Category: Nancy Elliot

Blog Post 8: Tables and Graphs

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The figure below (Figure 1) depicts dabbling duck abundance at my selected point count locations (1 through 8) in Colony Farm Regional Park. My research focused on habitat selection by dabbling ducks within constructed drainage channels that varied in percent cover of emergent vegetation.  I initially wanted to show the average abundance per point count location, however, the total number of ducks observed during my data collection was lower than I would have hoped. Thus, I used the total number of dabbling ducks observed at each point count location. The low numbers also presented some challenges later on when assessing statistical significance, as it would likely have benefited me to have greater sample sizes to work with to truly assess any preference or habitat selection by the ducks I observed. Summarizing the data I did have, however, was fairly straightforward, and is shown below. 

Figure 1. Total number of dabbling ducks counted at point count locations 1 through 8 within drainage channels of varying emergent vegetation percent cover.

During data analysis, I ended up grouping the point count location results into three groups based on emergent vegetation cover: Group 1 = <25% cover, Group 2 = less than or equal to 25% but <50% cover, and Group 3 =  greater than or equal to 50% cover. I divided the groups in this manner to see if there proved to be a significant difference between the varying amounts of emergent vegetation cover and how this may have affected abundance.

Since my initial prediction was that duck abundance would increase with increasing emergent vegetation cover in the drainage channels, my results surprised me. I was not expecting so much variation in my results, with the greatest number of ducks observed within the channel that had only 30% emergent vegetation cover. I also discovered that variations in duck abundance between groups were also not statistically significant.

In future, I would conduct this study later into September when more dabbling ducks are present within the park to generate a larger sample size (seasonal effect). With greater resources, I would have also measured other factors within the drainage channels, including water quality parameters (dissolved oxygen, pH, temperature) and perhaps also water depth. With more time, I also would have conducted sampling events during different seasons over multiple years to see if this affected my results.  It is clear from relevant literature that I have come across during my research project that understanding habitat selection for species can play an important role in habitat management and conservation of protected areas.

 

Blog Post 1

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The area that I have chosen to study is a boreal forest behind my home near Toronto, Canada during the month of December. I frequently walk through a man made pathway that goes over slightly steep hills that span the forest. Since it is December, the temperatures are cold and snow is covering the ground of the forest. Leafless white birch, balsam poplar, and trembling aspen as well as many different types of conifers such as black and white spruce, jackpine, and tamarack are abundant during this time. I’ve also seen lichens, shrubs, and mosses. Much of the area is forested and there are a few bogs as well. The animals that I usually see during the winter are squirrels, rabbits, birds, but I have heard of others seeing deers and wolves as well. The potential subjects that I am considering for this project are coniferous trees since they are the most abundant during this time of year. One idea that would be interesting to study is to see if elevation has an effect on the abundance of coniferous trees since they prefer dry, arid conditions and there are many hills throughout the forest. I could compare the abundance of conifers in bogs compared to other areas in the forest. I could also take a look at the types and abundance of animals as the elevation increases.

Blog Post 5

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The sampling strategy that I chose to measure the density of black spruce at three different elevations is the point centred quarter technique. The hill that I chose to conduct this study on has an elevation of 220m. The three elevations that I chose to measure the density of black spruce is 20m, 110m, and 200m. The hill is not very steep and is very wide. I conducted the point centred quarter technique at 5 points at each elevation, 5 meters apart from each other. Each point was divided into quarters so I measured the distance of the closest black spruce tree to the centre point for each quarter and then took the average of the four distances. I didn’t realize how much labour it would take to measure the distances. At first I went out on my own to get these measurements, however I realized that it would be much more efficient if I had someone to help me out so I had to come back with more individuals to help out. The data that I collected wasn’t surprising since it supported my hypothesis so I will stick with this sampling strategy. I think that the point centred quarter technique is the most accurate for this study since it collects the average of the distances from for quarters compared to other methods such as the neighbour distance method.

Left two comments on others’ posts.

Blog Post 4

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The virtual forest tutorial allowed for the testing of three different sampling strategies in the Snyder-Middleswarth Natural Area: systemic sampling, random sampling, and haphazard sampling. The technique that had the fastest estimated sampling technique was systematic sampling with a time of 12 hours, 36 minutes followed by random sampling and then haphazard sampling.

Yes, the accuracy changes with species abundance for all three sampling techniques. The percent error for the common species was very low compared to the percent error for the rare species. The two most common species were the Eastern Hemlock and the Sweet birch and appeared to be best represented by systemic and haphazard sampling methods. The two most rare species were the Striped Maple and the White Pine and appeared to be best represented by the same sampling methods.

