User: | Open Learning Faculty Member:
The graph i submitted displays the data from one of my 4 sample plots (Plot 3). The predictor variable, elevation from the lake waterline, is presented on the X axis with the response variable, species composition (by percentage), on the Y axis. The sample plot was divided into 5 elevation zones, which made it easier to determine changes in species composition as elevation increased. This also made the data relatively simple to organise and graph. I took the raw data from each of these elevation zones and calculated the percentage abundance of each of the species in each zone. While the other 3 sample plots produced results that aligned closely with my prediction, the results from Plot 3 were quite surprising. I had predicted that the relative abundance Alnus rubra would decrease with increasing elevation, while the abundance of conifer species would increase. However, the graph showed a spike in conifer abundance and a sharp decrease of Alnus rubra abundance in the 2-3m elevation zone, and exactly the opposite pattern in the 3-4m elevation zone. This prompted me to analyse the substrate descriptions that I had recorded for each species in each zone. In the other 3 sample plots, substrates had progressively transitioned from deep, spongy and moist soil in the lower elevations to drier, sandier and rockier substrates in the higher elevations. However, in Plot 3 there was a patch of drier, sandier substrate in the 2-3m elevation zone, which prompted a decrease in Alnus rubra and an increase in conifer abundance, and a patch of moist, spongy substrate in the 3-4m elevation zone which saw an increase in Alnus rubra and decrease in conifer abundance. Hence, this graph prompted me to give more consideration to the influence of substrate on species composition, and make another graph that depicts changes in species composition in relation to changes in substrate type – from the most moist and spongy soils to the driest and rockiest substrates.
