IB ESS SL

Ecocentric viewpoint

Holistic ideal, ecology and nature central to humanity, less materialistic approach, prioritizes biorights, encourages education and human self-restraint

Anthropocentric viewpoint

Humans must sustainably manage the global system, (taxes, regulation, legislation), pragmatic approach in solving environmental issues

Technocentric viewpoint

Technological developments can provide solutions, optimistic view for humans improving the world, scientific research encouraged to form policies

EVSs

Vary depending on cultures, time periods, individual

Discuss the view that the environment can have its own intrinsic value.

Value for its cultural, aesthetic, spiritual or philosophical (moral) value - e.g. ecotourism, sacred places, traditional customs

Evaluate the implications of two contrasting EVSs in the context of given environmental issues.

Problem: hydro electrical power plant - building of a large dam across a river -> flooding upstream, regulation of flow downstream. Reservoir provides water supply for locals.

Approach

Deep ecologist = destroys habitats, prevents flow of nutrients and migration routes, flooding forests produces methane, disturbs food chains

Cornucopian = creates employment, green energy production that helps locals + provides them with water, helps economy

Justify, using examples and evidence, how historical influences have shaped the development of the modern environmental movement.

Silent spring - Rachel Carson, 1962 (writes about use of DDT in USA - groundbreaking people started to care about ecology)

Paris Agreement 2015 (in effect 2016) - main aim to reduce global warming below 2 degrees Celsius - first time when so many states agreed on taking action

MEDCs to help LEDCs

System approach

a way of visualizing a complex set of interactions, storages and flows (flows inputs and outputs of energy and matter, transfers and transformations - change in chemical nature)

Open system

Exchanges both energy and matter, e.g ecosystems

Closed system

Exchanges only energy, only exists experimentally

Isolated systems

Exchanges nothing but is only hypothetical

Evaluate the use of models as a tool in a given situation, eg climate change predictions.

Pros: easier to work with than complex reality, can be used to predict the effect of a change of input, can be applied to similar situations, helps us see patterns, used to visualize really small/large things

Cons: Every model involves approximation and loss of accuracy. If assumptions are wrong, the model is wrong and predictions can be inaccurate.

First law of thermodynamics

Principle of conservation of energy - energy in an isolated system can be transformed but cannot be created or destroyed

Second law of thermodynamics

The entropy of a system increases over time (the measure of disorder in a system) - entropy causes loss of energy in each transformation (along food chain)

Negative feedback

Stabilizing - counteracts deviations (predator prey relationship)

Positive feedback

Destabilizing - amplifies changes, drives the system toward a tipping point where a new equilibrium is adopted

Resilience

Tendency to maintain stability (diversity and size of storages within systems contribute to their resilience)

Explain the implications of the laws of thermodynamics to ecological systems.

1st law = energy can be transferred but not created ->

2nd law = large proportion of the chemical energy (approx 90%) transferred between trophic levels is converted to heat energy - inefficient transfer of organic matter

Discuss the resilience in a variety of systems

Resilience in ecological systems refers to the ability of an ecosystem to recover from disturbances, maintain functionality, and adapt to changes, which is influenced by biodiversity and the interconnectedness of species.

Evaluate the possible consequences of tipping points.

New equilibrium created - can disrupt diversity, environmental factors such as food chains

E.g. eutrophication, extinction of a keystone species, coral reef death (acidity)

Sustainability

Use and management of resources - allows full natural replacement of those resources and full recovery of the ecosystems affected by their extraction and use

Natural capital

Natural resources - can produce a sustainable natural income of goods or services

Services: water replenishment, flood and erosion protection

Goods: timber, fish, crops

Environmental indicators

Biodiversity, pollution, population, climate

Natural income

Yield obtained from natural resources

Environmental impact assessment

Baseline studies before a development project - assess environmental, social and economic impacts of the project, predict and evaluate possible impacts and suggest mitigation strategies

Ecological footprint

Area of land and water required to sustainably provide all resources at the rate at which they are being consumed by given population (unsustainability is when ecological footprint is greater than area available to the population)

Explain the relationship between natural capital, natural income and sustainability.

Natural income comes from natural capital available, the sustainability regarding the use of natural capital determines the natural income. Additionally, natural capital provides services.

Discuss the value of ecosystem services to a society.

