Environmental systems and societies units 1 and 2 (and parts of 3)
strengths of pyramid of numbers
-a simple method of giving an overview of community structure -good for comparing changes in number of individuals over time
The Gaia hypothesis:
-compares the earth to a living organism in which feedback mechanisms maintain equilibrium. -it describes how the living and non-living components of the global biosphere regulate the conditions for life on earth -it was developed by James Lovelock and named after an accent Greek Earth goddess
Flow of energy through ecosystems: The first law of thermodynamics The second law of thermodynamics
-energy flows through ecosystems. energy enters as sunlight and is converted to new biomass and heat -the energy entering the system equals the energy leaving it (first law) -energy is inefficiently moved through food chains in the process of respiration and production of heat energy (second law) -initial absorption and transfer of energy by producers is also inefficient due to reflection, transmission, light of the wrong wavelength and inefficient transfer of energy in photosynthesis (second law) -light energy starts the food chain but is then transferred from producer to consumers as chemical energy -as a result of the inefficient transfer of energy, food chains tend to be shorter
Niche
-is 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 Essentially... The role of an organism in its environment - where, when, and how it lives -two species cannot share the same niche -species with overlapping niches will compete with each other e.g. nocturnal predator of small mammals in the forest
Daisyworld
-the daisy world model was developed by James Lovelock to show how the Gaia hypothesis could regulate life on earth -daisyworld is a simple model for a worldwide ecosystem -the only life on dais world is black or white daisies. The rest of the planet is bare earth -the temperature of the planet is determined by the amount of sunlight absorbed by the surface of the planet -the sun's heat output is gradually increasing -black daisies absorb more solar energy and warm the planet - they will become more abundant in the early history of daisy world when the sun is cooler -white daisies reflect more of the sun's energy-these will become more abundant as the sun's heat energy increases -the temperature of the planet remains the same, within narrow limits -the temperature of the planet it therefore self-regulating
Calculating dry weight biomass (extrapolation technique)
-the sample is weighed in a container of known weight -the sample is put in a hot oven (80C) -after a specific length of time the sample is reweighed -the sample is put back in the oven -this is repeated until the same mass is recorded from 2 successive readings -no further loss in mass indicates that water is no longer present -biomass is recorded per unit area (e.g. per metre squared) so that trophic levels can be compared. Not all organisms in an area need to be sampled -the mass of one organism, or the average mass of several organisms, is taken -this mass is multiplied by the total number of organisms to estimate total biomass
weaknesses of pyramid of numbers
-they do not take into account the size of organisms -numbers can be too great to reprint accurately -some animals feed at more than one trophic level (omnivores) and are therefore difficult to place
Model - disadvantages:
-they might not be accurate and can be too simple -they rely on the level of expertise of the people making them -different people can interpret them in different ways -they may be used politically -they depend on the quality of the data that go into the inputs -different models can show different outputs even if they are given the same data
Model - Advantages:
-they simplify complex systems and allow predictions to be made -inputs can be changed to see their effects and outputs, without having to wait for real events -results can be shown to other scientists and to the public. models are easier to understand than detailed information about the whole systems
Quadrat methods
-used to estimate the abundance of plants and non-mobile animals -Used for plants or sessile organisms 1.Mark out a gridline along two edges of an area 2.Use a calculator or tables to generate two random numbers to use as coordinates and place a quadrat on the ground with its corner at these coordinates 3.Count how many individuals of your study population are inside the quadrat 4.Repeat steps 2 & 3 as many times as possible 5.Measure the total size of the area occupied by the population in square meters 6.Calculate the mean number of plants per quadrate. 7. Then calculate the population size with the following equation: 7.N = (Mean # per quadrat) (total area) Area of each quadrate
Systems
1.Function and interact in some regular, predictable manner. 2.Can be isolated for the purposes of observation and study.
