Concepts and processes relating to ecology

Some definitions

Ecology how organisms interact with their environment

Ecosystem all the communities plus the physical factors of the environment in a given area and how they relate to each other

Environment all biotic and abiotic factors in an area that affect the organisms present

Biosphere all communities and physical factors in the world

There are two main factors to consider in the abiotic environment– Energy flow– Chemical recycling

Energy in the ecosystem

Plants capture energy from the sun– Done through photosynthesis– Captured in the chemical chlorophyll– light energy is used by chlorophyll to combine

carbon dioxide from air and water from roots– Oxygen is a waste product

Plants have manufactured all of the oxygen in the air

– Algae does same reaction in water

photosynthesis

Carbon dioxide + water

glucose+oxygen+water

sunlightchlorophyll

Flow of energy

Once photosynthesis has occurred the energy is locked in a chemical molecule and can be passed through a food chain

Note that plants do not produce glucose for the benefit of consumers – they produce glucose for themselves

Energy is released from glucose via process of respiration

Respiration

RESPIRATION IS NOT BREATHING.– Breathing is moving gas in and out of lungs– Respiration is combining oxygen and glucose to

release energy Glucose + oxygen carbon dioxide

+ water + energy (ATP adeno triphosphate) ATP is then changed into mechanical energy,

chemical energy, active transport, electrical energy or bioluminescence

enzymes

Eventually energy gets turned to heat, and is lost to space

Two main energy flows– Grazing relationship

Grass herbivores carnivores

– Organic detritus relationship Dead parts and wastes of organisms broken down by

bacteria and fungi

Only 10% of energy passed on, so most food chains limited to four links– Lettuce snail bird cat

Trophic or feeding levels

Trophic levels determine energy flow and chemical recycling

Note to TJ – draw it on the board!

Food webs and food chains

A food chain is straight. No branchesGrass sheep people

Food webs are more complex

Energy pyramids

Obviously, there is more energy in the lower parts of a food chain. So you can draw how much energy there is in each trophic level

The pyramid can be numbers or as biomass

How humans affect food chains and webs

Biological concentration– Chemicals concentrate in the fat of higher

consumers eg ddt in raptors Removing one part of food chain

– Farming, fishing, forestry– The lower down the food chain the more animals

are affected Introducing exotic species

– Weasels, rabbits, possums, deer, etc

Removal of too much of an organism– Makes ecosystems unstable– Remove too many of reproductive age animal,

and then there are no babies

Nutrient Recycling

You need to know – Water– Carbon– Nitrogen– Calcium/phosphorous (least important)

Water

Sea holds 98.7% of world’s water Two main processes make water go up

– Evaporation– Transpiration

1. Water evaporates off sea and land and transpires off plants

2. Water rises to cold atmosphere and condenses

3. Clouds move round and drop precipitate

4. Water passes into underground waterways or rivers back to the sea

Carbon cycle

Carbon is the molecule we are basically made from. It is part of fats, proteins and carbohydrates.

Most carbon is in the sea.(98% dissolved in sea). Lots of carbon is locked up in limestone. Fossil fuels are largely carbon. Air/atmospheric is 0.036% CO2

How humans affect the cycle

Burn the trees = more CO2 released

Burn the fossil fuel = more CO2 released

Plant the trees = more CO2 locked up

Note that CO2 acts like a blanket and traps the sun’s energy on the planet, so we warm up

Nitrogen cycle

Used to make proteins, which include muscles and enzymes, hormones and haemoglobin and antibodies

Air is 78% nitrogen. We can’t actually use it Nitrate ions are biologically active and

dissolve in soil water Nitrogen fixing is turning nitrogen gas into

nitrate

Other cycles

Calcium and phosphorous are other important nutrients that are recycled.

Calcium is used in bones and in cell membranes

Phosphorous needed to make DNA ATP and bones/teeth

Zoo breeding programs

Some animals unable to breed successfully in the wild– Insufficient habitat– Insufficient genetic diversity

Ecology management

People change the ecology – they add extra nutrients like nitrogen, they remove the trees, they may hunt for some animal in the food chain

Sometimes people try to improve an ecology back to its ‘natural’ state

They do – Pest management– Put in reserves– Artificial breeding– Selective logging

Pest management

Biological control, which is adding more consumers to a food web eg you have too many aphids, so you put more ladybirds into the system

Marine reserves

An area set aside so no-one fishes there Lots of fish breed there, and outside reserve areas

end up with increased fish stock Reserves are good for

– Making things look pretty– More fish in the sea– Endangered fish have a place to live– Science can see how many fish should be in the sea

Selective logging

Sometimes you take out particular trees eg big rimu by helicopter– Stops all the rest of the forest being destroyed

Compared to clear felling – a good thing