User: | Open Learning Faculty Member:
Over the past weeks I’ve visited the site a few more times and have indeed noticed additional ancillary patterns in regards to the presence of Alnus rubra. The remaining trees have a more clay-based soil still present around them and this suggests their survival is potentially related to the edaphic conditions of the soil that have not washed away yet. I have also recognized mistakes in my initial experimental design, and attempted data collection from a distance (as noted in one of my last posts) but it is not possible. It’s because of these factors that I need to adjust my hypothesis to reflect the new patterns i’ve noticed and I also need to alter my variables and sampling technique.
As the shoreline continues to rapidly erode at this location, the loss of soils capable of providing growing area for Alnus continues to disappear. The soil that continues to be washed away (mostly clay-based) appears to be the desired location for whatever Alnus rubra are present and potentially the desired location for their seed. These edaphic changes, combined with interspecific competition from plant species that are better adapted to the more sandy or gravelly soil mean that Alnus rubra will eventually no longer be able to survive and reproduce in this area.
If I believe that Alnus’ presence will decrease as soil type moves from clay to gravel, but may also depend on the plants that are most dominant in these zones as well, I can record data for these using two separate models and then analyze them to see if plant dominance does affect Alnus presence.
Response variable 1: Presence of Alnus rubra
Predictor variable: Soil type (stony/gravel zone, sandy/gravel zone, clay mix zone)
Response variable 2: Dominant plant type (based on plant with most % cover in each zone)
Predictor variable: Soil type (stony/gravel zone, sandy/gravel zone, clay mix zone)
Sample unit: 400-500 meter transect across the shore. The width is 6 meters, going up from the high tide line to the level top of the slope.
Subsample unit: Quadrats are randomly generated # of paced meters, continuing from one quadrat to the next. This area of study is difficult to access and is hard to record accurate data unless I use bigger quadrats than my last attempt. Each quadrat is a 2m (along shore) by 6m (up slope) rectangle. The presence of Alnus in each soil type as well as the dominant plant species in each soil type is recorded.
40 quadrats were randomly placed along the transect and data was recorded. A second round of data collection with a new set of random quadrats was completed on the same day, therefore I had one replicate.
I am expecting continued adjustments to my hypothesis and design as data is recorded and analyzed.
