Format: Submit your completed pollen diagram and an associated written discussion.
Reminders
• Read the assignment instructions carefully to fully understand what is expected of you.
Make sure to fully respond to all questions in the assignment to receive full marks.
• You are expected to submit your own work supported by relevant and reliable sources.
These sources must be credited using in-text citations and a references list in APA (7th
edition) format. The use of generative AI tools or apps may be permitted within the
limitations stated in the syllabus. Microsoft Copilot is the only acceptable AI application
for this course.
• After the assignment deadline and applicable extensions, a penalty of 5% per day
(including Saturday and Sunday) will be applied for up to one week past the original due
date on late submissions. See the syllabus for full details on late penalties and missed
term work. Extensions will be granted upon request, question-free with documentation
or for 5 “Weekly Challenge” points without.
Introduction
In Assignment 1, we explored how different plants from around the world have adapted to
their current environmental conditions. Yet, environmental conditions are temporally dynamic
which can result in changes in community composition and biome shifts over time (Cox et al.,
2020)
The goal of this assignment is for you to consider how plant communities and biomes have
changed over time following a recent deglaciation event using preserved pollen data.
Based on the course learning outcomes, this assignment provides an opportunity for you to:
• Identify and describe patterns of species distributions and explain how they are
shaped by various physical and ecological controls across spatial and temporal
scales.
• Explain how evolutionary, tectonic, and climatic processes influence the
distribution of species over geologic time.
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• Discuss modern species distributions in the context of biogeographical processes
and human activities.
• Apply quantitative and spatial reasoning through analysis and interpretation of
data, graphs, and maps.
• Synthesize reliable literature related to biogeography into written formats aimed at
an appropriate audience.
Background Information
Palynology and Pollen Diagrams
Palynology is the study of microscopic objects of
organic composition – things like pollen and
spores (amongst others) (MacDonald, 1988). An
abundant source of information concerning past
plant taxa stems from the preservation of
unique pollen and spores in various
environments, including lakes, bogs, peat
deposits, and more. Combined with radiocarbon
dating techniques, these preserved pollen and
spores can provide a record of changing local
communities over time (Figure 1) (MacDonald,
1988).
Using our modern understanding of the linkages
between vegetation and climate, we can apply
space-for-time substitution to approximate past
environmental conditions (Figure 2) (Chevalier
et al., 2020).
Figure 1 – Examples of different pollen morphologies and their associated common species names (top). Bottom - simplified pollen diagram from Nelson Lake, Illinois showing the changes in species-specific pollen abundance over the
last ~17 000 years (Bierman & Montgomery, 2020).
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Figure 2 - Space-for-time substitution principle used in many pollen-based climate reconstructions. At the top of the
diagram, the modern climate, vegetation, and pollen relationships are observed and known. These relationships are
then used to predict past climatic conditions based on the presence of certain observed fossilized pollen (bottom)
(Chevalier et al., 2020).
How to Read a Pollen Diagram
A pollen diagram generally displays pollen data for various plant species side-by-side (Figure 3).
In Figure 3, the x (horizontal) axis shows the abundance (e.g., percent) of each type of pollen
within the sample and the y (vertical) axis shows depth or time increments with the most recent
deposits at the top.
Figure 3 - Example pollen diagram for Nelson Lake, Illinois. The diagram shows how regional plant communities
changed over the last ~17,000 years. Note major changes in pollen types and/or percentages occurred
approximately 14 000, 12 000, 11 000, 2 000, and less than 1000 years ago. (Source: Illinois State Museum, 2000).
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Taxa represented in pollen diagrams may be grouped into representative categories. In Figure 3
it is done by colour – evergreen (blue), deciduous (green), evergreen/deciduous (orange), herbs
(yellow) (Illinois State Museum, 2000).
Obvious changes in pollen types and/or relative abundance are used to divide the pollen record
into ‘pollen zones’ (see the horizontal lines in Figures 1 and 3) (Allaby, 2010). Therefore, each
zone represents a period of time with relatively consistent pollen types and abundances (Allaby,
2010). With knowledge of the general environmental preferences of the taxa associated with
each pollen type, changes in composition may be broadly related to changing environmental or
land management conditions through time (Figure 2).
For example, compared to spruce trees, oak trees are generally found in warmer and wetter
climates (Bierman & Montgomery, 2020). Therefore, we can expect that around 11,000 - 12,000
years ago the conditions around Nelson Lake were becoming warmer and wetter as ash and oak
trees began to establish and the abundance of spruce trees declined (Figure 1 and Figure 3).
