ESS

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Foundations of ESS

1.4 Sustainability

• Sustainability

  • Sustainability: Using global resources at a rate that allows regeneration without depleting the natural capital

    • sustainability refers to the use of natural resources at a rate that allows regenerations. Sustainable development is the ability to meet the current needs of society without compromising the needs of future generation

  • Natural Capital: Planet’s natural resources including renewable or non-renewable resources, eg. trees, minerals, animal species

  • Natural Income: value or goods/services derived from natural capital : growth per year (need to specify timeframe). extraction of natural resources eg. timber, carbon sequestration.

  • Replenishment: restoration of a stock or supply to a former level or condition.

  Explain the concept of sustainability in terms of natural capital and natural income

  • Sustainability in terms of natural capital and natural income revolves around the idea of preserving natural resources in a manner that ensures their long-term availability and benefits for both current and future generations. It emphasizes the need to balance the utilization of resources with their capacity for replenishment and regeneration. It recognizes that ecosystems have limits and overexploitation can result in negative consequences.

  outline the difference between sustainability and sustainable development

  Describe and evaluate the use of environmental impact assessment

  • Three Pillars of Sustainability

    Integrated approach

    Sustainable development: meeting the needs of present generations without compromising the ability of future generations.

    • Economic: Economics sufficiency not greed

      • energy-efficient buildings

      • green commuting

      • reduced pollution

    • Environment:

      • renewable energy sources

      • waste management and water treatment

      • reduce, reuse, recycle policies

      • protected areas and wild-life corridors

    • Social: cultural diversity and social stability

      • lifestyle and recreational amnesties

      • protected common land

      • education and awareness

      • sustainable built environment

• Biodiversity

  Different kinds of life within an ecosystem (organisms, plants, animals, fungi, microorganisms)

  Mitigation: minimize impact

  • Human activities destroying biodiversity: Human pollution, agriculture (land), overfishing, climate change (wildfires), population growth, deforestation, industrial pollution like mining

  • Impacts of biodiversity loss

    • freshwater shortages and climate instability

    • ecosystems become more vulnerable to the impacts of climate change, such as droughts, floods, and extreme temperatures.

• Environmental impact assessment

  1. Baseline Study - understand the physical and biological environment of a place

  2. Prediction and possible impacts

  3. Mitigation - solution

• Practice questions

  how can you reduce your EF?

  What issues are taken to account when calculating the EF?

1.5 Pollution

• vocabulary

  effluent: liquid waste or sewage discharged into a river or the sea.

  greenwashing: marketing itself as more environmentally friendly then they are. . It's a deceitful marketing gimmick used by companies to exaggerate their environmentally friendly actions.

  Bioaccumulation - the retention or buildup of non-biodegradable or slowly biodegradable chemicals in the body

  Biomagnification - the process whereby concentration of a chemical increases at each trophic level.

• Humans and Pollution

  Pollution is the addition of a substance or an agent to an environment activity at an extent that normal environmental processes are adversely affected. Polluted elements and disagreeable, toxic and harmful.

  environmental pollution: industrial waste, litter

  water pollution: oil spill

  air pollution: smog,

  soil pollution: crop depletion

  sound pollution: Regular exposure to a higher sound level that impacts humans and other living organisms

  • point source and non-point source pollution

    Point source pollution - refers to discrete sources of contamination that can be represented by a single point on a map and the source of pollution can be tracked.

    • Eg, nuclear explosions at Chernobyl, Ukraine

    Non-point source pollution - refers to more dispersed sources from which pollutants originate and enter the environment.

    • E.g., air pollutants from numerous widely dispersed origins.

    • examples

      • Chemical fertilizer is being put in all parks and green spaces to help the grass grow, and infiltrating the groundwater non-point pollutants

      • Copper smelter (factory that removes copper from rock) releases acidic fumes from its smoke stack point source pollution

      • Smoke from cigarettes in a bar point pollutant. Non-point pollutant

      • Shrimp farm pumping effluent (shrimp waste water) through a pipe into the ocean. Point pollutant

      • People in a city spraying their gardens with pesticides to kill insects. Non-point pollutant

      Vehicles travelling along a road releasing nitrogen oxides .

      non point pollution

  • Primary vs secondary

    Primary: active on emissions.  A primary pollutant is an air pollutant emitted directly from a source

    • Eg. Burning fossil fuel, sulfur dioxide, carbon monoxide

    Secondary: arising from primary pollutants (undergoing physical and chemical change). forms when other pollutants (primary pollutants) react in the atmosphere.

    • eg, Ozone, nitrogen dioxide,

  • Acute vs chronic effects of pollution

    Acute: occurring after a short, intense exposure. Symptoms are usually experienced within a few hours

    • eg. air pollution have both chronic and acute effects: acute effects include asthma attacks, chronic effects include lung cancer, chronic obstructive pulmonary disease.

