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Post 2: Sources of Scientific Information

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The source of ecological information I have chosen is a scientific peer-reviewed research paper.

The paper is as follows:

Crothers, J. H. 1985. Dog-whelks: an introduction to the biology of Nucella lapillus (L.). 6: 291-360. https://learning.watfordboys.org/pluginfile.php/20239/mod_resource/content/2/Dogwhelk%20Biology%20Crothers.pdf

 

The author is an expert in the field as he has published several other studies in the field. He is part of the Field Studies Council in the UK. There are several in-text citations included in the paper. The paper also consists of a bibliography with a list of all the sources used. Furthermore, under the Acknowledgements section on page 45, the author lists the names of people who have reviewed the paper. The following is another one of several papers he has published:

http://fsj.field-studies-council.org/media/344189/vol2.5_55.pdf

 

Upon googling the author’s name, J. H. Crothers, a long list of published content can also be found with papers edited by him. Also one can find many of his papers in the Mendeley software.

Post 1: Observations

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The study sites that I have chosen for this research project are two rocky shores in Pembrokeshire, United Kingdom: Castle beach and Jetty beach. The beaches are in close proximity to one another and they are roughly a ten-minute walk apart. Each study area is approximately 0.6 metres by 15 metres. Castle beach is an exposed shore whereas Jetty beach is a sheltered shore. Castle beach consists of lower biodiversity compared to Jetty beach. It is Jetty beach has an abundance of animal and plant species. The vegetation at Jetty beach is composed of mainly seaweeds and lichens. Both beaches consist of a fair number of dog whelks. Dog whelks are also known as rock snails. The weather at the beaches in winter was sunny but cold. The temperature was about 10 °C. The beaches were visited on February 17, 2018 at 10:30 AM.

Three questions that are interesting or striking and could form the subject of my research project are:

  • How do edaphic characteristics affect the dog whelks’ abundance on Castle beach and Jetty beach?
  • How does rocky shore exposure to the tide at Castle beach and Jetty beach affect the size of dog whelks?
  • Does the sheltered shore consist of more soil nutrients than the exposed shore thereby supporting more biodiversity?

Castle beach

Jetty beach

Blog 4: Sampling Strategies

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Used the area-based method. The systematic sampling technique took 12 hr 37 min, random took 12 hr 43 min, and haphazard took 12 hr 28 min making it the fastest. Note that the different in time between the 3 different techniques is only a range of 15 minutes. Easter hemlock and sweet birch were the two most common tree species. The systematic sampling gave the lowest percent error (13.2%, 21.7%) making it the most accurate of the 3 samples.

Striped maple and white pine were the two rarest species. The haphazard sampling gave the most accurate experimental density have the lowest percent error (76.0%, 1.2%) from the 3 samples. In general the accuracy declined for the rare species and the vary low percent error for the white pine in the haphazard sample may just be luck.

Overall, the haphazard sample gave the more constant and lowest total percent error of all 4 tree species, also this took the shortest amount of time as stated in the beginning.

Note the majority of percent errors were very high which may be due to the sample size ( n=24) being too small. To experimentally collect a more accurate findings the sample size should increase to a large value, i.e. n=50.

Blog post 8 – Tables and Figures

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This is one of the graphs I made with the statistics program Minitab18 after I ran an ANOVA on my data. I struggled quite a bit remembering how to run the analysis but I’m happy that I figured it out. I made another one similar to this that used aspect (NSEW) as the categorical variable, and I made a simple bar graph to visually show the differences between lichen coverage between tree type.

I predicted that the crustose lichen would be higher in abundance on coniferous trees which it was, see Figure 1 (a) below, and I was surprised that fruticose, Figure 1 (c), was also significantly different (p=0.001), favouring coniferous trees. Although moss coverage was not in my hypothesis I thought it would be higher on deciduous trees which it was (d). Aspect did not turn out to have a significant effect on lichen distribution except for the fruticose type which had a higher abundance on the eastern side of the tree (Not displayed on this graph).

I have grown quite fond of lichens and would love to explore so much more about them. I noticed that a lot more lichens were growing up higher on the trunk and in the canopy, so it would be cool to study that.

