Impact of environmental change - Higher
Temperature
As you climb up a mountain the temperature reduces. This reduction, together with other abioticNon-living elements of an ecosystem, such as climate, temperature, water, and soil type. and bioticLiving elements of an ecosystem, such as plants and animals. factors, determines what speciesA type of organism that is the basic unit of classification. Individuals of different species are not able to interbreed successfully. of plant are found at different elevations.
Example:
Two students set up a transect A line created, for instance, with a tape measure, along which sampling occurs. up a mountain. Every one hundred metres of altitude they recorded the number of different species found per quadrat. This is called species richness. They also recorded the temperature.
Their results are shown below.
| Height above sea level (m) | 400 | 500 | 600 | 700 | 800 | 900 | 1000 | 1100 | 1200 | 1300 |
| Temperature (°C) | 16.8 | 15.9 | 15.5 | 15.1 | 14.6 | 13.9 | 13.5 | 13 | 12.6 | 12.1 |
| Quadrat 1 | 7 | 5 | 6 | 4 | 3 | 4 | 2 | 1 | 1 | 1 |
| Quadrat 2 | 6 | 11 | 5 | 9 | 4 | 1 | 2 | 1 | 2 | 1 |
| Quadrat 3 | 5 | 7 | 8 | 11 | 3 | 2 | 1 | 1 | 1 | 0 |
| Quadrat 4 | 7 | 5 | 5 | 6 | 4 | 3 | 5 | 1 | 1 | 1 |
| Mean plants per quadrat | 6.3 | 7 | 6 | 7.5 | 3.5 | 2.5 | 2.5 | 1 | 1.25 | 0.8 |
| Height above sea level (m) |
|---|
| 400 |
| 500 |
| 600 |
| 700 |
| 800 |
| 900 |
| 1000 |
| 1100 |
| 1200 |
| 1300 |
| Temperature (°C) |
|---|
| 16.8 |
| 15.9 |
| 15.5 |
| 15.1 |
| 14.6 |
| 13.9 |
| 13.5 |
| 13 |
| 12.6 |
| 12.1 |
| Quadrat 1 |
|---|
| 7 |
| 5 |
| 6 |
| 4 |
| 3 |
| 4 |
| 2 |
| 1 |
| 1 |
| 1 |
| Quadrat 2 |
|---|
| 6 |
| 11 |
| 5 |
| 9 |
| 4 |
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| Quadrat 3 |
|---|
| 5 |
| 7 |
| 8 |
| 11 |
| 3 |
| 2 |
| 1 |
| 1 |
| 1 |
| 0 |
| Quadrat 4 |
|---|
| 7 |
| 5 |
| 5 |
| 6 |
| 4 |
| 3 |
| 5 |
| 1 |
| 1 |
| 1 |
| Mean plants per quadrat |
|---|
| 6.3 |
| 7 |
| 6 |
| 7.5 |
| 3.5 |
| 2.5 |
| 2.5 |
| 1 |
| 1.25 |
| 0.8 |
Question
What does this table of data show happened to temperature? Use numbers in your answer. [1 mark]
As the students climbed higher up the mountain the temperature decreased from 16.8°C at 400 metres to 12.1°C at 1300 metres (1 mark).
Question
What does this table of data show happened to the mean number of plants per quadrat? Use numbers in your answer. [2 marks]
At higher elevations above sea level the number of mean plants decreased (1 mark). At 400 meters it was at its maximum of 6.25 per quadrat and at the highest height of 1300 metres the fewest plants per quadrat were seen or altitude up to 700 metres appears to have no effect on the numbers of plants per quadrat but after this height there is a reduction in the number of plants at each altitude (1 mark).
Question
What conclusions can you draw from the height and number of plants? [1 mark]
As the height up the mountain increased, the number of plants per quadrat decreased (1 mark).
Question
What limitations might there be in drawing these conclusions? [4 marks]
The two students only recorded two abiotic factors (height and temperature) (1 mark). The recording of additional quadrats would allow them to be more confident in their conclusions (1 mark). We cannot say whether the decrease in plants per quadrat was caused by the height, temperature or some other factor such as moisture and light (1 mark). Without further investigation, such as sampling at a different site with similar altitude but different temperatures, we can only say that that they are linked (1 mark).
