Category: Percy Hebert

Blog Post 3, Ongoing Field Observations

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The attribute I plan to study is the species variation dependent on the elevation in the valleyview nature park. As shown in my field journal, at the top of the hill, defined in the field journal as high elevation, there is the most variety of species of plants. I have identified the few small trees as young ponderosa pine trees. There is also lots of sagebrush, but most of them are very small, around 1-2 feet in diameter. There is an abundance of tall, dry grass covering the entire ground.There is a wider blade grass, sage green in colour that grows in small patches. There is one last new plant I found which has tiny ‘fluffy’ ends to it.

In the medium elevation, along the side of the hill as you are walking down the trail I noticed a few changes. There were no ponderosa pines, or the wide bladed grass. There were however still lots of the tall, dry grass and the fluffy ended plant. The sagebrush plants became visibly larger in diameter, this time around 2-4 feet in diameter. There was a new bush type plant that was not in the higher elevation, with thick dark brown stems and burnt orange leaves on the ends.

Lastly, in the lowest elevation of the park, the main walking trail through the 2 higher elevation sections, there is only sagebrush, tall dry grass, and the orange leaf plant. This time the sagebrush were larger again, with some being at least 4 feet in diameter.

One of the first things I noticed was the clear difference in size in the sagebrush along the elevation gradient.

Hypothesis: The size, in diameter, of sagebrush is determined by elevation level.

Prediction: The diameter of sagebrush becomes larger as the elevation becomes lower because they are more sheltered from the elements.

Response variable: The diameter of the sagebrush (continuous variable).

Explanatory variable: The elevation level (categorical).

field notes along a elevation gradient

Post 9: Field Research Reflections

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Designing and implementing a field research project for this class was a great way to provide practical experience in the work required, and difficulties encountered by a practicing field biologist.

While I had a concrete idea of what I wanted to study (impact of different habitats on bird species presence and abundance) it took quite a while to determine the correct location in which to implement this study to minimize confounding variables and ensure that the results between study sites would truly be comparable. I began my project at Surrey Bend Regional Park but with the help of Dr. Hebert quickly determined that the sites in this location were not similar enough to compare, and I would essentially be comparing species diversity and presence between two different habitats with differing levels of anthropogenic influence. As a result, it would be nearly impossible to determine if it was the habitat type or past human impacts that were influencing the birds present on the site. In the end, I changed my location to Burnaby Lake Regional Park and the surrounding area and evaluated bird species presence and abundance along an urbanized gradient.

Once my study site was selected I had no real difficulty in implementing the project design (point count surveys within each of the three habitat types representing different levels of urbanization). However, despite all my sites being relatively close to one another it still took a considerable amount of time to visit two point count survey locations in each of the three habitats on a number of different days. This really helped me understand the difficulty in ensuring that enough replicate samples are taken in a study to ensure that the data collected is truly representative of the conditions on the site.

Overall, this research project has given me an appreciation for the amount work and forethought that is required in developing and implementing successful research projects whose results can be robust enough to help develop and further the principles in ecological theory. I look forward to applying the skills I have acquired in this class to my work as an applied field biologist.

Blog Post 8 – Table/Graphs

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The results of my field data were easy to summarize and visually represent in tables and graphs. The bar graph I submitted summarizes bird abundance (number of individuals) observed at the three different sites along the urban gradient representing different levels of urbanization. I predicted that bird abundance would follow a gradient with the lowest number of individuals observed in the urbanized area (Site 1) and the highest number of individuals observed in the natural area (Site 3) . When I initially graphed this data I found that the highest abundance was in fact at the most urban site. However, further examination of the data indicated that this was due to the large portion of observations (roughly 2/3) in the urban area that consisted of rock doves. As a result, the graph I created displays the overall abundance along the urbanization gradient but highlights the proportion of rock doves at each site so that the underlying trend (when removing rock doves from the examination at all sites in which they were observed) becomes apparent, which confirms my prediction.

