Although energy is essential for life, organisms need much more

Over 95% of most living organisms are made up of just 4 elements1. Oxygen2. Carbon3. Hydrogen4. Nitrogen

These elements must be available in a form so organisms can take them in for cellular functions

Matter flows through an ecosystem differently than energy◦ Instead of a one way flow like energy, matter is

recycled within and between ecosystems

Biogeochemical Cycles – the passing of elements, chemical compounds and other forms of matter from one organism to another from part of the biosphere to another◦ Connects biological, chemical and geological

aspects of the biosphere

When an organism uses energy, the amount of energy remaining to the next trophic level is reduced (remember the energy pyramids…)

Unlike energy, matter is not used up, but transformed in the biosphere◦ Matter can be assembled as tissue or passed as

waste◦ Ex) plant takes in CO2 and performs photosynthesis,

plant releases O2, we inhale, we exhale CO2 (and the process goes on)

Living things require water to survive

Where does the water come from?

The water cycle shows how water moves between bodies of water, air and land

1. Turning water from liquid to a gas◦ Evaporation – the process by which water

changes from a liquid to a gas◦ Transpiration – the evaporation of water from

the leaves of plants

2. Turning water back into a liquid◦ Condensation – the formation of clouds◦ Precipitation – when water returns to the

earth in some form (rain, snow, sleet or hail)

These 2 steps happen over and over again

Nutrients – all the chemical substances that an organism needs to sustain life◦ Producers obtain them from sunlight or

chemical bonds of inorganic compounds◦ Consumers obtain them by eating other

organisms

Every living organism needs nutrients to build tissues and carry out essential life functions

Like water, nutrients are passed between organisms and the environment through biogeochemical cycles

How does carbon move through the environment1. Biological Processes –

photosynthesis, respiration

2. Geochemical Processes – erosion, volcanos

3. Biogeochemical Processes – decomposition (which makes fossil fuels)

4. Human Activities – mining, cutting forests, burning wood and fossil fuels

All organisms require nitrogen to make amino acids and build proteins

Nitrogen Fixation – the ability to convert nitrogen gas into usable nitrogen (nitrates) for other organisms◦ Done by bacteria that live on the roots of legumes

(beans)

Denitrification – the ability to convert nitrates (usable nitrogen) into nitrogen gas◦ Done by decomposers and return nitrogen to the

atmosphere

Phosphorus is essential to living organisms to make up molecules like DNA and RNA

it does not enter the atmosphere like C, O and N◦ remains mostly on land in rock and soil minerals or

in ocean sediment

Phosphorus is contained in rocks and sediment and is released as they wear down and can be dissolved into water◦ Some phosphorus can be washed onto land and

seep into soil where it then cycles between producers and consumers

Ecologists are interested in primary productivity of an ecosystem◦ The rate at which organic matter is created by

producers

If a nutrient is in short supply in an ecosystem, it could limit an organisms growth◦ Limiting Nutrient – a substance within an

ecosystem that is scarce or cycles very slowly◦ Can have adverse effects in an ecosystem if not

corrected ex. Placing fertilizer on fields to enhance crop growth