IB Environmental Systems and Societies Chapter 2

The study of the interactions between organisms and the environment in which they live.
look at and try to understand various aspects of organisms - how varied they are (diversity), where they are located (distribution), what they are (species) how many there are of them (population) and how they interact and adapt.
community of interdependent organisms and the physical environment they interact with. Made up of biotic and abiotic components.
the basic unit of biological classification. a group of organisms with common characteristics that can interbreed to produce fertile offspring.
group of individuals of the same species living in the same area at the same time. Must be close enough to interbreed
Species with the same common ancestor and similar physical characteristics
Binomial name
genus + species
The role an organism plays and the position it holds in the environment. It includes all the interactions the organism has with the abiotic and biotic environment.
Fundamental niche
The area where an organism could live if there was no competition
Realised niche
the part of the fundamental niche that the species actually occupies, usually defined by competition.
Taxonomic rank
the level that an organism is placed within the hierarchical level arrangement of life forms
limiting factors
resources in the environment that limit the growth, abundance and distribution of organisms/populations in an ecosystems.
density dependent factors
limiting factor that depends on population size
density independent factors
limiting factor that affects all populations in similar ways, regardless of population size
carrying capacity
the maximum number of individuals of a species that the environment can sustainably support in a given area.
Population growth curves
The changes in a population in response to changing abiotic and biotic factors can be shown as generalised graphical representations
Rate of death. Factor that affects population size.
Movement from one part of something to another. Factor that affects population size.
Rate of birth. Factor that affects population size.
J-shaped population curve
shows exponential population growth under ideal conditions with plenty of resources and limited competition. The population continues to grow until environmental resistance take effect, leading to population crash. Common with R-strategists.
S-shaped population curve
Exponential growth is only possible for a short period of time because as the population grows resources are depleted (limited factors are likely present) and the growth rate slows and will eventually plateau off. Typical of K-strategists.
Producers (autotrophs)
make their own food through photosynthesis or chemosynthesis
Consumers (heterotrophs)
obtain energy by consuming other organisms
interaction in which one animal (the herbivore) feeds on producers (such as plants)
A relationship in which one organism (the parasite) takes nutrients from another organism (the host), causing harm.
where one organism (the predator) hunts and kills another (the prey) in order to provide it with the energy for survival and reproduction.
parasites living on the outside of their host e.g. tick and fleas.
parasites that live on the inside of the host e.g. tapeworms spend part of their lives in the gut of their host.
two organisms of different species exist in a mutually beneficial relationship. Will cause an increase in the other.
departure from the normal state of functioning of any living organism. It is accompanied by signs and symptoms and may be the result of environmental agents, infective agents, genetic defects.
where organisms compete for a resource that is in limited supply, e.g. water, food, territory, mates, habitat etc.
Intraspecific competition
Individuals of the same species strive for the same results. E.g. mates, food or space. End result is likely to be a slight drop in population numbers as the weaker members of the species are outcompeted.
Interspecific competition
Individuals of two species compete for resources they both need. Worst case result would be instinction.
the close external resemblance of an animal or plant (or part of one) to another animal, plant, or inanimate object. E.g. the chameleon blends into its surrounding so it will not be found and eaten.
eat just plants - leaves, flowers, fruits and nuts or stems and wood. E.g. Capybara, a large South American rodent eats grasses, aquatic plants, fruit and tree bark.
eat only meat/other animals and these are the predators. E.g. African lions eat wildebeest, zebras, buffalo and warthogs.
eat both plants and other animals e.g. Red panda eats bamboo, small mammals, birds, eggs, flowers and berries.
Gain their nutrients by consuming detritus: plant and animal parts and feces, or decomposing organic material. E.g. snails, slugs, blow fly maggots & vultures.
Bacteria and fungi that obtain their energy from dead organisms by secreting enzymes that break down the organic matter.
Abiotic factors
A limiting factor that varies seasonally (though the year) and diurnally (though the day). If it deviates too much then organisms will be stressed and may die.
Green plants are able to take light energy from the sun and use it to make chemical energy. All life on earth need to take the chemical energy and use it for life processes.
Important green pigment including a special protein that is able to absorb the light energy from the sun.
Certain bacteria and a group of organisms called archaea take the energy released by inorganic chemical reactions to make sugar. Takes place in total darkness, mainly in hot springs and the deep ocean hydrothermal vents.
A chemical reaction in plants and animals that is more or less the reverse of photosynthesis.
The oxidation of glucose to release energy that is then used in all activities in the organism.
Trophic level
the position an organism (or group of organisms in a community) occupies in the food chain.
Food chains
Simple representation of a series of organisms each dependent on the next as a source of food. Simple single line of animals showing what eats what. Only has one arrow to and from each organism. Shows only one trophic level for each organism.
Food web
A number of interconnected food chains so it is a complex mass of lines, several arrows point away from an organism to everything it eats, can show organisms at different trophic levels, several arrows point towards an organism to show everything that eats it.
First law of thermodynamics
Energy is neither created nor destroyed
Second law of thermodynamics
As energy passes along the entropy increased
The 10% rule
during the transfer of energy from organic food from one trophic level to the next, only about ten percent of the energy from organic matter is stored as flesh. The remaining is lost during transfer, broken down in respiration, or lost to incomplete digestion by higher trophic level.
