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I was in a bit of rush to record my field data before autumn erased the data I was trying to capture and realized that I was about 10 samples short for a valid bivariate regression analysis so unfortunately, I have to add a caveat to results.  Like many science inquiries, this raised more questions for me than it answered.  The ecological conditions in the forest are more complex than a simple walk through the park suggests.  I cannot walk my dog through this portion of the forest anymore without thinking about the forest dynamics all around me.

The correlation between the data appears to be borderline and requires more in-depth analysis.  I expected a stronger positive correlation.  It is interesting to note the cluster that took place with the light intensity readings.  I am just guessing but this could be due to canopy openings are not as variable as they appear to the eye and form discrete opening sizes.  The one outlier defies explanation at this time.

It is common knowledge that plants need light, however, I am interested to know how strong the correlation is to the amount of available light and the proliferation of vegetation on the forest floor when the canopy has undergone a disturbance.  Additionally, the presence of pedestrian traffic through the study area ensures that there is continuous disturbance of the vegetation in the area of the footpath.  People routinely stray off-path, dogs run off-leash, and herbivores such as deer eat young vegetation as it develops.  These conditions offer benefits to invasive species as they can be found along any popular forest footpath in the area.  These factors probably have a major role in determining the overall composition of the ecological communities, but each community is primarily dependent on available light for photosynthesis.  Therefore, I believe that studying the relationship between light levels and amount of vegetation would provide an interesting insight into the revegetation in continuously disturbed areas.

Project Keywords:

Light-levels, vegetation ground cover, Human disturbance

My study transect followed a footpath through the park forest.  The segment of the path in the study area is roughly 200m so I decided that 20 stations at approximately 10m intervals would provide a good sample.  After recording weather conditions and time/date, I followed the following procedure at each interval.

1. Note interval station in Excel.
2. Record relative light level in Lux (3x)
3. Measure horizontal distance from footpath to significant change in elevation (not part of the study but I thought it might be interesting to collect this data)
4. Measure max height of vegetation 1m from path (again not intended to be part of the study)
5. Photograph the vegetation in the area perpendicular to the footpath.

Additionally, I took ambient light readings in urban areas, open areas and under full forest canopy to establish data boundaries.

The sampling strategy was efficient and didn’t cause any problems.  I was able to take the light reading in quick succession so that the ambient light would be fairly consistent and not changed due to time-of-day variation.  The photographic data collection was not as time-sensitive because of the colour and luminosity calibration which I included in each image.

Although plant height was extraneous to this study, I determined that there was some correlation between light levels and plant height but I have not completed the image analysis to comment on the central thesis of this study.

In designing a sampling strategy, time was of the essence.  I began the course in October when the vegetation had full foliage but I knew that within the next week or two, fall would begin, and the plants would begin to lose their foliage or die off for the winter.  I was able to go out for a couple of successive days to observe the environment and decide on a topic and strategy.  In deciding to investigate light levels with vegetation coverage, I realized that the most prudent approach would be to quickly obtain a photographic record of the study area and analyze the vegetation cover from the photographs rather than studying the plants in-situ.  This approach utilizes computer data processing tools with methodologies widely used in Remote Sensing studies and utilizing recognized academic software, giving it credence for a scientific inquiry.

I selected the starting point of the path (where it branched off another path segment) and recorded data at approximately 10m intervals.  Capturing the data and photos at each interval went quickly so rather than random sampling, I collected data samples along the entire transect and I can either use the complete data set or randomly select points along the transect and query the data collection at these points.  Again, a measure of expediency was directing my work because I realized that if there was a data deficit, I would not be able to collect the data again during the course of this study.

I would have preferred to construct an apparatus to ensure consistent height and angles for the camera but I compensated for this by using a highly coloured measuring stick in each photo where the spatial integrity can be confirmed.  Additionally, since the same colours are available in each photo, I can calibrate the images’ colour balance and luminosity in much the same manner as NASA used with the Mars rover images.

I would have preferred to use a laboratory-grade light meter whose calibration could be independently certified.  However, this was not possible due to the cost of such equipment, so I calibrated my meter statistically to ensure that its tolerances were of an acceptable level for the study.  Also, I am not actually interested in the specific Lux values from the meter, but rather the relative light readings from one station to another.  As such, it was only to necessary to confirm the light meter’s response relatively across the spectrum and not to specific laboratory standards.  In other words, if the same level of light gives the same results on separate readings, I am able to consider the instrument calibrated for the purposes of this study.

I did the image analysis later at my home using the ImageJ scientific image analysis software.  Ideally, I would have liked to write a macro to bulk process and analyze the images automatically but the complexity of this task was too much for the scope of this project.  Therefore, I used personal judgement in some of the image processing which unfortunately could introduce bias or error but I endeavoured to follow the level of precision in the analysis and I believe that any discrepancies in analyses are statistically insignificant and do not affect the overall analysis.

