Ecology and the Environment

Population: all the individuals of a particular species within a defined area.

Community: a group of different populations living in the same area.

Habitat: the physical, chemical and biological environment in which an organism lives.

Ecosystem: a community of living things and the environment in which they live.

Using Quadrats:

Total Population - Simply count the number in the Quadrat.

Percentage Cover - The quadrat is divided into 100 squares and the percentage cover is simply the number of squares filled.

Percentage Frequency - Divided into 100 squares. Number of squares that has this thing.

Biodiversity: the variety of species found in an ecosystem.

Biotic - Alive

• Predators and Prey
• Producers
• Diseases
• Reproduction

Abiotic - Not Alive

• Natural Disaster and Rainfall
• Temperature
• Soil type (ph)
• Atmosphere
• Humidity
• Wind Speed

Food chains are used to show the relationships between species in a habitat. E.g.

Fox                     The Secondary Consumer (eats the Primary Consumer)

Rabbit                The Primary Consumer (eats the producer)

Grass                 The Primary Producer (all food chains start with this)

Each level in a food chain is called a Trophic Level

Biomass – the mass of the organic material an organism is made from (i.e. water doesn’t count!)

Pyramid of Energy Transfer - Gives an indication of the wasted energy.

Energy can be lost through:

• Respiration(through heat)
• Undigested/Egested Food
• Used in movement

The 4 Parts to the Nitrogen Cycle

• Decomposers – turn nitrogen in protein into ammonium (NH4+)
• Denitrifying Bacteria – turn ammonium (NH4+) into N2
• Nitrifying bacteria – turn ammonium (NH4+) into nitrate (NO3-)
• Nitrogen-fixing bacteria – turn N2 into ammonium (NH4+)

Acid Rain - SO2, CO2 and NOx (oxides of nitrogen) dissolve in rain to form Sulphuric Acid, Carbonic Acid and Nitric Acid. This falls as acid rain, which destroys soil, pollutes waterways and causes erosion.

Greenhouse Gases

Water Vapour - Naturally occuring.

CO2 - Released from burning fossil fuels.

NOx - Released from burning fossil fuels.

Methane - Agriculture especially Cows and rice fields.

CFCs - Used to be a coolant in friges and propellant, now banned because of its effects.

These Cause

• Polar ice cap melting and Sea levels rising and changes in rainfall
• Extinction of species(e.g. Polar bears)
• Changes in species distribution (e.g. Mosquitos)

Eutrophication:

1. Nitrate enters a waterway (sewage or fertilizer run-off)

2. Nitrate causes algal bloom (rapid growth)

3. Algae block out light for plants living on the waterway bed

4. These plants respire as they can’t photosynthesize

5. O2 levels fall

6. Fish die

7. Dead fish are decomposed by bacteria, which themselves

respire, using up more O2

8. pH levels fall as decomposition produces acids

9. Everything dies. Waterway is incapable of supporting life

Deforestation:

Cutting down trees and not replacing them is bad. It causes;

   Leaching of soil minerals

   Soil erosion (no roots holding soil together)

   Desertion (new deserts forming)

   Disturbance of the water cycle (less transpiration can lead to flooding and / or drought)

   Increase in CO2 levels

   Decrease in O2 production