Figure 1: ANOVA results comparing the averages of the three dominant lichen growth forms (a, b, c) and moss (d) coverage between tree type, deciduous or coniferous. The means are displayed at each point on the interval plot.

Blog post 7

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I am interested in microclimatic factors influencing the preferred habitat of lichens (epiphytes). My first hypothesis relates to light availability and whether aspect, or cardinal direction, of the tree trunk is a predictor of lichen distribution or if it has nothing to do with aspect and only light availability from canopy openings or edge effects. I no longer think aspect is a major factor, for example, Nascimbene et. al (2009) found that species richness increased with tree age and height in open canopied sites with more light availability.

I am also interested in whether lichen abundance differs from deciduous to coniferous trees. The theoretical basis for that idea is that different tree species can have a wide array of bark textures which create microclimates, impacting light and moisture, some lichen species can colonize rough bark better than smooth bark, and the bark itself can have different pH levels attracting different species (Sales et. al, 2016). Though tree type can be a factor, one study has shown that tree age and size (height, branch size) had a positive correlation with epiphyte species richness (Nascimbene, 2009).

I am also interested in the relationship between moss and lichen coverage, where moss and lichen establish, the environmental factors that they are competing for, although I did not hypothesize about this relationship.

Keywords: microclimate, aspect, epiphyte

Nascimbene, J., Marini, L., Motta, R., & Nimis, P. L. (2009). Influence of tree age, tree size and crown structure on lichen communities in mature Alpine spruce forests. Biodiversity and Conservation, 18(6), 1509–1522. https://doi.org/10.1007/s10531-008-9537-7

Sales, K., Kerr, L., & Gardner, J. (2016). Factors influencing epiphytic moss and lichen distribution within killarney national park. Bioscience Horizons, 9(February), 1–12. https://doi.org/10.1093/biohorizons/hzw008

Blog post #7: Theoretical perspective

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In my experiment, I am looking at how the survival rate of the Nootka Rose hip varies according to the distance from an exposed cliff overlooking the ocean.  The theoretical basis for this research is to determine how the micro-climate of a cliff environment affects the survival of this particular species.

 

Plant species that grow along cliffs are more subject to harsh abiotic conditions including high winds, limited space and drier soil (Mathaux et al 2015). Therefore, I am interested to see how the survival rate of the Nootka rose hip varies along a gradient that differs in the distance from the cliff’s edge.

 

Keywords:

 

Cliff ecology, abiotic factors, Nootka rose

 

Reference:

 

  1. Mathaux C, Mandin JP, Oberlin C, Edouard JL, Gauquelin T, Guibal F. 2016. Ancient juniper trees growing on cliffs: Toward a long mediterranean tree-ring chronology. Dendrochronologia. 37:79-88.

 

Blog 6 – Data Collection

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My field data collection went well overall. I sampled 10 deciduous and 10 coniferous trees on each of my two transects for a total of 40 trees sampled. I sampled the first transect on February 26th and the second on February 28th, they each took roughly 2 hours. I did them separately because I have a knee injury so I’m trying not to over exert myself. I had originally planned to do my first transect on the Glendenning trail in the southern part of Mount Douglas Park, and the second transect on the Whittaker trail in the northern part. The first transect went smoothly, but when I went to do the second transect on February 27th, I realized that the northern part of the park was quite different than the southern part in that it was much more hilly and rocky, the understory shrub layer was dense which made it really difficult to move around in, and the deciduous trees were mostly arbutus which tend to have bent trunks not suitable for my sampling design. I checked some of the other trails on the north side of the park but they were all similar so I decided I would do my second transect in the southern part, as a continuation of my first transect on the Glendenning trail. I should have done site reconnaissance beforehand, I assumed that because the north and south were both in the “lower forest” designation that they would have been similar sites, but nope! It would have been interesting to sample the northern part because just from a quick observation I could tell there was higher lichen diversity and a different community composition.

Things I noticed/experienced:

The frequency of deciduous trees was much lower than coniferous trees, so when I would arrive at my random point and sample the closest tree to me, sometimes there wasn’t a deciduous tree close by so I would just sample the two closest at the next possible point. Not a big inconvenience and didn’t effect the randomization.

