User: | Open Learning Faculty Member:
I returned to the study site on September 28th, 2019 between 09:00 and 11:00. It was partly cloudy with light winds, and approximately 12 degrees Celsius. The biological attribute I plan to study is the relationship between tree species and the river. I would like to focus whether there is a correlation between the type and abundance of trees and shrubs, and the proximity of the river in regards to each species.
Since my last visit to this area, many of the leaves have changed color and dead leaves are scattered along the trails and river. The river has not changed and continues to flow moderately.
There are 3 different gradients along the site that I have observed:
Gradient 1: Closest proximity to the river bed (0-15 feet). This gradient consists primarily of large Red Alder trees, majority of them are leaning towards the river. Dispersed around the alder trees are Salmonberry shrubs. Moss is covering the approximately 60% of the rocks and lower parts of the trees.
Gradient 2: 15-30 feet from the riverbed. A thick row of fern can be seen as the gradient becomes elevated by 5 feet at approximately 15 feet from the river bed. Weaved within the ferns are very few Salmonberry. Further back into this gradient are a few Western Hemlock, Vine Maple, and Red Alder.
Gradient 3: 40-60 feet from the river bed, elevated about 15 feet. Various species of Maple, including Bigleaf and Vine Maple dominate this area. Need to research and return to the site to see if there are other types present, as it can be difficult to distinguish since there is a high density. Western Hemlock and Cedar are present in larger numbers and density than gradient 2.
A few things to consider about this site:
There is an overall elevation level of 15 feet, which could contribute to the change in vegetation, especially depending on how far the water table is underground. The forest is overall very dense, and majority of the light coming through is due to either fallen trees, or man-made trails that run through. The river is about 20 feet wide, and lets a considerable amount of light in. This could be another variable as to why the trees along the river bed are leaning inwards. Majority of the moss in the area can be found close to the river, which could mean that moisture levels in the air are higher overall.
My hypothesis:
The species of trees and shrubs that are closest to the river require more water and sunlight than trees further from the river.
Prediction:
My predictions are that Red Alder and Salmonberry require better access to water sunlight than the species present in gradients 1 and 2. Western Hemlock and Ferns are able to survive off less sunlight and a moderate amount of water. Maple trees require less water, but can grow tall enough to get adequate sunlight.
Response Variable:
Tree and Shrub Species – Categorical
Explanatory Variable:
Proximity to the river – Continuous
Hello!
You have picked a very interesting topic for your research study! The gradient you have observed appears to be very clear. I am curious how you will determine the cut off for counting tree species in each gradient considering the trees begin to grow in abundance to cut off sunlight. It is a good idea to have gradients that are different measurements from the river but have you considered what the width of your sampling area will be? will the greater abundance further from the river influence your results at all or will you take into account the smaller sample size closer to the river? The prediction appears to be falsifiable but I am assuming you have background knowledge or have scanned the literature for the sunlight and water needs of each tree species you observed in order to support or suspend judgement on this hypothesis.
Overall great study design and good luck with the rest of your research project! 🙂