Maintain life on earth. Ecological/sociocultural/economic or intrinsic values.

Discuss how environmental indicators such as MA (millennium assessment) can be used to evaluate the progress of a project to increase sustainability.

The goals of the assessment add to the measurability of the outcome.

Evaluate the use of EIAs. (Environmental Impact Assessments)

Cons: include the lack of a standard practice or training for practitioners, the lack of a clear definition of system boundaries, the lack of inclusion of indirect impacts.

Pros: provide some analysis to change the development plans to reduce the impact, improve long-term viability of many projects, offer alternative projects which may have more positive outcomes, provide an opportunity to learn from experience of similar projects and avoid the (often high) costs of subsequently mitigating unforeseen negative and damaging impacts

Explain the relationship between EFs and sustainability. (Ecological footprint)

If EF is greater than the area available to the population, it indicated unsustanability.

Pollution

The addition of a substance or an agent to an environment through human activity at a rate greater than it can be rendered harmless by the environment.

Types: point/nonpoint source, persistent/biodegradable, acute or chronic

Pollutants

organic/inorganic, light, sound, thermal energy, biological agents or invasive species

many derive from human activities

Primary pollutants

active on emission

Secondary pollutants

arising from primary pollutants undergoing physical or chemical change

Evaluate the effectiveness of each of the three different levels of intervention.

Change the human activity that generates the pollutant in the first place: the most proactive/preventative strategy - pollutant is not created (or less of it is created) but

tends to be difficult to achieve because it's necessary to change the behavior of people, businesses, and/or governments

Minimize the amount of the pollutant released into the environment: next most proactive/preventative strategy - pollutant is controlled at the place where it is released, frequently adopted by government agencies that regulate industries but this strategy fails to fully address the problem because the pollutant is still being produced

Clean up the pollutant and the affected areas after the pollutant has been released: reactive strategy, tends to be very expensive; usually takes a very long time to implement

Sometimes it may not be scientifically possible,

does not solve the problem

Evaluate the use of DDT.

Disadvantages: lead to premature birth, low birth weight and abnormal mental development of infants, would affect other wildlife, significant ecological effects, the effects of accumulation in human tissue are not fully known, loss and degradation of soil

Advantages: highly persistent giving long lasting effect, alternatives are not as effective

DDT significantly reduce malaria death e.g. in Ecuador between 1993-1995 (61% reduction)

species

group of organisms - share common characteristics + interbreed to produce a fertile offspring

habitat

environment where species normally lives

niche

particular set of abiotic and biotic conditions + resources to which an organism responds

fundamental niche

full range of conditions + resources in which species could survive and reproduce

realized niche

actual conditions and resources in which a species exists due to biotic interactions

abiotic factors

non-living: e.g. temperature, sunlight, pH, salinity, precipitation

termed biotic factors

relationships/interactions between organisms - predation (predator-prey relationship), herbivory, parasitism, mutualism, disease, competition

population

group of organisms of the same species living in the same area at the same time + capable of interbreeding

Explain population growth curves in terms of numbers and rates.

S-curves - exponential growth, no limiting factors at first, above a certain population size the growth slows down, gradually

finally reaching the carrying capacity and resulting in a population of constant size

J-curves - "boom and bust" pattern, population grows exponentially and then suddenly collapses (=diebacks), population often exceeds the carrying capacity on a long-term basis (=overshoot), typical for microbes, invertebrates, fish, small mammals

in practice, usually a combination of both curves

ecosystem

community (group of populations living+interacting with each other in a common habitat) and the physical environment with which it interacts

respiration

conversion of organic matter into carbon dioxide and water by all living organisms, releasing energy

(during the process large amounts of energy are dissipated as heat, increasing

the entropy in the ecosystem while enabling organisms to maintain relatively low

entropy and so high organization.

photosynthesis

Primary producers in most ecosystems convert light energy into chemical energy

in the process

trophic level

position that an organism occupies in the food chain

autotroph

= Producers - typically plants or algae that produce their own food

using photosynthesis and form the first trophic level in a food chain.

bioaccumulation

build-up of persistent or non-biodegradable pollutants within an organism or trophic level because they cannot be broken down

biomagnification

increase in concentration of persistent/non-biodegradable pollutants along a food chain

Explain the transfer and transformation of energy as it flows through an ecosystem.