Availability of water
All life on Earth needs water. Too much and some species will drown or rot. Too little and all species die. Two students set up a transect from the edge of a river running into a nearby field. They placed quadratA square frame of known area used for sampling the abundance and distribution of slow or non-moving organisms. every metre and recorded the percentage cover of each plant species in their quadrats. Their results are below.
| Distance from river bank (m) | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| Nettles | 0 | 0 | 0 | 0 | 0 | 5 | 10 | 30 | 15 | 20 |
| Grass | 10 | 20 | 25 | 35 | 95 | 90 | 90 | 70 | 85 | 75 |
| Cow parsley | 90 | 75 | 75 | 60 | 0 | 0 | 0 | 0 | 0 | 0 |
| Unknown species | 0 | 5 | 0 | 5 | 5 | 5 | 0 | 0 | 0 | 5 |
| Distance from river bank (m) |
|---|
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
| 8 |
| 9 |
| 10 |
| Nettles |
|---|
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 5 |
| 10 |
| 30 |
| 15 |
| 20 |
| Grass |
|---|
| 10 |
| 20 |
| 25 |
| 35 |
| 95 |
| 90 |
| 90 |
| 70 |
| 85 |
| 75 |
| Cow parsley |
|---|
| 90 |
| 75 |
| 75 |
| 60 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| Unknown species |
|---|
| 0 |
| 5 |
| 0 |
| 5 |
| 5 |
| 5 |
| 0 |
| 0 |
| 0 |
| 5 |
Question
What conclusions can you draw from this data? [4 marks]
Nettles grow in higher numbers further away from the river bank (1 mark). No nettles are seen closer than six metres to the bank (1 mark). Grass also increases in numbers further away from the bank but is seen at all distances (1 mark). Cow parsley is seen in higher numbers closer to the river bank (1 mark).
Question
What limitations might there be in drawing these conclusions? [2 marks]
The two students only completed one transect up the river bank (1 mark). Additional transects would allow them to be more confident in their conclusions (1 mark).
Atmospheric gases
Gases dissolve in liquids, thus oxygen in the air dissolves in water. It is this dissolved oxygen, together with that produced by plants and algae, that support aquatic life. When levels of pollution increase the levels of dissolved oxygen reduce.
Students kick-sampled a stream every 50 metres from a source of pollution, and their results are shown below.
| Distance from pollution source (m) | 0 | 50 | 100 | 150 | 200 | 250 | 300 | 350 | 400 | 450 |
| Mayfly larvae | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 3 |
| Freshwater shrimp | 0 | 0 | 0 | 0 | 0 | 0 | 4 | 1 | 3 | 5 |
| Water louse | 0 | 0 | 0 | 0 | 1 | 4 | 3 | 3 | 2 | 5 |
| Rat-tailed maggot | 20 | 19 | 17 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Sludgeworm | 11 | 14 | 15 | 9 | 4 | 0 | 0 | 0 | 0 | 0 |
| Distance from pollution source (m) |
|---|
| 0 |
| 50 |
| 100 |
| 150 |
| 200 |
| 250 |
| 300 |
| 350 |
| 400 |
| 450 |
| Mayfly larvae |
|---|
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 1 |
| 3 |
| Freshwater shrimp |
|---|
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 4 |
| 1 |
| 3 |
| 5 |
| Water louse |
|---|
| 0 |
| 0 |
| 0 |
| 0 |
| 1 |
| 4 |
| 3 |
| 3 |
| 2 |
| 5 |
| Rat-tailed maggot |
|---|
| 20 |
| 19 |
| 17 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
| Sludgeworm |
|---|
| 11 |
| 14 |
| 15 |
| 9 |
| 4 |
| 0 |
| 0 |
| 0 |
| 0 |
| 0 |
Question
What conclusions can you draw from this data? Use numbers in your answer [6 marks].
Mayfly larvae were not seen within 350 metres of the pollution (1 mark). Freshwater shrimp were only sampled after 300 metres from the pollution (1 mark). Water louse were only found 200 metres from the pollution (1 mark). For all three species the numbers increased further away from the pollution (1 mark). In contrast, rat-tailed maggots and sludgeworms were seen in much higher numbers and only close to the pollution (1 mark). The further from the pollution the fewer of these species were seen (1 mark).
Question
What limitations might there be in drawing these conclusions? [2 marks]
The two students only completed kick samples every 50 metres and they did this only once (1 mark). Additional kick sampling with more frequently placed sites would allow them to be more confident in their conclusions (1 mark).