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The organism I have chosen to study is the Western Sword Fern (Polystichum munitum), a common fern found in the Pacific North West region. The fern is commonly found in moist, mild and shady environments.
The reason I decided to study this organism is that it is commonly found throughout Pacific Spirit Regional Park, however there were some locations on within the gradient of study that I observed fewer sword ferns present. At the creek site (Site 2), on the west bank of the stream there were fewer ferns, however on the east bank of the stream there were many more. The ferns at the interior site (Site 1) appeared to be more vigorous and larger than the ferns at site 2. Site 1 is located amongst large coniferous trees and it appears that less light makes it through to the forest floor. This is an environment that would suit sword fern growth so I would predict that the ferns may grow more vigorously or have greater abundance at this site compared to the creek site (site 1). The banks of the creek are relatively open to the sun as the creek runs south and the trees at the edge of the forest have been thinned or cleared as the creek passes beneath the road. I would expect that this site, although moist, the sun exposure may affect the sword fern growth. I did notice that the ferns were more prevalent on the east side of the creek than the west side, and again this may be due to the sun exposure the different banks experience.
I hypothesize that the fern growth will be greater in the more shady areas of the forest as measured by crown count per unit area, and frond length. I am also interested in counting the density of spores to determine if that also varies by site. The explanatory variable will be the amount of light at each site classified as high and low. The response variable of crown number/ plot and frond length will also be continuous variables.
Interesting topic. I was wondering if you are looking for any indicators other than sunlight which might contribute to or inhibit growth of the sword ferns.
My understanding is that they are sensitive to moisture and that they can do well in sunny conditions if there is sufficient moisture.
Or, perhaps in the site where they are not so abundant, are there any indicator species present to suggest a different soil moisture regime or soil nutrient regime? Ie: different plants or trees that might indicate these changes.
It seems logical that sunlight is playing an important role. I think your idea would be strengthened if you were somehow able to remove the possibility that something like moisture or nutrient availability was not playing a significant role.
Sounds like an interesting project. I look forward to the results!
Thanks for your feedback. I agree that controlling for moisture and nutrient content could be a good idea. I am not sure how I would control for nutrient content and for moisture content it would be interesting to include an exposed site with no creek, unfortunately I have not come across one as the tree density is pretty uniform throughout the park. I appreciate your comments. Thanks!