Ecological pyramids
Quantitative models to show information about the feeding of organisms always shown with the trophic levels in the same order - primary producers at the bottom followed by primary consumers, secondary consumers, then tertiary consumers and quaternary consumers.
Pyramid of numbers
Shows the number of organisms at each trophic level in the food chain - the standing crop, and the unit is whole numbers.
Pyramid of biomass
graphical representation of the amount of living matter (standing stock of energy storage) at each trophic level. Measured in g m2
Pyramid of productivity
Shows the rate of flow of energy or biomass through each trophic level over a period of time. The units are given as energy or mass per unit area per unit of time: J m-2 yr-1.
increase in the concentration of a pollutant in an organism as it absorbs or it ingests it from its environment
increase in the concentration of the pollutant as it moves up through the food chain.
Solar radiation
the energy that drives processes on Earth come from the sun. Made up of visual wave lengths (light) and ultraviolet and infrared.
Solar constant
the average amount of solar energy that is received by the atmosphere when the sun is at its mean distance from earth, which is about 1,370 joules per second. Will vary depending on the time of year and the location relative to the equator.
The reflectivity of a surface. High in light colors.
where the light energy is retained by the substance and transformed into heat.
The conversion of energy into biomass in a given time expressed as J m-2 yr-1. The rate of growth of plants and animals in the ecosystem.
Gross primary productivity (GPP)
All the biomass produced by primary producers in a given amount of time (before any of it is used for respiration). Expressed as g m-2 yr-1
Net primary productivity
Represents the amount of usable biomass in an ecosystem some of this will be used for growth and some will be consumed by herbivorestakes into account respiratory losses (R): NPP = GPP - R. Expressed as g m-2 yr-1
Gross Secondary Productivity (GSP)
Represents the total amount of energy or biomass assimilated by consumers. Also referred to as assimilation. Expressed as g m-2 yr-1 or J m-2 yr-1.
GSP = food eaten - fecal loss
Net Secondary Productivity (NSP)
what is left at the end of all the processes for animal growth e.g. to make new muscle. Expressed as g m-2 yr-1 or J m-2 yr-1.
Sustainable yield
the amount of biomass that can be extracted without reducing natural capital of the ecosystem.
The major carbon stores
Sediments and sedimentary rock, Deep ocean, Atmosphere Phytoplankton and food web
Combustion (co2)
Burning fossil fuels releases carbon that has been stored for millions of year and it becomes an active part of the cycle. Breaks the long-chain hydrocarbons found in fossil fuels and wood and releases CO2 into the atmosphere.
Biological pump
Movement of carbon from the atmosphere through the marine food web into the deep oceans. Techniques to manipulate this is currently being investigated as a way of lowering atmospheric levels of carbon dioxide.
Nitrogen cycle
Describes the way nitrogen moves around the biosphere.
essential for all life on earth as it is a major component of amino acids - the building blocks for protein and nucleic acids (DNA and RNA) -> the building blocks of life.
Nitrogen transformations
Major ones are ammonium, nitrate and nitrogen gas. Transformations occur through biological (performed by microbes) or physical processes.
Lightning (nitrogen transformation)
Transform atmospheric nitrogen into nitrogen oxides, which then combine with moisture in the air to form nitrates that can enter the soil in rainwater. .
Bacteria transform ammonium into nitrates. The nitrates are absorbed by the plant, and then assimilated into the biomass to form amino acids, nucleic acids and chlorophyll.
Denitrifying bacteria in anaerobic (oxygen depleted) conditions found in wetlands and bogs where waterlogged soils are common, reverse the process by converting ammonium, nitrate and nitrite ions into nitrogen gas which escapes the atmosphere.
Flow into or out of the ground. Dissolve the soluble nitrates and wash them out of the soil.
Combustion (nitrogen)
releases nitrogen locked up in organic material as nitrogen oxide or nitrogen dioxide
a collection of ecosystems that are classified according to their predominant vegetation; they share similar climatic conditions and organisms that have adaptations to the environment.
Has to do with the shape of the land, mountains, altitude and aspect. Impacts climate on local scale.
The direction in which the slope face.
Five categories of biomes
Aquatic, forest, grassland, dessert, tundra
Freshwater biome
ponds and lakes, streams and rivers and wetlands such as bogs and swamps
Marine biome
deep ocean, coral reefs, estuaries and mangrove swamps
Forest biome
tropical rainforest, temperate forests and boreal or taiga
Grassland biome
savanna and temperate
Desert biome
hot, coastal and cold
Tundra biome
arctic and alpine
Precipitation/evaporation (P/E)
a way of assessing how much water stress there is in a biome. Ratio Below 1 is indicative of water shortages. Ratio of 1 will have good soil moisture conditions. Ratio above 1 suggests waterlogged or heavily leached soils
focus on increased quantity of offspring at the expense of quality. With little or no parental care survival chances are low but high numbers of offspring ensures at least some survive. Beneficial in unstable, unpredictable environments. Common in the pioneer stages.
produce very few offspring, but they increase the quality of them by investing in a lot of parental care. In this case quality means fit for purpose - survive long enough to reproduce themselves. Common in the climax community.
