ESS Term 2

• biosphere
• biome
• ecosystem
• community
• population
• organisms

• a group of organisms sharing common characteristics that can interbreed and produce fertile offspring
• problematic:
• sub-species (dogs can't reproduce anymore)
• crossing two organisms who have infertile offspring
• ring species - series of neighbouring populations that can interbreed but for which exist 2 'end' populations that are too distantly related to interbreed (gulls)

a group of organisms from the same species living in the same area at the same time

population size and how it changes

environment in which a species usually lives

• where, when and how an organism lives
• specific to a species

• living parts of the environment and the interactions between organisms
• predators, parasites, competitors, humans

• non-living parts of the environment
• salinity, day length, parent material, humidity etc
• determine the fundamental and realized niches

• the max number of individuals in a species that can be sustained by an environment
• difficult to establish

• when, where and how an organism could theoretically live
• always larger
• includes the entirety of tolerance range including the range of psychological stress

when, where and how an organism actually lives

• optimal range < tolerance range
• tolerance range includes the range of psychological stress

• predator-prey
• influences population size
• negative feedback causes time lags in population dynamics
• sometimes positive impact on prey - eats the old and sick

• animal feeds on plant
• grazing

• a relationship in which two organisms live together
• mutualism, parasitism, commensalism

• both organisms benefit
• obligatory (lichen)
• facultative (oxpeckers and zebras)

1 organism benefits, the other is harmed

• 1 organism benefits, the other doesn't benefit but isn't harmed
• barnacles and whales

• pathogen: an organism which causes disease
• population control

• s curve and j curve
• models showing population growth over time and the typical reaction of a population to certain circumstances

• sigmoid growth curve
• lag phase: small numbers, reproduction is slow, resources are not limiting
• exponential growth: the fastest rate of population increase, resources are not limiting
• transitional phase: limiting factors slow growth, reproduction slows, increased competition, predators, disease, and mortality
• stationary phase: the population has reached carrying capacity, stabilization, and fluctuation

• exponential growth: initially slow, becomes increasingly rapid
• doesn't slow as population increases
• resources are not limiting
• can be followed by a population crash due to mostly abiotic factors
• no transition phase or equilibrium
• often in species with little parental care, many offsprings

• limit distribution/numbers of population
• slow population growth as it approaches carrying capacity
• density-dependent: lower birth rate/raise death rate, lack of food/water, disease, parasites, competition
• density independent: change in temperature, natural disasters

• water-tolerant plants with root in the water
• mangroves

• inhabit moist but not wet environments
• plain rose

• inhabit dry environments
• cacti

• neither species benefits but better competitor suffers less
• interspecific: between species, overlap in niches, when resources are limiting
• intraspecifc: within the same species, more common (same niche)
• competitive exclusion: superior species eliminates other species

• group of populations living and interacting with each other in a common habitat
• include all biotic parts of the ecosystem
• influenced by abiotic factors

• community + the physical environment it interacts with
• biotic components: interdependent - depend on each other and abiotic components
• abiotic components: define which ecosystem can develop
• 3 types: terrestrial, marine, freshwater (aquatic)
• terrestrial: forests, grasslands, tundras..
• marine: sea, salt marshes, estuaries, mangroves
• freshwater: rivers, lakes, wetlands

• partially enclosed coastal brackish water
• has at least one stream flowing into it and free connection to the sea

• upper coastal area
• inter-tidal zone (regular flooding)
• brackish water

• tropical coastal vegetation
• along the coast or in brackish water
• protect from erosion and hurricanes

converts light energy to chemical energy which is stored in biomass

• releases energy so that it can be used to support the life processes of organisms
• aerobic process in mitochondria - starts off as anaerobic in the cytoplasm

• in hydrothermal vents at the bottom of the ocean
• without sunlight
• bacteria harvest energy from the hot, mineral-rich water escaping through the crust
• they convert it to biomass for other organisms to consume

• autotrophs
• make their own food by converting abiotic components into living matter
• constant input of energy and new biological matter
• phototrophs: use light energy, any green plants, algae, some bacteria
• chemoautotrophs: use chemical energy, chemosynthesis, some bacteria

• heterotrophs
• cannot make their own food
• eat other organisms to obtain energy and matter
• herbivores: feed on autotrophs
• carnivores: feed on other heterotrophs
• omnivores: feed on both autotrophs and heterotrophs
• insectivores - eat insects
• top predator: at the top of a food chain, feeds on others but is generally not consumed by them while alive

• heterotrophs
• obtain food and nutrients from breakdown of dead organic matter
• release nutrients
• essential for cycling matter
• contribute to the build-up of humus in soil
• bacteria, fungi, pill bug, earthworms, gastropods (snail), millipedes, protozoans