    Chronic: occurring after low-level, long-term exposure. Disease symptoms develop up to several decades later.

  • Persistent vs biodegradable pollutants

    Persistent: cannot be broken down by living organisms and accumulate in the chain. Organic persistent pollutants are organic compounds that are resistant to environmental breakdown.

    • eg. DDT, industrial chemicals, forever chemicals

    Biodegradable: capable of being broken down by natural biological processes

    • eg. food waste, paper waste

• Ban on DDT

  DDT was used to combat malaria, typhus, and the other insect-borne human diseases among both military and civilian populations. After ww2, DDT is used as an insecticide in farming

  DDT is soluble in lipids (fats) so it can buildup in fatty tissue. Through biomagnification, the end result is that top predators may have high concentrations of chemicals.

  Costs:

  • Large-scale spraying of DDT is killing wildlife and top predators. Moreover, it can can cause cancer in humans

  • Studies have shown that people exposed to DDT had a higher risk of liver, breast and/or pancreatic cancer

  • DDT exposure is a risk factor for early pregnancy loss, premature birth and/or low birth weight.

• Pollution management

  A - Altering human activity

  • altering human activity - campaigns, education, economic incentives/disincentives

  • promoting alternative technology - can be costly

  • need to come up with alternative if you want to remove it

  B - Controlling release of pollutants

  • regulating and reducing quantities of pollutants released at the point of emissions

  • developing/applying technologies for extracting pollutants from emissions

  • eg. flue gas desulfurization to remove sulfur dioxide (FGD), regulating standards of emissions,

  C - Clean up and Restoration of Damaged systems

  • extracting and removing pollutants from ecosystem

  • replanting/restocking lost or depleted populations and communities

  • often labor intensive, expensive

  Outline strategies for reducing the impacts of pollution

  • For pollution management, people adopt the ABC

  Describe the variations in the level of DDT along a food chain

• Practice questions

  1a. Should a small lake considered an open, closed or isolated system

  A small lake should be considered a closed system. In a closed system, there is no exchange of matter with the surrounding environment, but energy can still flow in and out.

  1b. Distinguish between transfer process and transformation processes.

  Transfer processes involve the movement of substances or energy from one location to another without any change in their chemical or physical properties. Examples of transfer processes include the flow of water in a river or the heat transfer through conduction.

  Transformation processes, on the other hand, involve the conversion or alteration of substances or energy into a different form. These processes result in a change in the chemical or physical properties of the substances involved. Examples of transformation processes include the combustion of fuel, the photosynthesis process in plants, or the chemical reactions that occur in a battery.

  In summary, transfer processes involve the movement of substances or energy without any change in their properties, while transformation processes involve the conversion or alteration of substances or energy into different forms with changes in their properties.

  1. Define the term pollution, and distinguish between point source and non-point source

  • q5 DDT

    WHO recommends only indoor residual spraying of DDT for disease vector contorl, evaluate this provision

    • This provision is not quite effective as seen in the graph because there were a 30% increase in cases of malaria in countries like brazil, Columbia and Venezuela however it is proven effective compared to no spraying at all as in Bolivia and paraguay where there are a 90% increase of malaria cases. Hence, there are 60% difference between countries who does not spray DDT and countries who implement WHO prevision.

    • There is a reduction in malaria prevalence because the DDT sprayed surfaced kills malaria vectors compared to no spraying at all.

    • In conclusion, although indoor residual spraying of DDT may not be completely effective in eliminating malaria cases, yet it is evident that there are reduction in malaria prevalence, which contribute to the overall reduction of malaria transmission.

    Suggest why an ecocentrist position might be opposed to indoor residual spraying

    • An ecocentrism might opposed to this implementation because of the potential health risks associated with DDT exposure. Ecocentrism values all life and the well-being of ecosystems including all living organism Indoor residual spraying with chemical pesticides can have negative impacts on non-target organisms, including beneficial insects and wildlife.

    Explain the vulnerability of top carnivores to non-biodegradable toxins like DDT entering the food chain

    • Due to biomagnification in the food chain, top carnivores become vulnerable with toxins like DDT because chemical increase in concentration at each trophic levels therefore top carnivores are exposed to high levels of toxins. As larger predators consume these smaller organisms, they ingest a higher concentration of toxins. This process continues up the food chain, resulting in top carnivores at the highest trophic level having the highest concentration of toxins. Therefore, top carnivores are more susceptible to the harmful effects of non-biodegradable toxins, such as DDT, as they accumulate in their bodies over time, leading to potential negative impacts on their health and overall population.

