicles.

Point Source Pollution

The release of pollutants from a single, clearly identifiable site; i.e. a factory chimney

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 Productivity (GP)

The total gain in energy or biomass per unit area per unit time, which could be through photosynthesis in primary producers or absorption in consumers. GP= NP+R

Gross Primary Productivity (GPP)

The total gain in energy or biomass per unit area per unit time fixed by photosynthesis in green plants.GPP=NPP+R

Gross Secondary Productivity (GSP)

The total gain by consumers in energy or biomass per unit area per unit time through absorption. GSP= Food eaten- Faecal matter

Net Productivity (NP)

The gain in energy or biomass per unit area per unit time remaining after allowing for respiratory losses (R). NP= GP+R

Net Primary Productivity

The gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses (R). NPP= GPP - R

Net Secondary Productivity

The gain by consumers in energy or biomass per unit time remaining after allowing for respiratory losses (R). NSP= GSP-R

Primary Productivity

The gain by producers in energy or biomass per unit area per unit time. Can refer to either net or gross productivity.

Secondary Productivity

The biomass gained by 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.

Sere

The set of communities that succeed one another over the course of succession at a given location.

Smog

The tern now used for any haziness in the atmosphere caused by air pollutants.

Society

An arbitrary group of individuals who share some common characteristics such as geographical location, cultural background, historical time frame, religious perspective, value system, etc,

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 parent material, revealing the soil layers of 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 condition following disturbance.

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.

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.

Sustainability

Use of global resources at a rate that allows natural regeneration and minimizes damage to the environment.

System

An assemblage of parts and the relationship 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.

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.

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.

ecological efficiency

(energy used for growth(new biomas)/ energy supplied x 100

bioaccumulation

the build-up of persistent/ non-biodegradable pollutants within an organism or trophic level because it cannot be broken down

biomagnification

the increase in concentration of persistent/ non-biodegradable pollutants along a food chain

pyramid of numbers

records the number of individuals at each trophic level coexisting in an ecosystem. Quantitative data for each trophic level are drawn to scale as horizontal bars arranged symmetrically around central axis

pyramid of biomass

represents the biological mass of the standing stock at each trophic level at a particular point in time measured in units such as grams of biomass per square meter

pyramid of productivity

shows the flow of energy( rate at which stock is being generated) through each trophic level of a food chain over a period of time. it is meausre in units of flow, joules(gm2, yr-1, jm2)

photosynthesis reaction

Carbon dioxide + water -------> glucose + oxygen

photosynthesis inputs

Sunlight as energy source, carbon dioxide and water

photosynthesis outputs

glucose, used as energy source for the plant ans as the starting material for other organic molecules

oxygen released into atmosphere through stomata

transformations

energy change is from light into stored chemical energy, and thus the chemical energy is stored in organic material(carbohydrates). Chlorophyll is necessary to capture certain visible wavelengths of sunlight and allows this energy to be transformed into chemical energy

respiration reaction

glucose + oxygen ------> carbon dioxide + water

respiration inputs

organic matter(glucose) and oxygen

respiration outputs

release of energy for work and heat

respiration processes

oxidation process inside cells

respiration transformations

energy transformation is from stored chemical energy into kinetic energy and heat. it is released in a for available for use by living organisms

producers

also known as autotrophs, they convert abiotic components into living matter, they support the ecosystem by constant input of energy and new biological matter. e.g. plants, bacteria, some algae

consumers

organisms that cannot maker their own foot eat other organisms to obtain energy and matter. they don't contain photosynthetic matter. they are also known as heterotophs which feed on producers(Autotrophs), carnivores feed on other heterotrophs and onmiovers feed on both