Identify the organism or biological attribute that you plan to study.
I plan to study the plant azalea (Rhododendron simsii)
Use your field journal to document observations of your organism or biological attribute along an environmental gradient. Choose at least three locations along the gradient and observe and record any changes in the distribution, abundance, or character of your object of study.
I have chosen three different locations of locations based on flower abundance (density). In area 3, there are almost no azaleas blooming. In area 2, there is a high density of flowers to the point where it is hard to recognize any inbetween leaves. In area 1, there is a bush of azalea where the flower abundance falls between the first two.
Journal Entry (May 24, 2023):
I’ve taken a preliminary temperature/humidity test of the three different areas when the sun was at its highest, and it seems they vary quite largely. I have yet to collect data from sunrise to sunset to see the true sunlight exposure times, but it seems the longest sun exposure is in area 1, shortest sun exposure in area 3, and mid-range sun exposure in area 2.
| Area 1 | Area 2 | Area 3 | ||||
| Temp (℃) | Humidity % | Temp (℃) | Humidity % | Temp (℃) | Humidity % | |
| 13:00 | 29.7 | 37 | 29.3 | 41 | 24.8 | 40 |
| 14:00 | 31.4 | 28 | 22.6 | 40 | 23.7 | 38 |
| 15:00 | 35.2 | 23 | 22.4 | 40 | 25.4 | 35 |
Think about underlying processes that may cause any patterns that you have observed. Postulate one hypothesis and make one formal prediction based on that hypothesis. Your hypothesis may include the environmental gradient; however, if you come up with a hypothesis that you want to pursue within one part of the gradient or one site, that is acceptable as well.
I believe there may be several factors that may underlie the observed flower abundance pattern. First is soil health – this includes factors such as soil pH, soil water content, and nutrient content (ie. nitrate). These are factors that I have not been able to measure yet since I would need the equipment to do so, but I would like to keep them in mind as one of my hypotheses. Another possible factor is the climate condition in each of these three areas, such as temperature, humidity, and sunlight exposure time. I have realized that areas 1 and 2 get more sunlight than area 3, which corresponds to the flower abundance pattern (areas 1 and 2 have more flowers than area 3). However, I am not yet sure as to why there is a difference between the flower abundance in area 1 and 2 since they both get sunlight – maybe there is a difference in sunlight exposure time. I postulate that sunlight exposure time may cause a difference in flower abundance. More specifically, I postulate that greater sunlight exposure time increases azalea flower abundance (or density).
Based on your hypothesis and prediction, list one potential response variable and one potential explanatory variable and whether they would be categorical or continuous. Use the experimental design tutorial to help you with this.
One potential response variable is the azalea flower density (possibly taken by a quadrat method?) and the explanatory variable could be temperature. In this case, both the flower density (flower abudance in a particular section) and temperature would be continuous variables. When the response and explanatory variables are both continuous, regression analysis can be applied.
How did you measure temperature and humidity? I think you mentioned only having one bush in one of the areas so you will have to think about replication in that area and could be a limiting factor in your study.
You can focus on temp / humidity / sunlight and not also measure the soil. You can keep that as a possible influence that you were not able to analyze as we don’t expect you to consider every possible variable.
Thank you for your response. I measured temperature and humidity using a digital thermometer.
Yes – in fact I only have one bush in all of the 3 areas. (I could not find areas where there is more than 1 azalea bush under the same sunlight conditions). Will this be an issue going forward? For my study, I increased my areas to 5 areas instead of 3 areas to increase number of samples. They are all in different locations, with different temperature/sunlight conditions.
As you have mentioned, I will make sure to raise the bush number as a limiting factor in my study.