I tried to incorporate as many of the sampling strategies of the virtual forest tutorial as possible.  However, due to the nature of my study some do not fit into the context of my investigation.  Collecting data along the study transect is a systematic sampling.  I collected data at all of the stations along the transect and could now apply a random aspect to the study by querying random samples from the complete data set.  At each interval, I conducted an Area-sampling by analyzing data from a square metre sample.   I am not concerned with specific species so the dispersion, succession and diversity sampling is not relevant.  There are topographical and edaphic factors which undoubtedly impact the ecology of the area but they are outside the scope of my study.

For my field study, I am going to examine whether there is a correlation between available light in a forest and the amount of ground cover in continuously disturbed areas.

Since the vegetation along the footpath in the study area undergoes continual but somewhat random disturbance from pedestrian traffic I am wondering if the amount of available light is the key resource that determines whether the forest floor revegetates after it is trampled by humans and pets.

My field observations consist of light meter readings at each interval and photographs of ground cover along a gradient extending perpendicular to the footpath.  The photographs will be digitally process to determine the percentage of ground cover at each interval.

Therefore, my null hypothesis is:

There is no connection between available light levels in the forest and the percentage of forest floor covered by plant leaves.

I predict that there will be a correlation between available light and ground cover.

My explanatory variable is Light level (measured in Lux) and my response variable will be the percentage of ground cover in each delineated area (measured in percentage).

The resource Climate is a stronger driver of tree and forest growth rates than soil and disturbance (https://www.jstor.org/stable/41058855) is a peer-reviewed report published in the British Journal of Ecology.  It is co-authored by eleven ecology academics from organizations with excellent credentials.  Since this was a study conducted by numerous professionals, published in a leading journal, peer-reviewed, and based on extensive primary research, I found that this resource to be a top-quality and reliable scientific source.  Its conclusions are important in the age of climate change.  The one possible drawback of this paper is that it was published in 2011 and while still presenting valid conclusions, there may be newer resources incorporating more recent data.

My intended study area is a four hundred metre length of the Spring Valley Trail which is located in Jerseryville Park in the City of Hamilton and part of a conservation area administered by the City of Hamilton and the Dundas Valley Conservation Area.  The study area is part of an irregularly shaped, mostly-contiguous protected area covering over 1200 hectares of conservation area and approximately 1500 hectares of private and crown land.  The conservation area has numerous streams and waterfalls and is comprised mostly of forests with small meadows which are artifacts of previous agricultural activities and human habitation.

Soil in the area was not studied but probably ranges from clayey to clayey-loam as it was once a riverbed and this would be consistent with other similar parcels in the general vicinity.

The study area runs linearly, approximately north-south, along a formal unpaved (municipally maintained) footpath called the Spring Valley Trail which connects to numerous other trails in the protected area.  The study area is bounded on the east side by Sulphur Creek which runs roughly parallel to the footpath and an irregularly shaped ridge line running roughly parallel to the study area to the west.  The height of the ridge is approximately 10-20 metres along its course creating a defined boundary to the study area ecosystem.  The study area itself has undergone significant human disturbance in the past and as a public-use facility, continues to undergo significant disturbance from high pedestrian and bicycle usage.

The actual study area is the disturbed area running adjacent to the public footpath.  Even to an unqualified observer, the difference in vegetation is apparent along a gradient from the pathway to the forest along the ridge.  The vegetation in the study areas appears to be mostly invasive species of which I am having trouble accurately identifying.  Queries to online forums have yielded only a common-catchall term of “hogweed” which apparently is a common term for unidentified low-value plants.  Dispersed throughout the study area are maple saplings which generally do not have the opportunity to mature due to human disturbance and the prevalence of herbivores (deer) in the area.

While walking through the area on numerous prior occasions, the difference in vegetation adjacent to the trail from the forest floor became obvious.  I also noted that some areas along the trail are much more sparsely vegetated and I wondered why.  Some possible questions regarding the observed phenomena are:

Is there a correlation between amount of available light and ground cover?

Are variations in ground cover due to recurring disturbances?

Are variations in ground cover due to topographical influences?

I would like to explore the available light aspect for my study.

The study area was visited on several occasions in early October to reconnoiter the area and evaluate specific study plots.  The main study visit was conducted on October 11, 2018 between 2-3PM.  The weather was sunny with very little cloud cover, 23°C, with very little or no wind.  Data collection consisted of taking photographs and measurements.  Although the floor was partially covered, it appears that the leaf litter was not due to seasonal autumn activities as most trees and plants had not shed their leaves giving the opportunity for plant identification.