The change in a vegetation community along an environmental gradient. The change may be caused by changes in altitude, depth of water, tidal level, distance from the shore etc. Changes are spatial and are determined by changes in the abiotic factors.
The predictable change in a vegetation community over time.
Pioneer community
simple ecosystems with high productivity but limited biodiversity
Climax community
large, complex ecosystems where productivity is less but biodiversity is high and the complexity results in stability of the system
Primary succession
occurs in areas that have never been occupied by an ecological community, e.g. bare rock or sand dunes.
Secondary succession
where there has been a natural or anthropogenic disturbance and the soil is still in place, e.g. abandoned fields, deforested areas, storm damage, flooding.
windward side
Side of mountain facing the direction of the wind
leeward side
side of mountain away from the wind
A frame of specific size which may be divided into subsections, used to calculate a sample of organisms
Sample path/line/strip along which you record the occurrence and/or distribution of plants and animals in a particular study area
Line transect
Consists of a string or measuring tape which is laid out in the direction of environmental gradient and species touching the string or tape are recorded
Belt transect
Two parallel lines are marked along the ground and samples are taken of the area at specified points
Continuous transect
The whole line or belt is sampled
Interrupted transect
Samples are taken at points along the line or belt, usually at regular horizontal or vertical intervals where quadrats are placed
The concentration of salt in a solution, expressed in %. Determined by measuring the electrical conductivity or the density of the water.
dissolved oxygen
Solubility of oxygen, affected by temperature and water pollution. Can be measured using an oxygen-selective electrode connected to an electronic meter, data logging or by a Winkler titration.
Cloudiness of a body of fresh water. Can be measured with optical instruments or using a Secchi disc.
Secchi disk
Disk attached to a graduated rope that measures turbidity.
Flow velocity
The speed at which the water is moving and it determines which species can live in a certain area. Can be measured with flow meter, impellers and floats
Can be measured with a pH meter or a datalogging pH probe
Type I
Low death rate. Many individuals live to old age. K-stragegists.
Type II
Moderate death rate. Individuals die at all ages. C-strategists.
Type III
High death rate. Many individuals die young, and few live to old age. R-Strategists.
an animal behavior characterized by being active during the night and sleeping during the day
organism is native to the area
Wind speed
Can be measured using anemometer (consisting of three cups that rotate in the wind) and ventimeter (calibrated tube over which the wind passes and reduces the pressure in the tube, making the pointer move). Can also observe the effect of wind on objects related to Beaufort Scale (1-12)
Can be collected using rain gauge.
Sweep nets
Can be swept through grasses at various heights in order to catch many insects. Then put in large clear container and the species and numbers recorded
Tree beating
Method to find insects in tree branches by placing a catching tray beneath a tree branch while gently tapping it. The tray will catch falling insects that can be counted.
Kick sampling
Place sweep net downstream from you. Shuffle your feet into the streambed for 30 seconds. Empty the contents of the net into a tray filled with stream water. Use a pipette to sort the various insects into small plastic cups and record your results. Repeat.
Succession in a body of freshwater. In this process small lakes may disappear and be replaced by the plant communities.
ACFOR scale
50% - Abundant. 25-50% - Common. 12-25% Frequent. 6-12% Occasional. 1-6% Rare.
Lincoln Index
N = n1 x n2 / m2
Succession in salt water marshes.
Succession along sand dunes. This stabilises the dunes and stops them shifting.
Succession starting from bare rock. This is seen most often on lava flows.
Succession in dry areas
Colonization (succession stage 1)
initiated by pioneer species, r-strategists, that are adapted to the extreme conditions. These hardy species find enough nutrients with in the environment to kick-start an ecosystem. Soil starts to form as weathering begins to break down the rocks and plants contribute organic matter to the debris.
Establishment (succession stage 2)
Ecosystem is just getting going as unified ecosystem. Soil becomes deep enough to provide niches for invertebrates, they breakdown the dead organic matter to form humus which improves water holding capacity. The quantity of resources increases and food, shelter, water and habitats develop.
Competition (succession stage 3)
Pioneer plants have taken a harsh, barren area and made it suitable to sustain a wider variety of plant life. Abiotic conditions are less extreme. Improvement in conditions means that more complex larger plants invade the area and outcompete the original species for space, light and nutrients. They provide shelter which changes conditions and the pioneers disappear. Succession is starting to stabilise and there are fewer new species entering the ecosystem. The rate of new species entering the system falls as trees now shade out the lower levels. K-strategists continue to dominate the ecosystem.
Latitude (resilience)
links to tipping points. Maximum amount of disturbance that a system can tolerate before it loses its ability to recover. Once past that tipping point the system will not recover easily, if at all.
Resistance (resilience)
how easily the ecosystem resists the change.
Precariousness (resilience)
how close the ecosystem is to its limit/tipping point. Ability to return to its previous state is dependent on its resilience. A system is more resilient if it has high biodiversity with complex food webs and nutrient and energy pathways.