T5 - On the Wild Side

What is a community?

Made up of different populations which live in the same environment or habitat. Species do not exist by themselves in their own isolated environment; they interact with other species, forming communities

What is an ecosystem?

A self regulatory system of all organisms living in a community (biotic) plus the physical environment (abiotic) that interact

What are characteristics of an ecosystem?

-Vary greatly in size and scale, can be very local e.g a rotting branch or large like an entire ocean

-Neighbouring ecosystems can be described separately or combined and described as one.

-Vary in complexity (no ecosystem is completely self-contained as organisms from one ecosystem can move to another)

What is a population?

-When a species is found in a habitat this is a population

-All of the individuals of one species living in a habitat

What is a niche?

-Each species in an ecosystem occupies its niche, which is the role of a species within its ecosystem or community.

-Will have ranges of abiotic factors to which the organism is adapted e.g temp, pH range an organism can tolerate

-Niches can be separated by time, location or behaviour and this is how similar organisms avoid competition in the same habitat

What happens if no interbreeding occurs?

The best adapted species (with the highest birth rate) will outcompete other species.

What is a habitat?

-The place where an organism lives

-Species are well adapted/suited to life on a particular habitat → can be large or small (microhabitats)

-The abundance of species in a habitat can be measured by size and species distribution within that habitat = exact location of a population within a habitat

What is the difference between species that are habitat specialists or generalists?

Specialists= they can only survive in a specific type of habitat

Generalists= Can survive in a range of habitats. More likely to invade and take over a new habitat (invasive species)

What happens when humans release new species into a habitat either accidentally or on purpose?

The species can disrupt the normal species interacting in a habitat and cause serious problems

What are abiotic factors?

-Non-living factors e.g temp, weather/climate, chemicals/pollution, pH of soil or water, light intensity, wavelength, humidity, O₂ or CO₂ concentration

What are biotic factors?

-Living factors that influence populations within their community and come about as a result of the activity of other organisms

-Competition, predation, disease, food availability and mutualism

Can two species fill the same niche within a habitat?

No - if this ever happens the two species will be in direct competition within each other for resources and one of the two species will out compete the other, causing it to die out in that particular habitat

What is the abundance within a habitat?

-The niche filled by a species determines its abundance within a habitat

-Defined as the number of individuals of a particular species living in a habitat

-If 2 species occupy a similar niche within a habitat, they will be competing with each other so their population will be smaller, and their abundance will be lower

What is the abundance and distribution of species within a habitat determined by?

Determined by a combination of biotic and abiotic factors. The niche filled by a species determines its distribution

Why can species only survive in habitats to which they are well adapted?

If they are not well adapted to a habitats biotic and abiotic factors then they will move to a more suitable habitat and their distribution will change

What is succession?

The process of ecosystem change over time is known as succession. It is when communities colonise an ecosystem change the ecosystem and are then replaced over time by communities. There is typically an increase in diversity over time

What are pioneer species?

-First species to occupy a new habitat, they are well adapted to the harsh environment e.g bare rock and start the new community

-Often have rapid reproductive strategies, enabling them to quickly occupy an uninhabited area

-Many of them have an asexual stage to their reproduction

What is a climax community?

-The stable community that is reached beyond which no further succession occurs.

-It is made up of the best competitors

What is primary succession?

-The process that occurs when newly formed or newly imported land is inhabited by an increasing number of species

-Newly formed land can be created e.g by the magma from erupting volcanoes or forming new rock surfaces or new rocky islands in the sea

-Newly exposed land can form e.g by a landslide that exposes bare rock, a glacier that retreats to reveal bare rock

What is colonisation?

-The arrival of organisms on bare land is known as colonisation and the bare land is said to be colonised

-Often the new colonising species then change the environment in such a way that it becomes less suitable for the previous species

How does primary succession occur?

-Occurs when the starting point is a bare ecosystem such as bare rock.

-The pioneer species are usually lichen, moss or algae

-They are able to survive in harsh environment

-As they live, die and decompose organic material builds up in the environment and begin to form humus/soil (abiotic conditions change)

-Pioneer species have to be well adapted to harsh conditions eg massive temp fluctuations

What happens after pioneer species are well adapted to harsh conditions during primary succession?

-Over several generations soil begins to form. The soil can be used by a more diverse range of plants with deeper root systems

-Gradually larger and larger plants occupy the ecosystem along with a diversity of animals

-Over time, the harshness of the environment decreases, the biodiversity and levels of competition increases

What happens after the harshness of the environment decreases and the biodiversity and levels of competition increases during primary succession?