Based on the values of the Shannon Weiner diversity index, systemic and haphazard are the most accurate since they have the highest value at T=1.5 E=1.4.

 

  Tree Species Actual Density Systemic Density % Error Haphazard Density % Error Random Density % Error
Common Eastern hemlock 469.9 476 1.3 500 6.4 456 -3.0
Sweet birch 117.5 116 -1.3 108 -8.1 200 70.2
Rare Striped maple 17.5 4 -77.1 16 -8.6 0 -100.0
White pine 8.4 8 -4.8 4 -52.4 0 -100.0

 

 

Blog Post 3

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The organism that I have chosen to study is the black spruce species (Picea mariana) since they are most abundant in the boreal forest where my study is taking place during winter in Canada. The different gradients that I will be looking at will be the different elevations on one of the hills in the forest.

Gradient 1: Low elevation
More leaf-less deciduous trees compared to coniferous trees, more animals/animal tracks such as feces,

Gradient 2: Medium elevation
Deciduous trees are decreasing in abundance compared to coniferous trees, vegetation is becoming more spaced out, more open areas, less animals/animal tracks

Gradient 3: High elevation
More coniferous trees compared to deciduous trees, less animals/animal tracks, vegetation more spaced out except for batches of coniferous trees, more open areas

My hypothesis is that the abundance of coniferous trees specifically the black spruce species will increase with elevation because they prefer more open, arid areas and there is less competition with deciduous trees. My response variable would be the abundance of black spruce trees which would be continuous by counting the number of these trees in a specified area. My explanatory variable would be the elevation which would be categorical.

Blog Post 2

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Link: https://www.sciencedirect.com/science/article/pii/S2287884X18300554

This source of scientific information is an academic, peer-reviewed research material. It is academic material because it was written by experts in the field, includes in-text citations, and contains a bibliography. It has been peer reviewed by National Science Museum of Korea (NSMK) and Korea National Arboretum (KNA) so therefore it is peer-reviewed academic material. The source also reports results of a field study containing sections such as “Methods” and “Results” so thus this makes it academic, peer-reviewed research material.

Blog Post 9

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Conducting the field experiment was challenging, but mostly due to labour, otherwise it was fairly uncomplicated. The point centred quarter sampling method was very efficient and I think it produced accurate results since it takes that average distances from four quadrants rather than the distance from one point. If I were to conduct this field experiment again, I would use more than 5 samples for each elevation gradient because accuracy increases with elevation. Engaging in the practice of ecology did alter my appreciation for how ecological theory is developed because it involves studying nature and things that cannot be easily controlled by humans so it involves thinking of different ways to test data and then deciding which one is the most accurate.

Blog Post 8

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I decided to use tables to represent my data. Initially, I did find it a bit difficult to organize the data that I collected and calculated especially since I collected data for the distance of the closest black spruce tree to the centre point in each quadrant and the DBH. I decided to make a table that shows the distances in each of the quadrants and then another table to show the DBH measurements. I then made a table to summarize all of the means such as the mean frequency, mean distance, mean area, mean density, and mean basal area. I had tables to summarize the calculations for the ANOVA analysis. The last table I had is to summarize the relative values such as relative importance value. The data expected as it supported my hypothesis since the dominance (relative importance) of black spruce species increased with elevation.

Blog Post 7

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For my study, I am analyzing whether elevation has an effect on the dominance of black spruce species in terms of frequency, density, and basal area. The ecological process that my hypothesis touches on is the competitive exclusion principle. Black spruce species dominate at higher elevations to avoid competition with other species such as deciduous trees. They dominate at higher elevations because they are adapted to withstand harsher conditions such as less moisture and nutrient in soil, more wind and more sunlight.

Blog Post 6

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The three elevation gradients that were chosen were 20m, 110m, and 200m. The point centred quarter sampling method was chosen for this study. Transect lines were set up horizontally across each of the three elevation gradients. Five points were set up along the transect lines, five meters apart from one another. As a result, five replicates were set up and randomization was established by placing them five meters apart. A compass was used to make sure that the lines were set up in the same direction. Each of the five points was split up into four quadrants. The distance of the closest black spruce species in each quadrant to the centre point was measured with a measuring tape and recorded. The diameter at breast height (DBH) was also measured for the closest trees by wrapping the measuring tape around the trunk of the tree at 4.5 feet above the ground and then dividing the measurement by 3.14.
I did experience a few problems while implementing my sampling design. I initially went out alone to collect the measurements but then had to return since I realized that I would need help from others to collect the measurements. It was also difficult to walk through the bushes and tree logs to measure the distance. I did notice ancillary patterns in that black spruce species prefer drier conditions as the elevation increases.