• position an organism occupies in a food chain
• position in the food chain occupied by a group of organisms in a community
• a single organism can occupy more trophic levels in an ecosystem
• energy and matter flow between them
• T1 - always producers

• flow of matter and energy from one trophic level to another
• producer --> primary consumer --> secondary consumer --> tertiary consumer --> quaternary consumer

• diagram that shows food chains linked together in an ecosystem
• shows whether/which organisms are impacted by the removal of another organism
• knock-on effect

• graphical models of quantitative differences between trophic levels of a single ecosystem
• usually measured for a given area and time
• show feeding relationships in a community
• pyramid of numbers, pyramid of biomass, pyramid of productivity

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

• biological mass of the standing stock at each trophic level at a particular point in time
• measured in units like g/m2 or J/m2
• can have season variation and can be inverted
• sampling: measure whole habitat size, take quantitative samples, dry samples to remove water weight, extrapolate dry mass sample to entire trophic level
• evaluation: it is an estimate based on assumption that all individuals at the trophic level are the same, the sample accurately represents the whole habitat

• flow of energy (rate at which the stock is being generated) through each trophic level over a period of time
• measured in units of flow like g/m2yr or J/m2yr
• energy decreases along a food chain - cannot be inverted

• limited length of food chains
• the vulnerability of top carnivores

• build up of persistent pollutants within an organism or trophic level because they cannot be broken down
• pops soluble in fats and liquids - pass through cell membrane
• Minamata disease

• increase in the concentration of persistent pollutants along a food chain
• silent spring

• energy emitted by the sun, particularly electromagnetic energy
• biological systems depend on the amount reaching the surface
• 1/2 of radiation is in the visible short-wave part of the electromagnetic spectrum
• 1/2 is in near-infrared part, some in ultraviolet part
• portion of ultraviolet light not absorbed by atmosphere produces suntan or sunburn

• absorption (69%): molecules and dust in the atmosphere (17%), clouds (3%), ground (49%) 
• relfection (31%): by scatter (3%), clouds (19%), ground (9%)

• ratio of irradiance reflected to irradiance received by surface
• proportion determined by properties of surface, spectral and angular distribution of solar radiation
• measure of reflectivity of a surface
• high albedo - most light reflected
• low albedo - most light absorbed

• accounts for the balance between energy the Earth receives from the Sun and the energy it radiates back into outer space after having been redistributed through the 5 components of the Earth's climate system and having powered the "Earth's heat engine"
• unit: Watt/m2
• not all solar radiation reaches producers
• not all radiation that reaches producers ends up being stored as biomass - losses of reflection from leaves, wrong wavelength

• once light energy has been converted into chemical energy and stored as biomass it is in a usable form - can be transferred along the food chain
• none of these processes are 100% efficient
• Ecological efficiency = energy used for growth (biomass)/energy supplied x100

• standing stock at each trophic level at a particular point in time
• g/m2 (biomass) or J/m2 (amount of energy)

• flow of energy or matter over a period of time
• g/m2yr or J/m2yr

• conversion of light e. to chemical e.
• transfer of chemical e. from one trophic level to another with varying efficiency
• overall conversion of ultraviolet and visible light to hear e. by an ecosystem
• re-radiation of heat e. to the atmosphere

• primary - total biomass/energy gained by producers in a specific area in a specific amount of time
• secondary - total biomass/energy gained by consumers in a specific area in a specific amount of time
• gross - total amount of something made as a result of an activity
• net - amount left after deduction (always lower)

• gross primary productivity (GPP): total gain in biomass made by producers through photosynthesis in a specific area in a specific amount of time
• net primary productivity (NPP): total gain in biomass/energy by producers in a specific area in a specific amount of time after allowing for respiratory losses
• NPP = GPP-R

Respiratory loss

• gross secondary productivity (GSP): the total gain in biomass by consumers through absorption (in g) in a specific area in a specific amount of time
• GSP = food eaten - fecal loss
• net secondary productivity (NSP): total gain in biomass by consumers once energy from respiratory loss has been removed (in g) in a specific area in a specific amount of time
• NSP = GSP - R

• high primary productivity - more energy available
• higher efficiency of energy transfer between trophic levels
• higher primary productivity & higher efficiency of energy transfer - more trophic levels

• rate of increase in biomass that can be exploited without depleting the original stock or its potential for replenishment
• resources can be harvested at a rate equal or lower to their natural productivity

• max flow of a given resource such that the stock does not decline over time
• = to net primary/net secondary productivity

• nutrients absorbed by organisms from soil/atmosphere circulate through trophic levels
• are released back mostly via detritus food chain

