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With my next visit to Heritage Park I looked toward the stream located on the west side down from the gravel walking path. I’ve decided to study how the plant community changes along the riparian stream side as proximity to the stream changes. I want to know if these changes also occur with increasing changes in elevation.
I began my observations at the lowest point of the stream that I could access before there is a sudden drop into a ravine. Here the stream forms a small pond near a walking bridge. I took note of the vegetation in three rough points: near the stream, mid point up the bank and the upper portion of the bank near the gravel path.
I did the same at a second site near a bubbling pipe that allows water to flow through an area with a small dam, and then again once more further upstream.
My observations seem to indicate, for one, that the type of flora along the riparian bank seems to be more influenced by other factors than just the presence of the stream itself, but that there is a slight increase in plant diversity as proximity to the stream decreased. Some species known for their preference of moist soils such as salmon berry (Rubus Specabilis) were often present with few others such as fern species near the water, with the exception of the first site which also had some ground cover plants mixed in as well. Further back up the bank I found species such as black hawthorn (Crataegus douglasii) and other tree and shrub species mixed in with Himalayan blackberry (Rubus armeniacus) as well as other invasive species such as creeping buttercup (Rananculus repens). It seemed there was more diversity of species the farther away from the stream I observed. How far does this diversity go? Is there an average to the maximum amount of diversity before the level drops again?
Hypothesis – Proximity to the stream affects plant diversity at Heritage Park
Prediction – Plant diversity increases with an increase in elevation away from the stream. There is a maximum to this however before diversity averages, then drops.
Response variable – Number of plant species present (Continuous)
Explanatory variable – Distance from the stream (Continuous)
Looks like you have a good idea for a study that could be relatively easy to implement. It mirrors one of the research papers we had to answer questions for in Module 6 which if you haven’t read yet would give you some good ideas. Your hypothesis is falsifiable, though I wonder if the word proximity is the best choice as the water level will change over the year. You mentioned elevation in your prediction which is something to consider as it is likely more relevant than the distance to the rivers edge which you stated as your explanatory variable. I also started to try and record all the species present in my own study, but found myself overwhelmed with the diversity of lichen, moss, and grasses that I couldn’t for the life of me identify. I wonder if it would be easier to focus on a few different species instead of all of them. If you are doing multiple transects I would make sure they all have the same aspect because if one part of the stream bank is south facing and one is west facing that could confound your results. Overall it looks like you have a good idea! Good luck with your research.
Great comments and suggestions from Kyle! You probably will want to identify the high water mark which can be defined in different ways and if you want help with a definition let me know. You can start below the high water mark if you want, but knowing where it is will be helpful as below this vegetation is experiencing different circumstances. In BC Riparian Areas Regulation has a definition. You will also have to consider how far to run your transect and think about why diversity might drop off. Kyle has a good point that identifying every species can be a challenge and so you could focus on certain functional groups (e.g. shrubs and grasses) and it is ok to have unknown species as if you are calculating overall diversity, it is ok to have a few unknowns that you were unable to identify.