Other changes in plant species composition examples are less environmentally driven. For
example, the appearance of ragweed in the last several hundred years is indicative of land
clearing following European settlement (Figure 1 and Figure 3) (Bierman & Montgomery, 2020).
Additional Background Resources
The following resources will provide important information for how to interpret your results. In
addition, the papers by Anderson (1989) and Jacobson et al. (1987) are great examples of how to
discuss pollen data. The following are available through Quercus ‘Library Reading List’ or online.
Anderson, T.W. (1989). Vegetation changes over 12,000 years: changes in eastern Ontario and
adjacent areas give evidence of global change. GEOS (Energy, Mines and Resources
Canada), 18, 39-47.
• Includes a vegetation reconstruction for eastern Ontario/southern Quebec, a site
located to the east of ours. It experienced slightly different patterns of vegetation
change and perhaps unique driving forces; the discussion in this paper will assist in
interpreting your own results.
Burns, R. M. & Honkala, B.H. (1990). Silvics of North America. U.S. Department of Agriculture,
Forest Service. https://www.srs.fs.usda.gov/pubs/misc/ag_654/table_of_contents.htm
• Provides helpful details on the known growth and climate conditions of trees.
Cox, C. B., Ladle, R. J., & Moore, P. D. (2020). Biogeography: An ecological and evolutionary
approach (10th ed.). John Wiley & Sons Ltd.
• Chapter 12, including pollen diagram examples
• Chapter 13, Section: The Environmental Impact of Early Human Cultures
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Drori, J. (2010, February). Every pollen grain has a story [Video]. TED Conferences.
https://www.ted.com/talks/jonathan_drori_every_pollen_grain_has_a_story?language =en
Jacobson, G.L., Jr., Webb, T., III & Grimm, E.C. (1987). Patterns and rates of vegetation change
during the deglaciation of eastern North America. In W.F. Ruddiman & H. E. Wright
(Eds.), North America and adjacent oceans during the.last deglaciation. (pp. 277-288).
Geological Society of America.
Macdonald, G. M. (2003). Biogeography: Introduction to Space, Time, and Life (1st ed.). John
Wiley & Sons, Inc.
• Chapter 8 provides useful details on pollen analysis and plant colonization.
Pielou, E.C. (1992). After the Ice Age: the return of life to glaciated North America. University
Chicago Press.
• Chapter 3 provides information on interpreting pollen diagrams.
• Chapter 4 considers the migration of vegetation on newly deglaciated land.
Instructions
For this assignment, you will create and use a simplified pollen record from a lake in Southern
Ontario to interpret the types of plant communities that occurred at different times during the
Late Pleistocene and Holocene. Using the temporal changes in the communities, you will
explain the broad changes in the physical and biological environments since the last
deglaciation (approximately 13,000 to 11,700 BP).
The data being used was collected from Sulley Lake*, a small lake (0.06 km2) in Southern Ontario.
Today, the lake is surrounded by a narrow band of mixed hardwood forest (e.g., beech and sugar
maple) and agricultural fields. Located near the present-day border between the Deciduous and
Great Lakes – St. Lawrence Forest regions (Figure 4), this area provides a long postglacial
palynological record.
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Figure 4 - Forest regions of Southern Ontario. The red star indicates the approximate location of Sulley Lake
(Modified from Ministry of Natural Resources and Forestry, 2016).
The data collected includes an approximately eight-metre core of lake sediment that was
retrieved from the lake. Five samples along the core were taken to determine radiocarbon dates
and provide chronological control for the core. Small samples were taken at regular intervals
along the full length of the core and chemically processed to isolate and concentrate the pollen
and spores. Pollen counts were made at each interval and approximate pollen percentages
calculated (# pollen grains of Taxon A / Total number of pollen grains of all taxa in that sample).
For the purposes of this assignment, the name of the lake has been changed and the data
simplified. As a result, the pollen percentages for each time may not equal 100%.
Create a pollen diagram and using reliable literature, address the following:
• Background – Briefly describe the history of the region. Explain how and why pollen
analysis can be used for reconstructing past environments (5 marks)
• Pollen Diagram – Create a pollen diagram for Sulley Lake. See “Tips for Creating Pollen
Diagrams” at the end of this assignment. (5 marks)
o Once created, divide the pollen record into ‘zones’ that you feel represent
relatively distinct communities in this area through time (like Figure 3).
o Submit your updated pollen diagram with clearly labelled zones with your
assignment.
