Biology 3A – Ecosystems – background. Terminology Pyramids Food chains Food webs Field work Sustainability Diversity Flexibility Matter cycles Energy.

Biology 3A – Ecosystems – background

Terminology

Pyramids Food chainsFood webs

Field work

SustainabilityDiversityFlexibility

Matter cycles Energy flows

InterdependenceRelationships

Global issues

Human impact

ConservationManagement

Applications &implications

Key concepts

Tools

Ecosystem concepts you need to be able to use

What you need to be able to discuss for 3A

What is ecology?

Ecological systemsBiosphere

Atmosphere

Lithosphere

Hydrosphere

Ecosphere

Biodiversity

Biodiversity = many living things• ecosystem biodiversity – a range of

different habitats and complex ecosystems are available around the world or within an area

• species biodiversity – different species exist within each ecosystem

• genetic biodiversity – variations exist within a species within an ecosystem

Ecosystems

HabitatParticular area in which a population lives

Abiotic factor Non living factors eg temperature, rainfall

PopulationAll the organisms from one species in an ecosystem

CommunityAll the organisms in an ecosystem

Environment All the abiotic factors

Biotic factorLiving factors eg predation, competition

Ecosystem is a term that describes ecological systems consisting of interacting organisms and their physical environment

Biomes

Ecosystems with similar abiotic factors

Biomes 2 Canada

AustraliaDry arid Temperate forest Temperate reef

NicheDescription of an organism’s role and or location within an ecosystem

Eg the fox can be described as 2nd order consumer or forest floor dweller

Ecological termsAutotroph makes own food (either by photosynthesis or chemosynthesis) = producerHeterotroph eats other organismsProducer makes own food (either by photosynthesis or chemosynthesis) = autotrophConsumer eats other organismsDecomposer feeds of wastes or dead animals = detrivoreDetrivore feeds of wastes or dead animals = decomposerDetritus wastes or dead matterFirst order consumer eats producersSecond order consumer eats 1st order consumers

Respiration manufacture of energy by burning organic compounds eg glucosePhotosynthesismanufacture of organic compounds eg glucose using the energy of the sunChemical energyEnergy gained from chemical reactions eg respirationThermal energyHeat energySolar energyEnergy from the sunTrophic level location on food chain eg producer

Matter and energy

• In most natural ecosystems, matter cycles and is re-used

• Energy flows and is lost

• At each trophic level most of the energy is lost in respiration

Food chains show energy movement

• Arrows show movement of energy• The direction of the arrow is from organism

being eaten to the organism doing the eating

Food webs show feeding relationships

• Arrows show movement of energy• The direction of the arrow is from organism being eaten

to the organism doing the eating

Energy flows in ecosystems

Energy available from previous level

Energy leaving as waste heat

Energy used for new growthRespiration

Energy lost in wastes

Measuring energy flowSun outputs ~ 40 000kJ per day

38 000kJ per day is reflected and not used

2 000kJ per dayis used by plants

Heat energy lost due to respiration

1200 kJ 220 kJ32 kJ

Energy used for growth and thus available to next level

320 kJ 40 kJ

480 kJ

60 kJ 8 kJ

548 kJEnergy in dead matter and wastes

Measuring energy flow

• Productivity - rate at which an ecosystem accumulates mass or energy – biomass/unit area/time period (eg kg/m2/day) or energy/unit area/time period (eg kJ/m2/day)

• Biomass – dry weight of organisms found in a trophic level - mass/unit area (eg kg/m2) or energy/unit area (eg kJ/m2)

• Gross primary productivity – how much solar energy is fixed as chemical energy by producers (ie measure of energy trapped by photosynthesis

• Net primary productivity – amount of energy available once respiration has occurred

Pyramids

• These show numbers of organisms, or energy/mass available at each trophic level

• The 4 types are numbers, size, biomass and productivity

Drawing pyramidsTrophic status

Organism Number of organisms

Size of organism Biomass (g Carbon/m2) New tissue produced (g/day)

Producer 1 5 m 150 6

1st order consumer

500 5mm 15 8

2nd order consumer

4 20 cm 1.5 0.3

3rd order consumer

40 1 mm 0.15 0.01

number

size

biomass

productivityproducer

1st order consumer

2nd order consumer

3rd order consumer

1st order consumer

1st order consumer

1st order consumer

producer

producer

producer

2nd order consumer

2nd order consumer

2nd order consumer3rd order consumer

3rd order consumer

3rd order consumer

<5000 mm

<500 mm

<50 mm

<5 mm

<1 mm

Types of ecosystem

• Natural – relatively unaffected by humans eg forest, reserves, parks

• Agricultural – farming ecosystems• Urban – human ecosystems eg towns and cities• Aquatic – ecosystems in water eg rivers, seas• Terrestrial –ecosystems found on land eg forests,

deserts

Measures of stability

• Stability ability to cope with change. The more stable an ecosystem, the better it can cope. Stable systems usually have high biodiversity, complexity and amount of recycling

• Biodiversity number of species present. The greater the number, the higher the biodiversity

• Complexity how many relationships can be seen, size of food web. The more complex the ecosystem the larger the food web, and the more relationships that can be seen

• Recycling amount of matter that is lost from the system. The greater the recycling, the less matter is lost to other ecosystem

Different ecosystemsCriteria Natural Agricultural Urban

Inputs Low – energy, water & nutrients

Migratory animals or flow from rivers or leeching from soil

High – energy & matter (+ possibly water – irrigation)

Stock & seedlings, fertilizers & pesticides

High – energy, water & matter

Raw materials and goods

Outputs Low – energy, water & nutrients

Migratory animals or flow from rivers or leeching from soil

High – energy & matter

Crops & animal products & wastes

High – energy & matter

Wastes & sewerage, manufactured goods

Ecological complexity• Biodiversity• Trophic levels• Stability• Recycling of matter

High

High

High (usually 5+)

High

High

Low

Low – 1 - 2 crops

Low (1- 2)

Low

Low - moderate

Very low

Very low

Low (1- 2)

Low

Low - none

Effects on neighbouring ecosystems

Low High – feral species, algal blooms, erosion, salinity, biological magnification

High – feral species, pollution, greenhouse, desertification, ozone depletion, algal blooms

Comparing natural, urban & agricultural ecosystems

Biotic

Biotic

Biotic

Abiotic

Abiotic

Abiotic

Natural ecosystem

AgriculturalUrban

HeatHeat

HeatSolar energy

Chemical energy Chemical energy

Recycling

Matter Matter

Feed, fertiliserpesticides

Seed, stock

Less recycling Very little recycling

Produce

Waste, produce

Heat, electricity

Wastes

Raw material,manufactured goods

Rubbish, seweragemanufactured goods