Almost all energy enters Earth's ecosystems as solar insolation, which is then transformed and used by the diverse variety of organisms that make up food webs.

Through photosynthesis, producers transform sunlight into glucose, which they then use for respiration.

Chloroplasts in plant cells - use sunlight to convert CO2 and water to glucose and oxygen gas.

Mitochondria - use the sugars for energy to drive respiration, their cellular processes required to stay alive.

Analyse the efficiency of energy transfers through a system.

Gross primary productivity - a measure of the energy that a plants transform from the sun.

Net primary productivity - the energy remaining after respiration

Energy will decrease with each increase in trophic level (second law of thermodynamics = during any transfer of energy, some is lost due to the tendency toward an increase in entropy)

Energy for higher trophic levels - loss due to metabolic respiration or movement

Energy transfer between trophic levels is generally inefficient (production at one trophic level is generally only 10% of the net production at the preceding trophic level)

Explain the relevance of the laws of thermodynamics to the flow of energy through ecosystems.

first law of thermodynamics - energy cannot be created or destroyed; it can only be changed from one form to another, energy for the functioning of an ecosystem comes from the Sun, Solar energy is absorbed by plants wherein it is converted to stored chemical energy.

second law of thermodynamics - whenever energy is transformed, there is a loss energy through the release of heat, when energy is transferred between trophic levels (as illustrated in a food web), when one animal feeds off another, there is a loss of heat (energy) in the process, additional loss of energy occurs during respiration and movement.

Hence, more and more energy is lost as one moves up through trophic levels.

Explain the impact of a persistent or non-biodegradable pollutant in an ecosystem.

cannot be broken down by microbes (= non-biodegradable) and continue to act for many years, and are classed as persistent pesticides.

difficult to deal with, long-term impact, biomagnification in food chains, bioaccumulation in tissues

pathways of energy through an ecosystem

conversion of light energy to chemical energy

transfer of chemical energy from one trophic level to another (varying efficiencies)

conversion of ultraviolet and visible light to heat energy

re-radiation of heat energy to the atmosphere

Net primary productivity (NPP)

calculated by subtracting respiratory losses (R)

from gross primary productivity (GPP)

Gross secondary productivity (GSP)

total energy or biomass assimilated

by consumers and is calculated by subtracting the mass of fecal loss from the mass of food consumed.

Net secondary productivity (NSP)

calculated by subtracting respiratory losses

(R) from GSP.

maximum sustainable yield

equivalent to NPP or NSP of a system

storages in carbon cycle

organisms and forests (organic), atmosphere, soil, fossil fuels, oceans (inorganic)

flows in carbon cycle

consumption, death and decomposition, photosynthesis, respiration, dissolving, fossilization

storages in nitrogen cycle

organisms (organic), soil, fossil fuels, atmosphere, water bodies (inorganic)

flows in nitrogen cycle

nitrogen fixation by bacteria and lightning, absorption, assimilation, consumption, excretion, death and decomposition, denitrification by bacteria in water-logged soils

Analyse the efficiency of energy transfers through a system.

energy losses between trophic levels - not efficient (10% passed, 90% lost)

Discuss human impacts on energy flows, and on the carbon and nitrogen cycles.

On energy flows - generally replacing natural vegetation with crops, deflecting natural succession, increasing the productivity of producers by fertilizers and soil improvements

carbon cycles - mining of fossil fuels, burning fossil fuels

nitrogen cycle - use of nitrogen fertilizers, pollution from vehicles and industrial plants, fossil fuel combustion and forest burning, livestock ranching

Biomes

collections of ecosystems sharing similar climatic conditions, can be grouped into major classes

Tricellular model of atmospheric circulation

explains the distribution of precipitation and temperature and how they influence structure and relative productivity of different terrestrial biomes (pg. 105)

Zonation

changes in community along an environmental gradient (changes in altitute, latitude, tidal level, distance from shore)

Succession

process of change over time in an ecosystem, involving pioneer, intermediate and climax societies

Succession productivity

early stages gross productivity is low (low density of producers, unfavorable initial conditions)

net productivity is high - proportion of energy lost through respiration is small

later stages - gross productivity high, balanced by respiration so net productivity approaches zero and productivity:respiration ratio approaches 1

Explain the distributions, structure, biodiversity and relative productivity of contrasting biomes.