• energy: flows through system, quality degrades from light to heat, endless supply from the sun
• matter: cycles, Gersmehl's nutrient model, characteristic for each ecosystem

• ammonium (NH4+)
• nitrous oxide (N2O)
• nitric oxide (NO)
• nitrogen gas (N2)

• waste product of metabolism of animals (excretion)
• oxidizes from nitrite (NO2-) to nitrate (NO3-)

• air pollutant
• 30% human activity

• bioproduct in almost all organisms
• toxic environmental pollutant (acid rain)

• in all organisms (amino acids)
• in the atmosphere (78%)

• nitrogen fixation
• nitrogen-fixing bacteria
• nitrifying bacteria
• denitrifying bacteria
• deamination

assimilation

• caused by lightning
• transformation of N2 to NO3 (nitrates)

• transformation of N2 into ammonium ions
• symbiotic (rhizobium) vs free living (azotobacter) bacteria

nitrate (NO3-) to nitrogen (N2)

break down of organic nitrogen (protein) into ammonia

• absorption by plants - transfer
• absorbed nitrates used for building amino acids and proteins - transformation
• available to the rest of the food chain through feeding - transfer

• deforestation - rainforest nutrient cycle by transferring nitrogen
• combustion of fossil fuels - increase of CO2 and temperatures
• monocultures
• use of fertilisers (often nitrogen based) - transferred into soil, with crops, washed away with rain (leeching)

leaching of nitrogen leads to underwater plants dying, increase in algae, less oxygen, fish dying - cycle

• collections of ecosystems sharing similar climatic conditions that can be grouped into five major classes
• classes: aquatic, forest, grassland, desert, tundra

• govern structure, function, distribution
• precipitation, insolation, temperature
• insolation: most stable at equator, varies due to tilt
• ocean circulatory system: influence on temperature and atmospheric circulation
• tricellular model of atmospheric circulation: pressure belt differences, precipitation differences

• Hadley cell: by equator - low pressure, clouds and precipitation (tropical rainforest), air rises and comes down at 30deg. - high pressure, no clouds, low precipitation (desert) -- between them temperate deciduous forest
• Ferrel cell: 60deg. - low pressure, clouds, precipitation
• Polar cell: north pole - high pressure, no clouds, low precipitation (polar/tundra)

desert < tundra < temperate grassland < taiga < savanna < temperate deciduous forest < tropical rainforest

loss of water-soluble plant nutrients mostly by rainfall but also irrigation

action of surface processes that removes soil, rock, dissolved material from one location on the Earth's crust and then transports it away to another location

• vegetation gradually moving towards poles and up mountain slopes
• vegetation gradually moving towards equator (unequal distribution of rainfall)
• low lying biomes might be completely lost
• consequences: expansion of areas with tropical disease vectors, loss of species diversity, migration, increased rates of primary productivity

• as a result of biome shifting
• africa - sahel region

• changes in community along environmental gradient
• due to changes in latitude, altitude, tidal level, distance from shore, coverage by water
• bands of vegetation
• spatial changes
• arrangement of pattern in communities in bands - response to change in environmental factor over a distance
• environmental gradient - cahnges over distance
• ex: sea on a rocky shore, mountains
• both local and global scale

• temporal changes
• process of change over time in ecosystem involving pioneer, intermediate, climax communities

• occurs on a previously uncolonized substrate
• rock - plant grows

• occurs in places where a previous community has been destroyed
• faster - soil already formed, seed bank

change in communities from earliest community to final community

• series of transitory plant communities that develop during ecological succession
• from bare ground to climax community

• first stage of ecological succession
• species able to live in difficult conditions

several stages of succession between pioneer and climax communities

• more or less stable community
• in stable-state equilibrium
• endpoint of ecological succession

• species and ecosystem diversity relatively stable
• gradual changes through natural succession
• large storages, complex food webs, npp balanced by rates of respiration, variety of nutrient and energy pathways contributes to stability

• depend on the type of environment occupied
• lithosere, hydrosere, xerosere

• on newly exposed rock surface
• left bare by glacial retreat/volcanic eruption

• starts in fresh water
• wetland

• dry habitat
• limited by water accessibility

• colonization
• establishment
• competition
• stabilization
• complex community

• soil: weathering rock, production of dead organic material
• plants: lichens
• animals: ants, mites, springtails
• little water, few organisms
• pioneer community - pioneer species: photosynthesis, effective absorption of water, growth reduces wind speed, increases temperature
• decomposition allows formation of simple soil for grasses

