IB SL Environmental and Social Systems Duck

Anil Nair- Overseas Family School, Singapore

(The words that are blue and underlined are usually images to help you, so click on them because i was lazy to insert them so they are hyperlinked. hmu if something is wrong)

GOOD LUCK.

Topic 1- Systems and Models

Topic 2- The Ecosystem

2.1 Structure

2.2 Measuring Abiotic Components of the system

2.3 Measuring Biotic Components of the system

2.4 Biomes

2.5 Function

2.6 Changes

2.7 Measuring Changes in the system

Topic 3- Human Population, Carrying Capacity and Resource Use

3.1: Population Dynamics

3.2: Resources- Natural Capital

3.3: Energy Resources

3.4: The Soil System

3.5: Food Resources

3.6: Water Resources

3.7: Limits to Growth

3.8: Environmental demands of human populations

Topic 4- Conservation and Biodiversity

4.1: Biodiversity in Ecosystems

4.2: Evaluating Biodiversity & Vulnerability

4.3: Conservation of Biodiversity

Topic 5- Pollution Management

5.1: Nature of Pollution

5.2: Detection and monitoring of Pollution

5.3: Approaches to Pollution Management

5.4: Eutrophication

5.5: Solid Domestic Waste

5.6: Depletion of Stratospheric Ozone

5.7: Urban Air Pollution

5.8: Acid Deposition

Topic 6- The issue of Global Warming

Topic 7- Environmental Value Systems

Topic 1- Systems and Models

What is a system?

A system is an assemblage of parts that are working together which in turn form a functioning whole.
The number of inputs, outputs, flows and storages increase as the size of the system increases.

Gaia Model/Hypothesis:

In 1979, James Lovelock created this idea that we all should look at the Earth as one whole living organism.
Basically it viewed the planet like a person, a living functioning whole.
Although system changes may have happened, the overall conditions remained similar throughout.

Open System: Exchanges matter and energy with its surroundings (most living things)
Closed System: Exchanges energy but not matter with the environment. (Does not exist naturally, but the planet is a closed system.)
Isolated System: Exchanges neither matter nor energy. (Does not exist)
Entropy: Amount of thermal energy not available to do work.
First Law of Thermodynamics: Energy can be neither created nor destroyed.
Second Law of Thermodynamics: Entropy of an isolated system not in equilibrium will tend to increase over time.
Equilibrium: Tendency of a system to return to an original state following a disturbance.

Steady State Equilibrium: Continuous inputs and outputs of energy and matter. Although there might be small term fluctuations, in the long term, no massive change.
Static Equilibrium: No change over time.

Positive Feedback: Results in the further increase or decrease in the output and results in the system becoming more unstable or moving to a new equilibrium. ( a change occurs)
Negative Feedback: Neutralises any movement from the equilibrium. (No change occurs)
Transfer: Movement of material in living organisms /non-living things / energy

Flows through a system and involves a change in location. Energy and matter can flow through an ecosystem, but can also be stored within an ecosystem.

Transformation: Interaction within a system and formation of a new end product or change in state

Examples: matter to matter, matter to energy, energy to energy, energy to matter.

Models: Simplified description designed to show the structure or workings of an object, system or concept.

They assist in making a prediction of a future event.
They are not accurate because it is only a prediction.

Topic 2- The Ecosystem

2.1 Structure

Biotic: Living Factors (plants/animals)
Abiotic: Non-Living Factors (precipitation/soil)
Trophic Level: Position of an organism or a group of organisms in a community occupies in a food chain.

Level 1: Producer
Level 2: Herbivore (primary consumer)
Level 3: Carnivore (secondary consumer)
Level 4: Carnivore (tertiary consumer)

Top Carnivores are found at the highest level, essentially they are animals which no one else eats.

Food Chain: Shows the flow of energy from one organism to the next
Food Web: Complex network of interlinked food chains
Producers (autotrophs): They manufacture their own food from sunlight
Consumers (heterotrophs): Feed on the producers or other animals
Pyramids:

Pyramid of Numbers

The literal number of species in an area

Pyramid of Productivity

Refers to the flow of energy through an ecosystem

Pyramid of Biomass

Represents standing stock of each trophic level.
Measured in gm^-2 or J m^-2 or kg

Bioaccumulation: Concentration of a toxin increases in a body over time

It could just keep becoming more and more concentrated as time goes on.

Biomagnification: As one goes through trophic levels, the amount of toxin increases.

If a plant species gets a toxin, and then a herbivore eats the species, as it is eating numerous plants, the amount of toxin in its body increases. From there, through reproduction, will spread the toxin, to which a carnivore may eat it and then the toxin biomagnifies in its body as time goes on.

Species: A particular type of organism
Population: Group of individuals of the same species living in the same place
Habitat: Environment where the species lives
Niche: Responsibility of an organism, its unique role in an ecosystem
Community: Group of population living and interacting with each other in a common habitat
Ecosystem: This is a community of interdependent organisms and the abiotic factors in the environment they live in.
Competition: Two or more organisms attempting to use the same resource.

If there is a limited amount of resources then competition is high.
If there is an abundance of resources; low competition.

