Ecology in the local environment

Question 1

What are ecosystems, habitats, communites and populations?

Answer 1

• An ecosytem, such as a garden, is made up of all the plants and animals living there and their surroundings. Where a plant or animal lives is its habitat.
• All animals and plants living in the garden make up the community. The number of a particular plant or animal present in the community is called its population.

Question 2

Natural vs Artificial Ecosystems

Answer 2

• Natural ecosystems, such as native woodland and lakes, have a large variety of plants and animals living there - this means it has good diversity.
• Artificial ecosystems, such as forestry plantations and fish farms have poor biodiversity.

Question 3

What happens in Artificial Ecosystems?

Answer 3

In artificial ecosystems, humans deliberately keep and protect only one species (such as salmon in a fish farm) and remove any other organisms that would compete with it and lower the yield. This does not happen in a natural ecosystem.

Question 4

How can the distribution of organisms be worked out?

Answer 4

The distribution of organisms can be mapped using a transect line. A long length of string is laid across an area such as a path or sea shore.At regular intervals the organisms in a square frame called a quadrant can be counted for animals or assessed for percentage cover for plants.

The data can be displayed as a kite diagram.

Question 5

What can a transect line show?

Answer 5

A transect line can show zonation in the distribution of organisms. Changes in abiotic factors such as exposure on the seashore or trampling near a footpath, cause zonation.

Question 6

What is proof of animal and plant interdependence?

Answer 6

Food chains and food webs show that plants and animals are interdependent, with energy being transferred from one organism to another. The exchange of gases in photosynthesis and respiration ensures an overall balance of these gases. An ecosystem is therefore self-supporting in all factors apart from having to have the Sun as an energy source

Question 7

Estimating population size

Answer 7

• Population size can be estimated by obtaining data from a small sample and scaling up. For example a 1 m² can be scaled up to 100 m².
• The bigger the quadrat the more accurate the estimation.
• Capture-recapture method can also be used:
• Population = no. in 1st sample x no. in 2nd sample/ no. in 2nd sample previously marked

Question 8

Using a capture-recapture method assumes:

Answer 8

• There are no deaths or reproduction and no movement of animals into and out of the area.
• Identical sampling methods are used for both samples.
• The markings do not affect the survival of the organism.