-A climax community is reached and species present do not change unless the environment changes in some way

-This is the final community that is formed, containing all the different plant and animal species that have now colonised the land

-The type of climax community that forms depends on the location of the original bare land. CC is not always the most biodiverse stage of succession, but its a stable community

What does succession do to change the biotic and abiotic conditions?

At each stage of succession, the newly arriving species change the local environment so that is becomes more suitable for other species that have yet colonised the new land

Give of an example of how pioneer species go through primary succession

-Pioneer species such as lichens help to slowly break apart the top surface of bare rock

-This fragmented rock, along with the dead organic matter left behind when the lichens die and are broken down, forms a basic soil

Also, species such as grasses grow roots that stabilise the soil, enabling it to hold more moisture and nutrients

What happens if pioneer species may not be found in a climax community?

They will be outcompeted for light and other resources by the species that arrive during the later stages of succession. Pioneer species are adapted for harsh conditions BUT are poor competitors

What happens as soil deepens and trees are able to grow?

They may block out the light to shrubs and other smaller plants, out-competing them and causing them to die

What is secondary succession?

-Occurs when the starting point is bare,existing soil (e.g following a fire, flood or human intervention)

-This type of succession proceeds in the same way as primary succession EXCEPT that the pioneer species tend to be grasses and fast growing plants and it occurs faster as soil is already there

How do human activities prevent or interrupt the process of succession?

By stopping a climax community from developing e.g regular moving prevents woody plants from establishing themselves in a lawn or the grazing of livestock prevent new plants from establishing

What is a plagioclimax?

Climax communities that are developed as a result of human intervention. These communities are stable but would not have occurred without human intervention e.g healthland

What is an example of secondary succession forming an oak woodland?

-Bare soil is colonised by grasses and pioneer plants

-Grasses begin to predominate with time

-Shrubs replace the grasses

-Fast growing trees appear

-Slow growing oaks create the climax community

What is productivity?

Described as the rate of generation of biomass in an ecosystem

What are producers?

They (plants) convert light energy into chemical energy stored in biological molecules during photosynthesis

What is primary productivity?

The rate at which producers convert light energy into chemical energy

What is gross primary productivity?

The total amount of chemical energy converted from light energy by plants in a given area or the rate at which chemical energy is converted in carbohydrates during photosynthesis.

Expressed as units of energy per unit per area per year kJm^-2 y^-1

Why is all of the light energy from the sun not converted to chemical energy by plants?

This is because it is: Reflected, Transmitted through the leaf, is the wrong wavelength, hits part of the plant that cannot photosynthesise

Why do limiting factors influence the rate of photosynthesis?

This is because not all of the energy arriving at the plant surface can be used to make organic molecules, even if it is absorbed by the photosynthetic pigments

How do you calculate NPP?

Gross Primary Productivity - Respiration

What is the link between NPP, GPP and Respiration?

GPP is the rate of energy incorporated into biomass in plants, but respiratory losses (in the form of heat) mean that only NPP is available as the source of energy for animals that consume plants

Why is NPP important?

-Represents the energy that is available to organisms at higher trophic levels in the ecosystem such as primary consumers and decomposers

-In area it is expressed as: Jm^-2 yr^-1

-In vol : Jm^-3 yr^-1 (to calc NPP in aquatic habitat)

What is 90% of the total energy stored in glucose during photosynthesis released from glucose used to create?

-To create ATP for the plant during respiration. 90% of the energy originally converted by the plant will be stored in glucose during photosynthesis. Therefore it will not be stored as new plant biomass and will not be available to be passed onto herbivores, known as primary consumers

What does the productivity of an ecosystem depend on?

-How much energy is captured by the producers

-How much is transferred to the higher trophic levels

What happens to the chemical energy that is stored in plant biomass that is passed to primary consumers?

During photosynthesis organisms such as plants covert light energy into chemical energy stored in biological molecules. The chemical energy stored in plant biomass is passed to PC when plant is ingested.

What are primary consumers?

-They are animals that eat plant material and can be herbivores or omnivores

-They digest plant tissues and use the stored chemical energy either to fuel respiration or to build up biomass → later means that the stored chemical energy is transferred to the tissues of the PC

What happens when a primary consumer is ingested by a secondary consumer?

-The stored chemical energy passes to the secondary consumer and up the food chain.

-And then when an organism dies the chemical energy stored in its tissues passes to decomposers e.g bacteria and fungi

What is a trophic level?

Refers to the stage in the food chain and in a food chain the arrows represent the transfer of energy from one trophic level to the next by the process of feeding

Why is the transfer of energy in a food chain not 100% efficient?

Energy is lost to the environment at every trophic level

Why is only 2-10% of the energy available to the consumer is stored in their tissues?