  7b) Explain why attitudes towards the environment change overtime, refer to named historical influences

  • Attitudes towards the environment change overtime as more people become socially conscious towards their impact on the environment.

  • 6 sustainable development

    a) state what is meant by environmental value system

    	Priority	Example
    self-reliance ecologist	social	Community cooperative set up to sell local produce and share production costs to increase profits
    conservation biologist	environmental
    Banker	Economic

during 7 or 9 point question should evaluate benefit and disadvantage and discuss its effectiveness. EIA - might be ignored by the government

• describe in detail what it is

• evaluate it

Ecosystems and Ecology

2.1 Species and Populations

• Species, habitat and niche

  species: a group of organism sharing common characteristics that can interbreed to produce offspring (fertile, inbreed) mule and liger are infertile

  Habitat: the environment in which the species normally live. eg, an african elephant habitat includes Savannah's, forests, marshes, deserts.

  Niche: an ecological niche is where, when and how an organism lives. The particular set of abiotic and biotic conditions and resources which an organism or population responds

  • Fundamental niche - full range of conditions and resources in which a species could survive to reproduce

  • realized niche - describes the actual conditions and resources in which a species exists due to biotic interactions.

• Abiotic factors and population interactions

  Abiotic factors - non living physical factors that influence the organism and ecosystem. eg, temperature, sunlight, acidity/alkalinity (pH), rainfall

  topography - shape of a land, flat, hilly, mountainous

  • hydrophyts - water-tolerant plants which can root in standing water

  • mesophytes - plants that inhabit moist but not wet environments

  • xerophytes - Plants that live in dry environments

  Biotic factors - living parts of the environment divided into specific types (predation, parasitism, mutualism)

  Carrying capacity - refers to the number of organism - or size of population - that an area or ecosystem can support sustainably over a long period of time

  Predation occurs when one animal or plants hunts and eats another organism

  Predator-prey relationship - often controlled by negative feedback mechanism that control population densities. predator eat another organism called a prey.

  Negative feedback are when things are kept imbalance, Positive feedback ar when things are unstable (big increase)

• Herbivory, parasitism, mutualism, competition

  Herbivory is an interaction where animal feeds on a plant. eg) hippo

  Parasitism: a parasite is an organism that benefits at the expense of another (the host) from which it derives food

  mutualism: both organism benefit from each other. eg) coral reefs and lichens

  Disease: an orgnaism that cause disease is known as a pathogen (bactteria, viruses, fungi)

  Competition: Competition is the demand by individuals for limited environmental resources. Infraspecific competition (from same species) or interspecific competition (between different species). Interspecific competition exists when niches of different species overlap.

  

• Population growth

  Population: all inhabitants in a particular environment or region

  Carrying capacity: is the number of organism - or size of a population - that an area or ecosystem can support sustainably over a long period of time

  • Limiting factors

    A limiting factor is a constrains a population's size and slows or stops it from growing

    Limiting factors slow population growth as it approaches the carrying capacity of the system.

    • For plants: light, nutrients, water, carbon dioxide and temperature

    • For animals: space, food, mates, nesting sites and water

    Carrying capacity is affected by these limiting factors:

    • The availability of food and water

    • territorial space

    • predation

    • disease

    • availability of mates

• S population curves (sigmoid growth curves)

  • Initial rapid growth (exponential growth) and then slows down as the carrying capacity is reached

  

  

  • graph slow growth at first when popualtion is small and lack of mature adults.

  • increases and decreases around carrying capacity are controlled by negative feedback mechanism

  • stages: Lag phase > exponential growth phase > transitional phase > stationary phase

  Name of stage	Description	Explanation
  Lag Phase	population numbers are low leading to low birth rates	- few individuals colonize a new area

  • because numbers of individuals are low, birth rates are also low | | Exponential growth phase | population grows at an increasingly rapid rate | - limiting factors are not restricting the growth of the population

  • there are favourably abiotic components, such as temperature and rainfall, and a lack of predators or disease

  • the numbers of individuals rapidly increases as does the rate of growth | | Transitional phase | population growth slows down considerably although continuing to grow | | | Stationary phase | population growth stabilizes (the graph ‘flattens’) and then population fluctuates around a level that represents the carrying capacity. | |

• J population curves

  exponential growth is an accelerating or accelerating rate of growth, growth is initially slow but becomes rapidly rapid and does not slow down as population increases.

  • exponential growth occurs when:

    • limiting factors are not restricting the growth of the population

    • there are plentiful of resources such as light, space, food

    • there are favorable abiotic components such as temperatures and rainfall.

  • Abiotic components can affect (eg. carrying capacity of an environment can be raised)

  • Sudden decrease in a population is called population crash.