• Results and Discussion – Start a new and clear section for your results and discussion.
For each zone you have delineated, briefly describe the dominant taxa and other
relevant changes between adjacent zones. Relate the observed changes to relevant
changes in physical and biological conditions over time. In your discussion, consider the
following:
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o Results: Describe how the composition and abundances (number of individuals
of a species) of the dominant taxa change over time and between each zone. Be
specific.
What taxa appeared or disappeared between each zone? (5 marks)
o Discussion: What do the major shifts in vegetation composition and dominance
suggest about the types of communities (and/or biomes) and the environmental
conditions (e.g., temperature, precipitation, soil, etc.) over time? How could
species’ dispersal abilities have influenced rates of community change? This
response should comprise most of your discussion. Make sure to link your
discussion to your diagram and zones. (15 marks)
• Future predictions and limitations (10 marks)
o Predict and explain how vegetative communities in Southern Ontario will change
in the future with increasing global temperatures. Use examples and refer to
your pollen work if possible.
o Consider the limitations of pollen analysis in studying past environments.
Your discussions must be supported by reliable sources such as the course textbook, helpful
resources (see assignment submission page and Library Reading List), and other scholarly
sources (10 marks). Lecture slides are not an appropriate source for this assignment.
Expectations and Evaluation
When submitting your written assignment, you are expected to:
Submit a completed pollen diagram and an associated written discussion addressing all
the required components.
Include captions and source information for all graphs, figures, and tables.
o Graphs must be neat and labelled appropriately (legend, title, caption etc.) and
large enough for easy readability.
Support your discussions with relevant and reliable sources and in-text citations.
Follow APA formatting (7th edition) for all in-text citations and reference lists.
Fall within the recommended word range of 1750 – 2000 words (which excludes in-text
citations, the reference list, and captions).
This assignment is worth 10% of your final grade and will be marked based on the following
criteria:
Criteria Marks
Background
5
Pollen Diagram 5
Results and Discussion 20
Future Predictions and Limitations 10
Format/ Writing/ Visuals 10
References 10
60 marks
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Excellent submissions will:
• Demonstrate critical thinking and a strong understanding of core course concepts.
• Use relevant photos, figures, maps, and tables as evidence to support claims, where
applicable.
• Use correct grammar and a writing style appropriate for an educated audience at the
level of your peers.
• Avoid the use of first-person pronouns (I, me, etc.).
• Paraphrase words and ideas from reliable sources and avoid using quotations.
• You should not use lecture notes as a reference, although they can be helpful to help
guide your thinking and research.
• Include correctly formatted scientific species names
Acknowledgements
This assignment was developed by Dr. K. McLeod (Wilfred Laurier). It has been modified by Dr.
N. Hewitt (UBC), Dr. S. Peirce (U of T), and G. Krezoski (University of Victoria) with permission.
References
Allaby, M. (Ed.). (2010). Pollen zone. In A Dictionary of Ecology. Oxford University Press.
https://www.oxfordreference.com/view/10.1093/oi/authority.20110803100335751
Bierman, P. R. & Montgomery, D. R. (2020). Key Concepts in Geomorphology (2nd ed.).
MacMillan Learning.
Chevalier, M., Davis, B. A. S., Heiri, O., Seppä, H., Chase, B. M., Gajewski, K., Lacourse, T.,
Telford, R. J., Finsinger, W., Guiot, J., Kühl, N., Maezumi, S. Y., Tipton, J. R., Carter, V. A.,
Brussel, T., Phelps, L. N., Dawson, A., Zanon, M., Vallé, F., … Kupriyanov, D. (2020).
Pollen-based climate reconstruction techniques for late quaternary studies. Earth- Science Reviews, 210, 103384. https://doi.org/10.1016/j.earscirev.2020.103384
Cox, C. B., Ladle, R. J., & Moore, P. D. (2020). Biogeography: An ecological and evolutionary
approach (10th ed.). John Wiley & Sons Ltd.
Illinois State Museum. (2000). Nelson Lake.
http://www.museum.state.il.us/muslink/forest/htmls/an_nelson.html
MacDonald, G. M. (1988). Methods in Quaternary Ecology #2. Palynology. Geoscience Canada,
15(1), 29–42.
Ministry of Natural Resources and Forestry (2016). Forest Resources for Ontario 2016.
Government of Ontario, Ministry of Natural Resources and Forestry.
https://www.ontario.ca/document/forest-resources-ontario-2016/geographic-profiles.
GGR305 Biogeography