I noticed that further up the trunks of the trees I sampled, or sometimes at the base of trees, there appeared to be higher lichen richness and abundance especially of the foliose and fruticose type. My study design focused solely on the 1 metre area that is 1.5 metres off the ground, excluding higher on the trunk and the canopy of trees. On the ground surrounding the trees there was often litter from the canopy which can give an idea of what lichens are growing up there, but I didn’t look at that for my study because it would have been too complicated.

On the larger trees sometimes the bark was so deeply and widely furrowed and lichens tended not to grow in the furrow, but on the ridges of the furrow. Due to the fact my transect was quite narrow, 10x100cm, sometimes the bare furrow would be right at the cardinal direction of the tree and I would have to put 0% coverage or a low% coverage which didn’t seem appropriate because there was high lichen coverage right beside. Perhaps having a wider quadrat and standardizing the tree size would be a way around this.

All in all, I deepened my appreciation for how much preparation and fine-tuning it takes to develop appropriate sampling designs and actually carry them out in the field.

 

Ongoing Field Observation

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Hypothesis: How does living moss population growing the the trunks of trees differ among trees that are sheltered, partially sheltered, or exposed to the weather?

Prediction: There will be a high population of moss on trees that are sheltered.

Response variable: moss population

(categorical)

Explanatory variable: trees snow/ rain fall exposer

(categorical)

 

 

Post 8: Tables and Graphs

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Figure 1: Boxplot showing median (thick line), interquartile range (box), variability (whiskers), and outliers of flower per plant measurements at each site.

Due to snow, I have changed my project and traveled several hours further afield to find sites that aren’t coated in a sheet of ice. As such, I am now investigating differences in average number of flowers on Achillea millefolium (commonly known as yarrow) at two sites near Abbotsford with different elevations.

Luckily for me, I am taking this course concurrently with statistics, and so I am becoming very comfortable with using R to analyze data and produce graphs. I decided that a boxplot was the best way to compare my data, due to the ease with which one can see the differences between the two categories in median and variability. Seeing the precise numbers of every sample is simply unnecessary.

The graph does show that Site B averages a higher number of flowers than Site A. Unfortunately, the graph also exposes that the differences are fairly slight and are not likely to be statistically significance (but maybe I’ll get lucky and they will be).

I feel like I could have used further observations to reduce the variability and be more confident that the differences aren’t chance, but unfortunately the snow shows no signs of melting and another four hour trip to Abbotsford is not particularly feasible, so I will have to settle for my poorly designed little experiment and hope to gain marks for pointing out how poorly designed it is.

Blog 5 – Design Reflections

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My sampling day went fairly well. I think I worked out some of the kinks in my mind beforehand, however once I was in the field collecting data I realized there were certainly things I needed to change. First of all, I was only recording presence/absence of the three lichen types on each aspect of the tree (NSEW). I have decided I want to record the percent cover of each type on each aspect of the tree, because sometimes all three types would be on one side but one was much more dominant and that information was being lost.

Secondly, I need to determine how far up and down the tree I want to sample so that there is consistency in the data. I could focus on the base of the trees, or perhaps one metre above and below breast height. I could even make transects on each tree.

Thirdly, I may need to only sample in the upper and lower forest strata, or focus my studies in the rocky outcrop only. The rocky outcrop, or Garry Oak ecosystem, at the top of Mount Douglas is quite a different community than the closed forests. All the trees were deciduous and the foliose lichen was present on every tree, whereas in the closed forest most of the trees were coniferous and the foliose lichen was only present on one of the ten trees which just so happened to be very close to the top of the mountain.

I think for my final data collection I will use the same sampling strategy that I used which is the distance based method. I used a random number generator on my phone to tell me how many paces to take on the trail, and how many paces to take perpendicular to the trail on the right or left side of the trail, then once I walked the paces I sampled the closest tree to me. I treaded carefully in the forest and was minimally invasive. Sometimes it was hard to walk a straight line because of downed logs or ditches which may have made it less random because I would sort of guess which way to walk and for that reason I may need to follow a compass bearing (I’ll think about this some more).

Finally, I would like to take replicates from more places in the park to get a more representative sample. I only sampled the southern portion for this preliminary data.