Decomposers
Break down organisms into simple organic molecules (recycling materials)
Temperate grasslands
Climate: -Precipitation 25-45 cm per year - enough to grow grass, -Semiarid -fire, drought, animals prevent tree growth -May be Tropical, Temperate -Moderate insolation Distribution: -9% of earth surface - Temperate Latitudes - Major ones NA tall grass prairie, steppes, pampas, veldt -Grasslands overall up to 40% of earth's surface Structure: Simple - grasses and herbaceous plants Relative productivity: -Medium to high - high turnover of grasses, rich soils
tundra*
Climate: -Precipitation under 15 cm per year - mostly snow & summer rain -Arid -Bitter cold: -57 - 50 C - permafrost -low insolation gives short growing season Distribution: -60 - 75 N latitude - northern North America, Asia, Greenland -About 20% of the earth's surface Structure: -Simple - low spongy mat of vegetation, lichens, mosses -Even trees are less than knee high Relative productivity: -Low - limited by temperature and insolation
Dessert*
Climate: -Precipitation under 25 cm per year - scattered unevenly through year -Arid -May be Tropical, Temperate and Cold types - always extremes -High to moderate insolation Distribution: -30% of earth surface -between 30 degrees north and south of the equator -Major ones Saraha (Africa), Gobi (Asia), Mojave (N. america) Structure: -Simple - very little vegetation -Most complex is temperate desert which has largest cacti Relative productivity: -Low - limited by water availability
Tropical rainforest*
Climate: -high rainfall (over 150 cm per year) -high sunlight and temperature -no seasons, so consistent light and temperature -high insolation gives long growing season Distribution: -found between the tropics of cancer and capricorn (2.35 N and S of equator) -About 2% of the earth's surface -Three chunks - S. & C. America, C. Africa, SE Asia Structure: -Complex - stratified layers -High diversity - 50-80% of terrestrial species Relative productivity: -Highest in terrestrial system - unlimited by temperature and insolation
The first law of thermodynamics: (law of conservation of energy)
Energy can be transferred and transformed but it can never be created nor destroyed -All energy in living systems comes from the sun -Into producers through photosynthesis, then consumers up the food web
example of positive feedback
Global warming 1.Temperature increases - Ice caps melt 2.Less Ice cap surface area - Less sunlight is reflected away from earth (albedo) 3.More light hits dark ocean and heat is trapped 4.Further temperature increase - Further melting of the ice
Discuss how the pyramid structure effects the functioning of an ecosystem
Limited length of food chains: •Rarely more than 4 or 5 trophic levels •Not enough energy left after 4-5 transfers to support organisms feeding high up •Possible exception marine/aquatic systems b/c first few levels small and little structure Vulnerability of top carnivores: •Effected by changes at all lower levels •Small numbers to begin with •Effected by pollutants & toxins passed through system Biomagnifications: 1.Mostly Heavy metals & Pesticides •Insoluble in water, soluble in fats, •Resistant to biological and chemical degradation, not biodegradable 2.Accumulate in fatty tissues of organisms 3.Amplify in food chains and webs 4.Sublethal effects in reproductive & immune systems 5.Long term health effects in humans include tumors, organ damage, ...
Consumers (Heterotrophs)
Must consume other organisms to meet their energy needs Examples: -Herbivores, Carnivores, Omnivores, Scavengers, Detritivores
Static equilibrium
No change at all - condition to which most natural systems can be compared but this does not exist
Decomposers
Obtain their food from the breakdown of dead organic matter. Examples: bacteria and fungi
Describe photosynthesis and respiration in terms of inputs, outputs and energy transformations.
Photosynthesis Inputs: -sunlight -carbon dioxide -water Outputs: -sugars -oxygen Matter transformations: -inorganic carbon (CO2) into ---> Organic carbon Energy transformations: -radiant energy into ---> chemical energy Respiration: Inputs: -sugars -oxygen Outputs: -ATP -carbon dioxide -water Matter transformations: Organic carbon compounds into-->inorganic carbon compounds Energy transformations: -chemical energy in carbon compoundsinto ---> chemical energy as ATP
Example of negative feedback:
Predator Prey -Snowshoe hare population increases -More food for Lynx - Lynx population increases -Increased predation on hares - hare population declines -Less food for Lynx - Lynx population declines -Less predation - Increase in hare population
Trophic level order
Producer Primary consumer (herbivore) Secondary consumer (carnivore) Tertiary consumer (top carnivore) Quaternary consumer 6th trophic level
Trophic level example - EVERGLADES HABITAT
Producer - Phytoplankton Primary consumer - Zooplankton Secondary consumer - Blue gill Tertiary consumer - Bass Quaternary consumer - Raccoon 6th trophic level - alligator
Trophic level example - ESTUARY SYSTEM
Producer - Turtle grass Primary consumer - Grass shrimp Secondary consumer - Pin fish Tertiary consumer - Spotted sea trout Quaternary consumer - osprey
Feedback
Self-regulation of natural systems in an attempt to attain equilibrium. Can be either negative or positive.