2.2 Communities and Ecosystems

Community many species living together population refers to a single species. eg. Savannahs

Ecosystem - community of interdependent organism (biotic and abiotic components) and their habitat

• Terrestrial include all land based ecosystems

• Marine ecosystem include sea, estuaries, salt marshes, mangroves

• Freshwater include rivers, lakes, wetlands

• Photosynthesis and respiration

  Photosynthesis converts light energy to chemical energy which is stored in Biomass

  Respiration releases this energy so it can be used to support the life processes of organism.

  • Photosynthesis

    Carbon dioxide + water → glucose + oxygen (→ light and chlorophyll)

    • Inputs - sunlight as energy source, carbon and water

    • Outputs - Glucose used as energy source for plants as a basic starting material for all organic molecules

    • Transformation - energy change from light energy to stored chemical energy and this chemical energy is stored in organic matter. Chlorophyll is needed to capture certain visible wavelengths of sunlight energy and this allows energy transform to chemical energy

  • Respiration

    releases energy from glucs and other organic molecules inside all living cells. It starts as an anaerobic process in the cytoplasm of cells and is completed inside mitochondria with aerobic chemical reactions occuring.

    Aerobic respiration

    Glucose + oxygen → carbon dioxide + water

    • Inputs - organic matter (glucose) and oxygen

    • Processes - oxidation processes inside cells

    • Outputs - release of energy for work

    • Transformation - energy transformation is from stored chemical energy to kinetic energy and heat.

• Feeding relationships

  • Producers

    Producers - certain organism in an ecosystem convert abiotic components into living matter. AKA Autotrophs.

    Producers (autotrophs) are typically plants or algae that produce their own food/glucose using photosynthesis and form the first trophic level in a food chain.

    • Producers change inorganic compounds into organic ones

    Exceptions include chemosynthetic organisms that produce food without sunlight.

    Give 4 reasons why the sunlight coming in is not converted to biomass

    • solar energy is reflected

    • energy lost through respiration

    • some wavelengths are not suitable

    • transmitted light goes through leaf and out otherside

    • Example

      

  • Consumers

    Organism that cannot make their own food because they don’t contain photosynthetic pigments like chlorophyll so they eat other organism to obtain energy and matter.

    Heterotrophs - an organism deriving its nutritional requirements from other organism.

    Herbivores feed on autotrophs, carnivores feed on heterotrophs, omnivores feed on both.

  • Decomposers

    Obtain their food and nutrients from the break down of dead organic matter. Decomposers also improve the nutrient capacity in the soil by breaking down the organic material.

    • These obtain their food from the breakdown of dead organic matter.

    • When they break down tissue, they release nutrients ready for reabsorption by producers.

    chemoautotrophs.

    • Humus is made by decomposition of plant or animal matter.

    • Some bacteria are autotrophs but rather than using sunlight energy, they use chemosynthesis (chemical energy) energy and are called

• Trophic level, food web, food chain

  Food chain - show flow of matter and energy from organism to organism

  trophic level - Position that an organism occupies in a food chain

• Pyramids of numbers, biomass and productivity

  representation of quantitive differences between each trophic levels of a single ecosystem.

  • Pyramids of numbers

    records the number of individuals at each trophic level coexisting. Pyramids of numbers can sometimes display different patterns; for example, when individuals at lower trophic levels are relatively large (inverted pyramids)

    Advantage

    • easy method of giving an overview

    • good for comparing changes in population numbers over different times

    Disadvantage

    • all organisms included regardless of their size

    • numbers can be too great to represent accurately

  • Pyramids of biomass

    represents biological mass at each trophic level at a particular point in time measured in units. Biomass may also be measured in units of energy such as Jm^-2. Measure an area, dry it then weigh it

  • Pyramids of productivity

    shows the flow of energy (eg. rate which stocks are being generated) through each trophic level of a food chain over a period of time. Measured in units of flow (gm-2yr-1)

• Review

  • define ecosystem with reference to a named example

  • Describe photosynthesis and respiration in terms of inputs, outputs and energy transformations.

  • Describe process of photosynthesis

  • Distinguish between autotroph and heterotroph

  • Define producer with reference to a named example

  • Define consumer with reference to a named example

  • Define decomposer with reference to a named example

2.3 Transfer and flows of energy

• Transfer and transformation of energy

  All energy come from the sun except for some from geothermal energy. Sunlight contains a broad spectrum of wavelengths from X-rays to radio waves that exist as ultraviolet, visible light and infrared radiation

  • Solar radiation (insolation) enters earth’s atmosphere, some energy is unavalibel for ecosystem as the energy is absorbed by inorganic matter or reflected back.