When a consumer ingest another organism not all the chemical energy in the consumers food is transferred to the consumers biomass because 90% is lost to the environment

Why is around 90% of energy lost to the environment?

-Not every part of the food organism is eaten

-Consumers are not able to digest all of the food they ingest as some ingested food remains in faeces

-Energy is lost to the environment in the form of heat when consumer

-Energy is lost to the environment when organisms excrete the waste products of metabolism

-The energy that is left after these losses is available to the consumer to fuel their life functions (including being stored in biomass during growth)

What is net productivity?

The rate at which energy is converted into biomass in the body of a consumer

Why is the transfer from producer to primary consumers not very efficent?

-Food chains only support 4/5 trophic levels because their net production is very low at the top of the food chain, so apex predators must eat large amounts of prey to consume enough energy

-BUT as you move up the food chain energy transfer becomes more efficient bc plants contain more indigestible matter than animals

How do you calculate the efficiency of energy transfer?

NP of trophic level / NP of previous trophic level x100

What is climate change?

Climate change is when the weather conditions in a region change significantly over a long period of time

What is climate change caused by?

-Changes in the climate have occurred frequently throughout Earths history due to changes in factors e.g atmospheric gas concentrations and volcanic activity

-Changes that have occurred since the mid-1800s are thought to be the result of human activities

-Changes to global climate patterns result in alterations in local weather patters e.g rainfall and temperatures

What is the atmosphere?

-A thin layer of gases extending 100km above the earth surface and held in place by gravity.

-Has been predicted that without an atmosphere, the temp of the Earth’s surface would fluctuate between every hot days → chilly nights (being 40C or lower)

-Important role in helping the earths average temp stable and suitable for living organisms

What is the greenhouse effect?

When the sun radiates energy (as visible light) → the earth absorbs some of this energy → earth warms up + radiates energy back into space as infrared radiation → some of the energy that is radiated by earth surface is absorbed by gases in the atmosphere → warming it → gases in the atmosphere that stop infrared radiation from escaping greenhouse cases → create the greenhouse effect, keeping earth warm

What is the enhanced greenhouse effect?

Idea that the activities of humans are inc. levels of CO₂ and other greenhouse gases in atmosphere → leads to inc. global temp + climate change → inc. rates of atmospheric warming → humans responsible for its anthropogenic climate change

What are examples of greenhouse gases?

-CO₂ , methane, nitrous oxide, water vapour, halocarbons

-Conc of CO₂ and methane has significantly increased due to human activity

What are the influences of concentration of greenhouse gases?

-Industrial activity = plants + factories prod. lots of smoke that contain CO₂

-Transport = train, cars, ships emit gases -CO₂ incl.

-Cattle = cows + other species prod. a lot of methane while grazing. Its prod. in large quantities as farmers usually have big herds conc. in one place

-Deforestation = to have fields to plant crops+ space for houses+ wood to build things, acres of forests are destroyed.

-Farming = some crops e.g rice lead to methane release

Why are trees the main natural tool that helps lower CO₂ content?

They take up CO2 and produce O2 instead so O2 conc. falls and CO2 conc. rises

What is the effect of CO2 on the atmosphere?

-Levels have fluctuated throughout earths history e.g volcanic eruptions + weathering of limestone rocks

-Fossil fuel combustion releases CO2 → a clear correlation can be seen between inc. levels of CO2 since industrial revolution + inc global temp

-CO2 is also released when natural stores (carbon sinks e.g trees, soils, peatbogs, oceans) of carbon are damaged or destroyed by human activities

What is methane?

-The main component of natural gas fossil fuel → can be produced by naturally occurring processes

-Released from the guts of cattle, landfill sites, extraction of fossil fuels from underground and release of methane from natural stores

What does evidence show about the change in the earths climate and effect on organisms?

-Shows that over the past few hundred years, Earths climate has changed considerably

-We are in a period of global warming that influences not only temp but rainfall and wind patterns

-Organisms have adapted over time bc of abiotic conditions in their environment + ability to survive and reproduce

-Affected the ability of organisms to survive in the new conditions → long term survival of many species is threatened

What does the effects of climate change (changing rainfall patterns+changes in seasonal cycles) lead to?

-Changes to development in plants changing distribution of species and altered development of life cycles

What is the effect of climate change to changes in species distribution?

-Climate change may cause a shift in plant and animal distribution.

-Some may benefit and dominate while others may be lost from the community.

-Species may colonise new areas, out-competing existing species, making them extinct.

-Other factors e.g change in rainfall pattern, soil moisture, winds and rising sea levels

What is the effect of climate change to changes in development in plants?

