My reason for predicting that there will be more algae on the NE side is due to the prevailing SW winds which will dry up the SW side and algae need moisture to grow so least algae will grow on the SW side.
Apparatus:
Quadrate, Log it sensors (heat + light intensity), Meter ruler, Compass.
Plan:
In my investigation I am going to investigate the distribution of algae at two heights 1.0M and 1.5M. I am going to take results from an exposed area and a sheltered area so that I can see if this affects algae growth. I am going to record heat and light intensity using Log it sensors, as these two factors affect the growth of algae. I stated this as an improvement in my initial experiment. I am also going to take readings from North, South, East and West so that I can see if the direction facing affects the growth of algae. I will use a quadrate with 25 squares by placing it on the tree trunk at the appropriate height and direction and count how many squares the algae covers out of the 25. One person in our group will take all the algae readings so that our results stay as consistent and accurate as possible.
Method:
- Measure the appropriate height on the tree.
- Find the appropriate direction using the compass.
- Record the heat and light intensity with the Log it sensors.
- Place the quadrate on the tree and see how many squares the algae fills
- Repeat for all the other directions
- Repeat all the above for 1.5M
- Repeat for sheltered area
Diagram:
Results:
1.0M Sheltered
1.5M Sheltered
1.0M Exposed
1.5M Exposed
Calculations:
Data analysis
Using the CHI – Square test
O = Observed result
X2 = ∑ (o – E)2 E = Expected result
E ∑ = Sum of
Algae distribution on trees may be random or uneven caused by environmental factors.
By calculating the X2 value for each site and height of tree the significance of my results may be determined.
A X2 value greater than 7.81 means that the distribution is not random but due to environmental factors we would expect to see 78 per side.
1.0 Exposed
X2 = ∑ (o – E)2
E
84+23+75+48 = 230 = 57.5 Expected algae
4
N = (84 – 57.5) 2 = 12.2
57.5
S = (48 – 57.5) 2 = 1.6 39.8 = X2
57.5 CHI – Square number
E = (75 – 57.5) 2 = 5.3
57.5
W = (23 – 57.5) 2 = 20.7
57.5
Because 39.8 is less than 7.81 is distribution of algae is NON random.
1.5 Exposed
X2 = ∑ (o – E)2
E
78+54+79+23 = 234 = 58.5 Expected algae
4
N = (78 – 58.5) 2 = 6.5
58.5
S = (54 – 58.5) 2 = 0.3 35.5 = X2
58.5 CHI – Square number
E = (79 – 58.5) 2 = 7.2
58.5
W = (23 – 58.5) 2 = 21.5
58.5
Because 35.5 is less than 7.81 is distribution of algae is NON random.
1.0 Sheltered
X2 = ∑ (o – E)2
E
72+78+54+93 = 297 = 74.3 Expected algae
4
N = (72 – 74.3) 2 = 0.07
74.3
S = (78 – 74.3) 2 = 0.2 10.5 = X2
74.3 CHI – Square number
E = (54 – 74.3) 2 = 5.5
74.3
W = (93 – 74.3) 2 = 4.7
74.3
Because 10.5 is less than 7.81 is distribution of algae is NON random.
1.5 Sheltered
X2 = ∑ (o – E)2
E
94+84+79+90 = 347 = 86.8 Expected algae
4
N = (94 – 86.8) 2 = 0.6
86.8
S = (84 – 86.8) 2 = 0.09 1.49 = X2
86.8 CHI – Square number
E = (79 – 86.8) 2 = 0.7
86.8
W = (90 – 86.8) 2 = 0.1
86.8
Because 1.49 is less than 7.81 is distribution of algae is random.
Statistical analyze of results:
X2 (CHI squared) value for:
Exposed site 1.0M = 39.8
1.5M = 35.5
Sheltered site 1.0M = 10.5
1.5M = 1.49
Null hypothesis that there is no difference in the amount of algae found on the N, S, E, W side of the tree.
A X2 value greater than 7.81, means than the distribution of algae is non random therefore the null hypothesis can be rejected.
Conclusion:
I predicted that you would find more algae on the NE side and least on the SW side due to prevailing winds. This can be seen clearly on my graph for the exposed site, but for the sheltered site it is only slight due to the shelter blocking most of the prevailing winds. On the exposes site you can see there is a much higher distribution on the NE side and hardly any on the SW side due to the prevailing wind. There is more total algae growth on the sheltered site as there is more moisture and less wind there are also warmer temperatures and greater light intensity, which promotes growth.
The bigger (older) the tree the bigger the trunk so there is more chance of algae becoming established on the tree.
Evaluation:
I circled the results from tree 3, (1.0M) in the sheltered area, as they were significantly lower than the other results.
I also circled tree 3 (1.5M) in the sheltered area because the results were significantly low.
I circled tree 1 (1,0M, 1.5M) in the exposed area, as the results were significantly high compared to our other result trends.
I also circled tree 2 (1.0M) in the exposed area, as one of the results was very low. Reasons for some of my results showing a discrepancy could be due to environmental factors, human error or inaccuracy in equipment used.
If I were to do this investigation again some improvements I would make are:
- Take a picture of the tree with a digital camera.
- Use the same species of tree so bark is relatively the same.
- Choose trees that are roughly the same age, as older trees tend to have more algae. I could do this by measuring circumference of the trunk.
- Repeat investigation in different areas of the country so that I could see how climate affects algae growth.
- I could repeat the algae count with three people and take the average of the results.
- We don’t know how deep the algae is so I could measure the thickness of the algae.
- I could measure the moisture using a dampness meter.
- I could measure the sulphar dioxide levels as this has an affect on the growth of algae.