Parasitism: A type of relationship between species, Essentially one species will benefit from the relationship, while the other does not. (Taken advantage of)
Mutualism: A type of relationship between two or more species, all benefit and non suffer
Commensalism: A type of relationship between species, one species is helped, but none are harmed
Predation: A type of relationship between species, one animal eats another animal
Herbivory: A type of relationship between species, when an animal feeds on plants

2.2 Measuring Abiotic Components of the system

Examples of Abiotic Components

Atmosphere
Climate
Soil
Water
Level of Pollution

Limiting Factors: Physical or biological necessities that an ecosystem can not live without. If there is a lack of their presence, adverse and negative effects can occur.

Temperature
Salinity
Dissolved Gases
Pressure

2.3 Measuring Biotic Components of the system

Dichotomous Key

There are two types, one a flow chart and one a questionnaire

Lincoln Index

Measures population size
In order for it to work, the Quadrats or Capture-Mark-Release-Recapture method must be used

Quadrats:

An area must be marked out
Quadrats are placed randomly throughout the selected area and then one must count how many individuals are in each quadrat and calculate the mean.

Quadrats are good for plants, since they don’t move, but to calculate animals quadrats will be very difficult.

Capture-Mark-Release-Recapture

Capture as many individuals as possible in the area
Mark each individual carefully

Ensure that it is not in a way which would affect the lifestyle of the animal.

Release them
Recapture a random amount, and count how many are marked vs unmarked
Use Lincoln Index.

Both these ways assume that the population is “closed” meaning that they will not immigrate or emigrate.

Diversity: A function of two components, the number of different species and the relative numbers of individuals of each species.

Simpson's Diversity Index

Measures Diversity in an ecosystem

2.4 Biomes

Biome: A collection of ecosystems which share similar climatic conditions so therefore have similar vegetation.
Examples of Biomes:

Tropical Rainforest

Distribution: within 5º North and South of the equator.
Climate: High rainfall 2000 – 5000 mm per year. High temperatures 26 - 28ºC mean and little seasonal variation. High levels of insolation due to closeness to equator.
Structure: Very high levels of biodiversity; plants compete for light causing multi-storey profile (stratification) from floor to canopy. Due to high plant diversity many niches and habitats for animals.
Relative Productivity: Estimated to produce 40% of NPP of all terrestrial ecosystems. Growing season all year round, fast decomposition, respiration and photosynthetic rates. Biomass gain is very high in immature plants, but there is no net gain in larger more mature plants. Rapid recycling of nutrients.
Issues and Human Activity: deforestation from logging and land clearing for agriculture. 50 % of world’s population live in the tropics and subtropics and 1 in 8 live in or near a tropical rainforest, which places a huge strain on tropical rainforests for resources.

Desert

Distribution: cover 20 – 30% of Earth’s land surface about 30º North and South of Equator, where dry air descends. Most are in the middle of continents (e.g. Gobi desert – cold desert). The Atacama desert in Chile can have no rain for 20 years or more, and is the driest place on Earth.
Climate: Water limited, precipitation less than 250 mm per year and irregular. Evaporation exceeds precipitation (E>P)
Structure: few species, low biodiversity. What can survive in deserts is well adapted. Soils can be rich in nutrients as they are not washed away. Plants mostly cacti and succulents. Reptiles are dominant, snakes, lizards, but small mammals can survive by adapting to nocturnal life or reduce sweat loss by not having sweat glands and absorbing water from their food. Slow rate of decomposition.
Relative Productivity: Both primary and secondary productivity are low due to limited water and plant biomass can not build up. Food chains tend to be short.
Issues and Human Activity: traditionally nomadic tribes herd animals such as camels and goats as agriculture. Population density low as cannot support large human population. Oil has been found under deserts and many are rich in minerals including gold and silver. Irrigation is possible by tapping underground aquifers but there is extremely high rate of evaporation causing increased salt content until crops can not grow (salinization).

Temperate Forest

Distribution: Between 40º and 60º North and South of the equator.
Climate: P>E. Rainfall is 500 – 1500mm per year. Winters freezing in some e.g. Eastern China, milder in Western Europe due to Gulf Stream. Temperatures range from -30º to +30ºC. Summers cool.
Structure: Fewer species than tropical rainforests, Relatively few species and many woodlands are dominated by one species. Beneath the canopy is a lower shrub layer is not too dense, is of covered in a thick undergrowth of brambles, grass, bracken and ferns. The forest floor has a reasonably thick leaf litter that is readily broken down. Rapid recycling of nutrients, although some are lost through leaching. Well-developed food chains in these forests with many autotrophs, herbivores (rabbits, deer and mice) and carnivores (foxes).
Relative Productivity: 2nd highest NPP after tropical rainforests but much lower than these because of leaf fall in winter so reduced photosynthesis and transpiration and frozen soils when water is limiting. Temperatures and insolation lower in winters too as further from the equator.
Issues and Human Activity: Much temperate forest has been cleared for agriculture or urban developments. Large predators (wolves, bears) virtually wiped out. Most of Europe’s natural primary deciduous woodland has been cleared for farming, for use as fuel and in building, and for urban development. Some that is left under threat, e.g. US pacific Northwest old-growth temperate and coniferous forests. Often mineral wealth under for forests is mined. Examples: US Pacific Northwest