  • Pathway of radiation involve loss of radiation through reflection and absorption

    • reflection from clouds - 19%

    • absorption of energy by clouds - 3%

    • reflection by scatter from aerosols and atmospheric particles - 3%

    • Absorption by molecules and dust in the atmosphere - 17%

    • Absorbed by plants 0.06%

    • reflection from the surface of earth - 9%

  Albedo surface: white surface reflect heat

  Negative feedback loop: more evaporation cause more cloud, clouds reflect the sun

  Energy in: 342 wm-2

  Energy out: 342 wm-2

  Ecological efficiency = (Energy used for growth(new biomass)/energy supplied) x100 usually 10% (vary between 5-20%)

  All energy lost from an ecosystem is in the form of heat, through inefficient energy conversions of respiration

  • systems diagram showing energy flow

    

• Primary and secondary productivity

  Primary productivity - the gain by producers(autotrophs) in energy or biomass per unit areaa per unit time.

  • conversion of solar energy into chemical energy, dependent on sunlight

  • highest in conditions optimal for growth: there are high levels of insolation, good supply of water, warm temp, high nutrient levels

  Secondary productivity - biomass grained by heterotrophic organism through feeding and absorption measured in units of mass or energy per unit area per unit time.

  • involves feeding and absorption, dependent on amount of food present

  Gross productivity (GP) - total gain in energy or biomass per unit area per unit time

  Net productivity (NP) - gain in energy or biomass per unit area per unit time remaining allow for respiratory losses (R).

  Primary productivity on the next test

  • Gross primary productivity (GPP) - equivalent to the mass of glucose created by photosynthesis per unit area per unit time in primary producers NPP+R

  • Net primary productivity (NPP) - gain by producers in energy or biomass remaining after allowing respiratory losses NPP = GPP - R

  Secondary productivity

  • Gross secondary productivity (GSP) - total enegy or biomass assimilated by consumers is calculated by subtracting faecal loss from the mass of food consumed. GSP = Food eaten - faecal loss

  • Net secondary productivity (NSP) - NSP = GSP - R

  • Net secondary production (NSP) the gain by consumers in energy or biomass after allowing for respiratory losses NSP = GSP -R

• Maximum sustainable yield

  Sustainable yield: rate of increase in natural capital that can be exploited without depleting the original stock or its potential for replenishmnet

  Maximum sustainable yield: maximum flow of a given resoruce such that the stock don’t decline over time.

• Nutrient Cycles

  Gersmehl diagram show the differences in nutrient flow and storage between different types of ecosystems

  factors that affect the store of nutrients and their transfer:

  • the amount and type of weathering

  • overland run-off and soil erosion

  • the amount of rainfall

  • rates of decomposition

  • type of vegetation

  • plant density

• Carbon Cycle (rmb some stores and transfers)

  organic storage:

  • organism including forest

  Inorganic storages

  • atmosphere, soil, fossil fuels, oceans.

  Transfer in carbon cycle:

  • herbivores feeding on producers

  • carnivores feeding on herbivores

  • composers feeding on dead organic matter

  • carbon dioxide dissolving in rainwater oceans.

  Transformations in the carbon cycle

  • Photosynthesis which converts inorganic materials to organic matter.

  • Respiration converts organic storage into inorganic matter. Respiration transforms organic matter such as glucose into co2 and water

  • combustion transforms biomass into carbon dioxide and water

  • fossilization transforms organic matter in dead organism into fossil fuels throguh complete decay and pressure

• Nitrogen cycle (rmb diagrams also)

  Nitrogen is an essential building block of amino acids and DNA vital for all organism. 80% in the atmospjere

  Organic storages

  • organism

  Inorganic storages

  • soil, fossil fuel, atmosphere, water bodies

  Transfers flow in nitrogen cycle

  • herbivores feeding on producers

  • carnivores feeding on herbivores

  • composers feeding on dead organic matter

  • Plants absorbing nitrates through their roots

  • Excretion: removal of metabolic waste products from an organism

  Transformations in the nitrogen cycle

  • lightening transforms nitrogen into NO3 (Nitrogen fixation)

  • Nitrogen-fixing bacteria transform nitrogen gas in the atmosphere into ammonium ions.

  • Nitrifying bacteria transform ammonium ions into nitrite and then nitrate

  • Denitrifying bacteria transform nitrates into nitrogen

  • Decomposers break down organic nitrogen (protein) into ammonia.

  • Nitrogen from nitrates is used by plants to make amino acids and protein (assimilation)

• Human activities on energy flow and matter flow

  Energy flows - combustion of fossil fuels altered the way energy from the sun interacts with the atmosphere, more co2 increase in temperature.

  • Human activities such as burning fossil fuels, deforestation, urbanization, and agriculture impact energy flows in the carbon cycle and nitrogen cycle.