Blog Post 2 – Scientific Information

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From my first blog post, I decided to pursue the question on whether vegetation has any variation between the lower and higher elevations of the park. I went online to the TRU library database to find papers that show studies of vegetation differences between elevation. I found many that focused just on low or just on high elevation. Although it was done in parts of Asia, I found a interesting research paper that compares vegetation through many different elevation levels. “Elevation-Dependent Vegetation Greening of the Yarlung Zangbo River Basin in the Southern Tibetan Plateau, 1999–2013″ can be found here: http://www.mdpi.com/2072-4292/7/12/15844/htm

 

This paper falls into the category of Academic peer-reviewed research material for many reasons. First off, it has been peer reviewed and we know that because it gives us the date is was received, accepted and published. We know it is research material (not just review material) because they discuss all of their methods and results as well in the paper.

Blog Post 7: Theoretical Perspectives

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The theoretical basis for my research project examines how varying levels of urbanization impacts bird species presence and abundance. To examine this I’m collecting data on bird species presence and abundance (response variable) within three areas that represent different levels of urbanization as determined by the percent cover of natural and anthropogenic habitat (explanatory variable).

Based on other research related to bird species presence and abundance along urban gradients (Hartje 2017, Blair 1996) there theoretically should be a difference in the species richness and abundance between sites with different levels of urbanization. More particularly, the most urbanized sites should theoretically have the lowest species richness, and the most natural sites should theoretically have the highest species richness. However, previous studies have not always aligned and some have found that species richness was highest in intermediately disturbed sites (Blair 1996) whereas other studies found species richness highest in the most naturalized sites (Hartje 2017). It will be interesting to see where the results from my research align in this respect. While theoretically abundance should also be highest in more natural sites, previous studies (Blair 1996) found that highly urbanized sites often have the highest overall abundance due to large flocks of a single species. Again, it will be interesting to see how my results compare to the other literature on the topic and if they align with the theoretical perspectives on bird species richness and abundance along urbanized gradients.

It is also important to think about how both species richness, and natural habitat is examined and characterized. Theoretically, species richness includes all species, both native and non-native, but it might be beneficial to tease these categories apart. For example, if an intermediately urbanized site has the highest species richness but hosts exclusively non-native species then its value as bird habitat would likely not be comparable to natural areas where species richness might be lower but is dominated by native bird species. Additionally when classifying habitat it is important to think about the impact native and non-native plant species play. An invasive Himalayan blackberry (Rubus armeniacus) thicket may host similar abundance values as a thicket of native vegetation but the overall species richness will be higher in the native thicket (Astley 2010). As a result, when classifying habitat should blackberry thickets theoretically be categorized as natural or anthropogenic habitat? While I won’t have the ability to examine these issues in my research project their theoretical impact on bird species presence and abundance, and the ways of evaluating overall richness and abundance do provide something to think about and will be mentioned in the final report.

Keywords: urban habitat, urbanization gradient, non-native species, bird species presence and abundance.

Post 2: Scientific Research

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Anna Zacaruk

September 30, 2017

I found a few interesting scientific papers on the subject of light competition in plants, with one of the most interesting being “The importance of light quality in crop-weed competition” by Lui JG et al. The paper discusses the notion that plant competition is thought to be driven by limiting resources such as light, which may disrupt physiological processes. The authors believe that changes in light resources may initiate a “shade avoidance response” in plants where they constrain their own development and reduce their own reproductive fitness in attempt to avoid growing in shaded areas and compete with other plants for light.

Another paper I found was called “Weed community characteristics and crop performance: a neighbourhood approach” by Pollnac FW et al. This paper discusses the possibility that the presence of weeds in crop fields causes crop yield reductions. The hypothesis tested was that increased weed species richness would decrease the effects of competition on spring wheat target plant performance. The authors ended up finding that species richness had no significant direct effect on spring wheat biomass, yield, or relative growth rate and that there were no significant neighbour species interaction terms. However, they did find that increasing weed species richness had a negative impact on the growth of individual weed species.