Evaluate the use of food chains:
Strengths: -see specific routes that energy is taking Weaknesses: -over-simplified -cant show multilevel feeding (only shows one trophic level, not everything the organisms need)
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.
Producers (Autotrophs)
Through photosynthesis convert radiant to chemical energy (energy transformation)
The second law of thermodynamics:
With every energy transfer or transformation energy dissipates (heat) so the energy available to do work decreases -Always less energy at higher trophic levels -- energy/matter go from concentrated to dispersed
Biome
a collection of ecosystems sharing similar climatic conditions example: tundra, tropical rainforest, desert
Population
a group of individuals of a certain species in a given area at a given time e.g. blue crabs in the Halifax river
Species
a group of individuals who can interbreed to produce fertile, viable offspring e.g. FL panthers
Diversity index
a numerical measure of species diversity calculated by using both the number of species (species richness) and their relative abundance
Model
a simplified version of a system. It shows the flows and storages as well as the structure and workings.
System:
an assemblage of parts and the relationship between them, which together constitute an entity or whole
Dry weight biomass-
biomass is a measure of the organic contents of organisms... water is not an organic molecule, so it is removed before biomass is measured Criticisms: -it involves the killing of living organisms (although not all the organisms in an area need to be sampled) -problems exist with measuring biomass of very large plants (trees with roots and underground biomass)
Simpsons diversity index
calculates species diversity D = N(N-1) / (sum)n(n-1) D= simpons index N- total number of organisms of all species found n= number of individuals of a particular species -comparisons can be made between areas containing the same type of organism in the same ecosystem -a high value of D suggest a stable and ancient site, where all species have similar abundance (or evenness) -a low value of D could suggest disturbance through, say, logging, pollution, recent colonisation or agricultural management, where one species may dominate
Photoautotrophs
convert sunlight energy into chemical energy example: all plants
Describe and explain the transfer and transformation of energy as it flows through an ecosystem
energy enters the ecosystem as sunlight energy, is transformed into chemical energy/biomass, is then transferred between trophic levels by consumers and ultimately leaves the ecosystem as heat energy •30% solar energy reflected back into space by atmosphere, clouds, ice •20% absorbed by clouds & atmosphere •50% remaining -Warms troposphere and land -Evaporates and cycles water -Generates wind •less than 0.1% captured by producers for photosynthesis •Energy eventually transformed to heat and trapped by atmosphere "Natural Greenhouse Effect" •Eventually reradiated into space
Open system
exchange both matter and energy with their surroundings (e.g. an ecosystem)
Closed system
exchange only energy but not matter with their surroundings (e.g. the earth)
Transfers:
flow through the system, involving a change in location (no change in state) for example water flowing from the groundwater into a river
outputs
flowing out of the system into sinks in the environment
unstable equilibrium
forms a new equilibrium following disturbance
diversity
generic term for heterogeneity (the variation or variety) -the scientific meaning of diversity becomes clear from the context in which it is used; it can refer to heterogeneity of species or habitat, or to genetic heterogeneity
Community
interacting groups of populations in an area e.g. the scrub community on campus
competition
is a common demand by 2 or more organisms for a limited supply of a resource such as food, water, light, space, mates, and nesting sites
ecosystem
is a community of interdependent organisms and the physical environment they inhabit
Entropy
is a measure of the amount of disorder, chaos or randomness in a system; the greater the disorder, the higher the level of entropy
Equilibrium
is a state of balance among the components of a system •A sort of equalization or end point •Equilibrium is stable (systems tend to return to the original equilibrium after disturbances)
Respiration definition
is the breakdown of glucose using oxygen, releasing carbon dioxide, water and energy
Habitat
is the environment in which a species normally lives
biosphere
is the part of the earth inhabited by organisms
stable equilibrium
is the tendency in a system for it to rerun to a pervious equilibrium condition following disturbance
