User: | Open Learning Faculty Member:
Identify the organism or biological attribute that you plan to study.
The organism I will observe is the presence or absence of the Parthenocissus quinquefolia, more commonly known as the Virginia creeper.
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 visually divided my observation area into three transects; the areas include a clear cut section where sand has been spread to form a makeshift road, a small area where regrowth is forming that had been selectively cleared, and an area that has only been affected by natural treefall. Changes of the Virginia creeper along the gradient includes the abundance, having a larger presence in the old-growth area than in the regrowth area or on the sandy road. The size of the Virginia creeper also differed. In the old-growth area there were many clumps and expanding vines, in the regrowth area there were smaller clumps with a few vine shoots, and finally, on the makeshift road there were fewer smaller clumps few big enough to shoot vines.
Think about underlying processes that may cause any patterns that you have observed.
Underlying processes that may cause patterns in my observations include differences in soil nutrients as well as different compositions resulting in the inhibition or deterrence of Virginia creeper to grow. On the makeshift road and regrowth area the size of the Virginia creeper plants and their density could be smaller because there is greater anthropogenic activity, the sand adds an extra layer of soil to grow through, and plants haven’t had as much time to regrow in these areas.
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.
My hypothesis is plant richness of Virginia creeper is negatively affected by anthropogenic activity.
One prediction is that the plant richness of Virginia creeper will be more abundant in areas with less anthropogenic activity.
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.
The response variables in the experiment included the absence or presence of the Virginia creeper. Given that the dependent variable(the presence or absence of Virginia creeper) is dichotomous, categorical I would test the hypothesis using logistic regression. The predictor variable is the locations (also a categorical variable). This is a categorical logistic regression design as the observation is to determine the overall presence of Virginia creeper growing in each transect.