-A few degrees of warming can lead to an increase in temperature crop yields esp if temp is already a limiting factor

-In the tropics, many crops are at the limit of their temp tolerance therefore even a small rise in temp could decrease yield

-Inc in CO2 could inc. yield but only to a certain point as other factors would start to limit the rate

What is the effect of climate change to changes in development in animals?

-Animals are likely to be affected if temp acts as an environmental cue or trigger for their development or behaviour

-In reptiles, temp affects the sex as global warming could cause a change in sex ratios of these species

What is the effect of climate change to changes in life cycles?

-Development + life cycles are determined by biological processes within organisms organs, tissues and cells

-There in turn are due to physiological processes dependent on proteins and enzyme so therefore are sensitive to the temp changes

-Some species are dependent on rainfall-related conditions for seed production and germination

How are changes in climate already seen in many parts of the world?

-Warming climates cause animals to move towards the poles or to higher altitudes (decreased biodiversity)

-Water availability is changing (some species may not be able to survive due to lack in rainfall, some may migrate to a new habitat or may become extinct)

-Polar ice and glaciers are retreating → may affect the water supplies of many people and surrounding wildlife

-Sea levels have been rising → putting more people and animals at risk of being flooded out of their homes → due to expansion of warmer weather due to melting polar ice

What are the evidences for the causes of climate change?

-Temp records

-Pollen from peat bogs

-Dendrochronology

-Ice cores

What is the purpose of temp records?

-Temp recorded with scientific equipment. Goes back hundreds of years. Change in temp can be recorded/monitored over time

-Thermometers can be used to measure air temp

-Thermometer records from diff places can be extended over periods of time and can be put together to show average global temp range over time

-The time period since mid 1800s corresponds with the time during which humans have been burning fossil fuels and therefore releasing CO2 into atmosphere

What are the adv and limits of temp records?

Adv :

-Scientific, not anecdotal, temp is recorded accurately, either line of best fit or curve of best fit can be used to identify patterns within general trends

Limits:

-Records go back 2-3 hundred yrs (no info about climate before that)

What is the purpose of pollen from peat bogs?

-Anaerobic and acidic conditions prevent plant insect material from decaying fully (conditions not suitable for decomposers and detritivores so materials preserved)

-Depth of preserved material indicated time, carbon-dating can determine age more accurately

-Nature and species indicates the climate as can compare to known preferred conditions/growth req e.g tree pollen (outer layer resists decay,adaptation)

How is peat formed?

-Under waterlogged and acidic conditions partly decomposed dead plant matter accumulates + becomes compacted under its own weight over time, which forms peat

-Peat builds up in layers, meaning that layers of peat at the top of a bog are recently formed

-Peat becomes older as you dig down into a bog.

How are peat cores taken from a bog?

-Peat cores can be taken from a bog and the layers can be analysed to assess the pollen grains that have become trapped in the peat

-So plant species that was growing around the bog at diff points in time can be identified

What are adv and limits of pollen from peat bogs?

Adv:

-Data goes back as far as 12,000 yrs ago

-Provides info on soil conditions such as pH, moisture as we know which conditions certain tree species prefer

Limits:

-No info before 12,000 yrs

-Temp is not determined accurately

-Other factors (not just climate) might affect species/seed abundance

-Age is not determined accurately compared to temp record or dendrochronology

What is dendrochronology?

-A new layer of xylem vessels is produced by trees every year. Vessels prod. in spring are larger and those produced in summer are narrower

-This prod. an identifiable annual pattern in the cross section of a tree trunk.

-Wider rings indicate better growth conditions (warmer,wetter) Thinner rings = poorer conditions

-The position of the ring is related to distance in time (nearer to outside, nearer to present)

What are adv and limits of dendrochronology?

Adv:

-Ring position can be used to accurately determine the specific range of each ring. Trees can be hundreds of yrs old

Limits:

-While time data is accurate, the climate condition data is not accurate, as not measured directly with specific equipment

-Other factors not just climate might not affect ring size

What are ice cores as evidence for climate change?

-When atmospheric CO2 levels have fluctuated throughout Earth’s history due to volcanic eruptions + weathering of limestone rocks

-Scientists know this from having analysed the gas composition of bubbles formed in ancient ice cores

-Ice is deposited as water freezes over time, so the deeper into the ice you go, the older it is

Why does correlation does not equal causation due to the CO2 released by human activities?

BC there is strong evidence that CO2 released by human activities since the industrial revolution is causing increasing global temperatures as correlation does not equal causation

Why is CO2 an important factor in predicting future climate change?

