I'm writing regarding a study design I am working with. I am assessing visitation rate of pollinators of soybean flowers in a fragmented landscape, where the matrix is covered with soybean crops that surround forest fragments of different sizes. In order to simplify my question, I will present a simpler design, but the basics are the same. Suppose I choose 2 forest fragments. In each one, I determine 2 transects from the forest edge into the soybean crop (separeted by 25 meters aproximately). Each transect consists of 3 sampling sites at three distances from the forest edge: 0m, 50m and 100m. The following image summarizes the design:
One of the questions I want to answer is if the visitation rate of soybean flowers diminishes with the distance to the forest edge. So, here comes my doubt: is the distance nested within each transect or are distance and transect crossed factors? I know that each level of the factor "Distance" is repeated in each level of the factor "Transect", so my first thought is that is a crossed design. But, each sampling site belongs to a unique transect (even though there are other sampling sites at the same distance in other transects), so maybe is a nested design. Defining this will be fundamental when analazyng my data and defining the statistical models. Thanks in advance!