  Matter cycles - timber harvesting impact nutrient cycling. Adding fertilizer to the nitrate can cause autrophication. .

2.4 Biomes, Zonation, Succession

• Biomes

  Biomes are collections of ecosystems sharing similar climatic conditions. Can be grouped into 5 major classes - aquatic, forest, grassland, desert, tundra. Temperatur and precipitation determine biome distribution around the globe.

  • the more productive a biome is, the higher its NPP.

  • Insolation, precipitation and temperature are the main factors distributions of biomes

  Convectional rain: precipitation that results from the upward movement of warm, moist air in the atmosphere.

  • when air rise, it is low pressure

  Singapore climate graph analysis

  

  • Tricellular model of atmospheric circulation

• Aquatic biomes

  Coral reefs found between the tropic of cancer and tropic of capricorn where seas are warm and strong sunlight throughout the year. Small animals called polyps take in co2 and calcium from seawater and transform it into calcium carbonate skeleton (which form reefs). Producivity within the polyps are high meaning also high production.

  • Hydrothermal vents

    • hottest environments on earth

    • sunlight does not penetrate through

    • found in volcanically active areas along tectonic plate margins.

    • occur when cold seawater penetrates the ocean crust and comes into contact with the hot rock below the surface.

    Only extremely heat tolerant organism can survive there (eg.chemosynthethic bacteria, some polychaete worms).

    thermophilic species = species that can survive high temperature.

    • Hot fluid released by vents is enriched with chemicals (hydrogen sulfide), therefore chemosynthetic bacteria can obtain energy

    Food chain are based on chemosynthetic bacteria, wherelse food chain in coral reefs are supported by photosynthetic algae.

• Effect of climate change on biome distribuition

  Distribution is controlled by a combination of temperature, insolation, and precipitation. Increases in CO2 levels in mean global temperature whcih affects rainfall patterns.

• Spatial and temporal changes in communities

  Communities can change along environmental radiants due to changes in altitude, latitude, or distance from the sea on a rocky shore.

  Zonation: is the arrangement or pattern of communities in bands in response to change in some environmental factor over a distance. eg. change in ecosystems up a mountain as altitude increases.

  Sucession: Succession is the long term change in the composition of a community. The change in communities from the earliest community to the final community is called a sere (rocks). The first stage of a succession is called the pioneer community. The final stage is the climax community. Climax community is mor stable than

  • changes in space wherelse zonation changes in time.

• R and K strategist species

  r specieis have a fast rate of increase. they produce many, small offspring that mature rapidly recieving little to no parental care

  k-strategist are slow growing organism tend to be limited by the carrying capacity of an environment. produce very few, often large offspring that mature slowly and recieves a lot of parental care. Due to low birth rate, they are vulnerable to high death rates and extinction.

  • r and K selection theory

    natural selection favors species that can maximize the use to natural resources which produce only a few young species that have a high rate of survival

    R-strategist	K-strategist
    initial colonizers	dominant species
    large numbers of a few species	diverse range of species
    highly adaptable	specialist
    rapid growth and development	slow development
    early reproduction	delayed reproduction
    short life	long living
    small size	large size
    very productive	not very productive

2.5 Investigating ecosystems

Dichotomous key is a stepwise tool for identification where there are two options based on different charcateristics at each step. The outcome of each choice leads to another pair of options. This continues until the organism is identified.

• Limitations: too many species ahve siilar attributes and some features cannot be easily established in the feild. Some organism significantly change their body and shapes during their lifetime which must be taken into account.

• Measuring abiotic components of the ecosystem

  Ecosystem divided into 3 types: marine, freshwater, terrestial

  • Abiotic factors of marine ecosystem include: Salinity (salt content in body of water), pH, temperature, dissolved oxygen, wave action

  • Abiotic factors of freshwater ecosystem: turbidity, pH, temperature, dissolved oxygen, flow velocity

  • Abiotic factors of terrestial ecosystem: temperature, light intensity, wind speed, particle size, slope/aspect, soil moisture, drainage, mineral content

  • techniques for measuring abiotic factors

    Light: use light meter to measure light intensity. meter should be in a fixed height above the ground.

    temperature: an electronic thermometer with probes (datalogger). Temp need to be taken on standard depth in soil

    pH: can be measured with pH meter or datalogging probe.

    Wind: observing the effect of wind on an object, then related to Beaufort scale.

    Particle size: particle size determine drainage and water holding capacity

    Slope: calculated using clinometer,

    Soil moisture: wighting samples before and afer heating in an oven gives the weight of water evaporated and therefore moisture levels.

