User: | Open Learning Faculty Member:
May 13 5:55 pm
Weather: 18 degrees, mostly sunny
I have chosen to study the factors that affect sword fern (Polystichum munitum) growth. From my previous trip, I noticed that sword ferns are densely populated in the middle of the forest and grow sporadically away from the center. This difference in fern density leads me to believe that there are conditions that favor fern growth in the center of the forest as opposed to the outskirts of the forest.
I have chosen 3 different areas to study. Each having similar composition in topsoil but differ in elevation and position.
The first area is close to the northern entrance of the forest at about 20 m elevation. It is heavily shaded by trees and only one fern is seen growing on a mound next to a covered manhole. I have counted 8 fronds on this fern, each of which grows at about less than 2 feet. The surface of this soil seems dry and is covered heavily by sticks, pebbles, and smaller unidentifiable plants growing around the fern.
The second area is at 25 m elevation moving west. This area is the closest to the center of the forest where there is a higher population of sword ferns growing closer together with longer fronds (approximately 4 feet). The area is moderately shaded with few spots where sunlight can peak through. Many of the ferns in this area appear to have spores. The fronds here are fuzzy in appearance and curl inwards at the tips. Soil in this area is composed of mostly sticks and pebbles, though in comparison to the first and third area, the soil looks darker.
The third area is at 30 m elevation. Here, there are only 3 ferns growing about 6 feet away from each other and there is little shade. Frond length is similar to the first area at about 2 feet or less in length with some fronds looking wilted/drooping. The soil here is mostly covered by sticks and there is little vegetation surrounding the ferns.
Patterns I have observed from this trip are that ferns found toward the center of the forest look much healthier and their fronds grow larger in comparison to ferns grown away from the center, which are smaller and have a larger portion of wilting/drooping fronds. Most of the ferns I had observed in all 3 areas grew on a slope or a mound. The soil in the center of the forest is also much darker looking than the other two areas. I am particularly interested in this difference as I suspect the difference in soil properties plays a role in fern growth. In addition to the varying soil properties, I believe slope and light variability also affect how favorable fern growth will be. However, I would like to focus my studies on how soil moisture and pH affects the length at which fronds grow as I believe it would be the easiest factor to study. I hypothesize that the availability of soil moisture will have an effect on the frond length of sword ferns (Polystichum munitum). I predict that as the level of moisture in soil increases, frond length will also increase.
My response variable will be the length at which fern fronds grow and my predictor variable will be the level of soil moisture. The response variable would be continuous, and the predictor variable would be categorical.
Hi Laura,
Great clear hypothesis and prediction. I like that you have boiled down your experiment to one easily testable prediction about the correlation of soil moisture and fern frond length. Large and small depressions in the ground can have a major impact in the moisture level of the soil. How will you be collecting soil moisture measurements and will you be collecting one moisture measurement for each location or one for each fern? Moisture level of soil will also be affected by rainfall and it maybe tough to measure any differences in topsoil moisture if there was very recent rainfall or if it has not rained in a long time. I also like you idea of detecting pH levels as pH level is impacted by the amount of organic material present. One confounding variable that will be hard to overlook is that ferns in the middle of the forest may have longer fronds due to the presence of more nutrients in the soil as opposed to at the edge of the forest.
Great study idea and best of luck!