• soil: further weathering, beginning of soil formation
• plants: annual plants and lichens, moss
• animals: ants, mites, springtails, spiders, nematodes, larval insects, ants, snails, termites
• pioneer community

• soil: further improvement
• plants: grasses and perennials, ferns
• animals: nematodes, larval insects, ants, snails, termites
• development of complex food webs
• pioneer community

• soil: deeper, more nutrient-rich
• plants: grasses, shrubs, shade-intolerant trees (pines)
• development of complex food webs
• intermediate species

• shade-tolerant trees (oak, hickory)
• complex food webs
• last stage
• relatively stable, in equilibrium
• greater biomass
• higher species diversity
• favourable soil conditions
• better soil structure
• taller and longer-living plant species
• greater community complexity and stability
• greater habitat diversity
• steady-state equilibrium

• symbiotic relationship between green algae and fungi
• mutualistic

• organic matter increase
• deeper soil - reduced soil erosion
• soil structure improves
• increase in mineral recycling
• grasses: attract more light, faster growth, roots trap soil
• dandelion: spread by wind, rapid growth
• these are intermediate species - better competition

• a previous community has experienced disturbance
• faster than primary
• disturbance can be tipping point
• no colonization

minimum amount of change within a system that will destabilize it, causing it to reach a new equilibrium

• social or ecological
• tendency of ecosystem to avoid tipping points
• contributed to by diversity, sizes of storages, variety of nutrient and energy pathways

• organic matter: storages bigger in late succession
• nutrients and minerals: increase in late succession
• nutrient cycles: cycles close towards late succession
• role of detritus: increase in role towards later succession
• depth of soil: increases in late succession
• size of organisms: larger in late succession
• diversity: more producers, more movement of biomass
• niches: realized niches in early succession are larger and wider
• stability: poor in early stages
• npp: high in early succession (less trophic levels, small respiratory losses), approaches 0 in late
• gpp: low in early succession (low density of producers), grows in time (increased consumer community, balanced by respiration)

• agriculture: livestock (feeds on saplings, trampling), crops prevent succession
• tourism: trampling
• slash and burn agriculture, burning of waste
• pollution
• introduction of non-native species

arrested stage of succession, often due to human activity

• P/R
• P=R - P/R=1: steady-state community
• P>R - P/R>1: biomass accumulation
• P<R - P/R<1: biomass depleting

• mostly in north polar region (arctic tundra), also antarctica and alpic tundra
• limiting factors: sunlight (low light intensity - low rate of photosynthesis, low insolation, short daylength), temperature (low insolation = low temperature, enzyme-driven chemical reactions are slower due to cold (photosynthesis, respiration, decomposition), soil permanently frozen, limiting nutrients (slow recycling), peat bogs form - storage of carbon), water (locked up in ice, little rainfall)
• low productivity
• small plants, low shrubs and grasses - not enough soil
• root systems are spread out
• large animals with lots of fur

• within tropics, close to equator (Amazon, South East Asia, Congo river)
• high and stable temperature (26deg)
• high species diversity
• sunlight and all year growing season
• soil is low in nutrients (rainfall - leaching)
• plants gain nutrients from detritus - decay causes growth
• shallow root systems
• canopy protects soil from rainfall
• varying levels of density
• high npp - 40% of world npp
• insects are majority of living animals

• lower density than rainforest
• less availability for niches
• dominated by 1 plant species
• 90% of them have only up to 6 species of plants
• productivity lower than rainforest (variation of insolation, seasons)
• mild climate, lower average temperatures and less rain (500 to 1500 mm per year)
• winters are mild, summers are hot
• evergreen trees
• limitation in height for trees - max 13m

• 20% to 30% of land surface
• temperatures: day 45-49, night 0-10
• low precipitation - under 250 mm per year, unevenly distributed
• organisms: limited number, highly adapted, low productivity
• small vegetation
• ex: cacti (spikes not leaves, store water in stems, thick cuticula, deep and extensive roots)
• sand soils - porous
• animals: snakes (cold-blooded metabolism, conservation of water), mammals (underground during day)
• source of water for animals = plants

• colder and warmer areas
• savanna
• one fifth of earth
• photosynthesise using less water than forests
• more diversity
• low productivity - less other organisms (animals) in the area

• high biodiversity
• lot of sunlight, warm water
• near equator
• corals have calcium carbonate skeletons
• algae - symbiotic, live within polyps, photosynthesis - constant input of energy, many niches
• ex: great barrier reef

• in ocean
• on tectonic plate boundaries
• cracks - vents that spew nutrients in hot water
• extremophile animals (thermophiles)
• no sunlight - no photosynthetic organisms
• bacteria productivity supports diverse range of species (chemosynthetic bacteria)