Photosynthesis definition
is the transformation of light energy into the chemical energy of organic matter
Transformations:
lead to interactions in the system, changes of state or forming new end products
Biotic
living components examples: (plants, animals, microorganisms)Biota
Producers
make their own food (glucose) and convert (fix) inorganic molecules into organic molecules example: plants, algae, some bacteria
Abiotic
nonliving components examples: (water, air, nutrients, soils solar energy (insolation))
Flows:
passage of elements within the system at certain rates (transfers and transformations) are represented by arrows -arrows represent inputs and outputs from the system
plotting of a pyramid of numbers
quantitative data for each trophic level are drawn to scale as horizontal bars, arranged symmetrically around a central axis
Pyramid of productivity
refer to the flow of energy through trophic levels and always show a decrease in energy along the food chain -productivity is defined by the amount of new biomass created per unit area per unit time -measured in units of flow (gm^-1yr^-1 OR Jm^-2yr^-1) -the only pyramid that is always pyramid shaped -shows the rate at which storages are being generated
species diversity
refers to the number of species and their relative abundance
pyramid of numbers
represents the NUMBER of organisms (producers and consumers) coexisting in an ecosystem -can be inverted -taken a certain point in time -show storage in the food chain Always pyramid shaped for: Grassland Inverted: forest (Especially temperate deciduous )
food web
show the complex feeding relationships that exist between species
Pyramid of biomass
shows the biological mass at each trophic level. -Each trophic level is measured in grams of biomass per square metre (gm^-2) -can also be measured in units of energy (Jm^-2) -biomass decreases along food chains (2nd law) -hence pyramids become narrower towards higher trophic levels -biomass is measured as dry weight (biomass minus water) -can be inverted -taken a certain point in time -show storage in the food chain Always pyramid shaped for: Grassland Inverted: antarctic open ocean habitat
Latitude
the angular distance from the equator (north or south of it) as measured from the centre of the earth (usually in degrees)
biomass
the mass of organic material in an organism or ecosystems, usually stated per unit area
population density (Quadrat methods)
the number of individuals of each species per unit area -it is calculated by dividing the number of organisms by the total area of the quadrats
percentage frequency (Quadrat methods)
the percentage of quadrate in an area in which at least one individual of the species is found
percentage cover (Quadrat methods)
the proportion of a quadrate covered by a species, measured as a percentage. -it is worked out for each species present. -estimates can be made by dividing quadrate into a 10x10 grid (100 squares), where each square is 1% of the total area covered
Isolated systems
these do not exchange either matter or energy with their surroundings (e.g. the universe)
Inputs
things entering the system -> matter, energy, information
Lincoln index:
this technique is known as the capture-mark-release-recapture method -it is used for estimating the population size of mobile animals process: -organisms are captured, marked, released, and then recaptured -marking varies according to the type of organism. (example: wing cases of insects can be marked with a pen, snails with paint, and fur clippings used for mammals) -markings must be difficult to see - high visibility increases predation risk -the number of individuals of a species are recorded at each stage •Repeat the recapture as many times as possible to ensure accuracy of results •Marking method should not affect the survival or fitness of the organism the population size is estimated using the following equation: N = n1 x n2 / (divided by) m N= total population of animals in the study site n1= number of animals captured (marked and released) on first day n2=number of animals recaptured on the second day m = number of marked animals recaptured on second day EVALUATION: -You don't have to count every single organism in the habitat -Best in closed environments -Moving Organisms only
Chemoautotrophs
use chemical energy from oxidation reactions to create glucose example: nitrifying bacteria
systematic sampling (Quadrat methods)
used along a transect where there is an environmental gradient
Random sampling (Quadrat methods)
used if the same habitat is found throughout the area
stratified random sampling (Quadrat methods)
used in 2 areas different in habitat quality
Reductionist approach
