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4 – Sampling Strategies

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For this experiment, I selected the Mohn Hill community. It had an abundance of unique species that I sampled across the 84 sampling opportunities. Red maple, white oak, and chestnut oaks were found at the highest density regardless of the sampling technique used. Many of the rare species were missed in the samples, while other rare species were measured inaccurately. Definitely, more accuracy of measurements were achieved in more common species as compared to those that are more rarely located.

The most efficient sampling method was definitely haphazard sampling (t = 4hr 24min) – taking an hour less than both the random and systematic sampling strategies (t = 5hr 6min and t = 5hr 4min, respectively). For most common tree species with frequencies >10% the densities were best estimated by random sampling (table 1). Rare species were difficult to measure with accuracy using any of the three sampling methods. 24 samples were not enough to accurately capture the number of species in this habitat.

Table 1. Percent error between the density of common and rare species (the two most common species were red maple and white oak, while my two rarest species were sweet birch and American basswood) for each of the three sampling methods used (systematic, random and haphazard).

 

Systematic Sampling

(% error)

 Random Sampling

(% error)

 Haphazard Sampling

(% error)
Red Maple 8.8% 0.1% 19.0%
White Oak 3.2% 4.4% 39.6%
Sweet Birch n/a 558.3% n/a
American Basswood 230.0% n/a n/a

 

Blog Post 8: Tables and Graphs

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Overall, the graph results from my data collection accurately represent what I have visually noted at my sampling sites, & I am pleased with the final outcome of the visual bar graph. The data collection was the easy part, since I have had to change my final project a few times & I feel pretty well versed in collecting data samples “in the field” now.  However, it was a challenge for me to learn how to create a visual chart using Excel, as I would typically sketch my results by hand, but I managed to find helpful videos online to aid in the structure of creating a proper graph.

 

As the winter hits our little island in the Pacific & the temperature drops, taking more plants into the ground, I find that this last data collection resulted in less plants observed than my last sample session, about a month & a half ago. I half expected this to be the result as the colder temperature kills off certain plants, but I was not expecting to count as many grasses as I did. That part surprised me.

 

If I were to recreate this scenario, I would like to have taken samples at different times throughout the year, to truly observe what is happening to the plant abundance throughout the whole year. For fun, I might just take that on as a project of further exploration & interest!  I would like to see if the abundance of grasses, shrubs & forbs remains the same throughout the year, especially here in Victoria, our temperate little hub of Canada.

 

 

Brush Bushes in Guerin Creek

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Since originally planning what I was going to study, it has turned from late summer to winter. So, instead of studying pollinators, I had to pick a new subject.

I really like the gradient I’ve chosen, so I thought I will still study the rabbit brush in the creek valley. But now, I want to look at the prevalence of Rabbit Brush and Sagebrush in Guerin Creek at various heights in the valley, I also plan to consider the direction of the slopes (whether they are facing south, east, etc.) to control for sun and weather exposure.

I have attached my field journal observations, and maps of the areas I plan to look at.

My hypothesis is that the process that is most influencing growth of the brush plants on the hill is access to water as the plants grow up the valley, away from the water source. Kamloops is extremely dry throughout the summer months, which would limit the growth of brush plants farther from a water source. 

Therefore, my independent (explanatory) variable is the distance up the valley from the creek at various increments. My dependent (response) variable is the number of brush plants per square meter. I think there will be more of both bushes closer to the creek, and fewest at the farthest point. Both measures would be categorical, as I will split the elevation into distinct segments and the number of brush plants is also categorical.

Post 3: Ongoing observations

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The latest observations were conducted on November 17th 2017 at 3:30pm under cloudy skies and a temperature of -8°C.

For the final project, I am planning to focus my attention on the black-billed magpie (Pica hudsonia) in a small area of Heritage park in Edmonton. This species prefers open areas with patches of trees and bushes such as the area I am studying. Black-billed magpies are known to be opportunistic omnivores who do not shy away from human presence.

I will observe the species’ distribution and surrounding environment amongst three different gradients of the area. The first gradient is by a parking lot where a man-made bird feeder is installed and regularly filled. The second gradient is at the entrance of the main hiking trail, where there are many patches of wild rose bushes. Finally, the third gradient is by the pond. The third gradient is the most open area, and it is where the garbage bins are located.

I plan on observing the distribution of the species in each gradient, its behavioural changes from one gradient to the other including nesting, feeding, food caching, etc. Also, I am interested in determining the influence of human presence on the black-billed magpie in the area. My hypothesis is that in this area in specific, human presence is a determining factor of the black-billed magpie’s nesting choice, and that it constitutes the main source of its feeding.