Tropical rainforest

distribution:

5 degrees North and South of the equator.

structure:

high levels of biodiversity - many species and many individuals of each species

Plants compete or light and so grow tall to absorb it so there is a multi-storey profile to the forests with very tall emergent trees (stratification).

epiphytes

many niches and habitats

relative productivity:

produce 40% of NPP of terrestrial ecosystems.

Growing season all year round, fast rate of decomposition and respiration and photosynthesis.

Deserts

distribution:

Cover 20-30% of the Earth's surface, about 30 degrees North and South of the equator where dry air descends. Most are in the middle of continents. (Some deserts are cold deserts, eg the Gobi desert.)

structure:

Few species and low biodiversity but what can survive in deserts is well adapted to the conditions.

Soils are rich in nutrients as they are not washed away.

Plants are drought resistant and mostly cacti and succulents with adaptations to store water and reduce transpiration

relative productivity

Both primary (plants) and secondary (animals) are low because water is limiting and plant biomass cannot build up to large amounts. Food chains tend to be short because of this.

Discuss the impact of climate change on biomes.

Sea ice and glaciers are melting all over the globe due to warmer temperatures. Over 60% of the world's freshwater is stored in the ice sheets covering Antarctica, Sea levels are already rising by 2mm a year

rising temperatures disrupt all ecosystem in all biomes

Describe the process of succession in a given example.

On the southern coast of England in Dorset is Studland Bay where sand dunes have continued to be formed since the 16th century.

BARE SURFACE of sand, vegetation colonizes the sand. The pioneer plants tend to be low growing - they have at fleshy leaves with a waxy coating and are able to survive being submersed (= under water) temporarily.

COLONIZATION: predominant plant species is marram grass on the seaward side due to its ability to cope with the environmental conditions (r-selected species). It, like the other grasses, have leaves which are able to old to reduce its surface area. Leaves are waxy to reduce transpiration and can be aligned to the wind direction. It incorporates silica into its cell structure to give the leaves extra strength and flexibility.

ESTABLISHMENT: As a result of the humus from the previous stages, a sandy soil has now developed. This is now able to support pasture grasses and bushes. Species such as hawthorn, elder, brambles and sea buckthorn (which has nitrogen-fixing root nodules so can thrive in nutrient-poor soil) are present. As the scrub develops, shorter species will be shaded out.

COMPETITION: The oldest dunes will have forest - first pine and finally oak and ash woodland growing on them (K-selected species); the climatic climax vegetation or the area. Here the species diversity declines due to competition

STABILIZATION: In every case, vegetation colonizes in a series of stages. The final one is in dynamic equilibrium with its climatic environment and hence is known as climatic climax vegetation. In the UK this is temperate deciduous forest.

As succession develops, there are increases in vegetation cover, soil depth and humus content, soil acidity, moisture content and sand stability.

Importance of quantification of biodiversity

important to conservation efforts - areas with high biodiversity may be identified, explored, appropriate conservation may be put in place

Distinguish between biodiversity, diversity of species, habitat diversity and genetic diversity.

​Biodiversity: The amount of biological or living diversity per unit area. It includes the concepts of species diversity, habitat diversity and genetic diversity.

species diversity: the range of species living in a specified area. An area may have a high density of wildlife, but if they are all from a few different species then it would have a low species diversity.

habitat diversity: the range of different habitats in an ecosystem (jungle or forest ecosystems are likely to have a higher habitat diversity than desert or tundra ecosystems)

genetic diversity: the genetic range that is present in a population of a species. Species that have a small genetic diversity are more at risk of being wiped out by diseases. Selective breeding by humans to domesticate animals or grow plants with specific traits has reduced the gene pool in many species.

Comment on the relative values of biodiversity data.

biodiversity is difficult to quantify precisely, it is necessary to measure the abundance of all organisms over space and time:

- taxonomy (number of species)

- functional traits

- interactions among species (predation, parasitism, competition, and facilitation such as pollination).

Even more important would be to estimate turnover of biodiversity, not just point estimates in space or time

Discuss the usefulness of providing numerical values of species diversity to understanding the nature of biological communities and the conservation of biodiversity.

diversity indices: eg. the Simpson's index.

important to conservation efforts - areas of high biodiversity are identified, explored, and appropriate conservation put in place where possible.

areas with high biodiversity = hotspots.