when a system is divided into parts, or components, which can each be studied separately
Holistic approach
when a system is studied as a whole, and patterns and processes are described for the whole system
herbivory
when an organism feeds on a plant
Storages:
within a system, where matter, energy, information can accumulate for a length of time (stocks) are represented by boxes
Interspecific competition
•2 or more different species involved •Competing for food, space, sunlight, water, space, nesting sites or other limited resource •If resources abundant, they can be shared but in nature they are always limited •If fundamental niches overlap --> leads to competition •One of the species must... 1.Migrate if possible 2.Shift feeding habits or behavior = Evolve 3.Suffer a sharp population decline 4.Become extinct
Positive Feedback:
•A runaway cycle - often called vicious cycles •A change in a certain direction provides output that further increases that change •Change leads to increasing change - it accelerates deviation IE Global Warming
Intraspecific competition
•Competition between members of the same species for a common resource •Resource: food,space, mates, etc. • Territoriality -Organisms patrol or mark an area and defend it against others -Good territories have: •Abundant food, good nesting sites, low predator pop. Disadvantage = Energy, Reduce gene pool
Explain the principles of pyramids of numbers, pyramids of biomass and pyramids of productivity
•Graphic models of quantitative differences between trophic levels •By second law of thermodynamics energy decreases along food webs •Pyramids are thus narrower as one ascends -Pyramids of numbers may be different - large individuals at low trophic levels - large forests -Pyramids of biomass may skew if larger organisms are at high trophic levels - biomass present at point in time - open ocean •Energy is lost between each trophic level, so less remains for the next level -Respiration, Homeostasis, Movement, Heat •Mass is also lost at each level -Waste, shedding, ...
predation
•Members of one species feed directly on all or part of a living organism of a different species •Individuals - predator benefits, prey harmed •Population - prey benefits: take out the weak, greater resource access, improved gene pool •Predator plays important ecological role
Negative Feedback:
•One change leads to a result that lessens the original change •Self regulating method of control leading to the maintenance of a steady state equilibrium IE Prey
commensalism
•One species benefits the other is neither harmed nor helped Examples: 1.Herbs growing in the shade of trees 2.Birds building nests in trees 3.Epiphytes = "Air plants" which attach themselves to the trunk or branches of trees -they have a solid base to grow on and better access to sunlight & rain
parasitism
•One species feeds on part of another organism (the host) without killing it •Specialized form of predation •Parasite Characteristics: 1.Usually smaller than the host 2.Closely associated with host 3.Draws nourishment from & slowly weakens host 4.Rarely kills the host Examples = Tapeworms, ticks, fleas, fungi
Apply the systems concept on a range of scales
•Small scale local habitat - Scrub habitat •Ecosystem - The everglades in South FL •Biome - Tropical Rainforest •The entire planet - Gaia hypothesis -all organisms and inorganic surroundings on earth are closely integrated to form a single self regulating complex system maintaining conditions for life on the planet
Steady-state equilibrium
•Steady state equilibrium -constant changes in all directions maintain a constant state (no net change) - common to most open systems in nature
mutualism
•Symbiotic relationship where both species benefit •Pollination, Nutrition, Protection are main benefits •Not really cooperation, both benefit by exploiting the other Examples: 1. Lichens - fungi & algae living together - food for one, structure for the other 2. Plants and Rhizobium bacteria - one gets sugars the other gets nitrogen 3. Oxpeckers and Rhinos - food for one, less parasites for the other 4. Protists and termites - break down wood for one, nutrients for the other
Describe and evaluate methods for estimating the biomass of trophic levels in an ecosystem
•Take quantitative samples - known area or volume •Measure the whole habitat size •Dry samples to remove water weight •Take Dry mass for sample then extrapolate to entire trophic level •sample biomass / sample area = total biomass / total area Evaluation: It is an estimate based on assumption that -all individuals at that trophic level are the same -The sample accurately represents the whole habitat -But it prevents you from killing the whole trophic level to get your measurement