    Mineral content: loss of ignition (LOI) can determine the mineral content

    Flow velocity:

  • Trapping methods

    pitfall traps, nets, flight interception traps, small mammals trap, light trap, tullgren fannels

• SImpson’s diveristy index (in this years mock)

  species diversity and species richness (num of species in an area)

  D = N(N-1)/En(n-1)

  • D is the Simpson’s index diversity index

  • N is the total number of organism of all species found

  • n is the number of individuals of a particular species

  • example

    

• The Lincoln index

  used to estimate the total population size of a motile (move) animal in the study area. Using the lincoln index involves collecting a sample from the population, marking the organism, releasing them back in the wild, then resempling some time later and count how many marked individuals in the second capture.

  Formula: n1 + n2/nm

  • n1 is the number caught in the first sample, n2 caught in the second sample, nm is the number caught in the seocnd sample which are previously marked.

  • Limitations:

    • animal may move in and out of the sample area, making the capture- mark-release-recapture method less trustworthy and the data invalid.

    • density of a population in different habitat might vary

    • some may be hidden by vegetation and difficult to find

    • seasonal variations that effect the population size

• Quadrat sampling

  Used to limit the sampling area when you want to measure the population size of non-motile organism. Vary from size 0.25m to 1m, should be optimal for the organism you are studying.

  Random Sampling: located at random number generator

  Stratified random Sampling: take sets of results from both area

  Systematic sampling: if along an environmental gradeint, place quadrats in set distances

  Continuos sampling: Samples along the whole length of the transect

  Population density: the number of individuals of each species per unit area. Population density = total number of a species in all quadrats/ (area of one quadrat x total number of quadrats)

  • plant abundance is best estimated using percentage cover

  Percentage frequency number of actual occurance divided by the number of possible occurrences, expressed as percentage.

IA: lab work is good,

• environmental issue

• Criteria

  Identifying context

  

  Planning

  

  Results, analysis and conclusion

  

  Discussion and evaluation

  

  Application

  

  Communication

  

Introduction to soil systems

5. 1 Introduction to soil systems

• Soil profiles and soil systems

  Soil profile is a vertical section through a soil, and is divided into horizons (distinguishable layers).

  • going down is leaching, going up is capillary action

  

  • soils are the medium for plant growth

  • roughly 5% of organic matter in the soil

  • soils contain important store of relatively accessible fresh water - approx. 7000km^3 or 0.005 percent of the global freshwater total.

  • soils filter materials added tot he soil thereby maintaining water quality

  • soil act as a habitat for billions of microorganism and some large animals

  • soils provide raw materials in the form of peat, clays, sands, gravels and minerals.

  • organic: feces and remains of organism

  

• Soil-forming processes

  • plant material = bedrock broken down by weathering (physical or chemical) releases humic acid

  • minerals are released to the soil and material comes from organic matter from air and water

  • gains and losses of material to and from the profile

  • movement of water between the horizons

  • chemical transformations with each horizon

  • clay soils come from chemical erosion of limestone

  Gains and losses of material

  input of organic matter: leaf litter and inorganic matter from parent material, precipitation, and energy

  output: uptake by plants and soil erosion

  Movement of Water

  Translocation processes by water, mostly downwards

  Leaching downward movement of a soluble material (A substance is soluble if it dissolves in certain fluids)

  • Chemical transformation

    decomposition: changes leaf to humus. plant litter are decomposed (humidified) into dark matter, it is a form of decomposition and disintegration.

    weathering: the decomposition and disintegration of rocks. Biological weathering is the weakening of rocks by plant, animals and microbes.

    • Decomposition: refers to chemical weathering and creates altered rock substances such as kaolinite from granite.

    • Disintegration: mechanical weathering producing smaller and angular fragments of the same rock.

    Nutrient cycling: interaction between soil, plants, and the atmosphere, and many food chain. Nutrient cycles can be sedimentary, in which the source of the nutrient is from rocks. can be dhown in simplified graphs (Gersmehl’s nutrient cycles)

• Soil Structures and Properties

  Soil provides plants with a number of benefits:

  • anchorage for roots, supply of water and oxygen, supply of mineral nutrients, protection agaisnt adverse changes of temperature and pH

  Soil conditions that restrict root growth. Physical conditions include:

  • mechanical barriers (usually associated with high bulk density, as occurs in compact soils)

  • absence of cracks

  • shortage of oxygen due to waterlogging

  • dryness

  • temperatures that are too high or low

  Chemical conditions include:

  • high aluminium concentration, usually with low pH

  • Low nutrient supply

  • phytotoxic chemicals in anaerobic soil

  • Soil texture

    soil structure refers tot he shape and arrangement of individuals soil particles (peds). The ideal soil cultivation is a loam in which there is a balance between water holding ability and freely draining, aerated conditions. A loam is a well-balanced soil with significant proportions of sand, slit, and clay.