-Enhanced global warming due to rising CO2 conc is one of the factors to affect future climate

-It is one that is changing at present and one that humans can influence

What do scientists use comp. models for predicting climate change?

They use it to study the interaction of many factors in an attempt to make predictions about likely climate change

Why is extrapolation used to predict future climate change?

-Using a series of known experimental data to identify pattern, The pattern is extended into the past or future to predict/estimate info

-When we extrapolate we make assumptions such as: we have enough data to identify trends/patterns and these trends/patterns will continue unchanged into the future

What are other factors that affect climate change?

-Other greenhouse gases

-Aerosols

-Degree of reflection from Earth’s surface not covered in ice or snow, cloud cover, changes in solar radiation

What causes models that predict climate change to be inaccurate?

-Limited data on which to base the model

-Limited knowledge of how climate system works

-Limitations in computing resources

-Not knowing all the factors that affect climate

-Changing trends

What can global warming predictions be used to?

-Plan for the future e.g building flood defences, funding scientific research into climate change technologies

-Encourage people to change their activities e.g decrease in the burning of fossil fuels, inc. the use of renewable energy sources e.g solar and wind energy, and reduce meat consumption

Why is climate change seen as controversial?

-Scientists cannot prove theories only disprove them. What is left is the best working theory, until evidence is found to disprove that

-Our data on the climate of the earth is incomplete, how much of the CO2 in the atmosphere due to burning of fossil fuels? → only an estimate

-Bc there is reasonable doubt in the theory, alternative reasonable views can be held, which leads to controversy.

-Credibility of views (influence of personal, political +economic considerations)

What are the ethical arguments when considering the issue of global warming?

-Individuals have a right to choose whether we use energy from fossil fuels or not

-Developing nations should have the chance to go through the industrialisation process (impacts quality of life)

-The environment must be preserved for future generations

Why is it difficult to make predictions about exact future climate conditions?

-Climate change is not expected to be linear in effect- which makes it difficult.

-Among the scientific community they agree that inc. conc of greenhouse gases cause global warming and human activities are the direct cause

What does the use of extrapolation to model climate change show?

Shows that the consequences of global warming could be extremely serious for humans and global biodiversity if we continue with current human activities

Why is it important to limit the consequences of global warming?

To limit the consequences of global warming it is essential to reduce carbon emissions and increase the rate at which carbon is removed from the atmosphere

How do we reduce carbon emissions?

By limiting the rate at which fossil fuels are burned This is challenging bc many of our daily activities depend on the burning of fossil fuels to release energy (transport of people+goods , electricity generation, food production)

What are the current ways of reducing carbon emissions?

-Burning biofuels instead of fossil fuels

-The use of other renewable energy resources

How can we help maintain the CO2 balance and manage the conflict between human needs and conservation?

-By using sustainable resources such as biofuels and reforestation

What is a biofuel with examples?

It is any source of energy produced, directly and indirectly in animals by recent photosynthesis. This provides a renewable energy source and its carbon neutral e.g bioethanol, biodiesel (veg oil), biogas (methane), wood, straw and dried chicken litter

What is the difference of first-generation biofuel and second-generation biofuels?

First gen= Fuels made directly from edible biomass

Second gen= Non-food parts of crops that contain the polymers cellulose and lignin

What are adv of biofuels?

-Carbon neutral

-No net increase in CO2 since the CO2 being released has been recently taken up by the plant due to the rising prices of petrol and diesel

-Biofuels are looking to be more cost effective

-Can also use waste products from human sewage (methane) as a biofuel

What are disadv of biofuels?

-Transportation: from where they are cut down to where they are needed→ req. the use of trucks which use fossil fuels (petrol) → net increase of CO2

-Not all parts of the plant are used (some left to burn →releases CO2→ leads to net increase→ burning fuel releases CO2→ net increase

-Deforestation (release of CO2)

-Land could be grown for food crops instead of biofuels → food shortage → inc in food prices

-Limited space to grow biofuel crops → destruction of habitat to make room for biofuel growth → could be endangered animals → but once habitat is lost its hard to restore it

What can methane produced from the anaerobic fermentation of human sewage be used for?

Used to generate enough electricity to make a modern sewage treatment plant energy self-sufficient. Methane can be produced from domestic waste and animal slurry → this methane is referred to as biogas→ when burned it is CO2 neutral

What is reforestation?

-Planting of trees in areas where there has historically been tree cover. In newly planted forest, all the trees are young and growing rapidly, turning CO2 into wood

-Very little old wood and little decay, so respiration is less than photosynthesis → system is a net absorber of CO2

-As plantation gets older → system will move towards a balance between photosynthesis + respiration → no longer will be a net absorber → becomes a carbon locked up in biomass