I will choose a fourth gradient within the area selected, a gradient which is not located near a parking lot, or trail, and which does not contain any feeder or any garbage bin. My prediction is that the black-billed magpie distribution in that gradient will be the lowest amongst all four.

One explanatory variable can be the frequency of human presence at each gradient, and response variables would be the black-billed magpie distribution in that gradient. The frequency of human presence is a continuous variable as it is strictly quantitative, e.g. the number of hikers passing by within an hour time frame at each gradient.

Hissan Zulfiqar

 

Post 9: Field Research Reflections

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I definitely experienced some issues with my experiment and was unable to course-correct due to changing field conditions.  I collected my field data in August and then did not proceed again until winter.  Big mistake!!!  As my experiment was concerned with soil moisture content, and I did not measure this adequately in the summer, I was unable to get better data when the ground froze and was covered with 3 feet of snow.

As I worked through the experiment a little more, I think it would have been more interesting to assess biodiversity among shorelines more generally instead of specifically thinking about 1 species (Labrador Tea).  This is my first time designing and implementing a field experiment and it has made me appreciate the breadth of knowledge and skills that it takes to collect sound data and then clearly communicate that to readers.  I have always understood that developing ecological theory is a slow evolution that takes skill and patience.  Performing my own experiment has made me realize that it is possible to do your own research and it doesn’t have to be complicated; however, the science can get really complex if you are interested in a higher level of research.  Support and guidance would be key in next-level analyses.

Post 8: Tables and Graphs

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Table 1: Biodiversity between Wetlands, Flooded Areas and Well-Drained Areas

 

I had a very difficult time trying to come up with a graph as I did a presence/absence quadrat and did not measure soil moisture content very precisely.  I definitely should have gotten quantitative values for the soil moisture content instead of using a general description.  I wanted to do a graph, but ended up making a table for lack of better ideas.

As I had to look long and hard at my field notes to decide what kind of graph or table to make, I ended up drawing a couple of unexpected conclusions about my data.  Initially I was focused on simply the presence/absence of Labrador Tea but I noticed that biodiversity in general was higher within the wetlands than at the more extreme dry or flooded areas.  Optimal soil moisture content promotes greater biodiversity.  I also noticed that the Labrador Tea was the most prevalent species, indicating it may be a stronger competitor than a lot of other wetland vegetation.  The general trend for biodiversity was unexpected, as I was only planning to make conclusions about optimal growth conditions for Labrador Tea.

Further exploration would entail more precise field measurements of soil moisture content.  Of course sampling more quadrats and identifying more species would give greater detail if I wanted to look at biodiversity more generally.

Post 7: Theoretical Perspectives

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My project examines the role that soil moisture has on the abundance and density of Labrador Tea in wetlands surrounding two small lakes.  The wetlands range in saturation from “flooded” (pooling water all season) to well-drained and range in distance from the lake shorelines.  The ecological processes that my hypothesis touches on is competition.  Plants that are stronger competitors and can thrive in a range a moisture levels are more likely to be able to survive in lake shorelines where changing water levels, wave action and ice scour are routine.  The ideas that underpin my research are that flooding intensity and duration are predictors of biological diversity and lake shoreline vegetation, therefore, is determined by changing water levels.  Another idea is that Labrador Tea, specifically, is common in wetland communities but not in well-drained or permanently flooded areas.

Three key words:  wetlands, shorelines, Ledum groenlandicum

Post 6: Data Collection

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I have sampled exactly as I described in the previous post: semi-randomly selected 5 shoreline sites on Eskers Lake West and Eskers Lake East 80-100m apart and within those 5 sites haphazardly sampled 3 1mX1m quadrats giving me 15 replicates.

The problems that I encountered were site access issues and difficulty identifying plant species.  In the end, the issue of site access may not be terrible.  The western shorelines of Eskers Lakes are at a lower elevation and have more wetlands while the northern and eastern shorelines are fairly steep and formed by eskers and would require boat access.  I am interested in soil moisture as the predictor variable so sampling well-drained steeper locations would not be as pertinent to the research.  As I expected, the plant identification was difficult for certain species so I made generalizations in my field notes (ie. “sedges” over “beaked sedge” or “water sedge”).

I have noticed that the Labrador Tea always co-exist with the Black Spruce.  Perhaps the presence of Black Spruce indicates higher soil moisture and the Labrador Tea is tolerant to a wide range of shade conditions.

Presence of spruce around wetlands proximal to Eskers Lake East.