- large numbers of endemic species (eg. Himalayas, Madagascar)

- measures of biodiversity are therefore essential in identifying areas that should be protected against damaging human activities.

Natural selection mechanism

1. within a population of one species, there is genetic diversity (=variation)

2. due to natural variation, some individuals will be fitter than others

3. fitter individuals have an advantage and will reproduce more successfully

4. the offspring of fitter individuals may inherit the genes that give that advantages

natural selection will contribute to the evolution of biodiversity over time

Use of sampling strategies

measure biotic and abiotic factors and their change in space, along an environmental gradient, over time, through succession, or before/after human impact

Distinguish the role of r and K selected species in succession.

r strategists: small, need low energy to make one individual, produces many offsprings, early maturation, short life, one-lifetime reproductive event

K strategists: large size, need high energy to make one individual, few offsprings produced, late maturation, long life, more than one reproductive events in life

Explain the general pattern of change in communities undergoing succession

The size of the organisms increases with trees, creating a more hospitable environment.

Energy flow becomes more complex as simple food chains become complex food webs.

Soil depth, humus, water-holding capacity, mineral content, and cycling all increase.

Biodiversity increases because more niches (lifestyle opportunities) appear and then falls as the climax community is reached.

NPP and GPP rise and then fall.

Productivity: Respiration ratio falls.

Discuss the link between ecosystem stability, succession, diversity, and human activity.

The latter the succession stage is, the more the ecosystem becomes stable (greater habitat, species and genetic diversity) and the more diverse it is, which might be disrupted by human activity that can prevent it from reaching its climax stage.

Discuss the factors that could lead to alternative stable states in an ecosystem.

Climatic factors

Soil properties

Random events

Species diversity

the number of species (richness) + their relative proportions (evenness)

Habitat diversity

range of different habitat in an ecosystem or biome

Genetic diversity

range of genetic material present in a population of a species

Diversity indices

to describe and compare communities; low diversity indicates pollution, eutrophication, recent colonisation of a site

Biodiversity

total diversity of living systems = species diversity + habitat diversity + genetic diversity

Speciation

formation of new species when populations of a species become isolated and evolve differently from other populations

Causes of isolation of populations

environmental changes forming barriers - mountain formation, changes in rivers, sea level change, climatic change, plate movements

surface of the Earth is dived into tectonic plates - led to creation of land bridges and physical barriers

Mass extinction causes

tectonic plate movements

super-vulcanic erruption

climatic changes (drought, ice ages)

meteorite impact

Explain how plate activity has influenced evolution and biodiversity.

it has isolated populations - causing them to interbreed and live under different environmental conditions, separation of gene pools (due to physical land barriers and bridges) lead to a greater biodiversity and evolution

Plate tectonics movements can change the nutrition available to animals and plants.

Large landforms such as placement of mountain ranges can actually influence the large-scale climate.

Methods of estimating the biomass and energy in trophic levels

measurement of dry mass, controlled combustion, extrapolation from samples

Abundance of non-motile organisms

quadrats

Evaluate sampling strategies.

Sampling Techniques

It is not possible to survey an entire area, so small areas called samples are taken, these are two methods used.

Quadrat sampling

Quadrats are more useful for comparing species in two different areas, and for practical purposes are used in ecosystems without tall vegetation - such as meadows or shores.

A problem is when counting plants, but they grow in clumps; this is overcome by calculating the density or the percentage of ground covered.

transect sampling

used to measure the change from one area to another

belt transect

two parallel lines are laid and the conditions between these measured.

Statistical Methods

standard deviation - measure of how spread out the data is.

Evaluate the methods to measure at least three abiotic factors in an ecosystem.

pH (pH meter), Temperature (thermometer), Light intensity (light meter), Salinity (salinity meter), Turbidity (secchi circle), Dissolved oxygen (oxygen meter)

Evaluate methods to investigate the change along an environmental gradient and the effect of a human impact in an ecosystem

(An environmental gradient is a gradual change in abiotic factors. Environmental gradients can be related to factors such as altitude, temperature, depth, ocean proximity and soil humidity)

Usually a transect is used, The simplest one is when a line of tape is layed down across the area wanted to be measured then to take samples of all the organisms touching the tape. Many transects should be taken to obtain quantitative data. A belt transect is used for bigger samples