Both papers I’ve chosen are academic papers written by Lui JG et al., and Pollnac TW et al. respectively. The two papers are both apart of the “WEED RESEARCH” Journal, which is “An International Journal of Weed Biology Ecology and Vegetation Management.” Both reports contain in text citations, multiple tables, results sections, bibliography and authors. Each paper is based off of experiments and testing performed by the authors, and each has detailed results sections. Considering this is an internationally published academic journal, and both papers are Peer-Reviewed, I would consider these both Academic, Peer-Reviewed Research papers.

Liu, J.G., K.J. Mahoney, P.H. Sikkema, and C.J. Swanton. 2008. The importance of light quality in crop-weed competition. Weed Research 49: 217-224.

Pollnac, F.W., B.D. Maxwell, and F.D. Menalled. 2008. Weed community characteristics and crop performance: a neighbourhood approach. Weed Research 49: 242-250.

Post 1: Observations

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Anna Zacaruk

September 29, 2017

After considering many different areas to study, I decided that an outdoor experiment at this time of year (autumn) in my region would be too complicated and risky knowing how unpredictable the weather is in Alberta. With permission from Dr. Percy Hebert, I’ve decided to do my project in my greenhouse, using some equipment from my mother who has her degree in agriculture and specializes in reclamation projects. I have decided to compare the interspecific competition between a weed plant species (dandelions) and a non-weed plant species (marigolds) for a light source. I was considering growing the plants for roughly 7 weeks in the same pots to see which will outcompete the other in both light and light-restricted conditions. My study area is technically my greenhouse, which has windows that are East and South facing. I intend to grow the plants in pots along the window sill in plastic potting trays until germinated, and then randomly remove some plants to a tray where light is limited by some sort of barrier (I was thinking mesh or burlap of some sort). I anticipate to allow the plants to grow for 7-8 weeks.

Questions I currently have are:

  1. How will limited light affect competition between dandelions and marigolds?
  2. How will limited light affect plant leaf and root growth?
  3. How will limited light affect plant overall (dry) biomass?
I found a few interesting scientific papers on the subject of light competition in plants, with one of the most interesting being “The importance of light quality in crop-weed competition” by Lui JG et al. The paper discusses the notion that plant competition is thought to be driven by limiting resources such as light, which may disrupt physiological processes. The authors believe that changes in light resources may initiate a “shade avoidance response” in plants where they constrain their own development and reduce their own reproductive fitness in attempt to avoid growing in shaded areas and compete with other plants for light.
Another paper I found was called “Weed community characteristics and crop performance: a neighbourhood approach” by Pollnac FW et al. This paper discusses the possibility that the presence of weeds in crop fields causes crop yield reductions. The hypothesis tested was that increased weed species richness would decrease the effects of competition on spring wheat target plant performance. The authors ended up finding that species richness had no significant direct effect on spring wheat biomass, yield, or relative growth rate and that there were no significant neighbour species interaction terms. However, they did find that increasing weed species richness had a negative impact on the growth of individual weed species.
I am curious to see what my findings may be, and if they will differ from those of the scientific papers I have been reading. Stay tuned for the riveting results!!!

 

Initial Data/Plan

Blog Post 6: Data Collection

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I have now completed around half of my point count surveys within the Burnaby Lake Regional Park area in an effort to measure bird species presence and abundance along an urbanized gradient (Site 1 – Urbanized Area, Site 2 – Moderately Urbanized Area, Site 3 – Naturalized Area).

