The site I have a chosen to study is a grass field containing a creek and hills in southeastern Alberta. When visiting this field, I took note of the abundance of jumping cacti (Cylindropuntia fulgida) in the area and have chosen this as my species of interest for my field project.
I observed that the jumping cacti are small, round, and green and covered in dozens of spikes. They are also grown in bunches. Interestingly, I observed singular jumping cactus attached to animals via their spikes. I also observed differing abundance of jumping cacti in different areas of the field. The locations I analyzed were:
- within the water of the creek. Here I observed no cacti, demonstrating that the plant needs soil to grow.
- along the sides of hills in the field. Here I observed cacti grown in bunches and some individual cactus randomly distributed throughout. I assume the individual cacti observed were separated from their bundle either by animals, or another mechanism.
- hilltops of various altitudes. Some of the hills in the field are higher than others, but bundles and individual cactus were found across hilltops of various heights.
An area that I have not yet observed, but am interested to, is the land directly adjacent to the creek. I assume there is no cacti growth in these locations, but I will need to observe more closely next visit to be sure. The clear difference between water and land was the absence and presence of cacti, respectively, but there was no clear differences between the hilltops and hillsides. However, I would like to look more closely at the locations to compare the density of cacti growth, and the size of the cacti and their needles.
Differences in cacti growth could be caused by several environmental factors. It is clear that soil is a necessity, but other factors could be the amount of moisture in the soil or the sunlight received. Since cacti are typically grown in dry conditions, I predict that moisture is a major component.
Hypothesis: The growth of cacti is influenced by the level of moisture in the soil, which in turn could be affected by altitude of land and distance from the creek.
Prediction: The most abundant cacti growth will be observed on hilltops far from the creek, as these are the areas likely to have the least amount of moisture in their soil.
For this prediction and hypothesis, a response variable would be the abundance of cacti growing in a specified area of land (for example, the number of cacti plants in a square meter). This response variable is an example of a continuous variable. A potential explanatory variable is the level of moisture in the soil, which could be measured directly or inferred from the height or distance from the creek of the land at where the cacti were counted.