Arctic Tundra

Distribution: Just south of the Arctic ice cap and small amounts in southern hemisphere. (Alpine tundra is found as isolated patches on high mountains from the poles to the tropics.)
Climate: Water is limiting but fire can also stop the climax community forming. Frozen ground (permafrost), cold, high winds and little precipitation mean the growing season is only 6 weeks per year. Permafrost reaches to the surface in winter but in summer the top layers of soil defrost and plants can grow. Low temperatures so rates of respiration, photosynthesis and decomposition are low. Slow growth and slow recycling of nutrients. Water, temperature, insulation and nutrients can be limiting. During spring and summer, animals are active, and plants begin to grow rapidly. Sometimes temperatures reach 30C. Much of this energy is absorbed as the latent heat of melting of ice to water.
Structure: No trees but thick mat of low-growing plants, e.g. grasses, mosses, and shrubs. Adapted to withstand drying out with leathery leaves or underground storage organs. Animals also adapted with thick fur and small ears to reduce heat loss. Mostly small mammals, e.g. hares. Predators e.g. the Artic fox, lynx, snowy owl. Most hibernate and make burrows. Low biodiversity and poor soil.
Relative Productivity: Very low. Slow decomposition rate so many peat bogs where most carbon is stored.
Issues and Human Activity: Few humans but mining and oil. Fragile ecosystem that takes a long time to recover from disruption. Mining and oil extraction in Canada and Siberia destroy tundra. Vulnerable to global warming effects.

2.5 Function

Producers: Converts light energy into chemical energy during photosynthesis. Starts all food chains. Extremely important
Consumers: They eat producers and other consumers. They do so to gain energy.
Decomposers: They obtain their energy from dead organisms and they also break down dead organic matter and return minerals + nutrients to the soil.
Photosynthesis: Process in which, Light Energy is converted to Chemical Energy.

Inputs: Water, Co2, Chlorophyll and Light
Outputs: Oxygen, Glucose and Water
Vital as it provides the basis for any food chain, the plant will harness the energy from the sun, providing it to others.

Respiration: Process in which chemical energy is converted into usable energy for an organism.

Inputs: Food and Oxygen
Outputs: Co2, Water and Waste
Glucose + oxygen → energy + water + carbon dioxide

When energy is transferred between different trophic levels, some of it is lost during the transfer.
Carbon Cycle: This is the process where through Photosynthesis, Respiration, carbon is absorbed by the atmosphere.
Nitrogen Cycle: This process is when nitrogen is used to help develop the ecosystem.

Nitrogen fixation: Nitrogen fixation is a process in which nitrogen (N2) in the atmosphere is converted into ammonium (NH4+).
Denitrification: Denitrification is essentially the conversion of nitrate to nitrogen gas.
Nitrification: Nitrification is the biological oxidation of ammonia or ammonium to nitrite followed by the oxidation of the nitrite to nitrate.

Hydrological Cycle: Transfer of water between the atmosphere and rivers lakes and oceans.
Gross Productivity: Total gain in energy or biomass per unit area per unit time.
Net Productivity: Gain in energy or biomass per unit per unit time after respiration.
Net Primary Productivity: Rate at which plants accumulate dry mass. Store of energy (NPP= GPP- R)
Net Secondary Productivity: Energy in the food ingested (NSP= GSP-R)
Gross Primary Productivity: Total amount of energy produced by plants from sunlight.
Gross Secondary Productivity: Gain in energy/biomass per unit area per unit time by consumers.

2.6 Changes

Limiting Factors: Factors that limit or prevent a community, population or organism from growing larger.
Carrying Capacity: The maximum number of species that an environment can sustainably support.
Population Curves:

J- Curve: Growth is exponential
S- Curve: Growth is rapid and it fluxuates

Density Dependent factors: These are factors that affect the population size based on the population density.

Predation
Disease
Availability of resources
Space

Density Independent factors: Affects the population size regardless of the population density.

Natural Disasters

Internal factors: include most density dependent, fertility or size of breeding territory.
External factors: includes most density independent factors, predation and disease.
K-Strategists: These are animals which are:

Larger
Slower Reproduction Rate
Long Lifespan
High Parental care
Population tends to be stable
Elephants, Humans, Tigers

R-Strategists: These are animals which are:

Smaller
Fast Reproduction Rate
Short Lifespan
Low Parental care
Population size is very unstable
Flies, Mosquitoes

Succession: This refers to the orderly succession of a species towards a climax community over time.

Primary Succession: Starts from bare rock, exposed rock and it will develop.
Secondary Succession: Begins on soil from which a previous community was there, but has been since removed.

Pioneer Community: The organisms in pioneer communities are specialized to take advantage of the newly open environment, They tend to include such organisms as grasses.
Climax Community: An ecological community in the final stage of succession, in which the species composition remains relatively stable until a disturbance occurs. The disturbance will not be completely permanent
Zonation: How an ecosystem changes along an environmental gradient or zone like water in soil.