IB Environmental Systems and Societies

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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
decomposers
obtain their food and nutrients from the breakdown of dead organic matter. when they break town tissue, they release nutrients reader for re absorption by producers. and form the base of decomposer food chains. and contribute to build-up of hummus(organic material in soil made by decomposition of plant and animal matter.
s-population growth curve
when a graph of population growth for such species is plotted againt time. also known as sigmoid growth curve. it shows the intial rapid growth and then slows down as the carrying capacity is reached
lag phase
first stage of an s-shaped population growth curve. population numbers are low leading to low birth rates. few individuals colonize a new area, because number are low, birth rates are also low
exponential growth phases
second stage of s-shaped population growth curve. population grows an increasingly rapid rate. limiting factors are not restricting the growth of the population. there are favourable abiotic components such as temp. and rainfall, and lack of predators and disease. the number of individuals rapidly increase as does rate of growth
transitional phase
third stage of s-shaped population growth curve. population growth slows down considerably although continuing to grow. limiting factors begin to affect the pop. and restrict its growth, increased competition for resources , increase in predators, disease and mortality due to increase in numbers of individuals living in small area
stationary phase
fourth and final stage of s-shaped population growth curve. population size stabilizes and pop. fluctuates around level that represents carrying capacity. limiting factors restrict pop. to carrying capacity(K), changes in limiting factors, predation, disease and abiotic factors cause pop. increase then decrease
density-dependent factors
those that lower the birth rate or raise the death rate as a population grows
density-independent factors
those which affect a pop. irrespecitve of population density.
intraspecific competion
competition within a species
interspecific competion
competition between species. exists when the niches of different species overlap. no two species can share the same niche, so degree to which niches overlap determines the degree of competition.
law of tolerance
states that "For each abiotic factor, an organism has
a range of tolerances within which it can survive."
fundamental niche
describes the full range of conditions and resources in which a species could survive and reproduce
realized niche
the actual conditions and resources in which a species exists due to biotic factors
light
light-meter can be used to measure the light intensity in an ecosystem. cloud cover and changes in light intensity during the day mean values should be taken at the same time of day. abiotic
temperature
electronic thermometer with probes allows this to be accurately measured in air, water, etc. problems arise if it is not deep enough.
pH
measure using a pH meter or data logging probe values range with 7 being alkaline 0 acidic
wind
measure using the beaufort scale. precise measures can be done with digital anemometer, can be mounted or hand held. abiotic factor
particle size
soil can be made up of these large, small or intermediate things. it determines draingine and water-holding capacity. smaller particles measured with series of sieves, fine mesh size. or using optical techniques. Abiotic factor
slope
surface run-off is determined by this. calculated using clinometer. care taken as slope can vary according to distance
soil moitsure
weighing samples before and after in an oven gives weight of water evaporated and therefore moisture levels/ probes also available abiotic.
mineral content
loss on ignition. soil samples are heated to high temps(500-1000 degrees) for hrs to allow volitile substances to escape. loss of mass is equivalent to quantity of volitile substances left.
flow velocity
measured by timing how long it takes a floating object to travel a certain distance. a flow-meter can be used. water flows can vary over time due to rainfall and/or glacial events
salinity
can be measured using electrical conductivity. or by the density of the water. often expressed as Parts Per Thousands(PPT)
dissolved oxygen
oxygen-sensitive electrode connected to meter can be used. Or a winkler titration, which is based on the principle that oxygen in the water reacts with iodide ions, and acid can be added to release iodine that can be quantitatively measured.
wave Action
measured using dynamometer measures the force of wave, areas with high wave action have high levels of dissolved oxygen due to mixing of air and water in the turbulance
turbidity
cloudy water is said to have high turbidity. it affects the penetration of sunlight into water and therefore rates of photosynthesis. measured used secchi disc. problems arise because of suns glare, or subjective nature of the measure.
first law of thermodynamics
energy can neither be created nor destroyed; it can only change form/
second law of thermodynamics
energy goes from a concentrated form(sun) into dispersed forms(heat)
tipping points
a critical threshold when a small change can have potentially drastic effects. Mostly linked to climate change and pollution and the increase in the emmition of greenhouse gases
positive feedback loop
an increase in temperature from increased greenhouse emissions and fossil fuels melts ice and glaciers at an increased rate which decrease the Earth's Alebdo(earth's ability to reflect sun back into space) which increase the temperature even more(climate change- global warming) and increase seal level impacting salinity, acidity in waters impacting fish such as coral and algae)
Negative feedback loop
an old tree in a rain forest fall over or dies due to wind etc, allows for more light to be accessible because there is less canopy reducing the light, so therefore there is more light available to younger trees which then growth, potentially taking over the old tree.
EIA(Environmental Impact assesment
the process of evaluation and identifying potentially environmental impacts following a project, such as the construction of an airport, on the surrounding environment, species and habitat.
The Basline study
First stage of an EIA:Determines the current state of the site's environment
measure the abiotic factors before the site is disturbed (some
examples are listed below, but these are not a complete list)
• microclimate
• water, soil, &/or air quality
• stream flow
• measure the biotic factors and diversity within an area
• species richness
• species evenness
scoping
second stage of an EIA.
Identifies and assesses the possible impacts
• What will definitely change?
• How will it change?
• How much will it change? (scaling)
mitigation
third stage of an EIA:
limiting the impacts to acceptable levels (mitigation = minimizing impacts)
What constitutes "acceptable" levels? Who determines those levels?
What must be done to limit those impacts?
Who is responsible for those actions?
non-technical Summary
last stage of an EIA:
Theoretically designed to explain the science in everyday language so that an average
citizen can understand the issues around the project.
Point source pollution
Refers to discrete sources of contamination that can be represented by single points on a map eg Chernobyl and Fukushima
Non point source pollution
Refers to more dispersed sources from which pollutants originate and enter the natural environment e g cars or industries
Primary pollutant
Active or emissions such as gas released from burning coal
Secondary pollutuon
Arising from primary pollutant undergoing physical change or chemical change such as car exhausts
Acute effects of pollution
Occurring after short period of time like asthma attacks
Chronic effects of pollution
Occurring after low level long term exposure e g air pollution
Persistent pollutants
Those that cannot be broken down by living organisms and so passed along a good change DDT
Persistent organic pollutants
Organic compounds that are resistant to environmental breakdown
Biodegradable pollutanrs
Those that are not stored in biological matter passed along food chains
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