1. Identify the organism or biological attribute that you plan to study
On the property I have been studying, there is a cluster of cherry trees. I plan to study the size of cherry trees and how their height difference compares to their variation in sunlight exposure.
2. 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.
The cherry trees that were planted at the back of the cluster appear to be taller with more vertical growing branches giving it a narrower appearance, The trees along the outside/front of the cluster appear to be shorter in height and have more horizontal growing branches that run parallel to the ground, giving the tree an overall wider appearance. The trees located on the sides of the cluster seemed to be in the middle height-wise and had a mix of vertical and horizontal branches.
3. 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.
The trees are all the same age and are growing in similar soil, however, they experience different ranges of sunlight. I think these changes in height and width may be the result of the different levels of sun exposure. The trees at the back of the cluster may have to grow tall to compete for the sun. They must compete the most as they are exposed to the least amount of sun because it is blocked by the other trees. The trees on the side of the cluster have to compete for sun exposure during some parts of the day. The trees at the front are the shortest and don’t ever need to compete for the sun as they get full exposure all day long. Also, there appears to be a correlation between the height and width of the trees. The taller a tree grows perhaps the more vertical the branches grow to allow it to increase in height. Trees exposed to full sun that don’t need to grow as tall can form branches that run more horizontally.
From this, I hypothesize if the tree is competing for sun exposure it must grow taller and narrower.
I predict that the cherry trees that are at the back of the cluster and must compete with the other trees to reach the sunlight will grow taller and therefore be of less width than those at the front and sides of the cluster.
4. 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 would be the tree height which is continuous.
One potential explanatory variable would be whether or not the tree has to compete for sun exposure which is categorical.