To date, I have completed 4 replicate point count surveys in each of three areas (2 replicate locations per area, on 2 different dates). I will complete at least one more day of data collection, with 2 more replicate point count surveys in each of the three areas over the next week. Since revising my research design as highlighted in Blog Post 5 I have had no issues in implementing it. Performing surveys between dawn and 10:00am has resulted in a high level of bird detectability. In addition, limiting the number of point count surveys to two per habitat has also made the surveys manageable as it still takes about 1 hour to complete all 6 point count surveys across the three areas on any given sampling day. Overall, the switch to Burnaby Lake Regional Park and the revised hypothesis seems to be going very well and this was a good decision to make sooner rather than later in the research project.

I calculated my explanatory variables for each area (approximately 300m x 300m area) as a whole using aerial photography to determine the percent cover of natural habitat (forest, wetland, etc…) and anthropogenic habitat (buildings, roads, trails, etc…). I used a systematic sampling strategy to place my point count survey sites within each survey area randomly along the road or trail that runs through them. A random number generator provided the first survey point location in each site, while the second survey point was systematically placed 200m away to maintain the minimum distance required for independence between sites. At each point count survey all birds seen and heard within a 50m radius of the observation point were recorded during a 5-minute period.

Looking at the data quickly some ancillary patterns reveal that the species richness is lowest in the most urbanized area but further analysis will be required to determine whether species richness is highest in the moderately urbanized or naturalized area. Bird abundance has been quite high throughout all the sites so it has been hard to determine which site has the highest abundance. Site 1 does have large flocks of rock doves flying through it which will definitely elevate the overall abundance numbers for that site, whereas the other two sites have smaller abundances by individual species but more species overall.

Blog Post 8: Tables and Graphs

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The graph I prepared was a visual representation of the raw data collected during my field study. The results were as expected with the fesuce grass species growing at a faster rate in shaded areas, compared to in full or partial sun areas. With the quantity of data collected it was hard to categorize the data. Averages of the growth in each area would have been more beneficial however the graph does give you a full representation. In collecting the data I would be curious to explore further, how other grass varieties are effected by sun exposure. I would also be curious to see if ambient temperature and rainfall also have an effect, in addition to sun exposure.

Blog Post 5: Design Reflections

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During the initial data collection efforts at Surrey Bend Regional Park, there were no difficulties in implementing my sampling strategy. However, after consultation with the professor we decided that the habitats being examined were not similar enough to compare, and that the anthropogenic influences on them were too different to be able to effectively account for any changes in bird species presence and abundance to only one explanatory variable. As a result, I have decided to change the location of my research project to Burnaby Lake Regional Park and the surrounding area, and focus the study on examining bird species presence and abundance at three sites along an urbanized gradient.

My revised hypothesis is: Bird species presence and abundance is impacted by the percent cover of natural habitat at a site. 

My revised predications are:

  1. Bird species richness will be highest in areas with the highest percent cover of natural habitat.
  2. Bird species abundance will be highest in areas with the highest percent cover of natural habitat.

My response variable will remain as bird species presence and abundance (continuous variable), and my explanatory variable of percent cover (categorical variable) of natural habitat (forest, wetland, etc…) vs. anthropogenic habitat (roads, buildings, trails) at each site as a whole will also remain the same.

In addition the followings changes will be made in the experimental design in regards to the way data is collected:

  1. Initial sampling took place mid-day and overall detectability was low. It is standard bird inventory procedure to sample only between dawn and 10:00am to increase detectability. I will now perform all my surveys during this period to maximize the birds being detected by sight and song.
  2. My new sampling strategy includes two survey sites (point count surveys) in each of the three habitats along the gradient. During the replicate exercise, I expanded the number of point count surveys in one of the sites to five. While it would be ideal to maintain this type of replication it is too time consuming to perform five replicate surveys in each of the three sites. As a result, I will perform two replicates per site, and will conduct surveys at each site on at least three different days.

During the next blog I will go into more detail on the sampling strategy, sample unit, how these changes have impacted the data collection, and any ancillary patterns that appear in the data to support the new hypothesis and predictions.