Ecology

sample meaning

a smaller part of something that gives an idea of the whole

Random sampling can be used to…

 give information about the population as a whole

Systematic sampling can be used to…

investigate the effect of a factor (such as light or water availability)

random sampling example

Estimating the total population in an area

Random sampling involves placing a quadrat in random spots in the field before calculating a mean. 

Systematic Sampling method

This method also uses quadrats but instead of the quadrats being placed randomly, the quadrats are placed at regular intervals (e.g. every metre) along a belt transect.

• place tape from one end of the field to the other

• place a quadrat at regular intervals along the transect line

• count the number of … in the quadrat at each interval

This allows us to determine if there is a pattern.

Why would throwing the quadrat not produce random locations for the quadrat to be placed at?

Throwing quadrats would not produce random locations because the thrower would not be able to reach beyond their throwing limit and they would be unlikely to throw very close to them.

random sampling method

1. Find a field and measure the length and breadth of it.

2. Use these to calculate the area of the field.

3. Randomly place the quadrat.

4. Count how many daisies are in the quadrat.

5. Calculate how many quadrats could fit in the area, then multiply the number of daisies in the quadrat by this number.

3 categories of environmental change & examples

Environmental changes can be seasonal, geographic or caused by human interaction.

Examples of environmental changes are temperature, availability of water and composition of atmospheric gases (including carbon dioxide).

environmental change: Human Interaction

Levels of carbon dioxide and methane in the atmosphere are increasing 

This is mainly due to the burning of fossil fuels

Deforestation also means that there are fewer trees to absorb carbon dioxide for photosynthesis 

These greenhouse gases contribute to global warming

There are severe biological consequences to global warming

Consequences of Global Warming

• Melting polar ice caps

• Rising sea levels

• Flooding

• Extreme weather patterns

Temperature increase can result in habitat loss (e.g. polar ice caps). This reduces the territory of a species, affecting their ability to find food, shelter and mates.

Less water availability, such as through droughts, can affect plant growth. Less water can result in a lower rate of photosynthesis. This reduces the amount of biomass available for the rest of the food chain

The biological consequences of global warming are:

• Loss of habitats 

• changing breeding patterns
  
  

• changing migratory patterns
  
  

These biological consequences cause changes to the biodiversity of an area. 

Temperature change can affect the migration patterns of birds. If birds arrive to their breeding grounds later or earlier, this can affect their ability to find food, shelter and breeding mates.

Explain the effect of changing temperature on bird migration patterns.

• Changing temperatures may signal to birds to arrive at their breeding ground earlier or later than usual

• This means they may find it difficult to find food, shelter or mates

Explain the effect of droughts (periods of low rainfall) on plant growth.

• Droughts cause there to be less water available for plants

• This means that the rate of photosynthesis will be lower

• (This means that they will produce less biomass for the rest of a food chain)

Explain the effect of increasing temperature on habitats in polar regions.

• Increasing temperatures are causing ice caps to melt

• This means that habitats of polar animals are being destroyed

• This means that animals may struggle to find food, shelter or mates