    Triangular graphs are used to show data that can be divided into 3 parts: sand, slit and clay for soil. Data must be in a form of percentage and the percentage add up to 100%.

    

    

    A= Clay: 60 Sand:20 Slit: 20

    B = Clay: 20 Sand:10 Slit: 70

    C = Clay: 10 Sand:70 Slit: 20

    Main advantages:

    • large number of data can be shown in one graph

    • groupings are easily recognizable

    • dominant characteristics can be shown

    • classifications can be drawn up.

    but they can be difficult to interpret and easy to get confused.

  • Soil types

    Agricultural potential of soil depends on:

    • the porosity and permeability of the soil

    • the surface area of the soil peds

    • Drainage and water holding capacity

      pore spaces in soil determines the rate at which water drains through a soil. The surface area of the peds determines the amount of water and nutrients in solution that can be retained agaisnt the force of gravity.

      Heavy clay soil can hold twice as much water as a light soil. Light soil (over 80% sand) are coarse textured and easilu drained of water and nutrients. They warm up more quickly. clay absorbs water, soo the soil swells when wet and shrinks when dry.

      

      AIR SPACES

      

    • Primary productivity

      • sandy soil – low primary productivity due to poor water-holding capacity and low nutrient status

      • clay soil – quite low primary productivity due to poor aeration and poor water infiltration

      • loam soil – high primary productivity due to medium infiltration rate, water-holding capacity, nutrient status, aeration, and ease of working.

    • Suitability of soils for food production

      Main limiting factors for light soils:

      • Drought during growing season since these soil have poor nutrient and water holding capacity

      Heavy soil are most difficult for arable cultivation. have higher water retentive, low permeability and feild drainage is slow.

  • Questions

    

    

5.2 Terrestrial Food Production Systems

• Sustainability of terrestrial food production systems

  sustainability of terrestrial food production systems is influenced by factors including: scale, industrialization, mechanization, fossil fuel use, seed/crop, livestock choices, water use, fertilizer, pest control, pollinators, antibiotics, legislation and levels of comercial versus subsistence food production.

  Main characteristics of agribusiness are:

  • large scale monoculture

  • intensive use of fertilizers and pesticides

  • mechanized ploughing and harvesting

  • food production geared to mass markets including exports.

  This form of argriculture has great impact on the environment: loss of biodiversity, increased run-off pollution (eg. eutrophication). GM crops are used to increase yeild, but can have a knock-on effect on wild populations if modified species cross-pollinate with wild ones.

  • Agricultural sustainability

    Use of fresh water abstraction fro human use has increased. The demand for water in food production

• Case studies

  p 287Shifting cultivation is known as slash and burn agriculture because new la nd is cleared by cutting down small areas of forest trees and setting fire to them: the ash fertilizes the soil for a while and the clearing produced enable crops to be grown.

  Slash and burn is possible due to low population densities can be supported by the food produced. If population densities increases too much, previously farmed land is returned to before soil fertility is restored.

  

  Wet rice ecosystems of South East Asia

  Paddy feild (wet rice) agriculture has become a dominant form growing rice in southeast asia. Example of intnesive subsistence farming, using high labour inputs but low technology. High rainfall in these regions facilitates this type of agriculture allowing extensive field irrigation to be maintained throughtout the year.

  Declining soil fertility has also been a problem, and rice yeilds have been reaching their maximum.

  Intensive beef production in MEDCs and the Maasai tribal use of livestock

  Main impact of fsrming:

  soil degradation: fertilizer cause soil to erode, can lead to dessertification

  pollution from insecticides, pesticides

  lost of valueble habitat

• Inputs, outputs and environmental impacts of terrestrial food production

  Inputs to food production systems include: fertilizer (artificial or organic), water (irrigation or rainfall), pest-control (pesticides or natural predators); labour (mechanized and fossil-fuel dependent or physical labour), seed (GM or conventional); breeding stock (domestic or wild); livestock growth promoters (antibiotics or hormones versus organic or none).

  Outputs: food quality/quantity, pollutants (air, soil, water), consumer health, soil quality (erosion, degradation, fertility); common pollutants released from food production systems include fertilizers, pesticides, fungicides, antibiotics and gases from the use of fossil fuel, transportation, processing, packaging of food may lead to futher pollution from fossil fuels.

  Terrestrial farming systems can be divided into several types:

  • Commercial farming: farming for profit - often a single crop

  • Subsistence farming produces only enough to feed the farmer and his or her family,

    with none to sell for profit.

  • Intensive farms generally take up a small area of land but aim to have very high output (through lage inputs of capital and labor)

  • Extensive farms are large in comparison to the money and labor