## BIOL4520 H 2015 Seed dispersal lab;

BIOL4520 H 2015 Seed dispersal lab;

For this lab you will answer questions about the dispersal ability of a local Ontario weed. This method can be

used for any plants that have seeds that are wind dispersed. I could not find any dog-strangling vine, so we will use a

native relative of this invasive pest, the milkweed.

You will:

1. find out how fast a seed drops from 1 metre heights

2. weigh each seed

3. measure how long the coma is (the fluff)

4. plot the fall or drop rate against seed weight and coma length to determine which governs the drop rate.

5. Calculate the mean and standard deviation of the three data sets: drop time, weight, coma length.

6. Determine the expected dispersal distance in wind speeds of 5, 10, 15 km/hour.

7. Compare the dispersal distances to that of the dog-strangling vine using the paper in Blackboard. Note that these

authors had a mean wind speed of 11.2 km/hour.

Details

You will work in groups, by the bench. You need to divide into smaller teams for dropping seeds, measuring coma length,

weighing the seeds.

Each group/bench

1. drop at least 30 seeds from 1 meter, and use the stopwatch find how fast they drop. KEEP TRACK OF WHICH SEED

IS WHICH USING THE PAPER BAGS, write the drop times on each bag and put the seed into the bag.

2. separate each seed from its coma and weigh them

3. measure the coma length of each seed

4. assemble your group’s data into an Excel spreadsheet table similar to the following:

and use this for your correlations, to see what governs the drop

speed. Email this spreadsheet to me OR fill it out now with Ariel a

or Donny at the computer at the front.

5. You will need to get the mean and standard deviations for the

drop times, seed weights, and coma lengths and produce a table of

these for your results.

6. Determine the expected dispersal distance in wind speeds of 5, 10, 15 km/hour. Use a spreadsheet and express each

windspeed as metres per second. Then assuming that each milkweed plant is 0.5 metre tall, fill in the column of the

expected seed distances for each

wind speed. The easiest way is to

organize your work on your

spreadsheet by adding columns to

the table: (HINT: 1km/h = 1000

m/h, 1000/(60*60) = m/sec).

Plot the seed weight on the x axis and

dispersal distances on the y axis.

7. Use the paper posted to BLACKBOARD to compare your results to that of dog strangling vine (use their Figure 1).

Hint, you will need to convert your data using a wind speed of 11.2 km.hr.

Write-up: Individual write-up using your group’s data.

Write a brief paper, with title, abstract (60 words), intro (200 words), methods (100-200 words), results (100-200

words), discussion (400-600 words), lit. (1 – 3 refs). Make sure you refer to your graphs and tables in your paper, and

include axis labels and figure captions etc. Also make sure you do the comparison to dog strangling vine.

You will need to include 2 tables: first a table of means + SDs, and 2nd, the complete table with your raw data and

calculations in an appendix; 4 graphs: 3 of these are the correlations from part 4, and 1 is the graph of expected seed

dispersal distances and weight for 11.2 km/h winds.

You will be marked as if this was a note or paper. That’s it!