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My study hypothesis was that the Broadleaf Stonecrop abundance is determined by substrate drainability (i.e most abundant in sites with either a high rate of water percolation or surface runoff). To demonstrate the results of my study, I plotted three graphs; one showing the relationship between substrate type and stonecrop abundance, one showing the relationship between degree of slope and stonecrop abundance, and a third showing the level of drainability and stonecrop abundance.
The first two graphs depicted strong relationships between stonecrop abundance and both substrate type and degree of slope individually.
The most difficult part was assessing the level of drainability within each quadrat as it combines the effects of two variables, slope and substrate type. A high degree of slope is going to increase surface water runoff, while a coarser grained substrate is going to increase the rate of percolation, both of which lead to a higher rate of water being drained from the area.
My graphs generally agreed with my hypothesis and demonstrated that the abundance of Broadleaf Stonecrop responds positively as water is drained faster from the substrate. My results also demonstrated that there are other confounding factors, as to be expected, that are also determining the abundance of my study subject. I had established four levels of substrate drainability, and predicted that the well and rapid draining sites would have the highest abundance of stonecrop, however my results indicated that the well draining sites in fact did not have the predicted response. It was later suspected that this is due to another factor, proximity to the ocean, as the majority of the well-draining quadrats were found to be facing the lagoon, as opposed to open ocean.
